Working fluid extraction system for a displacement machine and method of operating the system - Patents.com

Abstract

A working fluid extraction system for a displacement machine (210) for removing condensable working fluid (280) from a working fluid / lubricant mixture in an internal volume (218) of the displacement machine (210) separate from a working chamber (217) of the displacement machine (210), the system comprising a condenser (271) operably connected to the internal volume (218), the condenser (271) being settable to a temperature and / or pressure lower than the temperature and / or pressure of the internal volume (218) such that working fluid (280) is drawn from the internal volume (218) into the condenser (271) during use.

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates to a thermo-mechanical system having a condensable working fluid, and to a method of operating such a system.

[0002] [background] Thermal machines, such as heat pumps, are known devices. Heat pumps are commonly used to heat indoor spaces or provide hot water to users. The use of heat pumps is desirable because they provide more sustainable heat than heating devices that use fossil fuels. Heat pumps transfer thermal energy from a low temperature heat source to a high temperature heat sink.

[0003] A refrigerant is used in a heat pump system. A refrigerant is a specially selected fluid that absorbs or releases heat as it circulates through the heat pump system. A compressor, in the form of a displacement device, is used to pressurize the refrigerant and move it through the system.

[0004] An expansion valve is used in combination with the compressor as a control device to control the balance between operating pressure / temperature and refrigerant / working fluid flow. As will be readily understood by those skilled in the art, the expansion valve provides a simple means to reduce the pressure, and therefore the temperature, between the condenser and evaporator sections of the heat pump, thereby completing the thermodynamic cycle.

[0005] Many industrial processes require high temperature heat, for example in the form of steam or hot water, which are extremely energy intensive to produce, especially when primary energy sources are used. Examples of industries that utilize high temperature heat include paper, food and beverage, chemicals, automotive, metals, plastics, engineering, textiles, and wood. For example, in the food and beverage industry, high temperature heat is used in processes such as drying, evaporation, pasteurization, sterilization, boiling, distillation, blanching, parboiling, concentration, tempering, and smoking, just to name a handful.

[0006] Industrial waste heat is usually not utilized due to its low temperature, which is lower than that required in many industrial processes. This waste heat can be upgraded and thereby reused using high temperature thermal machines such as high temperature heat pumps, which has obvious economic and environmental benefits.

[0007] Current high temperature heat pumps face challenges with respect to the working fluid and with respect to maintaining the desired properties of the lubricant in the compressor.

[0008] In screw, scroll and vane compressors, a significant amount of lubricant is generally added to the working fluid to achieve good lubrication and good sealing between the flank of the screw / scroll / vane and the housing. When the temperature becomes high, e.g., >100°C, the lubricant deteriorates more quickly and the performance is greatly reduced, resulting in reduced uptime, increased amortization, and reduced service life. At even higher temperatures, the lubricant may completely deteriorate and even mechanical failure may occur. Therefore, it is very important to maintain good lubricant quality and integrity throughout the life of the equipment.

[0009] Reciprocating compressors are most capable of operating at temperatures above 100°C due to their construction being much like internal combustion engines, which are typically designed for operating temperatures of up to 900°C in the working chamber, with lubricant temperatures of up to approximately 100°C.

[0010] Current industrial heat pumps can provide a temperature rise up to about 160°C. At these temperature levels, the evaporator temperature is usually above 110°C, and the relatively high pressures and temperatures in the compressor housing affect the viscosity of the oil.

[0011] The use of a reciprocating compressor results in a small amount of working fluid blow-by (working fluid leakage past the piston) that enters the internal volume filled with lubricant. The working fluid condenses and mixes with the lubricant, reducing the viscosity of the lubricant. One way to reduce the interference of the working fluid with the lubricant is to heat the lubricant to a higher temperature, causing the working fluid to evaporate from the lubricant. However, heating the lubricant also results in reduced viscosity and a shorter service life.

[0012] SUMMARY OF THE PRESENT EMBODIMENT It is at least one object of the present invention to obviate or at least mitigate one or more disadvantages of the prior art.

[0013] [Summary of the Invention] According to a first aspect of the present invention there is provided a working fluid extraction system for a displacement machine for removing condensable working fluid from a working fluid / lubricant mixture in an internal volume of the displacement machine separate from a working chamber of the displacement machine, the system comprising a condenser operatively connected to the internal volume, the condenser being settable to a temperature lower than a temperature of the internal volume such that working fluid is drawn from the internal volume into the condenser during use, or settable to a pressure lower than a pressure of the internal volume such that working fluid is drawn from the internal volume into the condenser during use, or settable to a temperature and pressure lower than a temperature and pressure of the internal volume such that working fluid is drawn from the internal volume into the condenser during use, or settable to a temperature lower than a saturation temperature of the working fluid in the internal volume such that working fluid is drawn from the internal volume into the condenser during use.

