BONATSOS, George (Via Bariaga 16D, Gavardo, I-25085, IT)
| "A SYSTEM TO COLLECTIVELY UTILIZE SOLAR THERMAL ENERGY AND
THERMAL ENERGY OF A FLUID"
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CLAIMS 1. A system to collectively and cooperatively utilize, solar thermal energy and the thermal energy of at least one fluid to heat water, characterized in that it includes a heat pump, a solar thermal collector and a water storage tank, connected together functionally and united together in one singular unified and integral structure, forming a monoblock ready for installation, with all of the subsidiary elements necessary for its function and operation, to form a single functional apparatus ready for installation and use.
2. A system according to claim 1 , characterized in that the heat pump, the solar thermal collector, the water storage tank and all the subsidiary elements, are all on and contained within the same supporting frame and/or housing and/or protective enclosure against inclement weather and climatic weathering degradation, forming a single integral functional apparatus, and in that the sole means emerging from said apparatus, are the means to connect the heat pump to a power source, electrical and/or combustion heat source, command and control cables, and the hydraulic connections to a hydronic space and/or sanitary water heating system.
3. A system according to claims 1 and 2, in which a solar thermal collector having a solar radiation receiving and absorption surface, a circuit that contains a thermal transfer liquid associated to the said solar radiation receiving and absorption surface and connected to the water storage tank, and insulated section underneath said circuit, furthermore, characterized in that the heat pump has at least one evaporator circuit that contains the refrigerant, and is associated to the solar radiation receiving and absorption surface of the solar thermal collector, to absorb at least both the solar thermal energy and the thermal energy contained in the ambient air.
4. A system according to the claim 3, characterized in that that the solar radiation receiving and absorption surface of the solar thermal collector has integrated into it, essentially two circuits: a first circuit that contains the thermal transfer liquid and a second circuit that contains the refrigerant of the evaporator circuit that is connected to the heat pump.
5. A system according to any previous claims, characterized in that the heat pump has two evaporator circuits: a first one attached and associated with the radiation receiving and absorption surface of the solar thermal collector, and a second circuit positioηed below the thermal insulation section of the solar thermal collector.
6. A system according to any previous claims, characterized in that an additional hydronic circuit for the circulation of already used and stored hot water is placed below the thermal insolation section of the solar thermal collector. 7. A system according to claims 5 and 6, characterized in that the evaporator circuits of the heat pump are arranged in such a way that, one circuit absorbs directly the solar thermal energy, the thermal energy contained in the ambient air and the thermal energy contained in the thermal transfer fluid of the solar collector circuit, the other circuit absorbs thermal energy contained in air and the thermal energy contained in the additional hydronic circuit.
8. A system according to any previous claims in which the heat pump circuits are filled with refrigerant directly in the factory. 9. A system according to any previous claims, characterized in that the condenser of the heat pump is placed inside and immersed into the thermal transfer liquid, along with the heat exchanger of the space and/or sanitary water heating circuit coming from the edifice.
10. A system according to claim 9 r characterized in that the condenser of the heat pump and the heat exchanger of the space and/or sanitary water heating circuit coming from the edifice are integrated in a single heat exchanger having two separate circuit.
11. A system according to any previous claim, characterized in that, a fan is associated to the solar thermal collector to force air over the solar receiving surface of the collector. |
"A SYSTEM TO COLLECTIVELY UTILIZE SOLAR THERMAL ENERGY AND
THERMAL ENERGY OF A FLUID"
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Filed of the Invention
The present invention relates to a mechanical apparatus that can exploit multiple renewable energy sources concurrently, more specifically it relates to a hybrid solar thermal system, in general referring to technologies capable of utilizing alternative and renewable energy sources, and refers particularly to a system in which various components of a thermosyphon solar thermal collector and a heat pump are provided to interact physically and synergistically in a new and innovative manner to produce hot water efficiently.
State of the Art
The existing sanitary and space heating systems currently in use for domestic, commercial, and industrial buildings are numerous and well known. They range from systems that use electrical energy to combustion systems that use biomass and petroleum derivatives, to systems that use solar radiation for the production of heat. All of these systems have advantages and disadvantages that depend on various factors, such as the type of technology used, the cost of the energy source, cost of installation and maintenance of
the plant equipment, and thermal energy performance. Furthermore, in certain countries or geographical areas. The choice of which system is best to implement, can be influenced also by other factors, such as which energy source is easier to obtain locally, the type of building, and the annual climatic conditions that all further increase the types and number of systems available to produce thermal energy.
