SPECIFICATION

Technical Field of the Invention

The present invention relates to a system and method of energy harvesting for electric vehicles.

Background of the Invention

Growths in energy demand, climate change concerns, and polluted gas emission have pushed the humanity toward clean energy and energy harvesting, thereby minimizing fossil fuel consumption. During the past years, domestic power generation has gained considerable attention. As reported in the Annual Energy Outlook 2019 (S. Cases, I.T. Viewer, Annual Energy Outlook 2019 Release date: January 24, 2019; availed from the web address: https://www.eia.gov/outlooks/aeo/pdf/case_descriptions.pdf), the power generation from green resources is projected to increase for 13% by 2050, while a decreasing trend in the coal and nuclear resources is predicted. The major conventional sustainable energy sources are wind, solar, geothermal, and hydroelectric energies. New approaches are vital to secure the increase of the share of green sources.

The automotive manufacturing industry has witnessed a surge in global vehicle production volume. Statistics confirm that in 2018, 70 Million passenger vehicles and 25 Million commercial vehicles were produced worldwide (see: https://www.statista.com/statistics/262747/worldwide-automob ile-production-since-2000/). A 44% increase is currently witnessed when compared to 2008 statistics, (see: https://www.worldometers.info/cars/]), with 18 Million vehicles manufactured in the EU alone (see: http://www.oica.net/category/production-statistics/2018- statistics/). Automotive/mobility industry plays a significant role in the generation of the air pollution through widespread/mainstream usage of ICE (internal combustion engine) motors Automotive/mobility industry is lagging behind on the UNFCCC 2015 Paris agreement decarbonization targets as compared to other industries. Therefore, it is of higher priority and importance to push decarbonization enabling novel technologies in this sector.

Several efforts in finding alternative sources of energy for vehicles are reported in the literature. Richardson (US D374,656 in 1996) proposed an electric car with wind generators to supply the required power to run the vehicle. Boudreaux (US 7,605,493 Bl) in 2009 invented an electric car, which used gasoline to run a generator that powered the vehicle. The problem with this invention was the fact that gasoline was used and polluted the environment. Using air flow as a source of energy attracted many research teams, and several patents are reported by many groups such as Trumpy (US 4,282,944) (1981), Amick (US 4,117,900) (1978), and Bussiere (US 4,423.368) (1983). Hassan (US 2011/0100731 Al) in 2011 invented an electric car, which used both wind and solar energy to power the vehicle. They integrated air inlets on the top and sides of the car to let the air into the wind turbines and to meanwhile collect the solar energy from the body of the car by photovoltaic cells. This way, they could convert the maximum wind and solar power to electricity.

Battery powered fully electric cars (BEV: Battery Electric Vehicles) are attracting considerable attention of the automotive/mobility industry and researchers during the past years owing to their pollution-free performance. For example, an early electric car design is reported by Dykes (US 3,575,250) in 1971, which used separate motors for each wheel to run the two-wheeled vehicle. A quick-disconnect battery was placed between the wheels to provide the required power. The motors worked in series, while for turning one motor worked slower than the other and assisted the turning of the vehicle. Hafer (US 3,708,028) invented an electric car in 1973, where the battery package was installed on the sides. Air inlets on the top and sides of the car to let the air into the wind turbines and to meanwhile collect the solar energy from the body of the car by photovoltaic cells. This way, they could convert the maximum wind and solar power to electricity.In 2008, Roadster by Tesla Motors became the first highway legal serial production all-electric car to use lithium-ion battery cells (first modern BEV). After this date the Battery Electric Vehicle market is growing continuously thanks to advances mainly in Li-Ion battery technology. It is estimated that the cost of ownership of BEVs will be on par with the Internal Combustion Engine (ICE) counterparts by 2022, with a total sharing market of BEVs expected to have a 10% of the market share by 2024 (Deloitte report, New Market, New Entrants, New challenges! Battery electric vehicles, 2019). Given the negative environmental and climate impact of a growing ICE fleet in the EU and global transport sector (see: https://www.eea.europa.eu/themes/transport/ term/ term-briefing-2018), the transition towards EVs is considered imperative.

Transition to EVs necessitates the need for overcoming three main impediments: i) increase of vehicle range per single charge, ii) operation in well-defined temperature (10-25 degrees C) and voltage range (battery-dependent) to minimize the battery capacity fade and power fade, iii) reduction in energy feed towards auxiliary functions particularly HVAC sub-systems consuming up to ~15% of EV battery energy. The main factor behind impediment iii) is that BEVs unlike vehicles with internal combustion engine (ICE) generate much lower amount of waste heat in the powertrain. Therefore, it is not possible to use the waste heat for cabin climatisation implemented in traditional ICE vehicles. Another additional requirement is associated with extra electric battery heating, since the battery electric supply performance considerably (23%) decreases when the ambient temperature drops to -15°C (Shua Ma, Modi Jianga, Peng Tao, Chengy Songa, Jianbo Wua, Jun Wang, Tao Denga, WenShanga, Temperature effect and thermal impact in lithium-ion batteries: A review, Progress in Natural Science: Materials International, Volume 28, Issue 6, December 2018, Pages 653-666). In current BEVs, cabin and battery heating/cooling requirements are met via battery powered electric modules, which can consume up to %18 of total usable energy in heating mode and %14 of total usable energy in cooling mode (A. Boyle, T. Muneer, Energy consumption and modelling of the climate control system in the electric vehicle, Energy Exploitation and Exploration Journal, Volume: 37 issue: 1, page(s): 519-543, 2019) (the ratio naturally depends on ambient temperature levels). Concerning impediment ii) the BEV needs an independent and power-hungry heating/cooling system in order to keep the bulk battery of EV within ideal operating range. Consequently, impediment ii) and iii) as combined would cause considerable driving range drop and unpredictability (depending on ambient temperature) which is closely related to the vehicle range problem stated in impediment (i). Therefore, a paradigm shifting technology is necessary to generate sufficient heating and cooling for battery powered electric vehicles without relying on limited electric energy storage, which will make considerable impact on extending their drivable range.

Generating heating and cooling in BEVs under all weather conditions without using any battery electric supply requires an alternative innovative energy generation method. In BEVs, the major energy harvesting is the exploitation of the kinetic energy of the vehicle transferred to the battery via regenerative braking method (electric motor shifting to generator mode and converts rotational kinetic energy to DC electric power that is stored back in the EV battery). However, regenerative braking can only harvest up to 30% (V. Tvrdic, S. Podrug, I. Suljic, B. Matic, Hydraulic hybrid vehicle configurations and comparison with hybrid electric vehicle, Contemporary Issues in Economy & Technology, CIET 2018) of the available braking/coasting kinetic energy due to inherent system limitations such as low power density and high reconfiguration burden while shifting to regenerative mode. A newly emerging approach that would support or even possibly replace regenerative braking in BEVs is the fast storage of the bulk kinetic energy into hydraulic pressure accumulator systems during braking and coasting actions. In hydraulic energy storage systems, (known as Hydraulic KERS: Hydraulic Kinetic Energy Recovery System) the kinetic energy harvesting ratio is much higher than regenerative braking and could reach to 70-80% range (Xiaobin Ning, Jiarong Shangguan, Yong Xiao, Zhijun Fu , Gaolun Xu, Anqing He and Bin Li, Optimization of Energy Recovery Efficiency for Parallel Hydraulic Hybrid Power Systems Based on Dynamic Programming, Mathematical Problems in Engineering, Volume 2019, Article ID 9691507, 11 page). Small-scale Hydraulic KERS has been widely used in ICE heavy-vehicles and there have been some concept applications where kinetic energy harvested by large-scale hydraulic KERS is supplied into new generation hydraulic drivetrains for range extension and fuel saving purposes (for ICE/hybrid powered vehicles in urban traffic environments). In typical BEVs, for which the extra hydraulic drivetrain might not be feasible, it is possible to use the energy harvested by Hydraulic KERS for all types of auxiliary uses. Hydraulic KERS can be easily deployed in BEVs as cost effective subsystems that has been used in ICE+Hybrid vehicles. Thus, specially designed and dimensioned hydraulic KERS technology would be able to maximize the harvested kinetic energy that default regenerative braking system is unable to harvest in BEVs.

Cavitation has been known as an undesired phenomenon in the industry over many years specifically in the fields of turbomachinery (A. Adamkowski, A. Henke, M. Lewandowski, Resonance of torsional vibrations of centrifugal pump shafts due to cavitation erosion of pump impellers, Eng. Fail. Anal. 70 (2016) 56-72). However, during the past years, the released energy from the collapsing bubbles due to cavitation has been proven to be useful in some applications in the industry.

