US20160209100A1

US20160209100A1 - Refrigeration System with Hot Gas Defrost Mode

Info

Publication number: US20160209100A1
Application number: US14/986,768
Authority: US
Inventors: Christopher Lyn Jentzsch; Jim KITCHEN; Eric C. Moen
Original assignee: Heatcraft Refrigeration Products LLC
Current assignee: Heatcraft Refrigeration Products LLC
Priority date: 2015-01-20
Filing date: 2016-01-04
Publication date: 2016-07-21

Abstract

The present application provides a refrigeration system with a flow of refrigerant therein for a refrigerant mode or a defrost mode. The refrigeration system may include a four way valve, an evaporator in communication with the four way valve, a compressor in communication with the four way valve, and a condenser in communication with the four way valve. The four way valve directs the flow of refrigerant to the condenser in the refrigeration mode or to the evaporator in the defrost mode.

Description

TECHNICAL FIELD

This invention relates generally to refrigeration systems and more particularly relate to commercial refrigeration systems using a hot gas defrost mode for periodic defrosting of the evaporator coils and other components.

BACKGROUND OF THE INVENTION

Generally described, a typical refrigeration system includes one or more evaporators positioned about a space to be cooled, a condenser external to the space, a compressor, and an expansion valve. A refrigerant may be compressed by the compressor. The hot, pressurized refrigerant flows through the condenser to allow the refrigerant to dissipate the heat of pressurization. The refrigerant condenses into liquid and then flows through the expansion valve where the refrigerant moves from a high pressure zone into a low pressure zone so as to expand and evaporate. The refrigerant becomes cold in the evaporator as it passes through the coils therein and absorbs heat from the space to be cooled. Other types of refrigeration cycles and components also may be used.
Typical refrigeration systems also include some sort of mechanism to prevent a buildup of frost on the evaporator coils. Defrosting may be accomplished in a number of ways. For example, an external heater may heat the evaporator coils. Such external heating methods, however, may be time consuming. Hot gas systems also may be used. In these systems, the flow of the refrigerant may be reversed so as to flow hot refrigerant through the evaporator coils. Known hot gas defrost systems, however, may include multiple valves and controls in a somewhat complicated arrangement so as to cycle between a refrigeration mode and a defrost mode.

SUMMARY OF THE INVENTION

In certain embodiments, a refrigeration system with a flow of refrigerant therein for a refrigerant mode or a defrost mode is included. The refrigeration system may include a four way valve, an evaporator in communication with the four way valve, a compressor in communication with the four way valve, and a condenser in communication with the four way valve. The four way valve directs the flow of refrigerant to the condenser in the refrigeration mode or to the evaporator in the defrost mode.
According to some embodiments, a method of operating a refrigeration system in a refrigeration mode or a defrost mode may include the steps of directing a flow of refrigerant by a four way valve to a condenser and then to an evaporator in the refrigeration mode, modulating the flow of refrigerant to the evaporator with an electronic expansion valve in the refrigeration mode, directing the flow refrigerant by the four way valve to the evaporator and then to the condenser in the defrost mode, and modulating the flow of refrigerant to the condenser with an electronic pressure regulator in the defrost mode.
In particular embodiments, a refrigeration system with a flow of refrigerant therein for a refrigerant mode or a defrost mode may include a four way valve, an evaporator in communication with the four way valve, a condenser in communication with the four way valve, an electronic expansion valve for modulating the flow of refrigerant to the evaporator in the refrigeration mode, and an electronic pressure regulator for modulating the flow of refrigerant to the condenser in the defrost mode. The four way valve directs the flow of refrigerant to the condenser in the refrigeration mode or to the evaporator in the defrost mode.
These and other features and improvements of certain embodiments of the present disclosure will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a refrigeration system as may be described herein in a refrigeration mode.

FIG. 2 is a schematic diagram of the refrigeration system of FIG. 1 in a defrost mode.

