Patent Publication Number: US-2022235988-A1

Title: Systems and Methods for Compressing Gas Using Heat as Energy Source

Description:
FIELD OF THE INVENTION 
     The present invention relates to the technique of refrigerant compressors, and more particularly, to refrigerant compressors using thermal energy as power source for the compression. 
     BACKGROUND OF THE INVENTION 
     Heat pumps are commonly used in a variety of situations requiring the transfer of thermal energy between two paces. There are a variety of types of heat pumps including geothermal/water, geothermal/air, air/air etc. Each of these types uses different sources and sinks for the transfer of thermal energy. 
     Refrigerants used in heat pumps condense at various temperatures. Following condensation in a heat pump, the refrigerant often has only a slightly lower temperature than before condensation but has changed its physical state. For example, for a refrigerant having an evaporation temperature of 0° and a condensation temperature of 50°, this means the most optimal compression would result in a gas having exactly 50° and the saturation pressure corresponding to 50°. Temperatures above this correspond to unnecessary work. If one then lets the gas condense to liquid, it might have a temp of about 49°. If one assumes constant heat capacity over the range of 0 to 50, 49/50 of the work remains as heat. 
     By reusing this energy wisely, much can be gained. If this energy can be used to compress gas and do so with 100% efficiency, only a small amount of the original compression energy would be needed to compress new gas. If one were to use a regular heat engine, the maximum theoretical efficiency of a heat engine (which no engine ever attains) is equal to the temperature difference between the hot and cold ends divided by the temperature at the hot end, all expressed as absolute temperatures, which would approximately, using the temperatures above, render in a theoretical efficiency of about 15%. 
     A number of inventions cool down the refrigerant before the compressor to decrease the pressure of the refrigerant or possibly to increase the density and thus reduce the energy consumption of the compressor. 
     In U.S. Pat. No. 5,797,277, the refrigerant is cooled down by condensation from the evaporator in a heat exchanger that simultaneously cools the refrigerant condensed from the condenser. However, a pressure reduction of the refrigerant seems inevitable in this process. Furthermore, the gas is not superheated prior to the cooling, the cooling does not seem to be controlled as to recycle the energy whereby the compression isn&#39;t very energy efficient. 
     In U.S. Pat. No. 4,208,885 a transducer is used, which takes the expansion valve location, but also compresses the refrigerant out of the evaporator. The refrigerant that then flows towards the compressor can then be fed directly to the compressor or heat exchanged against refrigerant flowing from the condenser. 
     However, in neither of these patents it seems like the gas is consciously superheated solely for the purpose of applying pressure on cold gas and thereby compress it. None of the above patents shows a device where the refrigerant (after evaporator) is first heated, partly ejected into a compressor part, and then having non ejected gas cooled while at the same time recycling left energy. This behavior of the present invention solves the problem of getting low pressure gas entering the apparatus. Also, their only examples show cooling of evaporated gas, wherein the superheating of the gas tend to be very small, and therefore the pressure increase above saturated pressure is small. 
     To make the compression energy efficient it is recommended that cooling under pressure is done recycling the energy otherwise it won&#39;t render in energy efficient compression. To make the compression ratio large, a very large temperature increase is needed or several units working in series. None of the above show examples of such solutions. 
     One problem with the previously described solution in section is that it is difficult to inject low pressure gas into a high-pressure volume. Assume you have a sealed high pressure hot gas volume, applying pressure on a cold gas volume, compressing said cold gas volume. It can start to compress said cold gas volume, but when it loses its density it will have less pressure than the cold high-pressure destination, whereby it will not eject any gas into said flow. Neither will an evaporator add any gas into said hot high-pressure volume, since it has still quite high pressure. 
     Another problem with the previously described solution is that if you manage to achieve a volume of high pressure, it is difficult transfer that pressure to a different destination volume. For example, assume you have 2 containers, a source, and a destination, with the same volume, the source having a start pressure of 2 bar and the destination of 1 bar, whereby you would get something close to 1.5 bar in both containers when you connect them. Therefore, to keep the pressure high in the flow of the compressor part in previously described solution, you can only eject a small part of the superheated gas in the ejection part, to prevent it from decreasing in pressure. In theory this problem can be solved, since most of the energy is still in the non-ejected gas, which theoretically can be reused, to heat up new gas. Part of the solution is therefore an advanced heat exchanger unit for gas. In this solution, you often want to transfer energy from a refrigerant to a gas, gas to gas, and gas to refrigerant. This can be difficult, partly because hot gas has a higher pressure than cold gas and therefore cold gas will not flow towards hot gas, furthermore you might have to warm up the heat exchanger to heat the gas and this probably has greater mass than the gas. 
     Thus, there is a need for a system to address the problems discussed above. 
     SUMMARY OF THE INVENTION 
     The present invention is a system and method for using thermal energy to compress gas. The system of the present invention comprises a compressor chamber, a gas heating device, and a gradational heat transfer conduit. The method of the present invention comprises heating gas with the gas heating device to a high pressure, high temperature, and low density, then ejecting the heated gas into the gradational heat transfer conduit, cooling the heated gas as it passes through the gradational heat transfer conduit, and transferring the cooled gas to the compressor chamber with a low temperature, high pressure, and high density. 