[0014] The condenser may be configured to condense the working fluid drawn from the interior volume.

[0015] The working fluid extraction system may further include a first fluid pump configured to pump working fluid from the interior volume to the condenser to assist in drawing the working fluid from the working fluid / lubricant mixture in the interior volume to the condenser.

[0016] The working fluid extraction system may further comprise a receptacle fluidly connected to the condenser for receiving the condensed working fluid, in use.

[0017] The working fluid extraction system may further comprise a second fluid pump configured to pump condensed working fluid from the condenser to a working fluid circuit of a thermal machine comprising the displacement machine so that working fluid drawn from the working fluid / lubricant mixture in the internal volume can be reintroduced into the working chamber of the displacement machine.

[0018] The working fluid extraction system may further comprise a check valve disposed in fluid communication with the second fluid pump and the working fluid circuit and configured to allow fluid to be pumped from the second fluid pump to the working fluid circuit, but not from the working fluid circuit to the second fluid pump.

[0019] The check valve may be configured to route fluid to a pressure reducing valve in the thermal machine.

[0020] The working fluid extraction system may further comprise a vent connected to the internal volume and configured to allow excess working fluid to be discharged from the internal volume. The vent may be a check valve. The vent may be fluidly connected to the working fluid circuit of the thermal machine such that the discharged working fluid may be reintroduced into the working chamber of the displacement machine.

[0021] The displacement machine may be a compressor.

[0022] The working fluid extraction system may further comprise a fluid separator system for separating condensable working fluid from lubricant in the internal volume, the fluid separator system comprising a fluid separator chamber, a fluid separator inlet operably connected to the internal volume and configured to enable fluid communication between the internal volume and the fluid separator chamber, and a fluid separator shielding member disposed at the fluid separator inlet and configured to regulate an amount of working fluid / lubricant mixture entering the fluid separator inlet, the fluid separator chamber configured, in use, to provide a deceleration of the working fluid / lubricant mixture entering the fluid separator chamber from the fluid separator inlet such that, in use, the working fluid / lubricant mixture entering the fluid separator chamber is decelerated, thereby separating at least a portion of the working fluid from the lubricant.

[0023] The fluid separator system may further comprise a fluid separator channel fluidly connected to the fluid separator chamber such that, in use, separated working fluid may be exhausted from the fluid separator chamber through the fluid separator channel.

[0024] The condenser may be operatively connected to the internal volume via a fluid separator system such that, during use, the working fluid may be separated from the working fluid / lubricant mixture by the fluid separator chamber and routed to the condenser by the fluid separator channel.

[0025] According to a second aspect of the present invention there is provided a working fluid extraction system for removing working fluid from a working fluid / lubricant mixture in the internal volume of the displacement machine comprising a displacement machine having a working chamber and an internal volume, an evaporator, a pressure reducing valve, a recuperator, a receiver, a filter, a first condenser, a condensable working fluid, and a shut-off valve located between the recuperator and the displacement machine, the working fluid extraction system comprising a second condenser operatively connected to the internal volume, the second condenser having a temperature lower than that of the internal volume such that working fluid is drawn from the internal volume into the second condenser during use. and a working fluid extraction system which is settable to a temperature or a pressure lower than the pressure of the internal volume such that working fluid is drawn from the internal volume to the second condenser in use, or which is settable to a temperature and pressure lower than the temperature and pressure of the internal volume such that working fluid is drawn from the internal volume to the second condenser in use, or which is settable to a temperature lower than the saturation temperature of the working fluid in the internal volume such that working fluid is drawn from the internal volume to the second condenser in use.

[0026] The displacement machine may be a compressor.

[0027] The thermal machine may further comprise a fluid separator system for separating a condensable working fluid from a lubricant in the internal volume, the fluid separator system comprising a fluid separator chamber, a fluid separator inlet operably connected to the internal volume and configured to enable fluid communication between the internal volume and the fluid separator chamber, and a fluid separator shielding member disposed at the fluid separator inlet and configured to regulate an amount of working fluid / lubricant mixture entering the fluid separator inlet, the fluid separator chamber configured, in use, to provide a deceleration of fluid entering the fluid separator chamber from the fluid separator inlet such that, in use, the working fluid / lubricant mixture entering the fluid separator chamber is decelerated, thereby separating at least a portion of the working fluid from the lubricant.

