CONDENSER SUBASSEMBLY WITH INTEGRATED FLASH TANK

Abstract

A condenser subassembly for providing an economizer function in a refrigeration circuit, the condenser subassembly including: a condenser chamber 113; a flash tank chamber 114; an expansion device 117; and a housing, the housing defines a vessel 112a, the vessel comprising the condenser chamber 113 and the flash tank chamber 114, the condenser chamber 113 and the flash tank chamber 114 are separated from one another by a partition 115a in the vessel 112a and the expansion device 117 is arranged to pass condensed refrigerant from the condenser chamber 113 to the flash tank chamber 114.

Claims

1. A condenser subassembly for providing an economizer function in a refrigeration circuit, the condenser subassembly comprising: a condenser chamber; a flash tank chamber; an expansion device; and a housing, wherein the housing defines a vessel, the vessel comprising the condenser chamber and the flash tank chamber, wherein the condenser chamber and the flash tank chamber are separated from one another by a partition in the vessel and wherein the expansion device is arranged to pass condensed refrigerant from the condenser chamber to the flash tank chamber.

2. A condenser subassembly as claimed in claim 1, wherein the expansion device is an internal expansion device positioned inside of the vessel.

3. A condenser subassembly as claimed in claim 1, wherein the expansion device is a float valve coupled with a liquid duct from the condenser chamber to the flash tank chamber.

4. A condenser subassembly as claimed in claim 1, wherein the expansion device is an external expansion device positioned outside of the vessel.

5. A condenser subassembly as claimed in claim 1, wherein the vessel is substantially cylindrical and the partition divides the vessel at a chord length in its cross-section along the length of the vessel or wherein the vessel is an outer vessel and the partition forms an inner vessel including a pressure envelope for the flash tank chamber inside of a pressure envelope of the outer vessel.

6. A condenser subassembly as claimed in claim 1, wherein the condenser chamber comprises a heat exchanger for cooling a refrigerant flow through the condenser, wherein the heat exchanger preferably comprises a plurality of tubes passing through the chamber, wherein the plurality of tubes are preferably arranged to be surrounded by the refrigerant flow.

7. A condenser subassembly as claimed in claim 1, wherein the expansion device is fluidly connected to a point near the bottom of the condenser chamber, where during use, condensed refrigerant will collect under the action of gravity.

8. A condenser subassembly as claimed in claim 1, wherein the condenser chamber extends along the full length of the vessel and wherein the flash tank extends along at least part of the length of the vessel.

9. A condenser subassembly as claimed in claim 1, wherein the flash tank chamber comprises a vapour outlet and a liquid outlet, wherein the vapour outlet is arranged to be fluidly connected to an economizer circuit.

10. A refrigeration circuit comprising: a condenser subassembly as claimed in claim 1; a compressor; and an evaporator; wherein the condenser subassembly has a vapour outlet which is fluidly connected to an economizer port of the compressor and a liquid outlet which is fluidly connected to the evaporator via a main expansion device, and wherein a discharge port of the compressor is fluidly connected to the condenser chamber.

11. A refrigeration circuit as claimed in claim 10, further comprising an oil separator arranged to remove oil from a refrigerant flow and/or a sound muffler, wherein the oil separator and/or sound muffler is integrated into the condenser subassembly and positioned within the housing, preferably inside of the vessel.

12. A method of manufacturing a condenser subassembly for providing an economizer function in a refrigeration circuit, the method comprising: providing a housing, wherein the housing defines a vessel; providing a partition in the vessel; providing a condenser chamber and a flash tank chamber in the vessel, wherein the condenser chamber and the flash tank chamber are separated from one another by the partition in the vessel; and providing an expansion device, wherein the expansion device is arranged to pass condensed refrigerant from the condenser chamber to the flash tank chamber.

13. A method of manufacturing a condenser subassembly as claimed in claim 12, wherein the housing is a pre-existing pressure vessel, and the method comprises retrofitting the partition to the pre-existing pressure vessel in order to form the condenser chamber and a flash tank chamber.