     In some embodiments, movement of the gas through the gradational heat transfer conduit comprises a unidirectional flow. The unidirectional flow is cooled down in the flow direction by one or more heat exchangers, while hot gas at the same time applies pressure on the cold gas, whereby the density increases in the cooling direction. 
     In one preferred embodiment, the invention proposes an apparatus separated in two parts, a compressor part wherein hot gas applies pressure on cold gas and a second part comprising a heat exchanger unit for gas wherein gas is heated to a high pressure, whereafter it is ejected into said compressor part, whereafter thermal energy from non-ejected gas is recycled as described. 
     In some embodiments, the gas heating device comprises an apparatus that heats up cold gas while keeping it&#39;s density fairly stable, or in some cases increasing the density, wherein gas is heated to a high pressure, whereafter it is ejected into the gradational heat transfer conduit, whereafter thermal energy from non-ejected gas is recycled while cooling down said non ejected gas, whereby a volume cooled non ejected gas is either decreased in pressure, whereby new external gas with substantially the same temperature but with higher density can be absorbed into said volume. Or said cooled non ejected gas is decreased in volume whereby new external gas with substantially the same temperature and density can be injected in parallel to said volume. In this way hot gas can be constantly injected to the gradational heat transfer conduit. 
     Hence, according to the invention, the compressor chamber, gas heating device, and gradational heat transfer conduit, in combination, create a gas compressor system that receives cold gas of low pressure and eject slightly hotter gas of slightly higher pressure. The output from one gas compressor system can be injected into a second gas compressor system. The present invention can advantageously be implemented in several steps to become a gas compressor system that together can perform a large compression. Since it is suggested that thermal energy should be recycled as well as possible, both in the first and second part, recycled energy from one gas compressors system can be used as energy for another gas compressor system, and thereby you can get a large compression from a small energy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of the system of the present invention in accordance with at least one embodiment. 
         FIG. 2  is an illustration of the system of the present invention in accordance with at least one embodiment. 
         FIG. 3  is an illustration of the one-way valves of the present invention as used in chambers and conduits in accordance with at least one embodiment. 
         FIG. 4  is an illustration depicting the movement of gas through chambers and conduits of the present invention. 
         FIG. 5  is an illustration of the openable walls of the present invention as used in chambers and conduits in accordance with at least one embodiment. 
         FIG. 6  is an illustration of the gas heating device of the present invention in accordance with at least one embodiment. 
         FIG. 7  is an illustration of the components of the rotating portion of the gas heating device in accordance with at least one embodiment. 
         FIG. 8  is a series of graphs depicting the difference in work output for an embodiment of the present invention using the pressure transfer device. 
         FIG. 9  is an illustration of multiple heat transfer devices of the present invention connected in series in accordance with at least one embodiment. 
         FIG. 10  is an illustration of the pressure transfer device of the present invention in accordance with at least one embodiment. 
         FIG. 11  is an illustration of the pressure transfer device of the present invention in accordance with at least one embodiment. 
         FIG. 12  is an illustration depicting the movement of gas through the pressure transfer device of the present invention in accordance with at least one embodiment. 
         FIG. 13  is an illustration of the system of the present invention in accordance with at least one embodiment. 
         FIG. 14  is an illustration of the system of the present invention in accordance with at least one embodiment. 
         FIG. 15  is an illustration of the plurality of hot subpumps, plurality of hot pistons, and plurality of pressure transfer devices of the present invention in accordance with at least one embodiment. 
         FIG. 16  is a flowchart of a method of compressing gas in accordance with at least one embodiment of the present invention. 
         FIG. 17  is a flowchart of a method of managing gas flow as part of the method of compressing gas in accordance with at least one embodiment of the present invention. 
         FIG. 18  is a flowchart of a method of directing gas through the pressure transfer device as part of the method of compressing gas in accordance with at least one embodiment of the present invention. 
         FIG. 19  is a flowchart of a method of heating and cooling gas as part of the method of compressing gas in accordance with at least one embodiment of the present invention. 
         FIG. 20  is a flowchart of a method of operating pumps as part of the method of compressing gas in accordance with at least one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     As a preliminary matter, it will readily be understood by one having ordinary skill in the relevant art that the present disclosure has broad utility and application. As should be understood, any embodiment may incorporate only one or a plurality of the above-disclosed aspects of the disclosure and may further incorporate only one or a plurality of the above-disclosed features. Furthermore, any embodiment discussed and identified as being “preferred” is considered to be part of a best mode contemplated for carrying out the embodiments of the present disclosure. Other embodiments also may be discussed for additional illustrative purposes in providing a full and enabling disclosure. Moreover, many embodiments, such as adaptations, variations, modifications, and equivalent arrangements, will be implicitly disclosed by the embodiments described herein and fall within the scope of the present disclosure. 
     Accordingly, while embodiments are described herein in detail in relation to one or more embodiments, it is to be understood that this disclosure is illustrative and exemplary of the present disclosure and are made merely for the purposes of providing a full and enabling disclosure. The detailed disclosure herein of one or more embodiments is not intended, nor is to be construed, to limit the scope of patent protection afforded in any claim of a patent issuing here from, which scope is to be defined by the claims and the equivalents thereof. It is not intended that the scope of patent protection be defined by reading into any claim limitation found herein and/or issuing here from that does not explicitly appear in the claim itself. 