It is also correct to state, that the problem of industrial emissions (that create airborne particulates and greenhouse gasses) is another factor that further motivates designers, architects, and builders to consider utilizing clean and renewable energy sources for heating systems in their decision make process.
The present inventor has studied carefully the actual technologies in use for the production of heat; from electrical and liquid carbon energy sources (e.g. petroleum) and carbon source gasses (e.g. methane), mechanical thermodynamic systems (e.g. refrigeration technology) and renewable energy sources and technology (e.g. solar) and has surprisingly found that the use of hybrid systems engineered and combined in certain ways, can provide an excellent solution to the problem of reducing energy costs for heating purposes while utilizing clean energy sources. This invention can generate good market attraction worldwide, and assist the dissemination of solar energy water heating systems, that can consequently help to reduce greenhouse gas emissions that are also a chief cause of undesirable global climatic change.
The two basic technology systems that the inventor has studied are: heat pumps that use geothermal, air, water, materials that are subject to phase change, and solar thermal energy as heat sources - and solar thermal energy technology systems, more specifically systems that have integrated a solar thermal collector and a water storage tank. Still more specifically meaning systems that have a solar thermal collector and water storage tank attached and connected together in one complete integral structure, completely integrated and ready for installation and use, commonly known in the art as, thermosyphonic systems and/or "natural circulation by convection" systems (all hereinafter called: thermosyphon) .
To better reinforce the reasons and the essence of the present invention that will become steadily more clear further on, there is provided herein other information concerning the state of the art.
Regarding heat pumps. It is well know that it generally involves a technology that is capable to absorb the heat content of a substance, such as a fluid (e.g. air or water) and/or phase change material, and transfer and release such heat content, to another fluid (or substance) such as water in an insulated storage tank.
One type of heat pump called "air source" heat pump, generally finds its justified and convenient use in climatic zones which require moderate heating and refrigeration specifications. In such countries heat pump technology is becoming more well known and important day by day because of increasing media and "word of mouth" publicity from satisfied users. In other countries however this technology is not well known, implemented and/or not
considered convenient for the fact that (in this case) when air that is used as a heat source, decreases in temperature (such as in winter conditions) there is also a natural corresponding decrease in the efficiency of the heat pump (less heat is entrained in the ambient air). However recent progress in heat pump technology has produced surprising results regarding efficiency, also during cold weather, thus reawakening interest in the adoption of this technology even where the quantity of solar energy received at ground surfaces is in the order of 1000 kWh/m2 annually.
Air Source heat pump technology is capable of transferring heat from one fluid to another fluid, with a ratio of efficiency that is around 2.5 to 3.5 times the electrical energy required for its function. Therefore regarding part of the objective of the present invention, it is considered good to use a heat pump, to transfer the thermal energy of outside ambient air to a thermal transfer liquid (e.g. water and/or water/glycol mixture in the water storage tank of a thermosyphon system) because the great efficiency of the heat pump process. This efficiency is commonly called C.O.P (Coefficient of Performance) and is typically in the order of 2.5 to 3.5 times that of an electrical heating element (a typical electrical heating element has a C.O.P of 1 meaning that with 1Kw(e) of electrical energy it can produce around 1 Kw(t) of thermal energy).
There is also the possibility to use a type of heat pump called "absorption heat pump" which is thermally driven, typically by combustion of a carbon based energy source (e.g. methane) instead of being mechanically driven by electrical energy.
Furthermore regarding solar energy technology systems. One of the most efficient (cost to performance ratio) systems available today, is what is normally called in the art, thermosyphon systems. This system is efficient because due to the heat induced, natural liquid convection cycle, it does not require a pump, and because it can be supplied already assembled from the factory (water tank and solar thermal collector integrated together) the cost of maintenance and installation of these systems onsite are low when compared to other systems. As stated these systems can be installed already assembled and/or the solar thermal collector and the water storage tank can also be separately placed and assembled in order, and installed onsite. In any case, when assembled for correct function, the water storage tank and the solar thermal collector are in close and intimate contact, to avoid useless costs for installation and a waste of materials, to importantly avoid unnecessary thermal losses and reduced natural water circulation convection efficiency (e.g. if the water storage tank and solar thermal collector where to be installed distantly from each other) all of which would make it unjustified to use solar thermosyphon system technology.
