US3167930A

US3167930A - Refrigeration system

Info

Publication number: US3167930A
Application number: US238537A
Authority: US
Inventors: Block Leo; Berg Richard E Von; Rasovich Ivan
Original assignee: Freightliner LLC
Current assignee: Daimler Trucks North America LLC
Priority date: 1962-11-19
Filing date: 1962-11-19
Publication date: 1965-02-02
Anticipated expiration: 1982-02-02

Description

Feb. 2, 1965 BLOCK ETAL REFRIGERATION SYSTEM IIIIIIIIIIHIHHI CONDENSER EVAPORATOR 24 4 WAY VALVE FIG. 5

LEO LoW Low PRESSURE GAS RICHARD E.- VON BERG I H'GH PRESSURE LIQUlD BY MMMWQ LOW PRESSURE uoum FIG. 4

ATTORNEYS evaporator by the compressor.

from the compressor. vsion-is the main source of heat. compression is dependent upon the dlscharge pressure,

-United States Patent Ofiice 336 1935 Patented Feb. 2, 1965 This invention relates to an improved refrigeration system of the type suitable for both cooling and heating.

In the past, refrigeration systemshave been devised to effect a combination of both cooling and heating by suitably directing the refrigerant. During a cooling cycle,

refrigerant is supplied from the compressor through the The refrigerant is then It is withdrawn from the During a heating cycle, high pressure gas is applied to the evaporator directly condenser to the receiver. metered to the evaporator.

As is known, heat of the suction pressure, and the amount of refrigerant circulated. To obtain the maximum heating capacity for a system using heat of compression as the main heat source, substantially all the refrigerant of the system 1 should be circulated.

It is a general object of the present invention to provide an improved refrigeration system.

It is another object of the invention to provide a refrigeration system which is additionally capable of heating, wherein substantially all the refrigerant is circulated during the heating cycle;

It is still another object to provide an improved heat of compression refrigeration system for both cooling and heating, wherein during the heating cycle, refrigerant is withdrawn from elements inactive during heating, such as the condenser, for circulation through the elements active during heating, such as the evaporator.

A further object of the invention is to protect the compressor in a heat of compression system against entrained liquid entering the suction side.

. 1 A more specific object is to provide means for evaporating entrained liquid in an accumulator immediately upstream of the compressor intake. 7

These and other objects will be pointed out in the fol- 1 lowing description and claims and illustrated in the accompanying drawings.

In the drawings: FIGURE 1 is a schematic diagram of a refrigeration system according to the invention, conditioned to provide heating;

FIGURE 2 is a detailed view of a schematic representation of a four-way valve as conditioned during the cooling cycle;

FIGURE 3 shows the valve of FIGURE 2 as condil tioned during the heating cycle;

FIGURE 4 is a legend for the representation of the various fluid states of the refrigerant shown in the system of FIGURE 1 during the heating cycle; and

FIGURE'S is a detailed schematic view of a three- .way valve as connected in the system of FIGURE 1 to provide another embodiment of the invention. It is shown conditioned for the heating cycle.

Briefly stated, a refrigeration system suitable for both eration system, in general, employs a closed circuit ineluding in the following order, a compressor, condenser,

In other words, heat of comprescooling and heating is shown in FIGURE 1. The refriging the heating cycle, some cooling elements, such as the condenser, are by-passed and refrigerant therein is withdrawn for circulation through the elements actively serving to provide heating. (Where bigger compressors are used in the system it may be desirable for the pressure regulator and accumulator to be transposed to avoid turbulence in the accumulator.)

To accomplish this withdrawal during heating, we employ controls and connections to provide a first fluid path from the discharge side of the compressor to the evaporator while lay-passing the condenser. By these controls, a second fluid path is provided which leads from the condenser through the four-way valve and accumulator inlet to the suction side of the compressor, in a manner bypassing the evaporator. Thus, fluid will be withdrawn from the condenser (and also from the receiver) during discharge of compressed fluid directly to the evaporator via the first path. In the system as conditioned for cooling, the compressor discharges to the condenser and the evaporator to the suction side of the compressor. Control means are provided to selectively establish either the cooling or heating circuit.

Referring to the drawing and particularly to FIGURE 1, the system is shown conditioned for heating and includes a compressor 10 having discharge and suction connections 11 and 12, respectively. Discharge connection 11 leads to a four-way valve 13 which can be ac tuated by a solenoid 14. Valve 13 is provided with two

outlet ports

15 and 17. Port 17 leads to a hot gas line 28 described further below. Valve 13 includes a spool 16 having a longitudinal passage 18 extending along its length. Spool 16 is movable between the two positions shown in FIGURES 2 and 3 under control of the solenoid 14. Port 15 leads to a condenser means 19. Another port 39 for a purpose described below is formed in the end of valve 13 and arranged so that during heating it is conected via passage 18 in the spool 16 to port 15. I

The outlet side of condenser 19 is coupled to the inlet 20 of a receiver 21. The receiver 21 is provided with an outlet 22 which leads into an expansion valve means 23. Valve means 23 is of a suitable known design capable of permitting fluid to flow in a direction leading from the receiver along the outlet connection 22 but serves to block passage of fluid moving in a reverse direction.