[0028] The fluid separator system further comprises a fluid separator channel fluidly connected to the fluid separator chamber such that, in use, separated working fluid may be exhausted from the fluid separator chamber through the fluid separator channel.

[0029] The condenser may be operatively connected to the internal volume via a fluid separator system such that, during use, the working fluid may be separated from the working fluid / lubricant mixture by the fluid separator chamber and routed to the condenser by the fluid separator channel.

[0030] According to a third aspect of the present invention there is provided a method of extracting working fluid from a working fluid / lubricant mixture in an internal volume of a displacement machine, the method comprising the steps of providing a working fluid extraction system according to the first aspect of the present invention and one of the steps of setting a temperature of a condenser below a temperature of the internal volume, or setting a pressure of the condenser below a pressure of the internal volume, or setting the temperature of the condenser below the temperature of the internal volume and setting the pressure of the condenser below the pressure of the internal volume, such that working fluid in the internal volume is drawn into the condenser.

[0031] According to a fourth aspect of the present invention there is provided a method of extracting working fluid from a working fluid / lubricant mixture in an internal volume of a displacement machine, the method comprising the steps of providing a working fluid extraction system according to the first aspect of the present invention, separating the working fluid from the working fluid / lubricant mixture in a fluid separator system and one of the steps of setting a condenser temperature below the temperature of the internal volume or setting the condenser pressure below the pressure of the internal volume or setting the condenser temperature below the temperature of the internal volume and setting the condenser pressure below the pressure of the internal volume, such that the separated working fluid is drawn into the condenser.

[0032] According to a fifth aspect of the present invention there is provided a fluid separator system for separating condensable working fluid from lubricant in a working fluid / lubricant mixture comprising a fluid separator chamber, a fluid separator inlet and a fluid separator shielding member arranged at the fluid separator inlet and configured to regulate an amount of working fluid / lubricant mixture entering the fluid separator inlet, the fluid separator chamber configured in use to provide a deceleration of fluid entering the fluid separator chamber from the fluid separator inlet such that, in use, the working fluid / lubricant mixture entering the fluid separator chamber is decelerated thereby separating at least a portion of the working fluid from the lubricant.

[0033] The fluid separator system may further comprise a fluid separator channel fluidly connected to the fluid separator chamber such that, in use, separated working fluid may be exhausted from the fluid separator chamber through the fluid separator channel.

[0034] According to a sixth aspect of the present invention there is provided a method of separating a working fluid from a working fluid / lubricant mixture comprising the steps of providing a fluid separator system according to the fifth aspect of the present invention; passing the working fluid / lubricant mixture over a shielding member thereby delivering a regulated amount of the working fluid / lubricant mixture to a fluid separator inlet; passing the working fluid / lubricant mixture through the fluid separator inlet into a fluid separator chamber; and decelerating the working fluid / lubricant mixture in the working fluid chamber thereby separating at least a portion of the working fluid from the working fluid / lubricant mixture.

[0035] The method may further comprise the step of exhausting the separated working fluid from the fluid separator chamber through a fluid separator channel.

[0036] This extraction system may be advantageous in that it may allow for improved performance of the lubricant in the thermal machine by removing working fluid from the working fluid / lubricant mixture in the interior volume without requiring the temperature to be increased in the interior volume.

[0037] Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings, in which: [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 shows a typical heat pump system that uses a piston compressor. [Diagram 2] FIG. 2 shows a detailed view of the piston / cylinder arrangement of the piston compressor used in the heat pump of FIG. [Diagram 3] FIG. 2 illustrates an example of a working fluid extraction system for use with a displacement machine in a thermal machine, according to an aspect of the present invention. [Figure 4] FIG. 1 illustrates a piston compressor with a fluid separator system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] [Detailed Description of the Invention] FIG. 1 illustrates a prior art heat machine comprising a displacement machine utilizing a condensable working fluid. More specifically, FIG. 1 illustrates a prior art heat pump system 100 comprising a compressor 110 in the form of a piston compressor, an evaporator 120, a pressure reducing valve 130, a recuperator 140, a receiver 150, a filter 160, a condenser 170, a working fluid 180 and a lubricant 181. The compressor 110 comprises a housing 111, a heating element 112 and a vent 113, which will be described in more detail below. As will be readily understood by those skilled in the art, a plurality of pistons 114, 114', 114'', 114''' are disposed in connection with a crankshaft 114'''' driven by a motor 116. The compressor 110 has a working chamber 117 in which a working fluid 180 is compressed by the pistons 114, 114', 114'', 114''' and an internal volume 118 comprising the lubricant 181.