     Thus, for example, any sequence(s) and/or temporal order of steps of various processes or methods that are described herein are illustrative and not restrictive. Accordingly, it should be understood that, although steps of various processes or methods may be shown and described as being in a sequence or temporal order, the steps of any such processes or methods are not limited to being carried out in any particular sequence or order, absent an indication otherwise. Indeed, the steps in such processes or methods generally may be carried out in various different sequences and orders while still falling within the scope of the present disclosure. Accordingly, it is intended that the scope of patent protection is to be defined by the issued claim(s) rather than the description set forth herein. 
     The present invention is a compressor using heat as energy source. The present invention comprises a compressor chamber  3 , a gas heating device  4 , and a gradational heat transfer conduit  5 . While the apparatus may be used as a standalone system for gas compression, it may also be used in conjunction with a traditional energy source to lower the work performed by a compressor. Generally, the solution presented by the present invention uses superheated high pressure hot gas to put pressure on cold gas. This can be accomplished by having cold gas on one side and by repeatedly injecting hot gas on the other, compressing the cold gas. 
     In some embodiments, this is accomplished through unidirectional flow, cooled down in the flow direction. This cooling is performed by the one or more heat exchangers  51  while keeping the pressure substantially constant. while at the same time preventing mixing between hot and cold gas performing inductive heat exchange within the flow. One benefit of this solution, compared to using a double acting compressor, is the simplicity, you get a constant flow without having to empty and fill said compressor. Another benefit is the energy efficiency as much of the heat transferred in the one or more heat exchangers  51  can be recycled to heat up new gas for the system. 
     Referring to  FIG. 1 , in general, the present invention comprises a hot end  1  and a cold end  2 . The gas heating device  4  is located at the hot end  1  of the system, further comprising a heater chamber  41 , a heater inlet  42 , a heater outlet  43 , and a heating portion  44 . The compressor chamber  3  is located at the cold end  2  of the system, further comprising a compressor inlet  31 , and a compressor outlet  32 . Between the heater chamber  41  and the compressor chamber  3  is the gradational heat transfer conduit  5 . The gradational heat transfer conduit  5  further comprises a first end  52 , a second end  53 , and one or more heat exchangers  51  arranged in series. The gradational heat transfer conduit  5  is configured to have a substantially unidirectional temperature gradient and substantially unidirectional gas flow from the hot end  1  to the cold end  2 . It should be noted that the present invention may comprise more than one gradational heat transfer conduit  5  in various embodiments and configurations. In some embodiments, the gradational heat transfer conduit  5  is a singular apparatus. 
     The overall principle of the compressor system as shown in  FIG. 1  is as follows. The heater chamber  41  contains a hot source quantity of gas, and the compressor chamber  3  contains a cold destination quantity of gas. The hot source quantity of gas is superheated so that it has a pressure notably higher than gas with the same density and a saturated temperature. Hypothermic flow of gas occurs is a substantially unidirectional flow from the heater chamber  41  to the compressor chamber  3 , through the one or more heat exchangers  51 . The gas experiences a drop in temperature, but little to no drop in pressure during this flow. Much of the energy dissipated to the one or more heat exchangers  51  can be regained and recycled to be used at a later stage. In the preferred embodiment, the gradational heat transfer conduit  5  and one or more heat exchangers  51  are configured to cool the gas close to the saturation temperature of the gas when it reaches the cold end  2  of the system. 
     In short, gas enters the gradational heat transfer conduit  5  from the heater chamber  41  with high pressure, high temperature and low density, and exits the gradational heat transfer conduit  5  to the compressor chamber  3  with high pressure, low temperature, and high density. Thus, gas has been compressed using the pressure of input heat. A large amount of the energy used to heat the gas to its superheated state can be recycled by the energy gained in the one or more heat exchangers  51 . For example, the fluid used in the one or more heat exchangers  51  may be sent to gas heating device  4  by a heat recycling line  54 . 
     Referring to  FIG. 2 , the system of the present invention is illustrated with regard to the flow of heat that may occur throughout the system during operation with an expanded view of the gas heating device  4 . This figure is acts to show help illustrate the movement of heat and gas throughout the system and is only a single embodiment of the invention. In use Gas enters the device via an input  1 . 1 , from an external source  1 . 0 . The external source may be represented by an evaporator, outdoor air, another device or any other source that can supply a substantially constant pressured gas. The gas is then moved through the heater, passing by walls of gradually increasing temperatures until it reaches its maximum at position  1 . 5 . There in the heater chamber  41 , it now has a superheated temperature, and a superheated pressure notably higher pressure, than in  1 . 0 . The heater-chamber  41  is then connected to the input of the gradational heat transfer conduit  5 , having slightly lower pressure, applying pressure on the gas within the gradational heat transfer conduit  5 . The cold end of the gradational heat transfer conduit connects to a compressor chamber  3 , as part applying pressure on the gas within the compressor chamber  3 , thereby transferring some of the pressure from the heater-chamber  41  to the compressor chamber  3 . Hot, high-pressured gas enters the gradational heat transfer conduit at the hot end  1 , and cold, high-pressured gas exits the conduit at the cold end  2 . By cooling the gas in the gradational heat transfer conduit preferably in a counterflow manner, and more preferably using a liquid refrigerant, cooling the gas while trying to receive as high a temperature as possible at the output of the counterflow flow, a large amount of heat can be recycled and used to heat new gas (see  1 . 17 - 1 . 19 ). 
