The present invention relates an improved heat transfer system for cooling and/or heating items or areas, and more particularly to a heat transfer system which incorporates a turbine for compressing a heat transfer fluid.

Heat transfer systems are widely used for heating and cooling purposes by move heat towards or away from an article or area in order to heat or cool it as required. Typically, a heat transfer fluid is used which absorbs heat from one area and then expels that heat in another. One simple example of such a system is a domestic heating system in which water is heated up in a boiler and then pumped around a property and directed to pass through radiators, heating the radiators up, which, in turn, heat the area around the radiator and hence the room in which the radiator is located.

Another well-known system is an air conditioning system which is used to remove heat from an area in order to cool the area down. In a typical air conditioning system, a heat transfer fluid is compressed in a compressor, typically a piston based compressor, cause it to change state from a gas into a liquid. Once the fluid reaches a certain pressure, it is then passed through to a first heat exchange zone in the form of evaporator coils, where the pressure is reduce, allowing the gas to expand, a process which causes the gas to cool down, with the result that heat is absorbed from the atmosphere around the evaporator coils and that atmosphere is thereby cooled. The heated gas to then moved to a second heat exchange zone in the form of a condenser which is located away from the area to be cooled and is used to allow the heated gas to dissipate heat, whereupon it condenses back to a liquid before being passed back to the compressor to be compressed again and the cycle repeated.

The problem with existing systems is first that reliance on a liquid state as part of the process means that the existing systems are gravity specific and a result they must be installed in a fixed orientation. This is OK for some applications but severely restricts the use for other applications where different orientation is required due, for example, to space restrictions. Similarly, the efficiency of existing systems is limited.

According to the present invention there is provided a heat transfer system comprising a turbine having an inlet and an outlet, the turbine being configured to compress a fluid passing between the inlet and the outlet so as to increase the pressure thereof, an accumulator having an input fluidly connected to the outlet of the turbine for accumulating the pressurised fluid passing out of the turbine, the accumulator further including an outlet fluidly connected to the inlet of the turbine, a heat transfer means having an inlet fluidly connected to the outlet of the turbine and an outlet fluidly connected to the inlet of the turbine, and a control manifold configured to selectively control the flow of fluid through the heat exchange means and the accumulator so to selectively control the rate of flow of pressurised fluid through the heat exchange means and the rate of flow of pressurised fluid bypassing the heat exchange means.

A heat transfer system in accordance with the invention has the advantage that it avoids the need for a separate condenser, so as not to be gravity reliant for any part of its operation and hence does not require are particular orientation to work. As a result, the system is much more flexible in its applications. Furthermore, the effective output of the system of the invention is much higher compared with prior art systems of similar size, enabling it to be implements in much more compact and efficient arrangements.

Preferably, the heat transfer system is a cooling system, and the heat transfer means is a cooling means which is configured to reduce the pressure of the fluid passing therethrough, the reduction in pressure causing a reduction in temperature in the fluid which cools the heat transfer means so as, in turn, to cool the environment surrounding the heat transfer means.

IN a preferred embodiment, the fluid passing through the turbine, which in a particularly preferred implementation is a mixture of warmer liquid and colder gas, is compressed into a liquid as it passes through the turbine so that it is wholly a liquid as it leaves the turbine. The compressed liquid is then stored in the accumulator in its liquid state and is also a liquid at the inlet to the heat transfer means. During its expansion in the heat transfer means, the drop in pressure causes the liquid to change state into to become a gas, the gas exiting the heat transfer means and being fed back into the turbine inlet where it is mixed with the cold, high pressure liquid from the accumulator. By combining the warmer liquid and colder gas, the temperature of the liquid is reduced without the need for a separate condenser, which eliminates the prior art reliance on gravity for proper operation of the system.