Cavitation is a progressive cycle of vaporization, bubble generation and bubble blasting and/or implosion. It occurs when local static pressure in a flow is reduced below a critical pressure value. It is considered as one of the major phase change phenomena. Small energetic cavitation bubbles can be generated in small flow restrictive elements such as orifices or venturis, which induce sudden reduction in local pressure and cause hydrodynamic cavitation inception. The collapse of the emerging cavitation bubbles downstream of these elements leads to a high energy release, thereby generating highly localized, large amplitude shock waves and high velocity jets, which can significantly raise the local temperature. Hot spots over 1000 K and high speed micro-jets exceeding 300 m/s were reported in the literature for the collapse of cavitation micro bubbles. Having multiple cavitation bubbles nearby a surface will lead to a heat source with a uniform temperature distribution, which could be integrated to a thermoelectric-/thermophotovoltaic generator to supply power (WO 2018/030967 Al).

US 2016/280071 Al is related to hydraulic hybrid technology which can be also applied to vehicles embodying an electrical drivetrain. This document mentions small hydraulic driving motors being incorporated within wheel hubs driving the wheels and reversing to daw-back kinetic braking energy; wherein the hub motors eliminate the need for friction brakes. In this document, cavitation is referred to as a phenomenon which must be avoided.

Objects of the Invention

The primary object of the present invention is to overcome the shortcomings in the prior art. Another object of the present invention is to provide a system and method for non-battery heat generation/extraction serving dimatisation requirements of battery electric vehicles. A further object of the present invention is to provide a system and method for generating energy to partially or fully support pre-heating of batteries of electric vehicles prior to running the same in winter conditions.

Summary of the Invention

The present invention relates to a microfluidic heating/cooling system driven through a dimatisation fluid cycle and powered via harvesting of kinetic energy from vehicle's transmission sub-system. The system comprises an hydraulic cycle that encompasses an hydraulic low pressure container (also known as hydraulic container or low pressure hydraulic container, abbreviable as "LPC", or "HC"), a mechanically powered hydraulic pump and an hydraulic high pressure accumulator (i.e. pressure accumulator, abbreviable as "HPA" or "PA", which is an apparatus for hydraulically compressing a gas therein), and the hydraulic cycle circulates an incompressible hydraulic fluid.

The system further comprises a vehicle dimatisation fluid cycle that encompasses an hydraulically powered dimatisation fluid pump, an electrically powered dimatisation fluid pump (i.e. hydraulically powered fluid pump for pumping dimatisation fluid), and one or more devices which can be considered as microfluidic cavitational and non-cavitational solid-state modules.

The system further comprises a power transfer module (PTM) with clutch, and the PTM is arranged for, when integrated into a BEV, harvesting rotational angular energy from a respective vehicle transmission sub-system of the BEV by establishing a dutching-based mechanical connection to a respective transmission shaft at coasting and braking actions. The kinetic energy harvested via the PTM is utilized in activation of the mechanically powered hydraulic pump of the hydraulic cycle. The mechanically powered hydraulic pump retrieves hydraulic liquid from the low pressure container and pushes it to the hydraulic high pressure accumulator, thereby converting the harvested kinetic energy into pneumatic pressure potential to be stored (which can be considered as "indefinitely") for future uses. The accumulated potential energy is evidently proportionate with the pressure value of the compressed gas in said pressure accumulator.

In the case of vehicle dimatisation need, the stored pressure energy in hydraulic high pressure accumulator is used in pushing the hydraulic fluid to the hydraulically powered dimatisation fluid pump, e.g. via electronically controllable flow control valves. The hydraulically powered dimatisation fluid pump can be thus activated and drive the dimatisation fluid through the device(s) (microfluidic heating/cooling modules) with high pressure.

Depending on the extent of dimatisation requirement, said devices can either heat the dimatisation fluid via cavitation based fluid pressure to heat conversion, or cools down the dimatisation fluid via non-cavitation based heat extraction methods. Controller modules can manage kinetic energy harvesting, hydraulic energy storage and micro-fluidic based pressure to heat conversion processes. The present invention further proposes an alternate method of kinetic energy harvesting in BEVs, that is more efficient than common regenerative braking systems and that can be utilized for auxiliary needs such as cabin and battery heating/cooling.

Brief Description of the Figures

The figures, whose brief explanation is herewith provided, are solely intended for providing a better understanding of the present invention and are as such not intended to define the scope of protection or the context in which said scope is to be interpreted in the absence of the description.

Throughout the Fig.l to Fig.4, the solid boxes represent components of the system according to the present invention; the dashed boxes represent related components of a BEV to be provided with the system according to the present invention, and said components are not necessarily parts of the system; the solid arrows represent mechanical communication for kinetic energy recovery; the dotted arrows hydraulic fluid lines (e.g. oil lines); the dashed-dotted arrows represent climatisation fluid lines (e.g. water lines); the dashed bold arrow represent power flow from the battery to an (optional/preferable) electrically powered climatisation fluid pump; and the solid bold arrows represent heat transfer from/to the microfluidic thermoregulation apparatus; the reference signs between brackets indicate that the respective feature is an optional/preferable feature of the system

Fig.l shows schematics of an exemplary system according to the present invention, before being installed into a BEV. Flere, the system is arranged for selective climatisation in terms of both heating and cooling, i.e. with which both a cooling mode and a heating mode are available.

Fig.2 shows schematics of an exemplary system according to the present invention, and its possible connections (thermal and mechanical communication) when installed to a BEV. Flere, the system is arranged for climatisation in terms of heating.

Fig.3 shows schematics of an exemplary system according to the present invention, and its possible connections (thermal and mechanical communication) when installed to a BEV. Flere, the system is arranged for climatisation in terms of cooling.

Fig.4 shows schematics of the exemplary system shown in the Fig.l, and its possible connections (thermal and mechanical communication) when installed to a BEV.

Fig.5 is a perspective view schematizing an exemplary (microfluidic) device suitable for being employed in the system according to the present invention. The visualization of the indentations is merely given for showing an exemplary alignment of said indentations with respect to the fluid entrance into the flow restrictive element. In the detail, the device is shown as being made of a transparent material, merely for emphasizing a preferable presence of indentations inside the device.

Fig.6 shows schematics of an exemplary battery powered electric vehicle when provided with a system according to the present invention. The solid arrows, dashed arrows and bold solid lines respectively represent hydraulic fluid flow connections between various elements along the hydraulic cycle, logical communication of information and commands, and mechanical communication. The dashed-dotted region shows the borders of the respective exemplary embodiment of the system according to the present invention.

Fig.7 is a schematic of an exemplary experimental setup simulating an embodiment of the system according to the present invention, used for generating cavitation bubbles and micro/mini cavitating jets.

Fig.8 shows an exemplary P-T diagram of a fluid, exemplifying a possible route for onset of cavitation in said fluid, enabled by pressure drop (e.g. at constant temperature) to cross the liquid/vapor saturation line.

Fig.9 shows a perspective exploded view of an exemplary mounting means for arranging communication between a thermoelectric and/or photoelectric generator, a device and a hydraulic fluid flow path within the gist according to the present invention.

Fig.10 shows thermal contours captured by a thermal camera on the solid surface: (a) without spray exposure (152 pm), (b) just after the exposure (152 pm), (c) 30 s after the exposure (152 pm), (d) without spray exposure (504 pm), (e) just after the exposure (504 pm), and (f) 30 s after the exposure (504 pm). The selected box on the surfaces is the location where the emerging cavitation jet hits the surface. This approach helps to measure the mean temperature, where the most direct effect of the spray jet impingement occurs. AR01 represents the most relative area that the jet influences on the plate. It was tried to consider the same area of 1 x 1 mm ² for all cases. Flowever, as the area which was directly impacted by the cavitating jet from the tube with the inner diameter of 152 pm was less than 1 mm ² , a smaller area was introduced for this microtube.

Fig.11 (a) shows a plan view of a (micromachined) device which includes a plurality of (here: identical) flow restrictive elements; said device also including a flow alignment section (here: provided with micro-pillars), and a plurality of indentations;

Fig.11(b) shows a plan view of a device which includes a plurality of (here: identical) flow restrictive elements; said device also including a flow alignment section (here: provided with micro-pillars). It is shown Pressure sensors can be coupled to the device via pressure ports.

Fig.12 shows top view of a cascade configuration of a plurality of the devices.

