SUCTION COMPRESSOR TEMPERATURE REGULATOR DEVICE FOR TRANSCRITICAL AND SUBCRITICAL R-744 COMPRESSORS

Abstract

A suction compressor temperature regulator device, for use with at least one compressor of a R-744 refrigeration system, includes a heating mechanism located upstream of the at least one compressor of the refrigeration system, in a suction line thereof, for locally controlling the temperature of a R-744 fluid of the refrigeration system. The heating mechanism is typically in a form of a heat exchanger connected to the suction line and using a heating fluid to transfer heat therefrom to the R-744 fluid at the heat exchanger.

Description

FIELD OF THE INVENTION

The present invention concerns refrigeration systems and methods, and more particularly a suction compressor temperature regulator device for transcritical and subcritical R-744 compressors in R-744 refrigeration systems.

BACKGROUND OF THE INVENTION

Refrigeration systems are commonly used in supermarkets to refrigerate or to maintain in frozen state perishable products, such as foodstuff.

Presently the R-744 subcritical refrigeration systems are defrosted electrically for the low temperature applications and by air defrost for the medium temperature applications.

Furthermore, the suction temperature of R-744 compressors (subcritical or transcritical) is required to be maintained at a level at least 36° F. higher than the evaporating temperature in order to avoid oil foaming and to achieve reliable and stable operation. This is extremely difficult to achieve by the habitual methods used in Freon™ systems. The most common method used is suction to liquid heat exchanger. However in the case of R-744 system the liquid temperature is very low (around 20° F.) and is inappropriate for use in such heat exchanger. It would be also difficult to regulate the liquid flow rate through the heat exchanger in order to achieve stable suction temperature at the required level.

Accordingly, it would be desirable to have an improved suction compressor temperature regulator device for transcritical and subcritical R-744 compressors for refrigeration systems.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved suction compressor temperature regulator device for transcritical and subcritical R-744 compressors for refrigeration systems.

An advantage of the present invention is that the suction compressor temperature regulator device is simple and allows the corresponding compressor(s) to substantially remain within efficient operating conditions, as possible, by controlling the temperature of the R-744 fluid reaching the compressor(s). The heating mechanism of the device is typically regulated by a temperature sensor sensing the temperature of the R-744 fluid located between the heating mechanism and the compressor(s).

According to an aspect of the present invention, there is provided a suction compressor temperature regulator device for use with at least one compressor of a R-744 refrigeration system, said device comprising:

• • a heating mechanism located upstream of the at least one compressor of the refrigeration system, in a suction line of the at least one compressor for locally controlling the temperature of a R-744 fluid of the refrigeration system.

In one embodiment, the heating mechanism is in a form of a heat exchanger connected to the suction line and using a heating fluid, wherein heat from the heating fluid is transferrable to the R-744 fluid at the heat exchanger.

Conveniently, the heating mechanism includes a heating fluid circuit with heating fluid modulating valve regulating a rate of heating fluid circulating through the heat exchanger.

Typically, the modulating valve is controlled by a temperature of the R-744 fluid flowing in the suction line between the heat exchanger and the at least one compressor.

Preferably, the heating fluid circuit includes a pressure regulating valve located downstream of the modulating valve and upstream of the heat exchanger.

In one embodiment, the at least one compressor is a transcritical compressor, the suction line is a transcritical suction line, the heat exchanger is a transcritical heat exchanger, and the heating fluid modulating valve is a transcritical heating fluid modulating valve; the heating fluid circuit of the device further including a subcritical heating fluid modulating valve regulating a rate of heating fluid circulating through a subcritical heat exchanger connected to a subcritical suction line of at least one subcritical compressor for transferring heat to the R-744 fluid thereat.

Conveniently, the subcritical modulating valve is controlled by a temperature of the R-744 fluid flowing in the subcritical suction line between the subcritical heat exchanger and the at least one subcritical compressor.

Typically, the pressure regulating valve is located downstream of the transcritical and subcritical modulating valves and upstream of the transcritical and subcritical heat exchangers.

In one embodiment, the heating fluid circuit is part of a heat reclaim circuit of the refrigeration system.

Conveniently, the heating fluid reaches the heat exchanger before reaching a heat recuperator of the heat reclaim circuit.

Typically, the heat recuperator is located between the at least one compressor and a gas cooler of the refrigeration system such that heat from the compressed R-744 fluid is transferred to the heating fluid of the heat reclaim circuit.

In one embodiment, the heating mechanism is in a form of an electrical heating device located at the suction line for transferring heat to the R-744 fluid thereat.

According to an aspect of the present invention, there is provided a R-744 refrigeration system having at least one compressor and a suction compressor temperature regulator device as claimed in claim 1 for use therewith.

Other objects and advantages of the present invention will become apparent from a careful reading of the detailed description provided herein, with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects and advantages of the present invention will become better understood with reference to the description, provided for purposes of illustration only, in association with the following figure, wherein:

FIG. 1 is a schematic diagram of a suction compressor temperature regulator device for transcritical and subcritical R-744 compressors in R-744 refrigeration systems, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, there is shown a simplified R-744 transcritical refrigeration system 101 with a heat reclaim capabilities using a glycol solution as heat transfer fluid, incorporating an embodiment of a suction compressor temperature regulator device 100 for transcritical and subcritical R-744 compressors in accordance with the present invention.