More particularly, the phase changed gas exiting the heat exchange means is drawn into the turbine, helping to keep the heat exchange means at low pressure. At the same time, pressurised liquid from the accumulator is also released in a controlled fashion, in particular anywhere between 2 and 20 times a second, into the intake of the turbine to mix with the lower pressure gas from the heat exchange means. When the high pressure liquid enters the low pressure space of the turbine inlet chamber, it expands and uses the heat collected by the gas from the heat exchange means, removing the need for a condenser or separate heat exchanger for removing the heat from the gas exiting the heat exchange means. Since the liquid in the system of the invention is only present in a high pressure environment, then there is no reliance on gravity to move it around.

IN one embodiment, the control manifold has an inlet which is directly connected to the outlet of the turbine and includes first and second outlets, the first outlet being fluidly connected to the inlet of the heat exchange means and the second outlet being connected to the inlet of the accumulator. In this way, the manifold controls the flow through the accumulator and the heat exchange means by controlling the delivery of the fluid thereto. IN another embodiment, the accumulator is directly connected to the outlet of the turbine upstream of the manifold and the heat exchange means, the outlet of the accumulator being connected to the inlet of the manifold, which, in turn, has two outlets, one which connects to the heat exchange means and the other which connects to the turbine. In this configuration, the flow through the accumulator is controlled by the manifold on the downstream side by controlling the flow of fluid out of the accumulator. It will be understood that other configurations may be possible within the knowledge of the skilled person, it being necessary only that the system allows selective control of the flow of fluid through the heat exchange means and also selective control of fluid from the accumulator to bypass the heat exchange means and flow directly back to the inlet of the turbine.

Preferably, the heat exchange means is a cryoplate which contacts with the item or items which are to be cooled, for example, seated on top of a CPU or having an LED array mounted thereon.

In a preferred embodiment, the turbine comprises at least a first stage mounted on a main shaft having an Inlet primary impeller blade feeding to three compressor blades, the diameter of each of which is decreased compared to the preceding one. The first stage advantageously feeds to a second stage having an impeller blade and. three further decreasing compressor blades. In a particularly preferred configuration, the turbine has six stages, each stage comprising one shrouded impeller blade followed by three shrouded compressor turbine blades, each stage tapering in diameter, in particular smoothly tapering, and the impeller of each stage being of smaller diameter than the last compressor blade of the previous stage, all said stages being mounted on the single main shaft.

The turbine includes a housing having an internal surface which preferably includes rifled channels extending around the housing in the direction of rotation of the impeller and compressor blades, in a particularly preferred arrangement, the internal casing has 1:5 rifled channels feeding the outlet below the main shaft of the impresser assembly.

Preferably, an outlet of the turbine connects to a brass block micro electromagnetic valve body located in the output pathway of the turbine, with a pressure sensor located therein prior to a check valve that feeds the accumulator, where higher pressure liquid is stored.

In one embodiment, the manifold preferably includes an input line and a two-way micro electromagnetic valve having two outlet lines. In particular, a first outlet line of the manifold preferably connects to an expansion valve leading to the heat exchange means. When the low ^r pressure heat exchange means reaches maximum pressure for the Boyles phase change effect, the valve is closed to maintain storage pressure in the accumulator. A passive line out feeds to a dual high and low-pressure sensor module which send signals to a control board where a controller measures pressures from both regions to maintain temperature of the heat exchange means in the desired range either pre-set or user preference.

The second, outlet line of the manifold then feeds back to the turbine inlet, either directlv in an embodiment in which the manifold is located downstream of the accumulator, or via the accumulator in an embodiment in which the manifold is located upstream of the accumulator. A pressure sensor is preferably used to determine when to engage the turbine to reduce pressure in the heat exchange means to maintain the phase change effect. If starting from cold the accumulator charges the turbine by releasing a small boost from the accumulator, the accumulator then being recharged to peak pressure.

A line in may be provided from the low-pressure heat transfer means into the control manifold so vacuum can be applied by the turbine to maintain low pressure or desired pressure in the heat exchange means.

From the accumulator, it may pass through the main valve body where the low- pressure regulator feeds the expansion valve for the low-pressure heat exchange means.