Detailed Description of the Invention

Referring to the drawings, short explanations of which being provided above, the present invention is described below in detail. With reference to the above information, the present invention relates to a system and a corresponding method, which enable hydraulic recuperation (i.e. harvesting) of kinetic energy (hydraulic kinetic energy recovery system, hydraulic KERS) in battery powered electric vehicles. The system and method according to the present invention eliminate (or at least minimize) the climatisation subsystem energy dependency to the energy stored in a battery of a BEV. As a result, a considerably large amount of energy stored in the battery of a BEV that had to be used for climatisation purposes can be fully exploited in travelling longer distances with energy stored in the battery. Therefore, up to %10 range extension becomes possible in BEVs provided with the system and method according to the present invention. To this end, the present invention proposes a system (100) for energy harvesting in battery powered electrical vehicles (BEVs, 1000) which include a climatisation fluid cycle (63) and a transmission sub-system (15).

Main concept of the present application is as follows: The present invention proposes a system (100) for use in energy harvesting from a vehicle transmission sub-system (15) of a BEV (1000) having an HVAC sub-system (70) (for battery and/or cabin operating temperature management), when integrated thereto. The system (100) includes the following features:

- The system (100) comprises a hydraulic container (10), a pressure accumulator (12), and a mechanically powered hydraulic pump (111) for pressurizing a hydraulic fluid from the hydraulic container (10) into the pressure accumulator (12).

- The system (100) further comprises a PTM (13) with a clutch which is arranged for, when the system (100) is installed in the BEV (1000) and when the BEV (1000) is brought into a braking and/or coasting mode, being brought into mechanical communication with the vehicle transmission sub-system (15), and then transmitting rotational energy of the vehicle transmission sub-system (15) to the mechanically powered hydraulic pump (111) thereby running said mechanically powered hydraulic pump (111).

- The system (100) further comprises a climatisation fluid pumping unit (50) comprising a hydraulically powered climatisation fluid pump (51) which is arranged for being powered by the pressurized hydraulic fluid from the pressure accumulator (12), thereby pumping a climatisation fluid into a microfluidic thermoregulation apparatus (60). It would be evident to a person skilled in the art after reading the present specification, that a respective hydraulic fluid cycle (53) can be closed by arranging the climatisation fluid pumping unit (50) to return the hydraulic fluid into the hydraulic container (10).

- Said microfluidic thermoregulation apparatus (60) includes devices (20) for conducting the climatisation fluid. The devices (20) are arranged for, when the system (100) is installed in the BEV (1000), being in heat transfer communication with the HVAC sub-system (70). Thus, the system (100) can be considered as a heat dissipation and/or heat retrieval system. It would be evident to a person skilled in the art after reading the present specification, that a respective climatisation fluid cycle (63) can be closed by arranging the HVAC sub-system (70) to return the climatisation fluid into the climatisation fluid pumping unit (50).

The climatisation fluid pumping unit (50) can further comprise an electrically powered climatisation fluid pump (52) which is arranged for, when the system (100) is installed in the BEV (1000), being powered by the battery (72) of the BEV (1000).

For enabling climatisation by heating, some or all of the devices (20) can be in the form of heating devices (61) which comprise one or more flow restrictive element(s) (21) which are arranged for generating cavitation bubbles upon expansion of the climatisation fluid when passing therethrough. It would be evident to the skilled person after reading the present specification, to select or design devices (20) (e.g. microfluidic devices) arranged for generating cavitation bubbles in a controlled fashion using publicly available information, e.g. the EP 3 497 382 A1 publication. For enabling climatisation by cooling, some or all of the devices (20) can be in the form of cooling devices (62) arranged for avoiding cavitating flow of the climatisation fluid. Said cooling devices (62) can be arranged for partially restricting the flow of the climatisation fluid thereby generating a jet flow without causing cavitation.

For selective climatisation by enabling both heating and cooling using a single system (100) in the microfluidic thermoregulation apparatus (60), a part of the devices (20) can be in the form of heating devices (6G) which comprise one or more flow restrictive element(s) (21) arranged for generating cavitation bubbles upon expansion of the climatisation fluid when passing therethrough; and another part of the devices (20) can be in the form of cooling devices (62j arranged for avoiding cavitating flow of the climatisation fluid. The cooling devices (62) can be arranged for partially restricting the flow of the climatisation fluid thereby generating jet flow without causing cavitation .

In the case where the system (100) includes heating devices (61), heating device (61) inner surfaces which are arranged to be brought into contact with cavitated climatisation fluid, can be provided with indentations (23) for mechanically disturbing the cavitation bubbles, thereby triggering a blasting thereof. With this embodiment, the implosion/blasting of cavitation bubbles can be more strictly controlled. In an embodiment according to the present concept, at least a part of said indentations (23) can be provided at a downstream side (212) vicinity of the flow restrictive element(s) (21), preferably inside said flow restrictive element(s) (21) at a downstream vicinity of a hydraulic fluid entrance thereof.

The present application further proposes a BEV (1000) provided with an embodiment of the system (100) as disclosed above.

The present application accordingly proposes a method of non-battery climatisation for BEVs, powered by kinetic energy harvesting. The method includes the following sequential steps (i) to (iv): i. obtainment of a rotational kinetic energy from the transmission sub-system of a BEV (1000) at an occurrence of a braking or a coasting action. The below step (ii) is performed after the step (i). ii. Transferring the rotational kinetic energy into a mechanically powered hydraulic pump (111) via a PTM with a clutch (13), to a pressure accumulator (12) and pressurizing a gas in said pressure accumulator (12), thereby accumulating potential energy. After reading the present specification, it would be evident to a skilled person that the step (ii) can be performed by using the mechanically controlled hydraulic pump (111) to push an (incompressible) hydraulic fluid to a pressure accumulator (12) and compressing a (highly compressible) gas (in a pneumatic gas chamber) inside the pressure accumulator (12), (e.g. via a hydraulic fluid driven piston module); thereby pneumatically storing said potential energy in the form of increased gas pressure (e.g. a pneumatic gas chamber)), and thus the potential energy can be accumulated (in the pressure accumulator, in a controlled fashion). It would be further evident to a skilled person that the "hydraulic fluid" corresponds to a practically incompressible liquid, and a "gas" to be compressed is highly compressible, in particular when compared with the hydraulic fluid. The below step (iii) is performed after the step (ii). iii. Converting the potential energy (which is pneumatically stored in the pressure accumulator (12) in the step (ii)) into fluid pressure energy by decompressing the pressurized gas in the pressure accumulator (12) and thus pushing the hydraulic fluid into a hydraulically powered climatisation fluid pump (51), thereby pressurizing the climatisation fluid. After reading the present specification, the skilled person would also directly consider to perform said decompressing of the pressurized gas in a controlled fashion. The below step (iv) is performed after the step (iii). iv. Pumping the climatisation fluid by said climatisation fluid pump (51), into a microfluidic thermoregulation apparatus (60) to pass the climatisation fluid through heating devices (61) or cooling devices (62) in the microfluidic thermoregulation apparatus (60) which is in heat transfer communication with an HVAC sub system (70) of the BEV, by passing through said heating devices (61) or cooling devices (62). As a result, the temperature of the climatisation fluid is changed (i.e. heated or cooled, respectively). As a further result, a heat transfer is established between the climatisation fluid and the HVAC sub-system (70).

Thus, the method enables the climatisation of the cabin air and/or battery of the BEV by selectively providing heated or heat extracted climatisation fluid to the HVAC..

In order to provide climatisation by heating, the method can include generation of cavitation bubbles by passing the climatisation fluid through flow restrictive elements (21) of one or more heating devices (61) provided in the microfluidic thermoregulation apparatus (60).

In order to provide climatisation by cooling, the method can include the passage of the climatisation fluid through one or more cooling devices (62); and preferably restricting the flow of the climatisation fluid to generate jet flow without causing cavitation.

In the case where the accumulated potential energy drops below a value which is insufficient to push the hydraulic fluid into the hydraulically powered climatisation fluid pump as in the step (iii), the method can further include the passing of the climatisation fluid through the microfluidic thermoregulation apparatus as in step (iv) by utilizing electric power. Said electric power can be that stored in a battery of the BEV (1000) using an electrically powered hydraulic pump (52) for pumping said climatisation fluid.