In the suction line 1′ of the transcritical compressors 1 of the refrigeration system 101, the suction compressor temperature regulator device 100 includes a heating mechanism that is preferably in the form of a heat exchanger 4 that is connected through conduit 9 and through modulating valve 14 to conduit 15, and through conduit 8 to conduit 16 after the pressure regulating valve 10 of a heat reclaim circuit 11 having atypical recuperator 5 used to cool down the hot gas downstream of the compressors 1 (and provide comfort heating for the building (not shown) at the same time, or the like) before the gas reaches the gas cooler 6, thus allowing a warm glycol solution or the like to flow through heat exchanger 4 at a controlled rate. The flow rate of the warm glycol solution is typically regulated by modulating valve 14 and is controlled by the temperature, via a temperature sensor (not shown) or the like, of the R-744 fluid vapours between heat exchanger 4 and compressor 1.

Similarly, in the suction line 2′ of the subcritical compressors 2 of the refrigeration system 101, the suction compressor temperature regulator device 100 includes the heating mechanism that is preferably in the form of a heat exchanger 3 that is connected through conduit 7 and through modulating valve 13 to conduit 15, and through conduit 8 to conduit 16 after the pressure regulating valve 10, thus allowing a warm glycol solution or the like to flow through heat exchanger 3 at a controlled rate. The flow rate of the warm glycol solution is typically regulated by modulating valve 13 and is controlled by the temperature, via another temperature sensor (not shown) or the like, of the R-744 fluid vapours between heat exchanger 3 and compressor 2.

Although not shown, it would be obvious to one skilled in the art that any other warm fluid solutions could be considered to be used with the heat exchangers 3 and 4, or even different types of heating mechanism for controlled local heating, such as electrical heating device 3′ or the like, of the fluid just upstream (in the suction line) of the transcritical 1 and/or subcritical 2 compressors, and preferably controlled by the temperature, via a temperature sensor (not shown) or the like, of the R-744 fluid vapours inside the suction line 2′ just upstream of the compressor 2, without departing from the scope of the present invention.

Although the present invention has been described with a certain degree of particularity, it is to be understood that the disclosure has been made by way of example only and that the present invention is not limited to the features of the embodiments described and illustrated herein, but includes all variations and modifications within the scope and spirit of the invention as hereinafter claimed.

Claims

1. A suction compressor temperature regulator device for use with at least one compressor of a R-744 refrigeration system, said device comprising: a heating mechanism located upstream of the at least one compressor of the refrigeration system, in a suction line of the at least one compressor for locally controlling the temperature of a R-744 fluid of the refrigeration system.

2. The device of claim 1, wherein the heating mechanism is in a form of a heat exchanger connected to the suction line and using a heating fluid, wherein heat from the heating fluid is transferrable to the R-744 fluid at the heat exchanger.

3. The device of claim 2, wherein the heating mechanism includes a heating fluid circuit with heating fluid modulating valve regulating a rate of heating fluid circulating through the heat exchanger.

4. The device of claim 3, wherein the modulating valve is controlled by a temperature of the R-744 fluid flowing in the suction line between the heat exchanger and the at least one compressor.

5. The device of claim 4, wherein the heating fluid circuit includes a pressure regulating valve located downstream of the modulating valve and upstream of the heat exchanger.

6. The device of claim 5, wherein the at least one compressor is a transcritical compressor, the suction line is a transcritical suction line, the heat exchanger is a transcritical heat exchanger, and the heating fluid modulating valve is a transcritical heating fluid modulating valve; the heating fluid circuit of the device further including a subcritical heating fluid modulating valve regulating a rate of heating fluid circulating through a subcritical heat exchanger connected to a subcritical suction line of at least one subcritical compressor for transferring heat to the R-744 fluid thereat.

7. The device of claim 6, wherein the subcritical modulating valve is controlled by a temperature of the R-744 fluid flowing in the subcritical suction line between the subcritical heat exchanger and the at least one subcritical compressor.

8. The device of claim 7, wherein the pressure regulating valve is located downstream of the transcritical and subcritical modulating valves and upstream of the transcritical and subcritical heat exchangers.

9. The device of claim 5, wherein the heating fluid circuit is part of a heat reclaim circuit of the refrigeration system.

10. The device of claim 9, wherein the heating fluid reaches the heat exchanger before reaching a heat recuperator of the heat reclaim circuit.

11. The device of claim 10, wherein the heat recuperator is located between the at least one compressor and a gas cooler of the refrigeration system such that heat from the compressed R-744 fluid is transferred to the heating fluid of the heat reclaim circuit.

12. A R-744 refrigeration system having at least one compressor and a suction compressor temperature regulator device as claimed in claim 1 for use therewith.

13. The device of claim 1, wherein the heating mechanism is in a form of an electrical heating device located at the suction line for transferring heat to the R-744 fluid thereat.