DETAILED DESCRIPTION

Referring now to the drawings, in which like numerals refer to like elements throughout the several views, FIGS. 1 and 2 show a refrigeration system 100 as may be described herein. The refrigeration system 100 may be used to cool any type of enclosed or partially enclosed space. The refrigeration system 100 may include a flow of a refrigerant 110 therein. The refrigerant 110 may be a natural refrigerant such as carbon dioxide, a hydrofluorocarbon-based refrigerant, or any other type of conventional refrigerant. The refrigeration system 100 may have any suitable size, shape, configuration, or capacity.
The refrigeration system 100 may include a four way valve 120. The refrigeration system 100 may cycle between a refrigeration mode and a defrost mode based in part on the operation of the four way valve 120. The four way valve 120 may be of conventional design. The four way valve 120 may be in communication with a first side evaporator conduit 130, a suction accumulator conduit 140, a compressor conduit 150, and a condenser conduit 160. The four way valve 120 may selectively direct the flow of refrigerant 110 through any of the conduits in any direction. The conduits may have any suitable size, shape, or configuration. Other components and other configurations may be used herein.
The suction accumulator conduit 140 may be in communication with a suction accumulator 170 and/or a suction filter 175. The suction accumulator 170 and the suction filter 175 may be of conventional design. The suction accumulator 170 prevents compressor damage from a sudden surge of liquid refrigerant 110. The suction filter 175 serves to remove contaminates in the flow of the refrigerant 110. Other types of filters also may be used herein.
The refrigeration system 100 may include a compressor 180. The compressor 180 may be of conventional design and may have any suitable size, shape, or configuration. The compressor 180 may be a discus compressor and the like. The compressor 180 may be in communication with the suction accumulator 170 via a suction line 190. The compressor 180 also may be in communication with the four way valve 120 via the compressor conduit 150. Other components and other configurations may be used herein.
The refrigeration system 100 may include a condenser 200. The condenser 200 may be of conventional design and may have any suitable size, shape, or configuration. The condenser 200 may be in communication with the four way valve 120 via the condenser conduit 160. More than one condenser 200 may be used herein. An Oil separator also may be used. Other components and other configurations may be used herein.
The refrigeration system 100 may include a receiver 210. The receiver 210 may be of conventional design and may have any suitable size, shape, or configuration. The receiver 210 may include a dip tube on both the inlet and the outlet. The receiver 210 may store the refrigerant 110 until needed by the evaporator as may be described below. The receiver 210 may be in communication with the condenser 200 via a refrigeration receiver conduit 220 and a defrost receiver conduit 230. The refrigeration receiver conduit 220 may include a refrigerant receiver conduit valve 240 thereon. The defrost receiver conduit 230 may include a defrost receiver conduit valve 250 and an electronic pressure regulator 260. The electronic pressure regulator 260 may be of conventional design and may have any suitable size, shape, or configuration. An electronic expansion valve also could be used herein. The electronic pressure regulator 260 may modulate a flow of the refrigerant 110 to the condenser 200 in the defrost mode. The defrost receiver conduit 230 also optionally may include a filter dryer 270 thereon. The filter dryer 270 may be of conventional design. Other components and other configurations also may be used herein.
The refrigeration system 100 may include an optional sub-cooler 280. The sub-cooler 280 may be of conventional design and may have any suitable size, shape, or configuration. The sub-cooler 280 may be physically part of the condenser 200 or the sub-cooler 280 may be a separate stand-alone device. The sub-cooler 280 may be in communication with the receiver 210 via a sub-cooler input conduit 290. More than one sub-cooler 280 may be used herein. Other components and other configurations also may be used herein.
The refrigeration system 100 may include an evaporator 300. The evaporator 300 may be of conventional design and may have any suitable size, shape, or configuration. More than one evaporator 300 may be used herein. The evaporator 300 may be in communication with the sub-cooler 280 via a sub-cooler output conduit 310. The sub-cooler output conduit 310 may include a sub-cooler output conduit valve 320 thereon. A sub-cooler filter dryer 330 also may be positioned on the sub-cooler output conduit 310. The sub-cooler filter dryer 330 may be of conventional design. A sightglass 340 also may be positioned on the sub-cooler output conduit 310 or elsewhere. Alternatively, the evaporator 300 may be in communication with the receiver 210 via a sub-cooler bypass conduit 350. The sub-cooler bypass conduit 350 may have a sub-cooler bypass conduit valve 360 thereon. The sub-cooler output conduit 300 and the sub-cooler bypass conduit 350 may merge into a second side evaporator conduit 370. Other components and other configurations may be used herein.
An electronic expansion valve 380 may be positioned on the second side evaporator conduit 370. The electronic expansion valve 380 may be of conventional design and may have any suitable size, shape, or configuration. The electronic expansion valve 380 may modulate the flow of the refrigerant 110 to the evaporator 300 in the refrigeration mode. An evaporator bypass conduit 390 may extend from the second side evaporator conduit 370 to the first side evaporator conduit 130 for use in the defrost mode. An evaporator bypass conduit valve 400 may be positioned on the evaporator bypass conduit 390. A drain pan conduit 410 also may extend from the second side evaporator conduit 370 to the first side evaporator conduit 130. A drain pan conduit valve 420 may be positioned on the drain pan conduit 410. A first side evaporator conduit valve 430 may be positioned on the first side evaporator conduit 130. Other components and other configurations may be used herein.
