GB2495149A

GB2495149A - Refrigeration Apparatus With Subcooler

Info

Publication number: GB2495149A
Application number: GB201116957A
Authority: GB
Inventors: Edwin Arthur Gittoes; Stuart Lawson
Original assignee: Arctic Circle Ltd
Current assignee: Arctic Circle Ltd
Priority date: 2011-09-30
Filing date: 2011-09-30
Publication date: 2013-04-03
Also published as: GB201116957D0

Abstract

A refrigeration apparatus 26 has an evaporator 27 for causing liquid refrigerant to evaporate to gaseous refrigerant, a condenser means 8 which is air-cooled and which is for condensing the gaseous refrigerant to the liquid refrigerant, and a subcooler means 28 which is air cooled and which is for subcooling the liquid refrigerant. The subcooler means is regulated independently of the condenser means whereby the liquid refrigerant is able to be subcooled to near ambient temperature even when the condenser means regulates the condensing temperature to facilitate control of the refrigeration apparatus and/or to allow heat reclaim. The apparatus may have first and second control means, the first control means controlling the condenser, and the second control means controlling the subcooler. The condenser and subcooler may each have at least one fan, 10, 30, which are independently controlled. The arrangement may also include a reservoir 14 positioned between the condenser and the subcooler. The arrangement may further include an auxiliary condenser (34 fig 3) used to heat a fluid such as air or water, when used for heat reclaim.

Description

REFRIGERATION APPARATUS

This invention relates to refrigeration apparatus.

Known refrigeration apparatus comprises evaporator means for causing liquid refrigerant to evaporate to gaseous refrigerant, and condenser means which is air-cooled and which is for condensing the gaseous refrigerant to the liquid refrigerant-The evaporator means and the condenser means form a heat exchanger in the refrigeration apparatus. The refrigeration apparatus operates by evaporating the liquid refrigerant to absorb heat, with the liquid refrigerant evaporating after being passed through the evaporator means. The evaporator means is usually an expansion device such for example as a valve. The refrigeration apparatus works best when the refrigerant entering the evaporator is entirely liquid. The presence of vapour in the liquid refrigerant can reduce the performance of the evaporator means, and also the operational stability of the refrigeration apparatus.

It is known to employ subcooler means for subcooling the liquid

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* * refrigerant. The subcooler means is employed to increase the capacity of the

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*fl.*S * 5 refrigeration apparatus and/or to improve the stability of operation of the *.* S refrigeration apparatus. The subcooler means operates to ensure that the S.....

5 refrigerant entering *the expansion means is entirely liquid. This in turn ensures that the evaporator means operates in an optimal manner, and that

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the capacity of the refrigeration apparatus is not reduced by a poorly operating evaporator means.

When the subcooler means is used in the known refrigeration apparatus, the refrigerant generally leaves the condenser means with only a very small amount of subcooling. As the liquid refrigerant passes through the evaporator means, there are pressure drops and heat pick up in the conduit for the liquid refrigerant. The size of the pressure drops and the amount of the heat pick up depend on the design and size of the refrigeration apparatus.

Even with the subcooling, vapour bubbles may still be present in the liquid refrigerant as the liquid refrigerant enters the expansion means.

The known refrigeration apparatus with the subcooler means may be such that the subcooler means operates to achieve the cooling in ways that may include cooling suction vapour, boiling off liquid, or using ambient air.

The present invention is concerned with refrigeration apparatus having subcooler means that operates using ambient air.

With the known refrigeration apparatus having subcooler means that operates using ambient air, the subcooler means is employed in a condenser block which contains the condenser means. Thus both the condenser means * * . and the subcooler means are air-cooled. It is common practice to control the refrigeration apparatus by setting a minimum condensing temperature. This is because it is better to condense at the lowest possible condensing temperature, rather than to condense at a high temperature and then produce a lot of subcooling. Because it is better to condense at a low temperature, subcooling using ambient air is generally limited to an amount which guarantees stable operation of the expansion device, usually no more than 5k. The selling of the minimum condensing temperature maintains a sufficient pressure drop across the expansion means in order to achieve proper opetation and/or to enable heat reclaim. If the minimum condensing temperature is kept artificially high, this is most commonly achieved by reducing the condenser fan speed, which in turn decreases the airflow over the condenser means. If the airflow over the condenser means is reduced, then cooling through the subcooler means is also reduced. This in turn results in a loss of overall performance from the refrigeration apparatus.

It is an aim of the present invention to provide refrigeration apparatus which utitises subcooler means which is cpoled by ambient air, and which reduced the above mentioned problem.

Accordingly, in one non-limiting embodiment of the present invention, there is provided refrigeration apparatus comprising evaporator means for causing liquid refrigerant to evaporate to gaseous refrigerant, condenser means which is air-cooled and which is for condensing the gaseous refrigerant to the liquid refrigerant, and subcooler means which is air-cooled and which is for subcooling the liquid refrigerant, characterised in that the subcooler means is regulated independently of the condenser means whereby the liquid refrigerant is able to be subcooled to near ambient temperature even when the condenser means regulates the condensing temperature to an artificially high level in order to facilitate control of the refrigeration apparatus and/or to allow heat reclaim.