     After the heater-chamber  41  has connected to the gradational heat transfer conduit  5 , for applying pressure on the gas withing the conduit, due to pressure equalization. The remaining gas within in the chamber  41 , will have slightly dropped in temperature and pressure, due to expansion (illustrated by shaded volumes between 1.5 and 1.9). The heater chamber is then disconnected, having lower density. However, a significant amount of heat still remains, and can be used for heating gas in the gas heating device  4 . This is represented in the drawing by gas volumes, being moved towards colder positions  1 . 6 ,  1 . 7 ,  1 . 8 , (sparser stripes in the pattern representing lower density), while transferring heat to heated volumes (see  1 . 2 ,  1 . 3  and  1 . 4 ). After a volume of gas has cooled down to its initial temperature (equal to the source  1 . 0 ), it will have both low density and temperature (see ex  1 . 8 ). It will now easily be filled with new gas, when connected to an external source  1 . 0  (see ex  1 . 1  and  1 . 0 ). 
     The substantially unidirectional temperature gradient and gas flow in the in the gradational heat transfer conduit  5  may be achieved by the continuous supply of superheated gas from the heater chamber  41  to the gradational heat transfer conduit  5 , which promotes flow from the hot end  1  to the cold end  2 . Referring to  FIG. 3 , this substantially unidirectional gradient and flow can be promoted by the introduction of a plurality of one-way valves  501  in the gradational heat transfer conduit  5 . These one-way valves  501  should have a very low cracking pressure. In one embodiment, the one-way valves  501  may be tesla valves to promote the unidirectional flow through the gradational heat transfer conduit  5 . 
     Referring to  FIG. 4 , in an alternative embodiment, substantially unidirectional flow is achieved through the use of a plurality of narrow conduits  502  rather than a single larger conduit. In such an embodiment, the gradational heat transfer conduit  5  comprises a plurality of narrow passages. Using narrow passages in combination with a continuous supply of gas to the plurality of narrow passages promotes unidirectional flow and limits turbulation. 
     Referring to  FIG. 5 , in another alternative embodiment, the gradational heat transfer conduit  5  comprises a plurality of openable walls  503 . In this embodiment, the plurality of openable walls  503  is arranged in series throughout the gradational heat transfer conduit  5 . Each of the plurality of openable walls  503  may be opened individually to allow the gas on either side of the wall to mix. In use, each of the plurality of openable walls  503  is opened consecutively, starting with the one closest to the output and ending with the one closest to the input. Since the cold end  2  has slightly lower pressure than the hot end  1 , the gas closest to the output will expand, thereby slightly losing pressure, so when the next openable wall opens it will also open towards a section that has had a chance of expanding. Due to this the gas will tend to expand towards the output. 
     Another way to achieve substantially unidirectional flow in the gradational heat transfer conduit  5  is to repetitively connect the first end  52  to heater chambers  41  with new and high pressure and repetitively connect the second end  53  to the compressor chamber. Doing so will ensure that the output has lower pressure than the input and will therefore promote unidirectional flow. 
     Each of the above referenced embodiments for achieving substantially unidirectional flow in the gradational heat transfer conduit  5  may be used individually or in combination with another embodiment. For example, the one-way valves  501  may be used within the plurality of narrow passages. Additionally, while referred to here in connection with the gradational heat transfer conduit  5 , the above-referenced embodiments for achieving substantially unidirectional flow may be implemented in other pipe, conduits, chambers, etc., such as within the one or more heat exchangers  51 . 
     The gas heating device  4  comprises a heater chamber  41 , a heater inlet  42 , a heater outlet  43 , and a heating portion  44 . Input gas enters the gas heating device to be heated by the heating portion  44  and ejected out the heater outlet  43 . The heater outlet  43  is connected to the hot end  1  of the gradational heat transfer conduit  5 , allowing for ejection of heated gas directly from the heater chamber  41  to the gradational heat transfer conduit  5 . During ejection, a first volume of the heated gas is ejected to the gradational heat transfer conduit  5 , while a second volume of the heated gas remains in the heater chamber  41 . The heating portion  44  is configured to heat up the gas until it gets to a notably higher pressure than the input gas while maintaining as high a density as possible. The gas heating device  4  may further comprise a cooling portion  45  configured to cool the second volume of the heated gas after ejection to allow for addition of new, low-pressure gas to the gas heating device  4 . 
     In one embodiment of the gas heating device  4 , it is preferred that the heating portion  44  heats up the gas, using other warm refrigerant, bringing the gas as close to the maximum temperature of the warm refrigerant as possible, while stealing as little energy as possible from the other warm refrigerant, also while keeping the density of the heated gas as high as possible. In such an embodiment, the cooling portion  45  may cool down subparts of the heated gas within the gas heating device  4 , after other subparts of the heated gas have been ejected into the gradational heat transfer conduit  5 , using cold refrigerant, bringing the cold refrigerant temperature as close to the warm gas maximum temperature as possible, while stealing as little energy as possible from the warm gas, getting as low output pressure of the cooled gas as possible. 