The system (100) can be considered as including an "hydraulic KERS" for BEVs, by including the PTM with clutch (13), mechanically powered hydraulic pump (111), low pressure hydraulic container (10) and hydraulic high pressure accumulator (12). Said hydraulic KERS is arranged to be coupled with a vehicle transmission system (15) for harvesting available kinetic energy during braking and coasting actions. Said pressure accumulator (12) can include a pneumatic gas chamber which is filled with a gas to be compressed in order to store pressure potential, and a mechanical communication between the incompressible hydraulic fluid and the pneumatic gas chamber can be arranged via a piston/plunger mechanism variably delimiting the volume of said pneumatic gas chamber. Other common means for storing pressure potential are already available to skilled person, within the common general knowledge in mechanical engineering. The mechanically powered hydraulic pump (111) for pushing the incompressible hydraulic fluid is powered by the power transfer module (13) arranged for being brought into an electronically controllable mechanical connection with the vehicle transmission sub-system (15). Taking into account that the hydraulic fluid has a much higher pressure when pressurized into the pressure accumulator (12) in comparison with its pressure when inside the hydraulic container (10); the hydraulic container (10) and pressure accumulator (12) are to be respectively considered as a "low pressure hydraulic container" and a "hydraulic high pressure accumulator". The technical details of a pressure accumulator (12) and hydraulic container (10) to be employed in the system according to the present invention can also be considered analogous to those used in known hydraulic kinetic energy recovery systems (KERS).

As mentioned above, the system (100) further comprises a power transfer module (PTM) with clutch (13) which is in mechanical communication with the mechanically powered hydraulic pump (111). The power transfer module with clutch (13) is arranged for transferring the energy (i.e. angular kinetic energy, rotational energy) from the vehicle transmission sub-system (15) to the pressure accumulator (12) through the mechanically powered hydraulic pump (111), thereby converting said energy into pressure potential to be stored in the pressure accumulator (12).

The system (100) further comprises a climatisation fluid (which can be considered in a climatisation fluid cycle (63) when the system is integrated into a BEV (1000)) as connected with the high pressure accumulator (12). The climatisation fluid cycle (63) can be driven by an hydraulically powered fluid pump (222) that is powered by the incompressible hydraulic liquid when the latter is pushed by the high pressure accumulator (12).

A hydraulically powered fluid pump (222) can pressurize the climatisation fluid. By passing the pressurized climatisation fluid through the devices (20) in the form of the above mentioned heating devices (61) which trigger cavitation, the fluid pressure can be converted to heat that heats up the climatisation fluid (in which case, the flow restrictive elements (21) can be considered as a microfluidic heating sub-system); or alternatively, by passing the pressurized climatisation fluid through the cooling devices (62) the fluid pressure can be exploited to extract heat from the climatisation fluid for cooling purposes. The heated or cooled climatisation fluid can be then fed to an HVAC sub-system (70) for provision of heat transfer to/from a respective cabin air (81) and/or battery (82), thereby achieving climatisation. Then the climatisation fluid can be returned from the HVAC sub-system (70) to the climatisation fluid pumping unit (50) for closing the climatisation fluid cycle (63). Thus, a BEV can be climatised (here: a cabin and/or battery of the BEV can be heated up or cooled down) with the system (20) according to the present invention.

Within the context of the present application, The cabin (81) or a battery (82) of a BEV (1000), are considered as "(BEV-related) subject(s)" (80) which are to be subjected to heat transfer to/from the HVAC sub-system (70). the terms "cabin" and "cabin air" respectively correspond to a passenger compartment/cell/volume of the BEV, and to the air for filling the to the cabin air which is to be directed/circulated into the passenger volume over the respective HVAC sub-system (70). The climatisation of cabin is considered equivalent to the thermal management of the cabin air.

The generation of cavitation bubbles can be avoided by keeping the pressure drop/values in the climatisation fluid at passing through the cooling device (62), (e.g. through flow restrictive elements (21) provided therein) at an extent which does not cause generation of cavitation bubbles. In such case, the flow restrictive elements (21) can be considered as a microfluidic cooling sub-system. Taking the well-known "continuity equation" into consideration, by providing rather narrow flow paths, the flow restrictive elements (21) of the cooling device (62) provide increased linear flow rates (jet flows) in the hydraulic fluid, thereby thinning respective hydrodynamic film layers to increase overall heat transfer coefficients around the devices (20), which results in an enhanced heat transfer and enhanced climatisation (here: cooling). A person skilled in fluid dynamics is able to easily select pressure values and flow rates suitable for obtaining or avoiding cavitation bubbles, using thermodynamic properties related to respective fluids (e.g. the pressure-temperature diagram of a selected hydraulic fluid, for instance such diagram of water as a preferable hydraulic fluid).

The devices (20) can be in the form of heating devices (61) which comprise one or more flow restrictive element(s) (21) for generating cavitation bubbles upon expansion of a pressurized climatisation fluid when passing therethrough. With this embodiment, by adjusting the hydrodynamic conditions (i.e. pressure and temperature) inside the passing climatisation fluid, cavitation bubbles can be generated inside the climatisation fluid. The cavitation bubbles eventually collapse, thereby generating heat that heats up the climatisation fluid cycle (63). As a result, such embodiment of the system (100) converts kinetic energy into pressure potential, and then into thermal energy. Thus, kinetic energy recovered from a transmission sub-system and stored in the hydraulic accumulator (12) in the form of pressure potential, can be used in climatisation (here: in heating). Accordingly, for climatisation in the terms of heating, the method according to the present invention can include the step of generating and then imploding cavitation bubbles in the climatisation fluid, thereby converting the pressure potential energy into thermal energy. The conditions suitable for generating cavitation bubbles can be selected by a person skilled in fluid dynamics and thermodynamic properties of fluids, in particular phase changes related to temperature and pressure. Fig.8 shows an exemplary P-T diagram of a fluid, exemplifying a possible route for onset of cavitation in said fluid, enabled by pressure drop (e.g. at constant temperature) to cross the liquid/vapor saturation line.

The energy harvested with the system (100) can be also partially or completely directed to a battery heater of a respective BEV (1000), for preparing a respective battery (72) to operation in winter conditions (i.e. when the ambient/atmospheric temperature drops below 10°C). Thus, the system according to the present invention enables a conversion of braking/coasting kinetic energy in an extent which is not enabled with regenerative braking, and which is sufficient for cabin (71) and battery (72) climatisation, e.g. heating thereof without relying on battery (72), even in winter conditions. Within the context of the present invention: the term "climatisation" corresponds to an intervention to the temperature level of a cabin (71) and/or of a battery (72) of a respective BEV; and the term "battery" corresponds to an energy storage unit suitable for storing chemical energy for a future conversion into electric energy. Accordingly, the term "BEV" corresponds to a vehicle which employs such battery for provision of energy to be utilized in generation of momentum for transportation.

In the case where the device (20) includes heating devices (61) with flow restrictive elements (21) for generating cavitation bubbles inside the climatisation fluid under suitable conditions, both of the following two climatisation scenarios are rendered selectively available:

- The climatisation fluid is passed through cooling devices (62) (which preferably provide an inherently narrow flow path in terms of cross section in a momentary flow direction, therefore an increased linear speed to the hydraulic fluid, thereby minimizing the thickness of a thermal boundary layer in a respective heat transfer direction from the climatisation fluid cycle) at conditions (i.e. temperature and pressure) allowing the avoidance of emergence of cavitation bubbles inside the hydraulic fluid; thereby heat transfer from the climatisation fluid to the 'colder' climatisation fluid is established. Thus, the system and method serves for climatisation in the terms of 'cooling'.

- The climatisation fluid is passed through heating devices (61) having flow restrictive elements (21) at conditions allowing/causing the emergence of cavitation bubbles inside the climatisation fluid, the temperature of the climatisation fluid at the heating devices (61) rises to a level which can be inherently/inevitably higher than the temperature of a respective cabin (81) and/or battery (82) to be heated; and heat transfer from the 'heated' climatisation fluid to a 'colder' cabin (81) air and/or battery (82) to be climatised, is established over an HVAC (70) sub-system of the respective BEV (1000) which is subjected to thermoregulation by the microfluidic thermoregulation apparatus (60). Thus, the system and method serve also for climatisation in the terms of 'heating'.

In other words, the method according to the present invention can include selectively operable heating and cooling modes which are enabled as follows:

- the heating mode is established by elevating the temperature of the climatisation fluid, by passing the climatisation fluid through the flow restrictive elements of the heating devices (61) at conditions under which cavitation occurs in the climatisation fluid; and

- the cooling mode is established by passing the climatisation fluid through the cooling devices (62) at conditions under which cavitation does not occur in the hydraulic fluid. The cooling devices (62) can include flow restrictive elements (21) arranged for causing jet flows thereby increasing linear velocity of the climatisation fluid and thus minimizing a respective thermal boundary layer thickness, but further arranged for avoiding cavitation in the climatisation fluid.