14. A method of manufacturing a condenser subassembly as claimed in claim 12, the method comprising: determining a volume of the vessel, a volume of the condenser chamber and a volume of the flash tank chamber that is required in order to provide a certain economizer function in a refrigeration circuit.

15. A method of manufacturing a condenser subassembly as claimed in claim 12, the method comprising: determining a position and a required strength of the partition in the vessel in order for the partition to withstand a pressure difference between the condenser chamber and flash tank chamber when the condenser subassembly provides a certain economizer function.

Description

DRAWING DESCRIPTION

[0049] Certain example embodiments will now be described by way of example only and with reference to the accompanying drawings, in which:

[0050] FIG. 1a shows a schematic view of a known refrigeration circuit comprising a flash tank economizer;

[0051] FIG. 1b shows a schematic view of a refrigeration circuit comprising a condenser subassembly for providing an economizer function with an integrated flash tank chamber;

[0052] FIG. 2 shows a cross-sectional view of a condenser subassembly comprising an integrated flash tank chamber and an internal expansion device; and

[0053] FIG. 3 shows a cross-sectional view of another condenser subassembly comprising an integrated flash tank chamber and an external expansion device.

DETAILED DESCRIPTION

[0054] With reference to FIG. 1a, there is shown a conventional refrigeration circuit 11 that includes, in serial flow relationship, a compressor 12, a condenser 13, a flow control device 19, a flash tank 21, an expansion device 14, and an evaporator 16.

[0055] The compressor 12, which functions to compress and circulate refrigerant through the refrigeration circuit, comprises a single, multi-stage compressor having a lower compression stage 17 and higher compression stage 18.

[0056] The condenser 13 receives refrigerant from the discharge port of the compressor 12 and functions to cool the refrigerant therein so that it condenses to a liquid.

[0057] The evaporator 16 functions to cool a gas or liquid passing over it as the refrigerant therein is heated and evaporated. The heated vapour then passes to an inlet of the compressor 12.

[0058] Disposed between the condenser 13 and the expansion device 14 is the flow control device 19 and the flash tank 21. The flash tank 21, together with an economizer vapour line 22 fluidly interconnecting the flash tank 21 to an economizer port of the compressor 12, forms part of an economizer circuit.

[0059] In operation, the refrigerant exiting the condenser 13 passes through the flow control device 19 where it is expanded to reduce its pressure. The resulting mixture of liquid and vapour then enters the flash tank 21, with the liquid 24 settling to the bottom portion of the flash tank 21 and the vapour 26 residing in the top portion of the flash tank 21. The liquid refrigerant 24 passes to the expansion device 14 where it is expanded and subsequently enters the evaporator 16.

[0060] In a process known as economized operation, the vapour 26 passes along the economizer vapour line 22 to an economizer port of the compressor 12. As discussed above, a result of the separation of vapour and liquid refrigerant in the flash tank 21 is that the remaining liquid refrigerant in the flash tank 21 (which is subsequently expanded and passed to the evaporator 16) has a lower enthalpy, therefore increasing the capacity and efficiency of the system.

[0061] The flow control device 28, which is an electronically controlled flow control device such as a solenoid valve, is controlled by a controller 29 in response to sensed conditions at the flash tank 21 and at the compressor 12. For example, a sensor S1 senses an operational condition at the flash tank 21, and a sensor S2 senses an operational condition at a mid-stage point 27 of the compressor 12. The sensed conditions then cause the controller 29 to either open the flow control device 28 to permit economized operation or to close the flow control device 28 to thereby turn off the economizer.

[0062] Now with reference to FIG. 1b, there is shown a refrigeration circuit 111 that includes a vessel 112 comprising an integrated condenser chamber 113 and an integrated flash tank chamber 114. The structure of the vessel will be described in more detail below with reference to FIGS. 2 and 3.

[0063] The reference numerals in FIG. 1b represent similar components as those described above in relation to the same reference numbers of FIG. 1a.