[0040] 2 shows further details of one of the pistons 114 of FIG. 1. During use, a working fluid 180 is compressed by the piston 114 in the working chamber 115. Some working fluid 180 may leak past the piston 114 and migrate from the working chamber 115 to the internal volume 118, which is substantially filled with a lubricant 181 to increase the useful life of the compressor 110. When this happens, the working fluid 180 mixes with the lubricant 181 and negatively changes the properties of the lubricant 181, thereby causing the useful life of the compressor 110 to be reduced and / or more regular maintenance to be required. To remove leaked working fluid 180 from the lubricant 181 in the internal volume 118, the heating element 112 heats the lubricant 181 / working fluid 180 mixture in the internal volume 118 to ensure that the working fluid 180 evaporates from the lubricant 181 and to increase the pressure in the internal volume 118 to push the evaporated working fluid 180 out of the internal volume 118 through the vent 113. The vent 113 is typically in the form of a check valve. The main drawbacks of this system may include the above-mentioned adverse effects of increasing the temperature of the lubricant 181, namely, reduced viscosity and reduced performance.

[0041] FIG. 3 shows an example of an improved heat machine in the form of a heat pump system 200 using a working fluid extraction system. Similar to the system 100 described with reference to FIG. 1, the system 200 comprises a displacement machine in the form of a compressor 210 in the form of a piston compressor comprising a housing 211. A number of pistons 214, 214', 214'', 214''' are arranged in connection with a crank shaft 214'''' driven by a motor 216. The compressor 210 has several working chambers, which may be grouped together as working chamber 217 to aid in the explanation. It will be understood that the compressor 210 may have one or any number of working chambers depending on the number of pistons 214, 214', 214'', 214'''' in the system 200, as will be apparent to one skilled in the art. In the working chamber 217, a working fluid 280 is compressed by the pistons 214, 214', 214'', 214'''' when the system 200 is in use. The compressor 210 also includes an interior volume 218 that includes a lubricant 281. The interior volume 218 is the space within the compressor in which the working fluid 280 is not substantially compressed by the pistons 214, 214', 214'', 214'''.

[0042] The system 200 further includes an evaporator 220, a pressure reducing valve 230, a recuperator 240, a receiver 250, a filter 260, a first condenser 270, a working fluid 280, and a lubricant 281. The internal volume 218 is substantially filled with the lubricant 281 to extend the useful life of the compressor 210. As previously described, some of the working fluid 280 may mix with the lubricant 281 in the internal volume 218 to generate a working fluid 280 / lubricant mixture 281 in the internal volume 218. The heat pump system 200 further includes a shutoff valve 241 between the recuperator 240 and the compressor 210. Advantageously, the heat pump system 200 further comprises a second condenser 271 operatively connected to the internal volume 218 such that the working fluid 280 in the working fluid 280 / lubricant 281 mixture may be drawn from the internal volume 218 to the second condenser 271 where the working fluid 280 is condensed. In some instances, the working fluid 280 may flow from the internal volume 218 to the second condenser 271 without assistance. The greater the temperature difference between the hotter internal volume 218 and the cooler second condenser 271, the more efficiently the working fluid 280 will flow to the second condenser 271 without assistance. In this regard, it is preferred to maintain the internal volume 218 at a higher temperature than the second condenser 271 during use. In some instances, the system 200 may further comprise a first fluid pump 290, optionally located between the second condenser 271 and the internal volume 218. The first fluid pump 290 is arranged to pump the working fluid 280 from within the internal volume 218 to the second condenser 271. Such a first fluid pump 290 is particularly useful when the required temperature difference between the internal volume 218 and the second condenser 271 cannot be achieved. However, even when the required temperature difference between the internal volume 218 and the second condenser 271 can be achieved, the system 200 may also include a first fluid pump 290 to improve the efficiency of removal of the working fluid 280 from within the internal volume 218.