The hydraulic fluid can be (or include) water for its benefits such as being non-toxic, chemically inert, and low- cost.

The system (100) can further comprise a battery powered electrical climatisation fluid pump (52) (i.e. electrically powered climatisation fluid pump, or electrically powered hydraulic pump for pumping the climatisation fluid) coupled with the climatisation fluid cycle (63) to pressurize the climatisation fluid into the microfluidic thermoregulation apparatus (60). Such embodiment is in particular useful in the case where the pressure potential accumulated in the hydraulic accumulator becomes insufficient to power the hydraulically powered climatisation fluid pump (51) that drives the climatisation fluid cycle (63) that encompasses microfluidic devices for heating (61) and/or cooling (62). Or it could be possible that some transient/permanent technical failure occurs in Hydraulic KERS system which blocks kinetic energy harvesting and hydraulic/pneumatic energy storage. In such cases, the battery powered electrical climatisation fluid pump (52) works as a fallback and redundancy providing option and will drive the climatisation fluid cycle (63) (thereby enables climatisation of the BEV) until potential energy is stored in HPA or hydraulic KERS sufficient to resume its normal operation. An inner surface of the heating devices (61) in contact with the hydraulic fluid can be provided with indentations (23) to form a (structured-) surface arranged to mechanically disturb the cavitation bubbles for triggering a blasting thereof. By this way, a strict control can be applied on when/where the cavitation bubbles are to be imploded. Accordingly, the method according to the present invention can include a triggering of said blasting by contacting the cavitation bubbles with an indentated surface. In the case where the indentations (23) are provided in an inner surface of the cooling device (62), the indentations are considered as increasing the thermal contact surface area between the climatisation fluid and said surface, thereby (further) increasing the heat transfer rate between the climatisation fluid and a respective HVAC (70) sub-system.

In an embodiment of the system according to the present invention, in heating devices (61), at least a part of said indentations (23) can be provided at a downstream side (212) vicinity of the flow restrictive element(s) (21), preferably inside said flow restrictive element(s) (21) at a downstream vicinity of a hydraulic fluid entrance thereof.

In the system and method according to the present invention, energy can be stored for later use, by increasing the hydraulic pressure in the hydraulic accumulator (12).

Within the context of the present application, the flow restrictive element(s) (21) in heating devices (61) can be considered as e.g. orifices or venturis, for generating cavitation bubbles upon expansion of a pressurized hydraulic fluid (fed from an upstream side (211) of the flow restrictive element (21)) when passing through said flow restrictive element(s). The cavitation bubbles inevitably collapse shortly after being generated, which results in generation of a high amount of thermal energy; thus, the pressure-related potential energy in the hydraulic fluid is converted to thermal energy.

For providing of a better introduction on the gist of the present invention, preparation to the present development and application of exemplary proof-of-concept experiments are presented below without aiming to limit the targeted scope of protection.

Since the energy in Hydraulic KERS is stored as hydraulic/pneumatic pressure in the HPA, an important challenge is to exploit this limited energy most efficiently and transfer it to a heating medium that would be easily dissipated. This concept proposes high efficiency microfluidic cavitation method for converting pressure energy to heating and jet-flow based non-cavitating flow method to provide cooling. Although microfluidic cavitation has been known as an undesired phenomenon in the industry over many years specifically in the fields of turbomachinery, during the past years, the released energy from the collapsing bubbles due to cavitation has been proven to be useful in some applications in the industry. Cavitation is a progressive cycle of vaporization, bubble generation and bubble implosion. It occurs when local static pressure in a flow is reduced below a critical pressure value. It is considered as one of the major phase change phenomena. Small energetic cavitation bubbles can be generated in small flow restrictive elements such as orifices or venturis, which induce sudden reduction in local pressure and cause hydrodynamic cavitation inception. The collapse of the emerging cavitation bubbles downstream of these elements leads to a high energy release, thereby generating highly localized, large amplitude shock waves and high velocity jets, which can significantly raise the local temperature. Hot spots over 1000 K and high speed micro-jets exceeding 300 m/s were reported in the literature for the collapse of cavitation micro bubbles. Having multiple cavitation bubbles will heat the water in a uniform temperature distribution, and the heated water could be used for climatisation and thermoregulation of small confined areas (such as vehicle cabin and battery compartment) when dissipated within a water-cycle.

The proposed system is combining maximal energy harvesting via hydraulic KERS with climatisation fluid pressure to cooling/heating conversion (via with cavitating and non-cavitating microfluidic flows in solid-state modules) techniques to meet the heating and cooling needs of BEV under all weather conditions. The overall concept is to develop a clean, compact and low-cost, heat generation and cooling system based on high efficiency utilization of maximally harvested kinetic energy in battery electric vehicles. We will develop a new energy conversion technology to generate heat and provide effective cooling in BEVs through smart combination of energy harvesting and novel hydrodynamic cavitational/non-cavitational approaches with minimized reliance on battery power. Our primary benefit is the direct travel/driving range extension for BEV because we do not spend limited battery energy for heating and cooling of the cabin and battery. Therefore, more energy remains for the motion of car. The BEV can thus be able to travel 10% more distance with a given battery charge level. The battery life time extension is a secondary benefit (brought by first/primary benefit) we provide by extending the range per battery recharging (smaller number of recharge/discharge events occur so the battery life-time increases). The developed system will enable manufacturers to increase the manufacturing capacity of BEVs, accelerating their growth by means of economic incentives to the average customer. With less payback time it will ensure uptake of electric vehicles towards zero GHG (greenhouse gases) emissions in transportation.

The overall concept is shown in Fig.l, Fig.2, Fig.3, Fig.4 and Fig.6. Generation of heating and cooling in BEVs will follow a two climatisation fluid -cycles: cavitating for heating and non-cavitating flow (jet impingement) for cooling.

An exemplary system according to the present invention includes a power transfer module (PTM) with a clutch: It is a software controlled (the control algorithm takes into account the vehicle's braking regime, braking status, speed/acceleration and hydraulic storage level) module that is used to recuperate the kinetic energy in the transmission sub-system.

When the driver pushes the braking pedal or in coasting mode, the electric drivetrain is disengaged from the transmission sub-system. The transmission sub-system still has rotating kinetic energy that could be harvested. In state-of-art regenerative braking engagement scenario, the electric motor is switched to generator mode and rotational kinetic energy in the transmission sub-system is converted to electric energy through generator mode electric motor. In this concept solution regenerative braking controller will calculate the energy conversion efficiency (that depends on factors such as speed, braking harshness, coasting characteristic, motor braking effect etc.) of regenerative braking for all braking and coasting actions. For instance, if the energy conversion efficiency for regenerative braking is anticipated to be significantly lower than (for example lower than 30%) hydraulic KERS energy conversion efficiency, hydraulic KERS is engaged instead of regenerative braking. As hydraulic KERS has much higher power density and very low energy consumption for reconfiguration as compared to regenerative braking systems, its efficiency will thus be greater in almost all braking/coasting cases. In our concept, hydraulic KERS is engaged when there is a clear/substantial energy conversion advantage over default regenerative braking system. The first step for hydraulic KERS engagement is Kinetic Energy Harvesting Controller sending an "engage" command to PTM with clutch. With this command, PTM gets mechanically connected to the transmission sub-system and starts to harvest the rotating kinetic energy of the transmission sub-system with high efficiency. PTM transfers this kinetic energy to the hydraulic pump so that hydraulic/pneumatic based energy storage process is initiated.

Mechanically powered hydraulic pump (111): The mechanically powered hydraulic pump serves for transferring the hydraulic liquid from (low pressure-) hydraulic container to (high pressure-) hydraulic accumulator (HPA).

During the braking or coasting process in which regenerative braking is not engaged, hydraulic KERS can be engaged to harvest the kinetic energy. In this scenario rotational kinetic energy can be transferred from PTM to a hydraulic pump. , The hydraulic flow control valve regulating the hydraulic flow from hydraulic pump is switched to open state (enabling the flow) and the hydraulic flow control valve regulating the flow towards climatisation fluid pump is switched to closed state (so that hydraulic liquid remains in the closed container). The hydraulic pump will pump the hydraulic liquid from LPC to HPA and thus will increase the pressure in the HPA that is designed to act as an hydraulic/pneumatic accumulator. Thus, the kinetic energy can be stored locally in the HPA for further utilization.