Briefly returning to heat pumps. Also heat pumps (whose major components are: evaporator, where the major amount of heat is absorbed, condenser, where the major amount of heat is released, compressor, expansion valve, and the circuits charged with refrigerant) can be prepared as a single unit directly in a factory, ready for installation and use, or one or more of the major components can be assembled onsite and the circuit charged with the refrigerant and be made to operate.
In our case it is preferred that the heat pump is prepared in a factory as a unit ready for installation and use. In this case all the major components, including the compressor and both heat exchangers (e.g. serpentine tube) of the evaporator and the condenser, are charged with the refrigerant (typically a phase change substance) and placed inside a casing for protection against inclement weather conditions and weathering damage, and can be shipped as a complete unit, and be installed on a roof (and/or any suitable surface) with and connected to a water storage tank, to heat the water inside it - and/or the condenser heat exchanger placed inside a building and connected to the hydronic space heating (e.g. radiant floor) and/or sanitary water circuits.
At this point it could start to become quite evident that there could be enormous savings and increase of thermodynamic efficiency, if both of these systems could be engineered to be combined technologically in an new and innovative manner. More specifically the use of the low cost, good efficiency, low maintenance thermosyphon solar thermal collector (using free solar energy as a heat source) and the highly efficient and well proven, heat pump technology, that while using electrical energy for function, is so efficient that it furnishes 2.5 to 3.5 or more thermal energy in watt/h than could be produced by an electrical heating element using the same amount of electrical energy. It should now start even more evident that, this hybrid system could be designed and engineered and manufactured in a factory, tested, packaged and transported, placed and installed onsite as a long life, industrial quality, single unit, thus making the installation easy and simple for the installers, thereby saving time and costs, for various connections and cabling, rather
than if the heat pump and thermosyphon system were to be installed and used separately.
From the research made, and as per currant knowledge, no such system is offered in the marketplace nor has any such system been preconized. There are heat pumps that are assisted by solar thermal collectors, that are however, physically separated and installed separately from each other.
Even from a profound documentary patent research study, there has not been found any pertinent documentation that reveals or describes a similar system proposed by the inventor, or even the results or performance of the use of such a system . Object and summary of the Invention
The present invention has been conceived based on the inventive principles outlined above. In fact it is the objective of the invention to provide a new high efficiency system utilizing well known and well proven heat pump technology components, of industrial high quality and low cost, combined synergistically with systems and technology for the gathering of solar thermal energy, in a new and original way, and configured and packaged in such a way, that contributes to the complete simultaneous and easy installation and use of both technologies and apparatuses, to produce a single unified, integrated system with low cost and high performance (when confronted with other presently known systems) for water heating purposes.
This objective is achieved, in accordance with the invention, by combining a heat pump, solar thermal collector, water storage tank, and all the
subsidiary elements necessary for its function (e.g. sensors, switches, valves, electrical cables, command and control, system, etc.) in one technologically integrated, single unified structure, to produce and supply in one monobiock unit already prepared for installation and use, one cost competitive and high efficiency apparatus.
For a more complete comprehension:
By "one technologically integrated, single unified structure" also means "packaged together", further meaning, that all of the major and minor components of both technologies (heat pump; thermosyphon solar collector and water storage tank) are on the same supporting frame or carcass and in the same covering and enclosure against inclement weather and/or weathering damage, and which requires solely the connection to an electrical power supply, control and command cables, and inlet and outlet tubes of the water supply to be heated. By "one monobiock apparatus already prepared for installation and use" means that all of the components of both technology systems are united and fixed in a stabile and permanent fashion, in the same structural support, and that the frame or carcass that covers and encloses the components, forms and is also considered to be part of the structural support. By "collectively utilize solar thermal energy and the thermal energy of a fluid", intends to mean that the heat pump not only absorbs thermal energy from the outside ambient air, above and below the solar thermal collector, but also absorbs the solar thermal energy that is incident to the receiving surface (called also in the art - selective surface) of the solar thermal collector.
