GB2539911A

GB2539911A - Refrigeration apparatus

Info

Publication number: GB2539911A
Application number: GB1511457.2A
Authority: GB
Inventors: Scott Franzen Nicholas
Original assignee: Arctic Circle Ltd
Current assignee: Arctic Circle Ltd
Priority date: 2015-06-30
Filing date: 2015-06-30
Publication date: 2017-01-04
Also published as: GB201511457D0

Abstract

A refrigeration apparatus 10 comprises a compressor 12, a condenser 14, an expansion valve 16, an evaporator 18, a gas / liquid separator 20 for separating liquid refrigerant from a gaseous refrigerant passing from the evaporator to the compressor, and a heat exchanger 30 for transferring heat from refrigerant flowing between the compressor and the expander to liquid refrigerant separated by the separator. The separator may comprise an expansion chamber (22, fig 2) to decelerate flow of the refrigerant passing therethrough, and may separate the liquid from the gaseous refrigerant under gravity. A vapour return line 11g may permit evaporated liquid refrigerant to flow to the compressor. The heat exchanger may be located between the condenser and the expansion valve. A liquid storage chamber may collect the liquid refrigerant separated by the separator and the heat exchanger may transfer thermal energy (evaporate) to the liquid refrigerant in the storage chamber. An oil return line 40 may divert oil separated by the separator away from the liquid refrigerant and may be located between the separator and the heat exchanger. The heat exchanger may be a plate type or a first vessel inside a second vessel.

Description

TITLE: REFRIGERATION APPARATUS DESCRIPTION

The present invention relates to refrigeration apparatus.

Known refrigeration apparatus (e g. refrigerator, freezer or air-conditioning apparatus) typically achieves cooling of a thermal load by means of a vapour compression refrigeration cycle in which a refrigerant is first compressed in gaseous form by a compressor, then condensed by an air-cooled condenser to release heat to the atmosphere, and the resulting liquid refrigerant is then cooled by expansion and subsequently evaporated in an evaporator to absorb heat from the thermal load.

It is well known that saturated liquid in the suction line of a refrigeration system is a common cause of damage to refrigeration compressors. This problem is commonly known in the refrigeration industry as “liquid slugging”. Various methods have be employed to prevent damage to the compressor from returning liquid. A well-known solution involves use of a device known as a “suction line accumulator” operative to separate liquid from vapour passing from the evaporator to the compressor and temporarily store the liquid whilst awaiting natural evaporation to occur.

The present applicant has identified the need for an improved refrigeration apparatus capable of providing additional gains in efficiency compared with refrigeration apparatus of the prior art.

In accordance with the present invention, there is provided refrigeration apparatus (e g. refrigerator, freezer or air-conditioning apparatus) comprising; a compressor operative to compress and heat a refrigerant in a gaseous state; a condenser (e.g. air-cooled condenser) for condensing the heated refrigerant from a gaseous (e.g. vapour) state to a liquid state; an expander operative to expand the refrigerant (e.g. when received in a substantially liquid state) after exposure to the condenser; and an evaporator for receiving the refrigerant in a liquid state from the expander, the evaporator being operative to receive thermal energy from a thermal load and cause the refrigerant to evaporate to a gaseous (e.g. vapour) state before the refrigerant is returned to the compressor; wherein the apparatus further comprises: a gas/liquid separator (e.g. vapour/liquid separator) for separating liquid refrigerant (e.g. saturated liquid refrigerant) from the gaseous refrigerant passing from the evaporator to the compressor; and a heat exchanger for transferring thermal energy from refrigerant flowing at a point between the compressor and the expander to liquid refrigerant separated by the gas/liquid separator.

In this way, refrigeration apparatus is provided that acts both to reduce the risk of saturated liquid entering the compressor and provide useful subcooling to the refrigerant flowing between the compressor and expander.

In one embodiment the gas/liquid separator is operative to decelerate flow of refrigerant passing therethrough. For example, in one embodiment the gas/liquid separator comprises an expansion chamber for decelerating flow of refrigerant passing therethrough.

In one embodiment, the gas/liquid separator is operative to separate liquid refrigerant from gaseous refrigerant under gravity.

In one embodiment, the heat exchanger is configured to evaporate at least a portion of liquid refrigerant separated by the gas/liquid separator. In one embodiment, the apparatus further comprises a vapour return line for allowing evaporated liquid refrigerant to flow to the compressor (e.g. re-join the flow of gaseous refrigerant passing from the gas/liquid separator to the compressor). Advantageously this arrangement allows subcooling to be achieved whilst maintaining optimum vapour flow to the compressor.

In one embodiment, the heat exchanger is configured to transfer thermal energy at a point between the condenser and the expander.

In one embodiment, the refrigeration apparatus further comprises a liquid storage chamber for collecting liquid refrigerant separated by the gas/liquid separator. In one embodiment, the heat exchanger is configured to transfer thermal energy (from refrigerant flowing at the point between the compressor and the expander) to liquid refrigerant collected in the liquid storage chamber.

In one embodiment, the apparatus further comprises an oil return line for diverting oil separated by the gas/liquid separator away from the liquid refrigerant. In one embodiment, the oil return line is provided between the gas/liquid separator and the heat exchanger.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 is a schematic view of refrigeration apparatus in accordance with an embodiment of the present invention; and

Figure 2 is an enlarged schematic view of novel parts of the refrigeration apparatus of Figure 1.