The refrigeration system 100 may include a number of pressure sensors, temperature sensors, and/or other types of sensors. For example, an evaporator temperature sensor 440 may be positioned about the coils of the evaporator 300. A second side evaporator conduit temperature sensor 450 and a second side evaporator conduit pressure sensor 460 may be positioned about the second side evaporator conduit 370. A suction accumulator temperature sensor 470 and a suction accumulator pressure sensor 480 may be positioned about the suction accumulator 170. A compressor temperature sensor 490 may be positioned on the suction line 190 about the compressor 180. A condenser temperature sensor 500 and a condenser pressure sensor 510 may be positioned about the condenser 200. Other types of sensors may be used herein in other positions. The sensors and the valves may be operated via a controller and the like. The controller may be any type programmable logic device. Other components and other configurations may be used herein.
FIG. 1 shows the refrigeration system 100 in the refrigeration mode. In the refrigeration mode, the four way valve 120 receives a flow of refrigerant 110 from the evaporator 300 via the first side evaporator conduit 130. The four way valve 120 directs the flow of refrigerant 110 to the suction accumulator 170 via the suction accumulator conduit 140. The suction accumulator 170 forwards the flow of the refrigerant 110 to the compressor 180 via the suction line 190. The compressor 180 forwards the flow of the refrigerant 110 back to the four way valve 120 via the compressor conduit 150. The four way valve 120 in turn forwards the flow of the refrigerant 110 to the condenser 200 via the condenser conduit 160.
From the condenser 200, the flow of the refrigerant 110 flows to the receiver 210. The refrigeration receiver conduit valve 240 is open on the refrigeration receiver conduit 220 while the defrost receiver conduit valve 250 is closed on the defrost receiver conduit 230. The electronic pressure regulator 260 is closed. The flow of refrigerant 110 then flows to the sub-cooler 280 via the sub-cooler input conduit 290. The flow of refrigerant 110 flows to the electronic expansion valve 380 via the sub-cooler output conduit 310 and the second side evaporator conduit 370. The flow of refrigerant 110 to the evaporator 300 may be modulated by the electronic expansion valve 380. The sub-cooler output conduit valve 320 may be open while the sub-cooler bypass conduit valve 360 may be closed. Likewise, the evaporator bypass conduit valve 400 may be closed as well as the drain pan conduit valve 420. The flow of refrigerant 110 then may return to the four way valve 120 via the first side evaporator conduit 130. The first side evaporator conduit valve 430 may be open. Other components and other configurations may be used herein.
In transitioning from the refrigeration mode to the defrost mode, the refrigeration system 100 first may deactivate the compressor 180 and open the electronic expansion valve 380 fully so as to equalize the refrigerant pressure between the condenser 200 and the evaporator 300.
FIG. 2 shows the refrigeration system 100 in the defrost mode. In the defrost mode, the four way valve 120 may receive the flow of refrigerant 110 from the condenser 200 via the condenser conduit 160. The four way valve 120 then forwards the flow to the suction accumulator 170 via the suction accumulator conduit 140 and on to the compressor 180. The compressor 180 returns the flow to the four way valve 120 via the compressor conduit 150. The four way valve 120 then forwards the flow of the refrigerant 110 to the evaporator 300 via the first side evaporator conduit 140. The flow of the refrigerant 110 then may flow through the drain pan conduit 410 and into the evaporator 300. The drain pan conduit valve 420 may be open. The first side evaporator conduit valve 430 may be closed. The electronic expansion valve 380 may be closed. The flow of refrigerant 110 then may flow through the evaporator bypass conduit 390. The evaporator bypass conduit valve 400 may be open. The flow of the refrigerant 110 may flow through the sub-cooler bypass conduit 350. The sub-cooler bypass conduit valve 360 may be open while the sub-cooler output conduit valve 320 may be closed. The flow of refrigerant 110 then may flow through the receiver 210 and through the defrost receiver conduit 230. The defrost receiver conduit valve 250 may be open and the refrigeration receiver conduit valve 240 may be closed. The electronic pressure regulator 260 thus may modulate the flow of the refrigerant 110 to the condenser 200. The flow of refrigerant 110 then may return to the four way valve 120 via the condenser conduit 160. The refrigeration system 100 may return to the refrigeration mode after a predetermined amount of time has passed, after a predetermined temperature has been reached, or based on any other operational parameter.
The refrigeration system 100 thus provides the hot gas defrost mode with simplified mechanisms and controls through the use of the four way valve 120 instead of multiple solenoid valves on multiple conduits. The four way valve 120 permits easy cycling through the refrigeration mode and the defrost mode. Further, the overall refrigeration charge may be lower than known systems. The overall refrigeration system 100 thus may be highly efficient with a long component life time and limited down time. Moreover, the refrigeration system 100 may be less expensive to construct and to operate as compared to known systems.
It should be apparent that the foregoing relates only to certain embodiments of the present application and the resulting patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.