Hydraulic low pressure container / LPC (10): LPC can be the initial an final storage buffer for the low pressure hydraulic liquid that drives hydraulic-to-pneumatic (in the HPA) and hydraulic-to-fluid pressure (in the climatisation fluid pump) energy transfer processes. Therefore, LPC can be used to complete the hydraulic liquid flow cycle.

Hydraulic accumulator / high pressure accumulator / HPA (12): HPA stores the kinetic energy by compressing the compressible gas in the pneumatic container via hydraulic liquid transferring the pressure over piston system

The HPA can be implemented as a lightweight, durable, minimal noise and small/compact volume hydraulic accumulator that complies with all relevant transport and mobility safety standards. Embodying a pneumatic storage unit, the Hydraulic Pressure Accumulator is able to store the harvested kinetic energy transported via incompressible hydraulic liquid. When Microfluidic Subsystem Controller is ordered to start heating/cooling via microfluidic system, the hydraulic flow control valve regulating the hydraulic flow from hydraulic pump is closed. Then the hydraulic flow control valve regulating the flow towards climatisation fluid pump is opened so that the hydraulic liquid is pushed to the climatisation fluid pump by exploiting the stored energy in the accumulator. The high pressure container does also include an electronic pressure sensor so that the pressure could be controlled not to exceed industry relevant standards (e.g. ~400 bar). In the case of HPA pressure reaches higher limit, the Kinetic Energy Harvesting Controller will temporarily halt hydraulic KERS operation and available braking energy can be routed to standard electric regenerative braking until HPA pressure drops below the critical threshold.

Hydraulically and Electrically Powered Climatisation Fluid Pumps: These pumps will generate the necessary fluid pressure to drive the heating and cooling fluid cycles.

As proportional to heating and cooling requirement, Microfluidic Subsystem Controller will control the hydraulic flow output in the HPA output. HPA will push the hydraulic fluid to climatisation fluid pump. The climatisation fluid pump will use the high pressure from hydraulic fluid to propel the climatisation fluid in cooling and heating climatisation cycles. The hydraulic fluid in the output of the pump with lowered pressure can be sent to LPC for future use. Another electrically driven pump can be deployed in series for redundancy and fallback purposes. This electrically powered climatisation fluid pump can be powered through electric vehicle battery if there is no enough harvested energy in hydraulic KERS system and if Microfluidic Subsystem needs to produce heating or cooling.

Microfluidic Heating Module (i.e. device (20) in the form of a heating device (61)): This module uses cavitation phenomenon to convert climatisation fluid pressure to micro vapor bubbles that generate heat when they collapse in the output of cavitation device. Cavitation is a progressive cycle of vaporization, bubble generation and bubble implosion that manifests as a major phase change phenomenon, originating from the reduction of local static pressure in a flow below a critical pressure value. It is driven by the fluid pressure generated via hydraulically powered climatisation fluid pump. The level of cavitation that will provide the heating effect depends on the level of fluid pressure differential (cf. Fig.5).

In our approach, the pressure that has been incrementally built up in the hydraulic accumulator is used for the generation of cavitating flows in the climatisation fluid.

The climatisation fluid under pressure enters the configuration of a (microfluidic-) device (20) as seen in Fig.5. The device can be considered to be divided in three parts: inlet (24), microchannel (i.e. flow restrictive element 21) and outlet (25), respectively.

Inlet (24): Climatisation fluid enters the microfluidic device from the climatisation fluid pump of the inlet part that can include a flow aligner (250) section which can include a number of micro-structured flow aligners (e.g. in the form of pillars along longitudinal axes arranged transverse to a direction of flow of the climatisation fluid). From there, climatisation fluid flow is restricted at the microchannel inlet. The microchannel (21) is essentially a flow restrictive element that provides communication between inlet and outlet parts and is the place where bubbles are formed. Cavitating flow is achieved once climatisation fluid static pressure drops to its vapor pressure. Such local static pressure decreases in consistency with Bernoulli equation with a minimum pressure consistent with the Vena Contracta effect. Phase change takes place (cavitation inception) once a critical minimum pressure value is reached. This causes bubble-grow nucleation to a maximum size that is retained as long as the low-pressure condition lasts. The bubble diameter is preferably arranged to be not larger than the width of the microchannel. To enhance bubble formation and motion along the microchannel, the climatisation fluid contact surfaces of the microchannel are at least partly coated with materials of variant hydrophilicity (surfaces are different near two distal ends of each surface) in accordance with the climatisation fluid flow direction. Close to the inlet it is mostly hydrophobic, whereas close to the outlet is mostly hydrophilic. This allows cavitation to commence from the inlet side of the microchannel due to the presence of low-pressure zones and more pronounced surface effects (structured surface), which promotes bubble nucleation. The existence of wettability gradient further enhances transport of bubbles towards the outlet part.

Outlet (25): Once formed and exit the microchannel cavitation bubbles head towards the outlet end of the device. Upon pressure recovery bubbles collapse and form micro-jets which in turn causes shock waves that transfer an enormous amount of energy. Part of the potential energy of the cavitating bubbles is converted to heat after collapse (Pecha, R. and B.J.P.r.l. Gompf, Microimplosions: cavitation collapse and shock wave emission on a nanosecond time scale cavitation, Exp. Therm. Fluid Sci. 91 (2018) 89-102. 2000. 84(6): p. 1328).

In the case where a multiplicity of flow restrictive elements are arranged to have a uniform geometry and size, bubbles with uniform sizes can be generated from each of such flow restrictive elements. Considering that multiple bubbles of the same size correspond to a common extent of energy released when blasted, the uniformity in the size and number of bubbles will generate uniform heating on working fluid (here: hydraulic fluid). In its implementation the outlet part will incorporate a number of microfluidic channels to achieve maximum cavitation effect and uniform temperature rise on the working fluid.

As seen in Fig.10, collapsing bubbles will increase the temperature of the climatisation fluid.

Initial experimental investigations have proven that cavitating flows utilizing the cascade design depicted in Fig.12 are possible via control of inlet pressure and the utilization of suspension and heat generation up to 0.35 Watts from a 1mm x 1mm area was achieved (Morteza Ghorbani et al, Energy Harvesting in Microscale with Cavitating Flows, ACS Omega 2017, 2, 10, 6870-6877).

Microfluidic Cooling Module (cooling device (62), or device (20) when under non-cavitating flow conditions): Jet impingement cooling for battery compartment and vehicle cabin can be achieved. A first climatisation fluid cycle flow line can be utilized between the climatisation fluid pumping unit (50) and the heating devices (61). In such case, the heating devices (61) can be employed along with cooling devices (62) as depicted in Fig.l and Fig.4, for being operated in tandem in accordance with climatisation needs; or possibly without the presence of heating devices (61) as shown in Fig.2.

A second climatisation fluid cycle flow line can be utilized between the climatisation fluid pumping unit (50) and the cooling devices (62). In such case, the cooling devices (62) can be employed along with heating devices (61) as depicted in Fig.l and Fig.4, for being operated in tandem in accordance with climatisation needs; or possibly without the presence of heating devices (61) as shown in Fig.3. Here, non-cavitating climatisation fluid flow (in wider channels) can be guided to the battery (82) section and/or cabin (81) in order to cool them down as subjects (80) to be climatised. This will allow the battery to operate in optimum conditions within a well- controlled temperature and voltage range, as low or high temperatures have been shown to limited battery efficiency. Climatisation fluid flow will also be used for cabin cooling.

A jet flow through microfluidic channels can be generated and introduced to the target with structured surfaces to cool down the battery compartment. The use of surfaces with indentations (23) functional structures (see Fig.11(a)) will simultaneously enhance heat removal.

Fig.11(b) shows a plan view of a device which includes a plurality of (e.g.: identical) flow restrictive elements; said device also including a flow alignment section (here: provided with micro-pillars). It is shown Pressure sensors can be coupled to the device via pressure ports.

Heating device (61) can be comprised of multiple multi-modules concatenated via a cascade design exemplified in Fig.12, which shows a top view of an exemplary cascade configuration of a plurality of the devices (20). Here, the devices (20) are exemplified as heating devices (61). Upscaling of the devices (20) from "micro" modules to "macro" modules can be realized with this cascade design approach.