The refrigeration apparatus of the present invention is thus advantageous in that it is able to optimise on both the operation of the condenser means and the operation of the subcooler means. The refrigeration apparatus is thus able to avoid operation of the subcooler means adversely affecting the operation of the condenser means, and conversely operation of the condenser means adversely affecting the operation of the subcooler means. The refrigeration apparatus is especially advantageous in that, at times when the condensing temperature of the condensing means is being held artificially high for control of the refrigeration apparatus and/or heat reclaim, significant performance gains are able to be obtained by achieving high levels of subcooling.

The refrigeration apparatus of the present invention may include first control means for controlling the condenser means, and second control means for controlling the subcooler means, with the refrigeration apparatus being one in which the first and second control means are independently controllable so that the subcooler means is able to be regulated independently of the condenser means.

* * The refrigeration apparatus may be one in which the subcooler means * * is separate from the condenser means. In this case, the refrigeration apparatus may include reservoir means positioned between the condenser means and the subcooler means whereby in use of the refrigeration * : apparatus the liquid refrigerant leaving the condenser means passes to the reservoir means before entering the subcooler means.

The refrigeration apparatus may alternatively be one in which the subcooler means is located with the condenser means in an air cooled condenser block. In this case, the refrigeration apparatus may comprise at least one first fan for cooling the condenser means, with at least one second fan for cooling the subcooler means, and the refrigeration apparatus being one in which the first and the second fans are independently controllable so that the subcooler means is able to be regulated independently of the condenser means.

In all embodiments of the invention, the refrigeration apparatus may include auxiliary condenser means, the auxiliary condenser means being such that it is used for heat reclaim purpose.

The auxiliary condenser means may operate to transfer heat to a fluid.

The fluid may be air, water or another fluid such for example as another gas or another liquid.

Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 shows known refrigeration apparatus employing subcooler means; * . Figure 2 shows first refrigeration apparatus of the present invention; and * . ***.

Figure 3 shows second refrigeration apparatus of the present invention.

Referring to Figure 1, there is shown refrigeration apparatus 2 comprising a compressor 4 which provides hot gaseous refrigerant along a pipe 6 to condenser means 8. The condenser means 8 is air cooled by a fan 10.

The refrigeration apparatus 2 is such that liquid with minimal subcooling leaves the condenser means 8 via a pipe 12 and passes to reservoir means 14 which receives liquid refrigerant. The liquid refrigerant then passes along a pipe 16 to a subcooling section 18 of the condenser means 8.

The refrigeration apparatus 2 operates such that gaseous refrigerant from a load passes along conduit 20 to the compressor 4. Liquid refrigerant passes along a pipe 22 to the load. Liquid refrigerant passing along a pipe 12 to the reservoir means 14 has minimal subcooling prior to being introduced via a pipe 16 to the subcooling section 18 of the condenser means 8.

The refrigeration apparatus 2 is able to operate such that the subcooling section 18 in the condenser block 24 is able to produce a few degrees of subcooling in order to achieve stability of operation of the expansion device 25 and an evaporator 27. A problem occurs if it is desired to control the known refrigeration apparatus 2 by setting a minimum condensing temperature. The setting of the minimum condensing temperature * S * * *4 * . *....: may be done to maintain a sufficient pressure drop across the expansion means in order to ensure proper operation of the expansion means and/or it **** *:... may be to enable heat reclaim. If the condensing temperature is kept artificially high, then this is most commonly achieved by reducing the speed of ** operation of the fan 10. This reduces the airflow over the condenser means B in order to enable the condensing temperature to be kept artificially high. The problem is that it also reduces the airflow over the subcooling section 18. This in turn means that the subcooling section 18 loses performance because it is not receiving sufficient air to subcocl the liquid refrigerant as required.

Referring now to Figure 2. there is shown first refrigeration apparatus 26 of the present invention. Similar parts as in the known refrigeration apparatus 2 have been given the same reference numerals for ease of comparison and understanding.

In the refrigeration apparatus 26. there is included subcooler means 28 which is air cooled by a fan 30 and which is regulated independently of the condenser means 8 with its fan 10. Because the subcooler means 28 is regulated independently of the condenser means 8, the liquid refrigerant is able to be subcooled to near ambient temperatures even when the condenser means 8 is cooling the liquid refrigerant to an artificially high temperature in order to facilitate control of the refrigeration apparatus 26 and/or to allow heat reclaim.

The apparatus 26 includes first control means (not shown) for controlling the condenser means 8, and second control means (not shown) for controlling the subcooler means 28. The first and the second control means are independently controllable so that the subcooler means 28 is regulated independently of the condenser means 8.

As can be seen from Figure 2, the apparatus 26 is such that the subcooler means 28 is separate from the condenser means 8. The reservoir means 14 is positioned between the condenser means B and the subcooler means 28 whereby in use of the refrigeration apparatus 25, the liquid refrigerant leaving the condenser means 8 passes to the reservoir means 14 before entering the subcooler means 28.