[0064] Similar to the system shown in FIG. 1a, the compressor 12 of the refrigeration circuit 111 functions to compress and circulate refrigerant through the refrigeration circuit, and comprises a single, multi-stage compressor having a lower compression stage 17 and higher compression stage 18.

[0065] The vessel 112 receives refrigerant from the discharge port of the compressor 12 and this refrigerant enters the condenser chamber 113 of the vessel first, which functions to cool the refrigerant therein so that it condenses to a liquid.

[0066] An expansion device (not shown) inside of the vessel is arranged to pass condensed refrigerant from the condenser chamber 113 to the flash tank chamber 114.

[0067] The expansion device and flash tank chamber 114, together with an economizer vapour line 22 fluidly interconnecting a vapour outlet of the flash tank chamber 114 to an economizer port of the compressor 12, form part of an economizer circuit.

[0068] In operation, the refrigerant exiting the condenser chamber 113 passes through the expansion device where it is expanded to thereby reduce its pressure. The resulting mixture of liquid and vapour is passed into the flash tank chamber 114, with liquid settling to a bottom portion and the vapour residing in a top portion of the flash tank chamber (the dashed line within the flash tank chamber 114 schematically representing the limit between the liquid and vapour).

[0069] The vapour refrigerant passes from a vapour outlet of the flash tank chamber 114 along the economizer vapour line 22 to an economizer port of the compressor 12. As discussed above, a result of the separation of vapour and liquid refrigerant in the flash tank chamber 114 is that the remaining liquid refrigerant in the flash tank chamber 114 (which is subsequently expanded and passed to the evaporator) has a lower enthalpy, therefore increasing the capacity and efficiency of the system.

[0070] The liquid refrigerant passes from a liquid outlet of the flash tank chamber 114 to an expansion device 14 where it is expanded and subsequently enters an evaporator 16. Again, the evaporator 16 functions to cool a gas or liquid passing over it as the refrigerant therein is heated and evaporated. The heated vapour then passes to an inlet (suction port) of the compressor 12.

[0071] Similar to the previously described system, a flow control device 28, which is an electronically controlled flow control device such as a solenoid valve, is controlled by a controller 29 in response to sensed conditions at the flash tank chamber 114 and at the compressor 12. For example, a sensor S1 senses an operational condition at the flash tank chamber 114, and a sensor S2 senses an operational condition at a mid-stage point 27 of the compressor 12. The sensed conditions then cause the controller 29 to either open the flow control device 28 to permit economized operation or to close the flow control device 28 to thereby turn off the economizer. The controller can also control the rate of flow of refrigerant through the flow control device 28.

[0072] Possible structures structure of the vessel 112 will now be described in more detail with reference to FIGS. 2 and 3.

[0073] FIG. 2 shows a cross-sectional view of a vessel 112a that acts as a condenser subassembly. The vessel 112a is cylindrical and has a partition 115a dividing the interior of the vessel 112a into a condenser chamber 113 and a flash tank chamber 114. The partition 115a extends around the flash tank chamber 114 to form a flash tank pressure envelope that is semi-circular.

[0074] There is a liquid duct 116 fluidly connecting the bottom of the condenser chamber 113 to the flash tank chamber 114. This is connected to a point near the bottom of the condenser chamber 113 where liquid refrigerant will collect.

[0075] Coupled to the liquid duct 116 is an internal float valve 117 that acts as an expansion device for the liquid from the condenser chamber 116 and controls the rate of flow of refrigerant form the condenser chamber 113 into the flash tank chamber.

[0076] Inside of the condenser chamber 113 there is a plurality of heat exchanger tubes 118 that pass axially along the length of the chamber and which, in use, are surrounded by refrigerant, which is to be condensed. The heat exchanger tubes pass through the condenser chamber, the refrigerant enters from the top of the condenser chamber 113 and travels down past the heat exchanger tubes 118 through the action of gravity and under the force of the pressure/flow of refrigerant from the compressor.