By "monoblock" we intend to mean, a grouping of all minor and major components such as, heat pump, solar thermal collector, water storage tank combined operatively together, and not being more than 1 meter distance amongst adjacent major components. It becomes fundamentally important to understand that all of the actual systems in use, such as heat pumps assisted by solar thermal collectors and vice versa, are not united and integrated in one single monoblock structural unit, ready for installation and use, but are all connected and installed separately onsite, at the moment of installation. This is evident because in the art and in the industrial thermodynamic sector, these systems are commonly called "split" systems.
To further make more clear the scope and objectives of the invention, and the significance of the effectiveness and convenience of implementing an integration of both technologies in one singular structure, we hereby evidence that the three major components to integrate are: a solar thermal collector, a water storage tank, a heat pump.
In the marketplace currently there is only available, either solar thermosyphon systems, which are comprised generally of a solar thermal collector and water storage tank, or air source heat pumps that can also include a water storage tank.
Therefore it now becomes evident that this invention is useful and efficient because, whereas both systems mentioned above, utilize respectively separate water storage tanks - now in just one unified system: just one storage tank can be implemented and utilized (typically the one that is
indispensable to the function of the thermosyphon system) by both technologies, thus making significant savings.
Above all and most importantly, this innovation provides the possibility to charge the heat pump circuit with refrigerant, and test the system directly at the origin of production and assembly (e.g. the factory) thus avoiding what is normal practise when the major components of the systems are separate and independent, and must be assembled onsite: charging at the installation site the heat pump circuit with refrigerant.
It is therefore fundamentally important, that this invention creates effectively the conditions to fabricate directly in a factory, a high efficiency apparatus for the heating of water, that makes capable, as per the title of the invention to: collectively utilize solar thermal energy and the thermal energy of a fluid, through the use and combination of heat pump technology combined with a thermosyphon system (by integrating heat pump, solar thermal collector and water storage tank) in one structurally integrated and unified monoblock system, ready for installation and use.
Another innovative aspect, is that in the integrated monoblock system of the invention, the evaporator of the heat pump extends at least, and is affixed onto the solar energy receiving surface of the solar thermal collector, while the condenser of the heat pump, is substantially positioned in the water storage tank and immersed in the thermal transfer fluid.
Another important and fundamental aspect of the invention, resides in that at least part of the surface of the evaporator of the heat pump is also part of the solar energy receiving surface of the solar thermal collector, thus
augmenting the heat absorbing capacity of the entire system even in conditions of weak light (e.g. low solar isolation levels).
Another aspect of this invention, is that there is provided a second evaporator from the heat pump that is placed below the insulated surface of the solar thermal collector, enabling thereby the absorption of heat that is commonly dispersed from the roof surface of a building, surface of which the monoblock apparatus is mounted and installed. This innovation, the use of both (two) evaporator circuits is very advantageous, in that the heat absorbing surface area is doubled without doubling the installed surface area of the entire apparatus.
This aspect of the invention becomes even more important (and also is evident to those instructed in the art of heat pumps) when we consider that during the cold seasons, with temperatures around 4°C, a heat pump could possibly avoid to periodically entire into the common de-icing cycle, in which a reversing valve sends hot refrigerant into the evaporator circuit (that is in outside cold ambient air) for a few minutes at a time (generally 2 to 10 minutes). The reasons for this are that because in the integrated system, the evaporator is interposed between the insulation of the solar thermal collector and the roof, it is thus partially protected from the "open" air, and because it also receives the emission of thermal energy lost from the roof, it thus reduces in some measure the necessity to enter into the de-icing cycle, therefore amongst other things, saving energy costs.
Another important aspect of the invention is that the condenser of the heat pump, is in direct contact with the thermal transfer liquid that is to be
heated in the water storage tank of the thermosyphon system. The same condenser can also form part of a two circuit heat exchanger: a first circuit is for the water circulating in the space and/or sanitary water heat system of the edifice; a second circuit is for the hot refrigerant circulating in the heat pump. Another important fact, resides in that it is well known that water has a higher specific heat value than air, and thus can store more heat than air, and is also a more heat conductive material (than air) making it a more efficient means for the transfer of thermal energy. It is estimated that it requires around 4 times less energy to extract thermal energy with a heat pump from water as a heat source, rather than from "air" as the heat source.