Kinetic Energy Harvesting Controller Module (software/algorithm/logic): This module interworks with regenerative braking controller functional unit in the vehicle and obtains the braking/coasting driver action parameters such as vehicle ego-speed, braking harshness level, deceleration, coasting status, motor brake, torque and rotation speed. With these parameters the controller calculates the anticipated regenerative braking energy recuperation efficiency. If this efficiency is significantly lower than hydraulic KERS efficiency level, regenerative braking controller unit is notified to abort regenerative braking and hydraulic KERS based energy harvesting process is initiated.

If the anticipated energy recuperation efficiency is close enough to hydraulic KERS efficiency level, then the Kinetic Energy Harvesting Controller Module notifies the regenerative braking controller unit to proceed with regenerative braking action and hydraulic KERS subsystem is not engaged.

Once hydraulic KERS based energy harvesting process is initiated Kinetic Energy Harvesting Controller Module manages all devices/modules in hydraulic KERS so that maximal amount of kinetic energy is harvested/stored without violating any safety/regulatory boundaries. Kinetic Energy Harvesting Controller Module also interworks with Microfluidic Subsystem Controller through vehicle climatisation controller so that Microfluidic Subsystem remains inactive while hydraulic KERS is engaged and harvested kinetic energy is stored in hydraulic pressure accumulator.

Microfluidic Subsystem Controller Module (software/algorithm/logic): This module interworks with the climatisation controller functional unit in the vehicle and obtains the level of heating/cooling requirements for the vehicle battery and driver cabin. By taking into account the existing level of heating/cooling, this module manages microfluidic heating/cooling generation processes and modules in the heating/cooling climatisation fluid cycle. Depending on the heating/cooling requirement microfluidic subsystem controller SW module increases or decreases the climatisation fluid pressure level that climatisation fluid pump will produce.

Microfluidic Subsystem Controller also interworks with Kinetic Energy Harvesting Controller Module through vehicle climatisation controller to learn the level of hydraulically stored energy in the high pressure accumulator. If the stored energy is not sufficient to meet the heating/cooling needs, electrically powered climatisation fluid pump can be activated/powered so that the climatisation fluid-cycle for heating/cooling purposes can continue to function.

This technology will generate heating and cooling in continuously active, accurately controllable and highly efficient manner so that the cabin /battery heating and cooling requirements, which are dynamically dependent on ambient temperature levels and user preferences, could be fulfilled with optimal utilization of harvested/stored hydraulic energy. The invention clearly advances the state-of-the-art by introducing new models, algorithms and novel heat generation and energy conversion technologies enabling the application to BEVs with a degree of complexity never handled before. Hydraulic pressure driven microfluidic systems have never been adopted for the heating/cooling needs of the vehicles (electric, hybrid or combustion engine). Novel microfluidic-based energy generation via cavitation can be applied. The capability to harvest kinetic energy in maximalist method (hydraulic KERS) and meeting the auxiliary heating/cooling need via this harvested energy will extend drivable range of the BEV.

The HPA can be implemented as a lightweight, durable, minimal noise and small/compact volume hydraulic accumulator (12) that complies with all relevant transport and mobility safety standards. Embodying a pneumatic storage unit, the Hydraulic Pressure Accumulator is able to store the harvested kinetic energy transported via incompressible hydraulic liquid. When Microfluidic Subsystem Controller is ordered to start heating/cooling via microfluidic system, the hydraulic flow control valve regulating the hydraulic flow from hydraulic pump is closed. Then the hydraulic flow control valve regulating the flow towards climatisation fluid pump is opened so that the hydraulic liquid is pushed to the climatisation fluid pump by exploiting the stored energy in the accumulator. The high pressure container does also include an electronic pressure sensor, so that the pressure could be controlled not to exceed industry relevant standards (~400 bar). In the case of HPA pressure reaches higher limit, the Kinetic Energy Harvesting Controller will temporarily halt hydraulic KERS operation and all braking energy can be routed to standard electric regenerative braking until HPA pressure drops below the critical threshold.

This novel technology will generate heat in continuously active, accurately controllable and highly efficient manner so that cabin /battery heating requirements, which are dynamically dependent on ambient temperature levels and user preferences, could be fulfilled with optimal utilization of recuperated/stored hydraulic energy.

In the proposed system, a simple hydraulic system that has been commercially implemented and proven itself in mobility/transport industry can be utilized for the harvesting of braking kinetic energy in electric vehicles. Hydraulic systems through their very high power density and very low reconfiguration burden can harvest up to %90 percent of kinetic energy in vehicle transmission sub-systems and they are more efficient as compared to state-of-art electric regenerative braking in the cases of (a) low speed braking, (b) high speed harsh braking, (c) short-term coasting and (d) EV battery operating outside of optimal temperature range.

This energy is stored in hydraulic accumulators in an indefinite fashion and then used to drive a cavitation based pressure to heat generation and/or to a non-cavitation based cooling system. The heat generation and cooling processes in solid-state systems/devices are thoroughly manageable and adjustable according to heating/cooling requirements of the battery compartment and driver cabin. The term "solid state" is herein attributed to the device which can be described as being formed from rigid components which are substantially not movable relative to each other. Thus, the system according to the present invention is durable and easy to operate, at least because of the merits related to that the devices (20) have the quality of being 'solid state'.

The advantages of the system and method according to the present invention, as compared to available ones, can be listed as follows:

- Minimum addition of hardware such as power transfer module (13), pressure accumulator (hydraulic accumulator 12) and cavitational/non-cavitational microfluidic solid-state modules (in a microfluidic thermoregulation apparatus 60 which includes devices 20: heating devices 61 and/or cooling devices 62) that could be miniaturized in accordance to sizing and safety limits/standards of battery powered electric vehicles.

- The energy for heating/cooling is harvested through the braking kinetic energy so that limited/precious electric power reserved in a respective battery is not/less exploited for purposes other than motive functions. This will lead to 10% increase in the driving range of BEVs especially in low ambient temperature driving situations (such as in winter conditions). Also the service cycle and the service life of battery will increase thanks to decreased utilization per driven kilometers.

- The kinetic energy recuperation ratio available with the system and method according to the present invention increases the braking systems longevity, since a minimized extent of mechanical energy load on standard braking. Thus, braking gear life-time will considerably increase in BEVs.

- The system and method are completely environmentally friendly, since the working fluid (i.e. the climatisation fluid) is non-toxic (e.g. water) and the components making up the system can be made of materials which are non-toxic and degradable in nature.

- Since the system inherenty incudes an climatisation fluid pump and the climatisation fluid is heated/cooled via non-electrical methods, HVAC subsystem cost and complexity in BEVs could be decreased considerably (no electrical pumps or resistor based heaters).

- The operation of the devices (20) (heating devices (61) and/or cooling devices (62)) in a microfluidic thermoregulation apparatus (60) is safe for the users since the devices can withstand very high pressures without failure.

- There is no need for employing electrically powered heaters which are used in the state-of-art systems that constitute a safety hazard in BEVs.

Proof of concept experiments:

In our previous study (M. Ghorbani, A. Mohammadi, A.R. Motezakker, L.G. Villanueva, Y. Leblebici, A. Kosar, Energy Harvesting in Microscale with Cavitating Flows, ACS Omega. 2 (2017) 6870-6877), compared to the studies available in the literature, we proposed a novel approach utilizing the energy produced during the interaction of the spray affected by the hydrodynamic cavitating flow and a thin target plate.

It was clearly shown that with the aid of hydrodynamic cavitation generated inside a nozzle in addition to the optimization of the distance between the outlet of the flow restrictive element (here: tip of the channel configuration) and the solid surface, surface temperatures can be increased up to 5°C under the conditions of this experimental study. The temperature rise on the surfaces near the collapsing small bubbles was exploited for energy harvesting in small scale in such a way that miniature, cost-effective, and environment friendly energy harvesting devices can be developed. Such devices will not require any external power and moving parts in contrast to common energy-harvesting devices, such as those involving piezoelectric materials and micro-engines.

To explore the difference in the temperature rise with different flow restrictive element (channel) diameters and also with different upstream pressures, the cavitation flow patterns are captured and analyzed using an advanced high-speed visualization system. The analysis of the captured data showed that different flow patterns exist for different diameters of the flow restrictive elements, including a pattern shift from micro- to macroscale, which accompanied the pattern of temporal results very well.