In use, the turbine is preferably started when the pressure in the heat exchange means reaches the point when the fluid ceases to be at Phase state, creating vacuum to reduce pressure in the low-pressure portion of the system, until the desired temperature range is achieved. Once the turbine shuts down, a check valve from the low pressure may- then be closed and at first start up fluid from the accumulator may be released into the turbine to assist start up and lubricate the turbine. Pressure between the high and low systems is preferably regulated by micro electromagnetic control valves, actuated by- signals from the pressure sensors in the valve body and governed by the control board program.

Maintaining a high and low-pressure system ensures availability to charge the heat exchange means from reserve pressure in the accumulator.

The turbine gains an assist on when the pressure in the heat exchange means becomes too high or the pressure in the accumulator drops too low, this maintains equilibrium between the two systems.

In one embodiment, the turbine may have a single impeller having a pitch angle preferably in the range of 7.5° to 13°, and an angle of attack in the range of 28° to 42°. The impeller may feed a series of 5 sets of blades, preferably having a 45% to 60% mesh ratio and a 19° -28° reduction ratio, and the blades preferably having a pitch angle in the range of 5° to 11° and an angle of attack preferably in the range of 75° to 87°. The compression ratio may be between 420% and 475% from inlet to output, providing sufficient compression to compress the fluid into a liquid, such as trichloroethylene into an effervescent liquid in a solution of olerathyn based suspension. The specific gravity in that case might be substantially 6 to 9 mol.

IN particular, the system may have a single impeller of 7.5° pitch angle with a 38° angle of attack feeding a series of 5 sets of blades with a 50% mesh ratio and a 25° reduction ratio and blades with a 6° pitch angle 82° angle of attack, producing a compression ratio of about 430% from inlet to outlet, with a fluid having a specific gravity of around 7mol. In one embodiment, the interior chamber of the turbine is angled downward toward the outlet, and in the final portion of the interior chamber a rifled twist is preferably- applied to assist the outflow.

Preferably, the primary impeller has a small concave near the trailing edge to catch the pressure from the internal assist. The blades are preferably shrouded, in a particularly preferred embodiment, a first blade array comprises a primary impeller which feeds a first set of compression blades. The next blade array has an anti-cavitation impeller which feeds to a second set of compression blades, followed by further blade sets, each of which decreases in size compared to the previous set, preferably following a constant taper. The blade array will then comprise an anti- cavitation impeller with compression blades, following the same rate of decrease in diameter.

The inlet to the turbine preferably comprises two inlet pipes, one from the low pressure heat exchange means and one from the high pressure accumulator, the pipes feeding top and bottom on the intake with the high-pressure feed from the accumulator angled to the top of the primary impeller. The low pressure is drawn from the lower pipe as the impeller makes its lowest point of turbulence, near the bottom of the intake.

In one optional development, the system may include two accumulators so the pulses of assist thrust would, be more constant. The primary impeller may have a biconvex leading surface, whilst the actual lift value surface would be in accordance with the mass coefficient flow formulae, and variant surface so no cavitation is possible from the compressed vortices, A steady reduction of 18° to a following series of counter rotating blades separated by static stators between each series of 3, to a final drive reverse impeller directing the high pressure flow to a twin outlet, which would create a more constant state and balance across a much wider svstem. The drive system for the turbine may be realised as ultra-high frequency electromagnets.

The present invention further provides a method of operating cooling system comprising using a turbine to compress a gas or semi-gaseous fluid into a liquid, feedings some of the compressed fluid to a heat exchange means, storing at least some of the compressed gas in an accumulator, allowing the fluid to expand in the heat exchange means such that the temperature of the fluid reduces and the fluid absorbs heat within the heat exchange means, feeding the lower pressure fluid back to the turbine and mixing it with pressure fluid from the turbine outlet before passing the mixture back into the turbine to be recompressed.

In order that the invention may be well understood, there will now be described an embodiment thereof, given by way of example, reference being made to the accompanying drawings, in which:

Figure 1 is a schematic view of a cooling arrangement as an embodiment example of the system of the invention;

Figure 2 are variable views of an embodiment of a housing for a turbine which forms part of the invention;

Figure 3 is a side view of a blade assembly for the turbine of the invention; and

Figure 4 is a side view of a turbine housing with the blade assembly mounted therein.