Claims

We claim:

1. A refrigeration system with a flow of refrigerant therein, comprising:

a four way valve;

an evaporator in communication with the four way valve;

a compressor in communication with the four way valve; and

a condenser in communication with the four way valve;

wherein the four way valve directs the flow of refrigerant to the condenser in a refrigeration mode or to the evaporator in a defrost mode.

2. The refrigeration system of claim 1, further comprising a suction accumulator in communication with the four way valve and the compressor.

3. The refrigeration system of claim 1, further comprising a receiver in communication with the condenser.

4. The refrigeration system of claim 3, wherein the receiver is in communication with the condenser via a refrigerant receiver conduit in the refrigeration mode and a defrost receiver conduit in the defrost mode.

5. The refrigeration system of claim 4, wherein the defrost receiver conduit comprises an electronic pressure regulator thereon to modulate the flow of refrigerant to the condenser in the defrost mode.

6. The refrigeration system of claim 3, further comprising a sub-cooler in communication with the receiver and the evaporator.

7. The refrigeration system of claim 6, wherein the sub-cooler is in communication with the receiver via a sub-cooler input conduit.

8. The refrigeration system of claim 6, wherein the sub-cooler is in communication with the evaporator via a sub-cooler output conduit.

9. The refrigeration system of claim 3, wherein the receiver is in communication with the evaporator via a sub-cooler bypass conduit in the defrost mode.

10. The refrigeration system of claim 3, further comprising an evaporator bypass conduit in communication with the four way valve and the receiver in the defrost mode.

11. The refrigeration system of claim 1, further comprising an electronic expansion valve in communication with the evaporator in the refrigeration mode to modulate the flow of refrigerant thereto.

12. The refrigeration system of claim 1, further comprising a drain pan loop in communication with the four way valve and the evaporator in the defrost mode.

13. The refrigeration system of claim 1, further comprising one or more filter driers.

14. The refrigeration system of claim 1, further comprising a plurality of temperature sensors and a plurality of pressure sensors.

15. A method of operating a refrigeration system, comprising:

directing a flow of refrigerant by a four way valve to a condenser and then to an evaporator in a refrigeration mode;

modulating the flow of refrigerant to the evaporator with an electronic expansion valve in the refrigeration mode;

directing the flow refrigerant by the four way valve to the evaporator and then to the condenser in a defrost mode; and

modulating the flow of refrigerant to the condenser with an electronic pressure regulator in the defrost mode.

16. A refrigeration system with a flow of refrigerant therein, comprising:

a four way valve;

an evaporator in communication with the four way valve;

a condenser in communication with the four way valve;

wherein the four way valve directs the flow of refrigerant to the condenser in a refrigeration mode or to the evaporator in a defrost mode;

an electronic expansion valve for modulating the flow of refrigerant to the evaporator in the refrigeration mode; and

an electronic pressure regulator for modulating the flow of refrigerant to the condenser in the defrost mode.

17. The refrigeration system of claim 16, further comprising a compressor and a suction accumulator in communication with the four way valve.

18. The refrigeration system of claim 16, further comprising a receiver in communication with the condenser and the evaporator.

19. The refrigeration system of claim 18, wherein the receiver is in communication with the condenser via a refrigerant receiver conduit in the refrigeration mode and a defrost receiver conduit for use defrost mode.

20. The refrigeration system of claim 18, further comprising an evaporator bypass conduit in communication with the four way valve and the receiver in the defrost mode.