[0043] In some examples (not shown), the working fluid 280 that has passed through the pistons 214, 214′, 214″, 214′″ (blow-by) may be discharged from the system 200 as the working fluid 280 is extracted from the internal volume 218, for example, to a suitable storage receptacle (not shown). In such examples, the working fluid 280 in the system may be replenished to replace lost working fluid 280 that has been discharged to the storage receptacle by introducing new working fluid 280 into the system from the working fluid reservoir (not shown). The storage receptacle and the working fluid reservoir may be the same container or may be different containers that may be fluidly connected to enable transfer from the storage receptacle to the working fluid reservoir. Alternatively, the storage receptacle and the working fluid reservoir may be different containers that may not be fluidly connected to enable transfer from the storage receptacle to the working fluid receptacle. In such cases, the working fluid in the storage receptacle may need to be drained and / or additional working fluid 280 may need to be added to the working fluid reservoir during servicing of the heat pump system 200.

[0044] Referring again to the system 200 shown in FIG. 3 , in other words where the working fluid 280 is not discharged to a storage receptacle but instead recycled within the system 200, a second fluid pump 291 is connected to the second condenser 271 for conveying the working fluid 280 extracted from the internal volume 218 to the normal working fluid circuit of the heat pump system 200. In this manner, any working fluid 280 that leaks beyond any of the pistons 214, 214′, 214″, 214′″, commonly referred to as “blow-by”, is efficiently extracted from the working fluid 280 / lubricant 281 mixture and reintroduced into the working fluid circuit, where it is desirable to maintain the working fluid 280 such that the working fluid 280 does not alter the carefully selected properties of the lubricant 281.

[0045] 3, in the example just described, the working fluid 280 recovered from the interior volume 218 is reintroduced into the working fluid circuit through the check valve 292 and mixed with the working fluid 280 in the working fluid circuit before the combined working fluid 280 enters the pressure reducing valve 230. In some alternative examples, the working fluid 280 recovered from the housing 211 may be reintroduced into the working fluid circuit through the check valve 292 and mixed with the working fluid 280 in the working fluid circuit after the pressure reducing valve 230, in other words downstream of the pressure reducing valve 230.

[0046] Advantageously, use of the system 200 just described allows the condensation temperature in the second condenser 271 to be regulated (e.g., by a control system (not shown)) independently of the evaporation temperature in the evaporator 220, and allows the condensation temperature of the second condenser 271 to be maintained sufficiently low relative to the evaporation temperature of the evaporator 220 such that a negative pressure arises in the internal volume 218, which draws the working fluid 280 from within the internal volume 218 towards the second condenser 271.

[0047] A pressure differential between the evaporator side and the internal volume 218 sufficient to ensure that any working fluid 280 that leaks past the piston is immediately evaporated as the working fluid 280 enters the internal volume 218 and remains a vapor due to the low pressure in the internal volume 218 is highly advantageous.

[0048] The system 200 just described can thereby enable lower pressures and temperatures to be maintained in the internal volume 218, which can ensure evaporation of the working fluid 280 from the working fluid 280 / lubricant 281 mixture, thereby maintaining desired properties of the lubricant 281, including the desired viscosity.

[0049] Heat pump system 200 of FIG. 3 may, in some examples, further include a vent (not shown in FIG. 3) similar to vent 113 of system 100 described in FIG. 1 as a safety feature to ensure that working fluid 280 that breaks through the piston can always be vented from interior volume 218.

[0050] FIG. 4 shows a simplified drawing of a piston compressor 310 in a so-called "V" configuration, comprising a compressor block 311, a first cylinder head 312 and a second cylinder head 313. The compressor 310 further comprises first and second pistons 314, 314', angularly separated by approximately 90° as shown. The pistons 314, 314' are arranged in connection with a crank shaft 314'''' driven by a motor (not shown). The crank shaft 314'''' comprises a counterweight 315 to reduce vibration. In other examples, the compressor 310 may comprise many more pistons 314, 314'. Preferably, there is an even number of pistons 314, 314', for example 16 pistons, although an odd number of pistons 314, 314' is also possible. The compressor 310 has several working chambers, which may be grouped together as working chamber 317 to aid in explanation. It will be appreciated that the compressor 310 may have one or any number of working chambers 317 depending on the number of pistons 314, 314' as will be apparent to one skilled in the art. The compressor 310 further comprises a first inlet valve 316A and a first outlet valve 316B associated with the first piston 314, and a second inlet valve 316'A and a second outlet valve 316'B associated with the second piston 314'. Additionally, the compressor comprises a standard first valve control component 319 and a standard second valve control component 319' configured to open and close the first and second inlet and outlet valves 316A, 316B, 316'A, 316'B as will be familiar to one skilled in the art. In this regard, the configuration of the first and second valve control components 319, 319' may take many forms and will not be described here for the sake of brevity and clarity.