     Referring to  FIG. 6 , in one embodiment, the gas heating device  4  may comprise a plurality of heater inlets  401 , a plurality of heater outlets  402 , and a plurality of heater chambers  403  in addition to the heating portion  44  and the cooling portion  45 . The plurality of heater chambers  403  may be arranged radially in a rotating portion and configured to move around a central axis  404  while the plurality of heater inlets  401  and plurality of heater outlets  402  remain stationary, configured to connect to each of the plurality of heater chambers  403  sequentially as they move. In such an embodiment, new external gas enters the plurality of heater chambers  403  through the plurality of heater inlets  401 , the gas is heated by the heating portion  44  as the plurality of heater chambers  403  move toward the plurality of heater outlets  402 . Once each of the plurality of heater chambers  403  reaches one of the plurality of heater outlets  402 , the first volume of gas is ejected from the heater chamber  41  out the heater outlet  43 , while the second volume of gas remains in the heater chamber  41 . This applies for each of the plurality of heater chambers  403  passing by each of the plurality of heater outlets  402 , meaning that each of the plurality of heater chambers  403  ejects lesser and lesser pressure for each of the plurality of heater outlets  402  it passes. The second volume of gas in each of the plurality of heater chambers  403  is cooled by the cooling portion  45  as it moves back toward the plurality of heater inlets  401 . Once each of the plurality of heater chambers  403  reaches the plurality of heater inlets  401 , the cycle begins again with introduction of new external gas. 
     The components of the rotating portion  400  of the gas heating device  4  are shown in  FIG. 6 . The rotating portion comprises a base  405 , a plurality of walls  406 , and a lid  407 . The plurality of walls  406  fits within the base  405  and is sealingly covered by the lid  407 , creating the plurality of heater chambers  403  within the rotating portion  400 . The plurality of walls  406  is ideally made of a light and highly insulating material to prevent heat transfer between the plurality of heater chambers  403 . Referring to  FIG. 6 , the heating portion  44  and the cooling portion  45  may be operated by the transfer of hot and cold refrigerants from one or more refrigerant reservoirs  408 , through a plurality of refrigerant lines  409 . The refrigerant lines  409  are arranged against the rotating portion of the gas heating device  4  and configured to provide and remove heat from specific areas of the rotating portion. The refrigerant lines  409  are shown in  FIG. 7  to run behind the rotating portion in contact with the base  405  of the rotating portion, however, the plurality of refrigerant lines  409  may also run along the lid  407  of the rotating portion. 
     In use, the gas heating device  4  embodiment shown in  FIG. 6  operates as follows. Input gas enters the gas heating device  4  through the plurality of heater inlets  401 . Each of the plurality of heater inlets  401  may be associated with a different pressure. In  FIG. 7 , the first input (i1) contains the highest pressure with the pressure decreasing sequentially, i.e. (i8) has the lowest pressure, and in between there will be different pressures, varying between the lowest and the highest. The rotating portion  400  moves clockwise one step at a time, allowing each of the plurality of heater chambers  403  to pass from position A to position H, taking in incrementally higher-pressure gas from a different heater inlet  42  at each position. The plurality of heater chambers  403  is then heated while moving from position Ito P, the gas incrementally increasing in temperature and/or pressure. The plurality of refrigerant lines  409  running along this area of the rotating portion transfer heat to the rotating portion. The refrigerant temperature and specific arrangement of refrigerant lines  409  may be adjusted to achieve preferred heating within this section of the rotating portion. After heating, the gas is ejected through the plurality of heater outlets  402 . Each of the heater outlets  402  may be associated with a different pressure. In  FIG. 7 , the first output (o1) receives the highest pressure with the pressure decreasing further to the right. Thus, as the plurality of heater chambers  403  advance from position Q to X, a portion of the gas is ejected through each of the plurality of heater outlets  402 , with the remaining gas in the heater chamber  41  reducing in pressure with each ejection. Finally, the plurality of heater chambers  403  is then cooled while moving from position Y to FF, the gas incrementally decreasing in temperature and/or pressure. The plurality of refrigerant lines  409  running along this area of the rotating portion remove heat from the rotating portion. The refrigerant temperature and specific arrangement of refrigerant lines  409  may be adjusted to achieve preferred cooling within this section of the rotating portion. This cooling allows the remaining non-ejected gas to be compatible in pressure with the gas entering the plurality of heater chambers  403  through the plurality of heater inlets  401  at positions A through H. 
     Referring to  FIG. 9 , multiple gas heating devices  4  may be connected in series. Through the use of multiple gas heating devices  4  and multiple gradational heat transfer conduits  5 , the compression ratio of the compressor may be the product of the compression ratios from each gas heating device  4 . Additionally, refrigerant can be recycled between gas heating devices  4 , making for a more efficient overall use of thermal energy. 
     Note, however, that the chambers in the following gas heating device  4  should be smaller than those in the previous one so that the compression achieved is not wasted. Furthermore, it can be seen at the inflow of the subsequent gas heating device  4  that, each cooled heater chamber will be sequentially connected to outflows, from the prior gas heating device, of different pressures, and does so in order of incrementally increasing pressure. 