Experimental Setup: Considering that the information provided in this section relates to design alternatives, the cavitating -flow (mini cavitating jets) generation setup used in this study is shown in Fig.7. In the exemplary experimental setup, a nitrogen tank (400) is connected to a liquid container (401) which is monitored using a pressure gauge (402), and this flow path continues over a first (fine-) control valve (403), a micro filter (404), a further pressure gauge (405), a second (fine-) control valve (406), a further pressure gauge (407) and reaches to a micro/mini-channel (408) serving as the flow restrictive element (21) wherefrom a cavitating flow (409) (in the form of a spray) emerges and gets directed onto a target plate (410) (here, a black colored aluminum plate). The cavitating flow is illuminated using a light source (411, here: a power LED source); and captured using a high speed camera (414). The temperature of the target plate is monitored using a thermal camera (413). Both of the thermal camera (413) and high speed camera (414) are connected to a computer (412, a workstation PC). The target plate (here: a target plate) has a surface of 1 x 1 cm ² and weight of 1.85 g is kept at a specific distance (1.8 cm) from the outlet of the flow restrictive elements (here: the tip of the channels) to act as the exposed surface for impingement of the micro-jets resulting from the exiting spray. The depth of the target plate utilized in this study was 1 mm. Except certain cases, the area that was chosen to calculate the effect of temperature rise was l x l mm ² . In other cases, modifications in calculations were considered to ensure a reasonable judgment. The tests are performed in four different flow restrictive element (here: channel) configurations. In the presence of intense cavitating flows downstream of the (cavitating-flow generator-) device, a heating effect can be accomplished. The temperature variations are recorded using a thermal camera system, whereas the flows are visualized using a high-speed camera system.

Fig .9 shows a perspective exploded view of an exemplary mounting means for arranging communication between a thermoelectric and/or photoelectric generator (22, here: a thermoelectric module), a device (21) and a hydraulic fluid flow path including an inlet (24) and outlet (25) within the gist according to the present invention. The hydraulic fluid flow path pressure is monitored using a pressure sensor (26).

Device Characterization: The setup generates cavitating flows with flow-restrictive elements, which are selected to be in the form of channels (here: micro-channels or mini-channels formed from polyether ether ketone (PEEK)) with various diameters. A stainless steel tubing with a diameter of 4.5 mm is connected to the micro-/mini- channels. The connection between the tubes is selected to (e.g. include proper Swagelok fittings to) provide a sudden reduction in diameter, thereby reducing the static pressure, which leads to the generation of cavitation bubbles and cavitating jet flows. The flow path lengths inside the flow restrictive elements (here: lengths of the channels along a fluid flow direction therethrough) are selected to be adjusted in such a way that the generated bubbles and vapor phase could reach the outlet of the flow restrictive elements (here: exit of the channels). Thus, this length is kept e.g. at 4.5 mm to better exploit the energy released from the collapse of the cavitation bubbles. To reduce light reflection from the target plate and increase emissivity, besides the calibration of the thermal camera, the target plate is colored black.

Experimental Procedure: The experiments are carried out in two separate steps. In the first step, temperature variations on the target plate are measured using the thermal camera system. The target plate is connected to the system via sustaining clamps, which hold it against vibration. A thermal camera (FLIR Systems) and a workstation with an image post processing software capture the temperature variations on the target plate resulting from exposure to cavitating jet flow. The target plate is held by means of clamps, e.g. at a distance of 1.8 cm from the outlet of the flow restrictive element (here: exit of the channel). The selected upstream pressures are 10, 40, and 60 bar. The exiting jet is exposed to the atmospheric pressure of 1 bar. Surface temperatures are recorded at three different time steps for each micro-/mini- tube and each upstream pressure. Time steps are selected as 0 (just after), 30 seconds, and 120 seconds after the exposure of the surface of the target plate to the cavitating flow.

In the second step, the flow structure is visualized utilizing a high-speed camera system for the aforementioned channels at different segments relative to the exit of the channels and injection pressures. The spray structure is divided into six identical segments from the emergence of the jet at the outlet of the channel down to the location where the flow (including a cavitating jet) interacts with the target plate. Each segment is selected to have a length of e.g. 3 mm. The visualization experiments are performed at several upstream pressures e.g. ranging from 5 to 60 bar. To study the spray formation in the different segments, the exposure time is adjusted to a very low value e.g. of 1 ps. The images of the cavitating flows are collected by a double-shutter CMOS camera, which allows the acquisition of two successive images with a resolution of 1280 x 800 pixels (pixel size of 0.02 mm) within a very short time delay. The CMOS camera is equipped with a macro camera lens (type K2 DistaMax with focal length: s = 50 mm and f-number: f = 1.2) and is mounted at a distance of 342 mm from the imaging plane, yielding a magnification of M = 0.137. This optical arrangement ensures that only a central region of the lens is used, where aberration can be neglected. The images are exposed in a background illumination mode using a pulsed LED array consisting of 551 high-performance LEDs with a total area of 160 mm x 100 mm. In front of the LED array, an opaque plate is installed to produce diffuse illumination. The typical duration of the light pulses is 0.05-0.07 ms, whereas the time delay between the two successive images is adjusted to the local flow velocity in the range of 1-3 ms.

Flow Characterization: The mass flow rate is obtained by measuring the fluid mass passing from the flow restrictive element outlet cross-sectional area over a given time period. The experiments are carried out at a broad range of upstream pressures, and all temperature measurements and visualization tests are repeated several times to ensure the reliability of the obtained results. Using the manufacturer's specification sheets and also the propagation from the uncertainty propagation method by Kline and McClintock, the average uncertainties in cavitation number (±6.7%), flow rate (±1.4%), inner diameter (±0.002 mm), and pressure drop (±0.3%) are obtained.

The results show a temperature rise in all of the cases. In Fig.10, the contours on the left side of each row indicate the temperature profile before jet impingement. The subsequent contours show the temperature variation after approximately 1 (named as 0) and 30 s surface exposure to the cavitating jet.

Each cavitating bubble, which is generated in the microchannel carries a potential energy expressed with the following Eq. (1):

Half of the potential energy of the cavitating bubbles is converted to heat after collapse. Therefore, finding the number of bubbles entering the extension and collapsing there could reveal an estimation of the heat generation of the cavitating bubbles. Since the whole volume of the microchannel is occupied with bubbles, when supercavitation happens in the micro orifice, the volume fraction of vapor in the bubble number density calculation can be approximated as one. Multiplying the bubble number density by the vapor occupied volume leads to the number of the bubbles in that control volume in accordance with the following Eq. (2):

The above equations 1 and 2 lead to an estimation of the potential energy of the cavitating flow and consequently the estimated heat generation that can be converted to electricity. From a single micro orifice covering an effective exposure area of several mm2, an output power of several hundred mW could be achieved (M. Ghorbani, A. Mohammadi, A.R. Motezakker, L.G. Villanueva, Y. Leblebici, A. Kosar, Energy Harvesting in Microscale with Cavitating Flows, ACS Omega. 2 (2017) 6870-6877). By applying an appropriate upscaling technique, the amount of heating can be in the order of magnitude of hundreds of Watts, which is adequate to satisfy auxiliary heating/cooling requirements of an electric vehicle in most ambient temperature conditions.

The figures presented for supporting the specification, representatively show a combination of separate features which are disclosed in the specification; and any alternative combinations of said features which are in consistency with the teaching of the specification are also within the targeted scope of protection related to the present invention.

Reference signs:

10 hydraulic low pressure container 11 mechanically powered hydraulic pump

12 hydraulic high pressure accumulator 13 power transfer module (PTM) with clutch

15 vehicle transmission sub-system 20 device

21 flow restrictive element 211 upstream side

212 downstream side 22 thermo- and/or photoelectric generator

23 indentations 24 inlet

25 outlet 26 pressure sensor

50 climatisation fluid pumping unit 51 hydraulically powered climatisation fluid pump

52 electrically powered climatisation fluid pump 53 hydraulic fluid cycle

61 heating device 62 cooling device

63 climatisation fluid cycle 70 HVAC sub-system

80 BEV-related subject to heat transfer 81 cabin of BEV, cabin air of BEV

82 battery of BEV 100 system

111 mechanically powered hydraulic pump

221 vehicle transmission, regenerative braking and climatisation controllers 224 kinetic energy harvesting controller module 225 valve for adjustable hydraulic flow control

226 microfluidic system controller module 250 flow aligner

400 tank (e.g. high pressure nitrogen tank)

401 liquid container 402 pressure gauge 403 first fine control valve micro filter 405 pressure gauge 406 second fine control valve pressure gauge 408 micro/mini channel as flow restrictive element cavitated spray 410 target plate 411 light source computer 413 thermal camera 414 optical camera