[0051] In the working chamber 317, working fluid is compressed by the pistons 314, 314' when the compressor 310 is in use. The compressor 310 also includes an internal volume 318 that includes a lubricant 381. The internal volume 318 is the space within the compressor 310 where working fluid is not substantially compressed by the pistons 314, 314'.

[0052] External to the compressor 310, the working fluid may undergo heat exchange in one or more heat exchangers (not shown), as previously discussed with reference to the heat pump system 200 in Figure 3. The working fluid is typically directed to the compressor through a pipe or manifold.

[0053] Some working fluid may leak past the pistons 314, 314′ and migrate from the working chamber 317 into the interior volume 318, which is substantially filled with lubricant 381 to extend the useful life of the compressor 310. When this occurs, as previously discussed, the working fluid may mix with the lubricant 381 and negatively alter the properties of the lubricant 381, thereby causing the useful life of the compressor 310 to be reduced and / or requiring more regular maintenance.

[0054] It is generally highly desirable to separate at least a portion of the working fluid from the working fluid / lubricant 381 mixture. Preferably, a significant amount of the working fluid may be separated from the working fluid / lubricant 381 mixture. More preferably, all of the working fluid may be separated from the working fluid / lubricant 381 mixture. In some configurations, the working fluid may be separable from the lubricant 381 within the compressor 310 and without the need for further processing, in other words, the working fluid may be directly recycled or reintroduced into another portion of the compressor 310 or into another system, for example, a heat pump system of which the compressor is a part.

[0055] Alternatively, the compressor 310 may be attached to a second condenser 271 (FIG. 3) or to another system configured to extract and / or treat the working fluid from the working fluid / lubricant 381 mixture. Regardless of the presence of a downstream system, which may or may not be attached to the compressor 310, to extract and / or treat the working fluid from the working fluid / lubricant 381 mixture so that the working fluid may be recycled or reused, the compressor 310 shown in FIG. 3 includes a fluid separator system 340 for separating at least a portion of the leaked working fluid from the lubricant 381 within the compressor 310.

[0056] Such separation ensures that at least a portion of the working fluid is sufficiently separated to be effectively processed by downstream processes that may return the working fluid to another part of the heat pump system 200 via the second condenser 271, as in the example given in FIG. 3. In such cases, it is often highly desirable to ensure that as much of the lubricant 381 as possible is removed from the working fluid / lubricant 381 mixture, since the presence of the lubricant 381 in the working fluid being extracted and processed may impede the processing of the working fluid and / or affect the performance of other components of the system to which the compressor 310 is attached or of which it may form part, for example, the heat pump system 200 of which the compressor 310 may form part. In such cases, the presence of the lubricant 381 may affect the performance of the second condenser 271. For example, a thin layer of the lubricant 381 on the working surface of the second condenser 271 may significantly reduce the heat transfer coefficient of the working surface, thereby significantly affecting performance. Next, the configuration of a fluid separator system 340 to enable separation of at least a portion of the working fluid from the working fluid / lubricant 381 mixture in the compressor 310 is described.

[0057] Fluid separator system 340 includes a fluid separator channel 341, a fluid separator shielding member 342, a fluid separator chamber 343, and a fluid separator inlet 344. Fluid separator channel 341 is fluidly connected to the interior volume 318 of compressor 310. In this regard, working fluid / lubricant 381 mixture is directed over fluid separator shielding member 342 and into fluid separator chamber 343 through fluid separator inlet 344. Shielding member 342 functions to limit the amount of lubricant 381 droplets carried into fluid separator chamber 343 with the working fluid. The fluid separator chamber 343 has sufficient volume space to ensure that the velocity of the working fluid is reduced when the working fluid / lubricant 381 mixture enters the fluid separator chamber 343, and the lubricant 381 droplets are thereby separated from the working fluid before the working fluid is discharged through the fluid separator channel 341 and allowed to proceed to a downstream collector or recycle system, such as the second condenser 271 arrangement described above with respect to FIG. 3, or to be used directly within the compressor 310.

[0058] In some examples, a 20-30 kW condenser may be used with a 1 MW compressor. In other examples, a 100-150 kW condenser may be used with a 5 MW compressor. In other examples, a 200-300 kW condenser may be used with a 10 MW compressor.

Claims

1. A working fluid extraction system for a displacement machine (210) for removing a condensable working fluid (280) from a working fluid / lubricant mixture in an internal volume (218) of the displacement machine (210) separate from a working chamber (217) of the displacement machine (210), the system comprising a condenser (271) operably connected to the internal volume (218), the condenser (271) being settable to a temperature and / or pressure lower than a temperature and / or pressure of the internal volume (218) such that working fluid (280) is drawn from the internal volume (218) into the condenser (271) during use.