     In the above manner incremental compression is achieved, i.e., a gas volume starting with a low pressure isn&#39;t compressed with gas of maximum pressure directly, instead said low pressure gas volume is compressed, in sequence, by gas volumes with incrementally higher pressure, preferably only slightly higher than the low-pressure gas volumes momentary pressure. This means less work is done by the volumes of higher pressure, meaning the work resembles the graph in  FIG. 8 c   , instead of the graph in  FIG. 8 b   . The more increments used, and the closer they are in pressure, compared to the destination, the closer the work gets to the graph of the optimal work described in  FIG. 8   a.    
     The above device/method for transferring more gas to higher pressure, from a source-gas chamber to a destination-gas chamber, is here called pressure-transfer-device/pressure-transfer-method. 
     The system of the present invention may further comprise a pressure transfer device  6  between the gas heating device  4  and the compressor chamber  3  or between one gas heating device  4  and a second gas heating device  4 . The pressure transfer device  6  may be fully contained within the gradational heat transfer conduit  5  or may otherwise connected in series with the gradational heat transfer conduit  5 . The pressure transfer device  6  more efficiently equalizes the pressure difference between the gas ejected from the gas heating device  4  and the gas already present in the gradational heat transfer conduit  5  or compressor chamber  3 , allowing more superheated gas from the gas heating device  4  to be ejected in each transfer, thereby increasing the volume of the first volume of gas in the heater chamber  41  to be ejected and reducing the volume of the second volume of gas in the heater chamber  41  to be cooled and reused. In sum, improved pressure transfer can be achieved by connecting two chambers of different pressures by way of a parallel array of intermediate chambers of decreasing pressure rather than a single chamber. 
     Referring to  FIG. 10 , the pressure transfer device  6  comprises an input coupling device  61 , an output coupling device  62 , and a plurality of pressure chambers  63 . Each of the plurality of pressure chambers  63  has a high-pressure end  64  and a low-pressure end  65 . The plurality of pressure chambers acts as chambers of varying intermediate pressures. The input coupling device  61  connects the heater outlet  43  of the gas heating device  4  to the plurality of pressure chambers  63  of the pressure transfer device  6 . The input coupling device  61  is selectably fluidly coupled with the high-pressure end  64  of each of the plurality of pressure chambers  63 . The output coupling device  62  selectably fluidly couples the low-pressure end  65  of each of the plurality of pressure chambers  63  to the gradational heat transfer conduit  5  or directly to the compressor inlet  31 . In use, the high-pressure gas from the gas heating device  4  enters the input coupling device  61  and is distributed to each of the plurality of pressure chambers  63  one at a time, resulting in each pressure chamber having a volume of gas with a pressure less than that of the preceding pressure chamber. Once the gas is distributed among the plurality of pressure chambers  63 , each of the pressure chambers  63  is connected to the output coupling device  62 , one at a time, in the opposite order that they were filled by the input coupling device  61 . For example, in an embodiment of the pressure transfer device  6  with three pressure chambers  63 , the input coupling device  61  couples with a first pressure chamber, filling it with a first volume of gas with a high pressure, then couples with a second pressure chamber, filling it with a second volume of gas with a medium pressure, then couples with a third pressure chamber, filling it with a third volume of gas with a low pressure. The output coupling device  62  then couples with the third pressure chamber, removing the third volume of gas, then couples with the second pressure chamber, removing the second volume of gas, then couples with the first cooling compressor, removing the first volume of gas. It should be noted that even the “low-pressure” third volume of gas in this example has a higher pressure than the gas present in the gradational heat transfer conduit  5  prior to pressure transfer. This process is additionally illustrated in  FIGS. 11 and 12 . 
     A benefit of using the pressure transfer device  6 , is that compressing a destination volume with incrementally increasing pressure is more energy efficient. If, for example, a large volume of high-pressure gas (Ex. 2 Bar) is to be discharged into a small volume of low-pressure gas (Ex. 1 Bar), the work performed could be represented by the graph in  FIG. 8 b   , while total needed work is represented by  FIG. 8 a    only. By compressing the destination volume in 4 steps, the work is represented by  FIG. 8 c   , which is an improvement compared to  FIG. 7   b.    
     Referring to  FIG. 9 , in one embodiment of the present invention, the pressure transfer device  6  is integrated between a first gas heating device  411  and a second gas heating device  412 . In such an embodiment, the plurality of heater outlets  402  of the first gas heating device  411  connect to the plurality of heater inlets  402  of the second heating device  412  by way of the pressure transfer device  6 . 
     Referring to  FIG. 13-14 , in one embodiment of the present invention, the cold end  2  of the compressor system further comprises a cold pump  701  and a cold piston  702 , and the hot end  1  of the compressor system further comprising a hot pump  703  and a hot piston  704 , wherein the cold piston  702  and the hot piston  704  are interconnected and move synchronously. In this embodiment, the cold end  2  and the hot end  1  are connected by the one or more heat exchangers  51 . The gradational heat transfer conduit  5  in this embodiment is combined with the pressure transfer device  6 , in that the plurality of parallel heat transfer conduits  5  act as the pressure chambers for the pressure transfer device  6 , allowing for the superheated gas to be cooled by the one or more heat exchangers  51  while traversing the pressure chambers  63  of the pressure transfer device  6 . The hot pump  703  and the hot piston  704  are contained within the gas heating device  4  of the present invention. 