Figure 1 shows refrigeration apparatus 10 comprising pipes 1 la-1 Ig, a compressor 12, an air-cooled condenser 14, an expander 16, an evaporator 18 operative to receive thermal energy from a thermal load (e g. refrigerator, freezer or air conditioning load), a vapour/liquid separator 20, a heat exchanger 30 and an oil return line 40.

In use, refrigeration apparatus 10 operates in accordance with a conventional compression refrigeration cycle. Refrigerant in the form of a saturated vapour is compressed by compressor 12 to form a superheated vapour, thermal energy is rejected from the refrigerant by passing the compressed refrigerant through air-cooled condenser 14 to produce a saturated liquid. The refrigerant is then expanded in liquid form by expander 16 to produce a low temperature vapour/liquid flow before being evaporated in evaporator 18 (and thereby absorbing thermal energy from the thermal load to achieve the desired cooling) and returning to saturated vapour form before flowing back to compressor 12.

In the absence of any superheat, refrigerant gas returning from evaporator 18 to compressor 12 may contain refrigerant in its liquid form (mixed phase refrigerant with both liquid and vapour at saturation). In accordance with the present invention, the saturated vapour returning to compressor 12 from evaporator 18 passes through vapour/liquid separator 20 located between pipes lid and lie with liquid separated from the vapour flow being directed through heat exchanger 30 via pipe 1 If At the same time, saturated liquid flowing from aircooled condenser 14 to expander 16 passes through heat exchanger/liquid accumulator 30 connected between pipes 11b and 11c. In this way, thermal energy is transferred from the saturated liquid flowing from air-cooled condenser 14 to the saturated liquid separated by vapour/liquid separator 20 resulting in evaporation of the separated liquid and subcooling of refrigerant flow from air-cooled condenser 14 to expander 16. The evaporated liquid refrigerant is returned to pipe 1 le via vapour return pipe 1 Ig to re-join the vapour flow to compressor 12.

Any oil separated by vapour/liquid separator 20 is diverted away from the liquid refrigerant by oil return line 40 provided between vapour/liquid separator 20 and heat exchanger 30.

As illustrated in Figure 2, vapour/liquid separator 20 includes an expansion chamber 22 for decelerating flow of refrigerant therethrough. Pipe 1 If is connected below expansion chamber 22 to collect liquid refrigerant under gravity.

Heat exchanger 30 is configured to transfer thermal energy from the condenser flow to the separated liquid refrigerant with the two liquid paths in counter flow. In one embodiment, heat exchanger 30 may comprise a heat plate exchanger (with capacity to hold a volume of liquid). In another embodiment, heat exchanger 30 may comprise a first liquid vessel provide inside a second liquid vessel arranged so that thermal energy can be exchanged between the high pressure liquid refrigerant (liquid line) and the low pressure liquid refrigeration (suction line). Heat exchanger 30 may be regarded as a multi-function unit since it acts as a heat exchanger, liquid receiver and a suction line accumulator all in one.

Claims

Claims:

1. Refrigeration apparatus comprising: a compressor operative to compress and heat a refrigerant in a gaseous state; a condenser for condensing the heated refrigerant from a gaseous state to a liquid state; an expander operative to expand the refrigerant after exposure to the condenser; and an evaporator for receiving the refrigerant in a liquid state from the expander, the evaporator being operative to receive thermal energy from a thermal load and cause the refrigerant to evaporate to a gaseous state before the refrigerant is returned to the compressor; wherein the apparatus further comprises: a gas/liquid separator for separating liquid refrigerant from the gaseous refrigerant passing from the evaporator to the compressor; and a heat exchanger for transferring thermal energy from refrigerant flowing at a point between the compressor and the expander to liquid refrigerant separated by the gas/liquid separator.

2. Refrigeration apparatus according to claim 1, wherein the gas/liquid separator is operative to decelerate flow of refrigerant passing therethrough.

3. Refrigeration apparatus according to claim 1 or claim 2, wherein the gas/liquid separator comprises an expansion chamber for decelerating flow of refrigerant passing therethrough.

4. Refrigeration apparatus according to any of the preceding claims, wherein the gas/liquid separator is operative to separate liquid refrigerant from gaseous refrigerant under gravity.

5. Refrigeration apparatus according to any of the preceding claims, wherein the heat exchanger is configured to evaporate at least a portion of liquid refrigerant separated by the gas/liquid separator.

6. Refrigeration apparatus according to claim 5, wherein the apparatus further comprises a vapour return line for allowing evaporated liquid refrigerant to flow to the compressor.

7. Refrigeration apparatus according to any of the preceding claims, wherein the heat exchanger is configured to transfer thermal energy at a point between the condenser and the expander.

8. Refrigeration apparatus according to any of the preceding claims, wherein the refrigeration apparatus further comprises a liquid storage chamber for collecting liquid refrigerant separated by the gas/liquid separator.

9. Refrigeration apparatus according to claim 8, wherein the heat exchanger is configured to transfer thermal energy to liquid refrigerant collected in the liquid storage chamber.

10. Refrigeration apparatus according to any of the preceding claims, wherein the apparatus further comprises an oil return line for diverting oil separated by the gas/liquid separator away from the liquid refrigerant.

11. Refrigeration apparatus according to claim 10, wherein the oil return line is provided between the gas/liquid separator and the heat exchanger.