[0077] In the flash tank chamber there is a screen 119 positioned between the liquid duct 116 and a vapour outlet 120. The vapour outlet is positioned towards the top of the chamber and leads to the economizer vapour line and an economizer port of the compressor as described above in relation to FIG. 1b.

[0078] The flash tank chamber also has a liquid outlet 121 positioned near its bottom that leads to an expansion device where it is expanded and subsequently enters an evaporator as described above in relation to FIG. 1b.

[0079] In operation, refrigerant passes from a compressor discharge port into the condenser chamber 113, where it is cooled via heat exchange with the plurality of heat exchanger tubes 118. The heat exchanger tubes can be arranged to carry any suitable coolant fluid, such as water or some other refrigerant received from a separate refrigerant circuit.

[0080] The refrigerant in the condenser chamber 113 is cooled and condensed such that it collects towards the bottom of the condenser chamber 113. The float valve 117 remains open as long as the liquid level in the flash tank chamber 114 has not risen high enough to push the float of the float valve upwards. When the float is pushed upwards by a rising liquid level in the flash tank chamber 114, a closing part on the other end of a pivoting arm of the float valve 117 reduces the size of the orifice through which refrigerant can flow from the condenser chamber 113 to the flash tank chamber 114, thus reducing the flow rate. The float valve is arranged to control the flow rate in this way in order to match the flow rate of refrigerant leaving the flash tank chamber 114, thereby maintaining a substantially constant liquid level in the flash tank chamber 114.

[0081] The vessel thus comprises two different pressure envelopes, the higher pressure envelope of the condenser chamber 113 and the lower pressure envelope of the flash tank chamber 114.

[0082] The screen 119 in the flash tank chamber 114 slows the flow of refrigerant towards the vapour outlet so that it has time to expand properly in the flash tank chamber 114. The screen also prevents liquid refrigerant splash or spray from entering the vapour outlet 120 to ensure that the refrigerant which exits the vapour outlet 120 is only expanded vapour and not liquid, which is undesirable.

[0083] The refrigerant in the flash tank chamber 114 then separates into liquid towards the bottom and vapour towards the top portion of the flash tank chamber 114 (the two phases are shown separated by a horizontal dashed line in the flash tank chamber 114 of FIG. 2).

[0084] As discussed above in relation to FIG. 1b, the vapour refrigerant passes from the vapour outlet 120 of the flash tank chamber 114 along an economizer vapour line to an economizer port of the compressor. The liquid refrigerant passes from the liquid outlet 121 of the flash tank chamber 114 to an expansion valve 14 where it is expanded and subsequently enters an evaporator.

[0085] FIG. 3 shows a cross-sectional view of another vessel 112b that acts as a condenser subassembly. This vessel 112b essentially comprises the same components and operates in a similar manner to the vessel shown in FIG. 2 as described above but in place of the liquid duct 116 and internal float valve 117, this vessel comprises an external expansion device 122. As the liquid duct 116 is no longer required, the partition 115b fully divides the interior of the vessel into the condenser chamber 113 and the flash tank chamber 114, thus sealing the two from one another.

[0086] The external expansion device 122 is fluidly connected to a point near the bottom of the condenser chamber 113 and draws condensed liquid refrigerant out of the condenser chamber, expands it and passes it into the flash tank chamber 114 where the refrigerant separates into a liquid and vapour as previously described.

[0087] The expansion device 122 may be an electronic expansion valve, or a fixed orifice device, such as a capillary tube, all of which operate to expand the liquid refrigerant flowing through the expansion device 122 into a mixture of liquid and vapour that is passed into the flash tank chamber 114.

[0088] It is worth noting that in any of the embodiments described above, the vessel 112, 112a, 112b may be formed from a pre-existing pressure vessel that has already been approved for meeting industry standards for use with the pressure envelopes of the condenser chamber 113 (and the flash tank chamber 114). As such, any of the partition 115a, 115b, liquid duct 116, screen 119 and float valve 117 or expansion device 122 may be retrofitted to such a pressure vessel.