The refrigeration apparatus 26 is able to independently control the subbooler means 28. Thus any regulation of the subcooler means 28 is independeAt of the control of the condenser means 8. This enables the liquid refrigerant to be cooled to near ambient temperature, even when the condensing temperature is being kept artificially high in order to facilitate good control of the refrigeration apparatus 2 and/or to allow heat reclaim.

Referring now to Figure 3, there is shown second refrigeration apparatus 32 of the present invention. Similar parts as in the first refrigeration apparatus 26 of the present invention hav9 been given the same reference numerals for ease of comparison and understanding.

The refrigeration apparatus 32 includes auxiliary condenser means 34.

The auxiliary condenser means 34 is such that it is used for heat reclaim purposes. The auxiliary condenser means 34 operates to transfer heat to a fluid such for example as air or water. The refrigeration apparatus 32 includes valves 36, 38, 40, 42 as shown.

:4 The refrigeration apparatus 32 operates such that hot gaseous refrigerant from the compressor 4 is directed either to the condenser means 8 or to the auxiliary condenser means 34. The auxiliary condenser means 34 is used to reclaim, i.e. recover, heat if heating is required. Liquid refrigerant enters the reservoir means 14 and then passes to the subcooler means 28 which is cooled by the fan 30. When the refrigeration apparatus 32 is operating in a heating mode with the auxiliary condenser means 34 being used, then the refrigeration apparatus 32 will invariably be condensing gaseous refrigerant into liquid refrigerant substantially above ambient temperature. Using the separate subcooler means 28 allows the liquid refrigerant to be cooled to just above ambient temperature regardless of the condensing temperature in the condensing means 8. If the refrigeration apparatus 32 is operating such that the condensing temperature in the condensing means is being regulated to achieve operational stability, then using the independently controlled subcooler means 28 enables an improvement on system capacity and efficiency for a significant part of the year in the United Kingdom. If the condensing temperature in the condenser means 8 being kept artificially high to facilitate operation such for example as heat reclaim, a more subètantial increase in subcooling is able to be achieved by the use of the subcooler means 28, and this in turn leads to greater efficiency of the entire refrigeration apparatus 32.

It is to be appreciated that the embodiments of the invention described above with reference to the accompanying drawings have been given by way of example only and that modifications may be effected. Thus, for example, the refrigeration apparatus of the present invention may be such that the subcooler means 28 is located in the same condenser block 24 as the condenser means 28. If this should be the case, then the fans 10, 30 are :5 independently controlled. More than one fan 10 and/or more than one fan 30 may be employed. Individual components shown in the drawings are not limited to use in their drawings and they may be used in other drawings and in all aspects of the invention.

Claims

<claim-text>CLAIMS1. Refrigeration apparatus comprising evaporator means for causing liquid refrigerant to evaporate to gaseous refrigerant, condenser means which is air-cooled and which is for condensing the gaseous refrigerant to the liquid refrigerant, and subcooler means which is air cooled and which is for subcooling the liquid refrigerant, characterised in that the subcooler means is regulated independently of the condenser means whereby the liquid refrigerant is able to be subcooled to near ambient temperature even when the condenser means regulates the condensing temperature to an artificially high level in order to facilitate control of the refrigeration apparatus and/or to allow heat reclaim.</claim-text> <claim-text>2. Refrigeration apparatus according to claim I and including first control means for controlling the condenser means, and second control means for controlling the subcooler means, and in which the first and second control means are independently controllable so that the subcooler means is able to be regulated independently of the condenser means. * *S</claim-text> <claim-text>* 3. Refrigeration apparatus according to claim I or claim 2 in which the a...subcooler means is separate from the condenser means.</claim-text> <claim-text>** ...S * S S. ** 4. Refrigeration apparatus according to claim 3 and including reservoir * I means positioned between the condenser means and the subcooler means whereby in use of the refrigeration apparatus the liquid refrigerant leaving the condenser means passes to the reservoir means before entering the subcooler means.</claim-text> <claim-text>5. Refrigeration apparatus according to claim I or claim 2 in which the subcooler means is located within the condenser means in an air-cooled condenser block.</claim-text> <claim-text>6. Refrigeration apparatus according to claim 5 and comprising at least one first fan for cooling the condenser means, and at least one second fan for cooling the subcooler means, and in which the first and the second fans are independently controllable so that the subcooler means is able to be regulated independently of the condenser means.</claim-text> <claim-text>7. Refrigeration apparatus according to any one of the preceding claims and including auxiliary condenser means, the auxiliary condenser means being such that it is used for heat reclaim. * 0</claim-text> <claim-text>8. Refrigeration apparatus according to claim 7 in which the auxiliary condenser means operates to transfer heat to a fluid. *00*</claim-text> <claim-text>9. Refrigeration apparatus according to claim 8 in which the fluid is air or water.</claim-text> <claim-text>10. Refrigeration apparatus substantially as herein described with reference to Figure 2 or Figure 3 of the accompanying drawings. * **0*000 * * *0** * * *0SSS*0Se** * * *0 ** * * * * SS S..S</claim-text>