     In addition, it can be noted that in  FIG. 1 , the heating portion  44  of the gas heating device  4 , responsible for heating the gas on its way to the heater-chamber, is integrated with the cooling of the gradational heat transfer conduit  5 . This is not necessary but provides the possibility to directly use recycled heat from the cooling for heating new gas. 
     In use, input gas enters the system at the cold end  2 . The first and second side of both the hot pump  703  and the cold pump  701  may then be connected, pumping a first volume of gas from a first side of the cold piston  702  to a second side of the cold piston  702  and simultaneously pumping a second volume of gas from the first side of the hot piston  704  to the second side of the hot piston  704 . The first side and the second side of both the hot pump  703  and the cold pump  701  are then disconnected. The second side of the hot piston  704  then connected to the pressure transfer device  6  at the heater outlet  43 . Decreased pressure from gas flow into the pressure transfer device  6  enforces compression of the gas on the second side of the cold piston  702 . 
     The hot pump  703  and cold pump  701  stabilized at a position where the pressure difference between first side and second side of the cold pump  701  equals the pressure difference between the first side and second side of the hot pump  703 . When the passages are open between the second side of cold piston  702  and the first side of the hot piston  704  with equal pressure within this domain, movement of gas from the cold end  2  into the one of more heat exchangers  51 , and movement of gas from the one or more heat exchangers  51  into the hot end  1  can occur without added work. Referring to  FIG. 14 , note that the compressor chamber  3  is being compressed by gas of increasing pressure, since the output of the pressure transfer device connects the compressor chamber  3  to gradational heat transfer conduits  5  of increasing pressures. To reinforce this movement of gas through the one or more heat exchangers  51 , a physical rectifier may be implemented on the cold piston  702  and/or the hot piston  704 , prohibiting movement in the backward direction. The rectifier may be further configured to be deactivated or to switch from one side of a piston to the other in order for the pistons to move in the opposite direction. 
     Note that it is advantageous to use previously described techniques, such as those shown in  FIG. 3-5 , to achieve unidirectional flow even when heating. As with cooling, they can be used separately or in combination in order to achieve the preferred results. In particular, the technique of  FIG. 5 , wherein a plurality of walls  503  separate warmer and colder parts of a conduit in the heat exchanger, whereafter they open step by step, in order by their distance from the outlet. Starting closest to the outlet (in this case in the hottest part) and ending closest to the entrance (in this case in the coldest part). Thereafter they are closed step by step in the opposite order, i.e., starting closest to the heat exchanger input (in this case in the coldest part) and ending closest to the outlet (in this case in the hottest part). Advantages of this technique are that it does not have cracking pressure, and can handle large pressure differences. 
     Referring again to  FIG. 5 , in such an alternative embodiment, the gradational heat transfer conduit  5  includes a plurality of openable walls  503 . In such an embodiment, the plurality of openable walls  503  are arranged in series throughout the channels of the gradual heating member. Each of the plurality of openable walls  503  can be opened individually to allow the gas on each side of the wall to mix. In use, each of the plurality of openable walls  503  is opened in succession, beginning with the nearest exit, and ending with the nearest entrance. Since the hot end  1  closest to the outlet opens first, the gas there can expand and thereby drop the pressure slightly, so when the next openable wall opens towards a warmer section which has had a chance to expand, it is more likely that it initially has a greater pressure. Due to this, the gas will tend to expand towards the outlet. 
     As the second volume of gas passes through the pressure transfer device  6  and the gradational heat transfer conduit  5 , it is cooled by a counterflow of the first volume of gas through the heat exchanger from the cold end  2  to the hot end  1 . The second volume of gas reaches the compressor chamber  3  through the compressor inlet  31  after passing through the pressure transfer device  6  and gradational heat transfer conduit  5 . At this point, the first volume of gas becomes the second volume of gas for the next cycle as a new first volume of gas enters the system at the cold end  2 . 
     In the one or more heat exchangers  51  of this embodiment, it is advantageous if the heated gas to be substantially moving unidirectionally towards the hot end  1 . To enforce this, the same techniques can be used here, as in gradational heat transfer conduit  5 . For example, openable walls  503 , opening in sequential order, may be used within the one or more heat exchangers  51 . In the embodiment using openable walls  503 , the openable walls  503  in the one or more heat exchangers  51  may be the same openable walls  503  used in the gradational heat transfer conduit  5  or otherwise connected to the openable walls used in the gradational heat transfer conduit  5  where the openable walls  503  in the one or more heat exchangers  51  open in the opposite order as those in the gradational heat transfer conduit  5  starting with the one closest to the input and ending with the one closest to the output. Through this embodiment, the same set of openable walls  503  can promote substantially unidirectional flow in opposite directions in the one or more heat exchangers  51  and the gradational heat transfer conduit  5  respectively. 
     In the embodiment described in the preceding paragraphs, the hot pump  703  may comprise a plurality of hot subpumps  801  with a combined volume equal to that of the cold pump. This embodiment may additionally comprise a plurality of hot pistons  802  associated with the plurality of hot subpumps, as well as a plurality of pressure transfer devices  803 . Such an embodiment is shown in  FIG. 15 . Increased efficiency in heating can be achieved by incremental gas transfer in this manner. 