Referring to Figure 1 there is shown a cooling system according to the invention which may be used to cooling a variety of different things from individual items which as a computer processors, an LED array or even an environment which as to cool a room. The example shown in Figure 1 utilises a cryoplate 6 as discussed below to cool, say, a computer processor but it will be understood that the system may be applied to a wide range of applications and may also be used to heat rather than cool if desired. The system is based on a typical air conditioning type system in which a fluid is compressed and then passed to a cooling zone where it is allowed to expand, the drop in temperature associated with the expansion causing heat to be absorbed into the fluid in the cooling zone, and the heated fluid is then moved to another zone where the heat is removed before being recirculated back for compression again.

In difference to systems known in the prior art, the heart of the system of the present invention is a turbine 1 which is used to compress a heat transfer fluid. The turbine 1 has an input end la by means of which low pressure fluid enters the turbine, and an output end lb by means of which compressed, higher pressure fluid exits the turbine.

The output end lb of the turbine 1 is connected by means of a conduit 2 to the inlet 3 a of a manifold which controls the outlet of the pressurised fluid between two outlets 3b, 3c to feed either the crypoplate 6 or an accumulator 4. More particularly, one outlet 3b extends from the manifold 3 to the accumulator 4 where the pressured fluid may be stored. The other outlet 3b feeds to the inlet of the cryoplate 6. Suitable control means is connected to the manifold for controlling the feed of the fluid between the crypoplate 6 and the accumulator 4. The control means also controls an outlet valve (not shown) in the accumulator 4 by means of which the flow of pressurised fluid out of the accumulator and back to the inlet la of the turbine 1 may be controlled as described below.

The cryoplate 6 includes an expansion valve (not shown) by means of which the high pressure fluid entering the cryoplate 6 is allowed to expand, causing the pressure and hence the temperature of the fluid to drop as it passes through the cryoplate, and the liquid to evaporate to a gas. As the low temperature gas passes through the cryoplate 6, it absorb heats from the cryoplate to cool it down and hence the environment around the cryoplate, such as an item on which the cryoplate is mounted. The now low pressure gas, which has been heated by the heat absorption which occurs within the cryoplate, then passes out of the cryoplate 6 and is fed back to the input of turbine where it is mixed with pressurised, lower temperature fluid from the accumulator. In Figure 1, the two feeds are illustrated as joining upstream of the turbine inlet, but in a preferred embodiment, the turbine has two inlets, one which feeds from the accumulator 4 and one which feeds from the cry opiate 6, the physical location of each inlet being chosen in order to optimise the efficiency of the system and in particular of the operation of the turbine 1.

The turbine 1, shown in more detail in Figure 2, is formed by a housing 10 having a central shaft 21 (shown in Figures 3 and 4) on which are mounted a number of blades 22 in a well-known manner. The blades 22 in the turbine 1 of the invention are arranged in sets 22a, 22b, 22c, 22d, 22e, 22f in a cascade fashion, with each set having an impeller blade 23 at its upstream end followed by a number of compressor blades 24, the last compressor blade 22 in the set feeding to the impeller 23 of the next set. As shown in Figure 2a, the housing 10 has an internal cavity 11 in which the blades are housed, the cavity 11 being open at the inlet end la and the outlet end lb. The cavity 11 extends longitudinally through the housing 10 concentrically about the longitudinal axis 12 with which the shaft is coincident for the length of the blade array formed by the sets of blades. The walls 13 of the cavity 11 tapers inwards towards the longitudinal axis 12 towards the outlet end lb of the housing 10 at a constant taper angle, and the diameter of the blades reduce in a corresponding fashion so that radial space between each blade and the cavity wall 13 remains substantially constant along the length of the blade array. The blades 22 are not present all the way to the outlet end lb of the housing 10, but finish short thereof, the fluid passing the last blade being fed into an outlet 14 having an axis which is inclined to the longitudinal axis 12 of the cavity as shown in Figure 2 so that the outlet 15 is off-centre in the outlet end lb of the housing 10. In the preferred embodiment, the final portion of the chamber which angles towards to the outlet 15 has a 3: 1 rifled twist to assist outflow, and the chamber is angled by 3 degrees towards the outlet.