Thus another fundamentally important aspect of the invention, is that it is possible to place in a building (e.g. basement of a house) a secondary water storage tank, that is made to contain already used hot water (before being discard into a sewer) in which a bypass valve can be opened on command and have the warm water stored in such secondary tank be made to flow in an additional hydraulic circuit associated with one of the evaporator circuits (preferable the evaporator circuit below the insulated surface of the solar thermal collector). This innovation will enable the heat pump to extract some of the residual heat of the stored water, and transfer this heat to the water storage tank further augmenting the efficiency of the system. This innovation helps to extend greatly the operative seasonal time that the system can operate efficiently, in that during the cold season (also with below freezing temperatures) by using opportune microprocessors and software associated with the heat pump and it's sensors, the heat pump can "calculate" when it
would be the most energetically efficient to extract heat from the secondary water storage tank instead from the cold ambient "air" as a heat source, thereby reducing the frequency of the de-icing cycle, and further increasing the general efficiency of the system especially during the winter seasons. Another consequential, however important aspect of the invention, is that the solar thermal collector has integrated into it two separate circuits: one is the typical thermal transfer liquid (typically water/glycol) circuit of the solar thermal collector system and a second circuit typically the evaporator circuit of the heat pump containing the refrigerant. It is even possible that the same solar thermal collector can have three circuits incorporated into it; the two circuits already mentioned above, and a third hydraulic circuit that comes from the secondary water storage tank that contains the already used and stored hot water that can flow into the third circuit of the solar thermal collector.
Another aspect of this system is that the circulation of the thermal transfer liquid (e.g. water or water/glycol mixture) in the circuit of the solar thermal collector can be by natural convection, or by the assistance of a pump.
Another aspect of this invention is that the air source heat pump may be provided with a fan to force air over the receiving surface solar thermal collector (if enclosed with glass) to augment the transfer of the thermal energy from air to evaporator circuit. Detailed Description of the Invention
More details of the fundamental elements are evidenced and made more clear, by the description of the attached schematic designs that exemplify an embodiment of the invention, in which: Fig. 1 - shows the system of the invention, in one monoblock apparatus; Fig. 2 - shows a partial cutaway of the integrated system to evidence the circuits of the solar thermal collector and the heat pump. Fig. 3 - shows a cross-section of part of the solar thermal collector of the integrated system.
As represented, the integrated system includes at least one solar thermal collector 11 , a heat pump 12 and a water storage tank 13 that contains the thermal transfer liquid to be heated, all unified together physically and functionally.
As in the usual manner, the solar thermal collector 11 has a solar radiation reception and absorption surface 14 (that can also have what is well known in the art, a selective surface, incorporated on it) and it's own hydraulic circuit 15, that contains the thermal transfer liquid, and that has thermal insulation 16 placed underneath, to impede thermal dispersion.
Furthermore as the thermal transfer liquid acquires heat from the solar radiation surface 14 of the solar thermal collector and then circulates by heat induced natural convection (and or by assistance of a pump - not shown) into the water storage tank 13, it heats the space water heating fluid or sanitary water flowing through a heat exchanger 24 (Fig.1) that is in contact with the now hotter thermal transfer liquid in the water storage tank. The water storage tank 13 is usually insulated to reduce heat dispersion, and the heat exchange
24 can be connected, through a circuit 24', to whatever kind of space and/or sanitary water heating system is used in a building.
The heat pump 12 has a compressor 17 that can be placed in an opportune enclosure 18 and associated with the solar thermal collector 11 and with it's relative water storage tank 13. The compressor 17 is connected to the evaporator 19, typically a metallic serpentine tube also functioning as a heat exchanger, and a condenser 20' also typically a metallic serpentine tube functioning as a heat exchanger.
As also stated previously, the evaporator serpentine 19 extends and is integrated into the top surface of the solar thermal collector 11 and more precisely below the solar receiving surface 14.
The condenser serpentine extends and is positioned in the water storage tank 13 in contact with the thermal transfer liquid, or it can also be integrated into the space and/or sanitary water heat exchanger 20, that is immersed into the thermal transfer liquid.
The system can also include and consist of a second evaporator serpentine 21 placed below the insulation 16 of the solar thermal collector, and can include an additional hydraulic circuit 22 destined to circulate the already used hot water that is recovered and stored in the secondary water storage tank (not shown).
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