2. The working fluid extraction system of claim 1 , wherein the condenser (271) is configured to condense the working fluid (280) drawn from the internal volume (218).

3. 3. The working fluid extraction system of claim 1, further comprising a first fluid pump configured to pump working fluid from the internal volume to the condenser to assist in the drawing of working fluid from the working fluid / lubricant mixture in the internal volume to the condenser.

4. 4. The working fluid extraction system of claim 1, further comprising a receptacle fluidly connected to the condenser (271) for receiving, in use, condensed working fluid (280).

5. 5. The working fluid extraction system according to claim 1, further comprising a second fluid pump (291) configured to pump condensed working fluid (280) from the condenser (271) to a working fluid circuit of a thermal machine comprising the displacement machine (210) so that the working fluid (280) drawn from the working fluid / lubricant mixture in the internal volume (218) can be reintroduced into a working chamber of the displacement machine (210).

6. 6. The working fluid extraction system of claim 5, further comprising a check valve (292) disposed in fluid communication with the second fluid pump (291) and the working fluid circuit and configured to allow fluid to be pumped from the second fluid pump (291) to the working fluid circuit but not from the working fluid circuit to the second fluid pump (291).

7. The working fluid extraction system of claim 6 , wherein the check valve (292) is configured to deliver fluid to a pressure reducing valve (230) in the thermal machine.

8. 8. The working fluid extraction system of claim 1, further comprising a vent (113) connected to the internal volume (218) and configured to allow excess working fluid (280) to be released from the internal volume (218).

9. The working fluid extraction system of claim 8, wherein the vent (113) is a check valve.

10. 10. The working fluid extraction system of claim 8 or 9, wherein the vent (113) is fluidly connected to the working fluid circuit of the thermal machine such that the discharged working fluid (280) can be reintroduced into the working chamber (217) of the displacement machine (210).

11. The working fluid extraction system of any one of claims 1 to 10, wherein the displacement machine (210) is a compressor.

12. A fluid separator system for separating the condensable working fluid (280) from a lubricant in the interior volume (218), the fluid separator system (340) comprising: A fluid separator chamber (343); a fluid separator inlet (344) operably connected to the interior volume (218) and configured to allow fluid communication between the interior volume (218) and the fluid separator chamber (343); a fluid separator shielding member (342) disposed at the fluid separator inlet (344) and configured to regulate an amount of working fluid / lubricant mixture entering the fluid separator inlet (344); Fluid separator system comprising: Further equipped with the fluid separator chamber (343) is configured, in use, to provide a deceleration of the working fluid / lubricant mixture entering the fluid separator chamber (343) from the fluid separator inlet (344) such that, in use, the working fluid / lubricant mixture entering the fluid separator chamber (343) is decelerated, thereby separating at least a portion of the working fluid (280) from the lubricant; A working fluid extraction system according to any one of claims 1 to 11.

13. 13. The working fluid extraction system of claim 12, wherein the fluid separator system (340) further comprises a fluid separator channel (341) fluidly connected to the fluid separator chamber (343) such that, during use, separated working fluid (280) can be discharged from the fluid separator chamber (343) through the fluid separator channel (341).

14. 14. The working fluid extraction system of claim 13, wherein the condenser (271) is operatively connected to the internal volume (218) via the fluid separator system (340) such that, during use, a working fluid (280) can be separated from the working fluid / lubricant mixture by the fluid separator chamber (343) and routed to the condenser (271) by the fluid separator channel (341).

15. a displacement machine (210) comprising a working chamber (217) and an internal volume (218); An evaporator (220); A pressure reducing valve (230); A recuperator (240); A receiver (250); A filter (260); A first condenser (270); a condensable working fluid (280); a shutoff valve (241) located between the recuperator (240) and the displacement machine (210); a working fluid extraction system for removing working fluid (280) from a working fluid / lubricant mixture in the internal volume (218) of the displacement machine (210), the working fluid extraction system comprising a second condenser (271) operably connected to the internal volume (218), the second condenser (271) being settable to a temperature and / or pressure lower than a temperature and / or pressure of the internal volume (218) such that working fluid (280) is drawn from the internal volume (218) into the second condenser (271) during use; A thermal machine comprising:

16. The thermal machine of claim 15, wherein the displacement machine (210) is a compressor.

17. A fluid separator system (340) for separating the condensable working fluid (280) from a lubricant in the interior volume (218), the fluid separator system (340) comprising: A fluid separator chamber (343); a fluid separator inlet (344) operably connected to the interior volume (218) and configured to allow fluid communication between the interior volume (218) and the fluid separator chamber (343); a fluid separator shielding member (342) disposed at the fluid separator inlet (344) and configured to regulate an amount of working fluid / lubricant mixture entering the fluid separator inlet (344); A fluid separator system (340) comprising: Further equipped with the fluid separator chamber (343) is configured, in use, to provide a deceleration of fluid entering the fluid separator chamber (343) from the fluid separator inlet (344) such that, in use, the working fluid / lubricant mixture entering the fluid separator chamber (343) is decelerated, thereby separating at least a portion of the working fluid (280) from the lubricant; A thermal machine according to claim 15 or 16.

18. 20. The thermal machine of claim 17, wherein the fluid separator system (340) further comprises a fluid separator channel (341) fluidly connected to the fluid separator chamber (343) such that, in use, separated working fluid (280) can be discharged from the fluid separator chamber (343) through the fluid separator channel (341).

19. 19. The thermal machine of claim 18, wherein the condenser (271) is operably connected to the internal volume (218) via the fluid separator system (340) such that, during use, a working fluid (280) can be separated from the working fluid / lubricant mixture by the fluid separator chamber (343) and routed to the condenser (271) by the fluid separator channel (341).

20. 1. A method of extracting a working fluid (280) from a working fluid / lubricant mixture in an interior volume (218) of a displacement machine (210), the method comprising: Providing a working fluid extraction system according to any one of claims 1 to 11; b. drawing working fluid (280) in said internal volume (218) into said condenser (271); i. setting the temperature of the condenser (271) below the temperature of the interior volume (218), or ii. setting the pressure in the condenser (271) below the pressure in the internal volume (218); or iii. Setting the temperature of the condenser (271) less than the temperature of the internal volume (218) and setting the pressure of the condenser (271) less than the pressure of the internal volume (218). One of the A method comprising:

21. 1. A method of extracting a working fluid (280) from a working fluid / lubricant mixture in an interior volume (218) of a displacement machine (210), the method comprising: c. Providing a working fluid extraction system according to any one of claims 12 to 14; d. separating the working fluid (280) from the working fluid / lubricant mixture in the fluid separator system (340); e. The separated working fluid (280) is drawn into the condenser (271); i. setting the temperature of the condenser (271) below the temperature of the interior volume (218), or ii. setting the pressure in the condenser (271) below the pressure in the internal volume (218); or iii. Setting the temperature of the condenser (271) less than the temperature of the internal volume (218) and setting the pressure of the condenser (271) less than the pressure of the internal volume (218). One of the A method comprising:

22. A fluid separator system (340) for separating a condensable working fluid from a lubricant in a working fluid / lubricant mixture, said fluid separator system (340) comprising: A fluid separator chamber (343); a fluid separator inlet (344); a fluid separator shielding member (342) disposed at the fluid separator inlet (344) and configured to regulate an amount of working fluid / lubricant mixture entering the fluid separator inlet (344); Equipped with the fluid separator chamber (343) is configured, in use, to provide a deceleration of fluid entering the fluid separator chamber (343) from the fluid separator inlet (344) such that, in use, the working fluid / lubricant mixture entering the fluid separator chamber (343) is decelerated, thereby separating at least a portion of the working fluid from the lubricant; A fluid separator system (340).

23. 23. The fluid separator system (340) of claim 22, further comprising a fluid separator channel (341) fluidly connected to the fluid separator chamber (343) such that, during use, separated working fluid can be discharged from the fluid separator chamber (343) through the fluid separator channel (341).

24. 1. A method for separating a working fluid from a working fluid / lubricant mixture, the method comprising: f. Providing a fluid separator system (340) according to claim 22 or 23; g. passing the working fluid / lubricant mixture past said shielding member (342), thereby delivering a regulated amount of the working fluid / lubricant mixture to said fluid separator inlet (344); h. passing the working fluid / lubricant mixture through the fluid separator inlet (344) into the fluid separator chamber (343); i. decelerating the working fluid / lubricant mixture in a working fluid chamber, thereby separating at least a portion of the working fluid from the working fluid / lubricant mixture; A method comprising:

25. When dependent on claim 23, j. Discharging the separated working fluid from said fluid separator chamber (343) through said fluid separator channel (341).

25. The method of claim 24, further comprising:

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