     Each of the plurality of hot subpumps  801  can also use the one single pressure transfer device  6 , wherein each of the plurality of hot subpumps  801  connects its output to the pressure transfer device  6  that then runs through the same process for each subpump. It should however be noted, that in this case, when a subpump has been connected to a conduit with minimum pressure, it should be connect to that conduit, via some other connection than the input coupling device, otherwise the following subpump will be directly connect to the final conduit, which is not intended. 
     In use, Referring to  FIG. 15 , input gas enters the system at the cold end  2 . The hot pump  703  and the cold pump  701  may then be activated, pumping a first volume of gas from a first side of the cold piston  702  to a second side of the cold piston  702  and simultaneously pumping a second volume of gas from the first side of the plurality of hot pistons  802  to the second side of the hot piston  804 . The second side of the first hot piston  8041  then connected to the pressure transfer device  6  at a first heater outlet  431 , while the two sides of the remaining hot subpumps  801  remain connected. Decreased pressure from gas flow into the pressure transfer device  6  enforces compression of the gas on the second side of the cold piston  702 . In order, one by one, the two sides of remaining hot subpumps  801  will be disconnected from each other and connected to pressure transfer device, each time further enforcing compression of the gas on the second side of the cold piston  702 . Once all right sides of the hot subpumps  801  are connected to the gradational heat transfer conduit  5 , with a pressure equal to the input of the cold pump the cold piston  701  stabilizes at the same position as the previous embodiment. However, smaller total volumes have been connected to pressure transfer device  6 , ending up with same final low pressure, thus, initially, less gas is entering the cold pump than existing the hot subpumps  801 . In running through several cycles, an increased density at the output of the heating device is generated. The increased density will further increase the pressure of the input of the hot subpumps  801 , further enforcing compression of the gas on the second side of the cold piston  702 . Over the course of several cycles, the average amount of gas entering the system must equal the amount exiting. As for previous embodiment, when the second volume of gas, in this case for each hot subpumps  801 , passes through the pressure transfer device  6  and the gradational heat transfer conduit  5 , it is cooled by a counterflow of the first volume of gas through the one or more heat exchangers  51  from the cold end  2  to the hot end  1 . The second volume of gas reaches the compressor chamber  3  through the compressor inlet  31  after passing through the pressure transfer device  6  and gradational heat transfer conduit  5 . At this point, the first volume of gas becomes the second volume of gas for the next cycle as a new first volume of gas enters the system at the cold end  2 . 
     Each of the embodiments discussed above may further comprise additional heating elements for heating gas before it enters the gas heating device  4 , while in the gas heating device  4 , or before entering the gas heating device  4  from the recycling line  54 . For example, the embodiment shown in  FIG. 12  may further include a heating element beyond the gas heating device  4  to heat gas on the hot end  1  of the system. 
     It should also be noted that the embodiments above utilizing pumps can be coupled in series of several compressor device according to the embodiments, such that compressed gas from one compressor device can enter a subsequent compressor device to further compress the gas. One benefit of compressing by heating followed by cooling, is that recycled heat can be used again for the same gas, so long as the recycled heat has significantly higher temperature than the compressed gas. If heat is recycled efficiently, external heat only needs to be added to account for the amount not being recycled. 
       FIG. 16  is a flowchart of a method  1000  of compressing gas. Accordingly, at  1002 ,  1000  may include heating, using a gas heating device, a gas to an increased temperature and pressure. Further, at  1004 , the method  1000  may include ejecting, using a heater outlet, the gas from the gas heating device to a first end of a gradational heat transfer conduit. Further, at  1006 ,  1000  may include cooling, using one or more heat exchangers, the gas to a cooled temperature. Further, at  1008 ,  1000  may include transferring, using a compressor inlet, the gas to a compressor chamber. 
       FIG. 17  is a flowchart of a method  2000  of managing gas flow as part of the method of compressing gas. Accordingly, at  2002 ,  2000  may include promoting, using the gradational heat transfer conduit, unidirectional gas flow from the first end of the gradational heat transfer conduit to a second end of the gradational heat transfer conduit. Further, at  2004 , the method  2000  may include transferring, using a recycling line, heat from the one or more heat exchangers to the gas heating device. 
       FIG. 18  is a flowchart of a method  3000  of directing gas through the pressure transfer device as part of the method of compressing gas. Accordingly, at  3002 ,  3000  may include sequentially directing, using the input coupling device, incrementally lower-pressure gas into the plurality of pressure chambers. Further, at  3004 , the method  3000  may include sequentially expelling, using the output coupling device, incrementally higher-pressure gas from the plurality of pressure chambers. 
       FIG. 19  is a flowchart of a method  4000  of heating and cooling gas as part of the method of compressing gas. Accordingly, at  4002 ,  4000  may include providing, using one or more refrigerant reservoirs, refrigerant to the heating portion and the cooling portion. Further, at  4004 , the method  4000  may include providing heat, using the heating portion, to the gas. Further, at  4006 ,  4000  may include removing heat, using the cooling portion, from the gas. 
       FIG. 20  is a flowchart of a method  5000  of operating pumps as part of the method of compressing gas. Accordingly, at  5002 ,  5000  may include pumping, using a hot pump, gas across a hot piston. Further, at  5004 , the method  5000  may include pumping, using a cold pump, gas across a cold piston. 
     Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.