The primary impeller 23 at the inlet end la has a small concave near the trailing edge to catch the pressure from the internal assist. The blades 22 are preferably shrouded, and the thickness including the shrouds, in the preferred embodiment, for the primary impeller is 3.5mm thick and 26.6mm wide, and the following series is 3.25mm wide. The first set including the impeller is 4 blades; the next set is 3mm wide with an anti- cavitation impeller followed by 5 blades then a 2.5mm wide set of 7 decreasing in size by 15° final drive is 2.5mm wide anti-cavitation impeller and 5 2.25mm wide compression blades following the same rate of decrease in diameter.

IN an alternative embodiment, the inlet is formed by two pipes feeding top and bottom on the inlet, the high pressure feed from the accumulator being angled at 6° to the top of the primary impeller, and the low pressure being drawn from the lower pipe as the impeller makes its lowest point of turbulence, near the bottom of the intake.

The system of the invention uses Boyle's law and the physics of the material phase change in conjunction with a re-circulating compression turbine system to keep a steady state between the high and low pressure systems which are not gravity specific to remove heat from the cryoplate and keep a sustained temperature of a specific designated range at the cryoplate.

The system operates as follows:

The turbine is started to draw in fluid into the inlet and compress it. When starting from cold, if any pressurised liquid is present in the accumulator, it is used to charge the turbine by a release valve being opened by the controller to release a small boost of high pressure fluid from the accumulator. As the turbine spins up, the compression of the fluid across the turbine increases and the compressed fluid is used to recharge the accumulator and also to feed the cryoplate, the intake of fluid into the turbine, which is drawn from the cryoplate, developing the low pressure environment in the cryoplate. The temperature and pressure throughout the system is monitored by an array of temperature and pressure sensors, and the controller controls the amount of pressurised fluid fed from the accumulator for mixing with the low pressure feed from the cryoplate in order to control the temperature of the cryoplate.

The turbine may be switched off during operation once the cryoplate has reached its target temperature. It may then be started when the pressure in the cryoplate reaches the point when the fluid, ceases to be at Phase change. Starting the turbine will create a reduction in pressure to reduce pressure in the low-pressure portion of the system, until the desired temperature range is achieved. Once the turbine shuts down, the check valve from the lo pressure is closed. When start up is required, again, fluid from the accumulator is released into the turbine to assist start up and lubricate the turbine. Pressure between the 2 systems high and low is regulated by micro electromagnetic control valves, actuated, by signals from the pressure sensors in the valve body and governed by the controller.

Maintaining a high and low-pressure system ensures availability to charge the cold sink from reserve pressure in the accumulator.

The turbine gains an assist on when the pressure in the cold sink becomes too high or the pressure in the accumulator drops too low, this maintains equilibrium between the two systems.

Although the system has been described above in relation to a cooling solution, it will be understood that it would be equally applicable to heating solutions. In that case, the recycle would be diverted to an even larger cold sink, to draw in more heat, which would be combined with the heat generated by the compression process and that would be fed by a secondary circulation, along with the heat acquired by the cryo system, to a heat exchange through a condenser or the like. Heat could be ambient or extracted by air or water passing through the exchanger.

A heating configuration would operate using the same principles of the cooling solution of the invention. The heating solution would will additionally include a primer pump and would operate to draw heat from the environment, which does not necessarily have to be at a particularly high temperature for the system to work, the heat which the system can produce being the difference between the ambient temperature of the environment and the lowest temperature at which the heat transfer fluid undertakes a phase change of state. The size of the required heat exchanger and the required primer pressure will likely necessitate a second accumulator in the heating system. The system of the invention has been described in connection with a small scale cooling requirement such as for a micro-processor. However, it will be understood that the system is scalable and could be used for any cooling application which might be required.