The means for cooling or heating a space such as a refrigerated truck, meat locker or the like, includes a heat exchange unit 24 serving during the cooling operation as an evaporator unit and during the heating cycle as a condenser. Unit 24 is located downstream of the expansion valve 23. The outlet 25 passes fluid to a valve 26 regulating pressure at the compressor suction. The pressure regulating valve 26 may, for example, be set between 20 to p.s.i. to ensure that the pressure is low enough to prevent over-loading of the compressor prime mover. Interposed between valve 26 and the suction side 12 of compressor 10, there is provided a suction accumulator unit 27 for receiving any liquid which may be entrained in the low pressure gas from the heat exchange unit 24. Unit 27 serves as an evaporator means during the heating cycle.

Means have been provided for operating the abovedescribed closed circuit system whereby heat exchange unit 24 is utilized to heat the space surrounding same, or for defrosting. One fluid path comprises a hot gas line 28 forming a direct connection from port 17 (FIGURE 2) to the up-stream side of heat exchange unit 24 at a point between the valve 23 and the heat exchange unit. Line 28 includes a heat exchange portion 29 disposed in heat exchange relation with respect to accumulator 27. For example, line 29 can be'formed with a number of fins 30 or comprise a number of turns of line 28 disposed within accumulator 27.

Means are provided to limit direction of fluid flow in line 28. Thus, line 28 further includes a check valve 31 oriented to pass fluid coming from port 17 to prevent movement of fluid in a reverse direction. Another fluid path forms a direct connection from the condenser 19 to the suction side of the compressor 10. Thus, a small diameter 32 leads from port 39 of valve 13 to the suction side of compressor 10. Line 32'preferably is disposed .to discharge into the upper region of accumulator 27 so as to provide a liquid trap which guards against slugging the compressor. However, in some instances, it may be more convenient to couple line 32 directly into the suction line '12. An oil drain33 is provided between compressor and accumulator 27 and serves to drain accumulated oil from the accumulator 27.

In operation, cooling is effected by conditioning solenoid 14 so as to position the spool 16 of valve 13 to the left-hand position to make the connection as shown in FIGURE 2. Thus, compressor discharge connection 11 leads to port and line 32 connects to port 17. Check valve 31 prevents flow of fluid between

ports

17 and 39. The compressor discharges high pressure gas into condenser 19.

In the condenser, the refrigerant is condensed into a liquid. This high pressure liquid then flows to the receiver and from the receiver to the expansion valve 23 where the pressure of the liquid is reduced. Low pressure liquid then enters the evaporator and absorbs heat from the surrounding air which circulates over the evaporator. The absorbed heat causes the low pressure liquid to boil and form a low pressure gas or vapor. The vapor is conducted through the pressure regulating valve, the suction accumulator and then enters the compressor.

Any liquid refrigerant and oil that may be entrained .in

the low pressure gas in the accumulator will drop to the bottom. Thus, the compressor is protected against'liquid slugging. Any liquid refrigerant in the accumulator will eventually boil ofl to form a vapor and the oil will gradually drain to the compressor through the small diameter oil drain line 33. 7

When a heating operation is called for, as detected by a thermostat 42, valve 13 isoperated to make the connections schematically illustratedin FIGURE 3. Compressor discharge connection 11 is connected to port 17 while line 32 is coupled to port 15 ,to evacuate condenser 19. The system is thus conditioned ,to ,generatefluid phases as shown in FIGURE 1. High pressure gas, high pressure liquid, low pressure liquid and low pressure gas are respectively shown by the

legends

34, 35, 36 and 37.

The gases being dischargedfrom compressor 10 are heated by thecompressor'action and are passed directly along hot gas line .28 through valve 13. Thus, heat exchange is eifected in accumulator 27 and the gases enter the heat exchange unit or evaporator 24 at .the upstream end, The hot gas is condensed to a liquid due tothe relatively cool air being circulated over the evaporator coils. At least part of the gas leaves the evaporator as a high pressure liquid. Pressure regulating valve 26 serves to throttle this liquid to alow pressure and allows it to enter the suction accumulator. This reduction in pressure results in some of the hot liquid flashing into a vapor. Since the outlet of the suction accumulator is at the top thereof, only vapor is conducted to the suction side of the compressor and it is protected against entrained liquid. In this heating cycle, it is to be noted that.

the heat exchange unit 24 performs the function of a condenser, the pressure regulating valve serves to func-.

With valve 13 shifted to operate the system as a heat-' ing system, line 32 serves to connect the suction side of compressor 10 directly tocondenser19 via port 39, pasis drained from the inactive units of the system and circulated through the elements active in the heating cycle.

The heat exchange portion 29 of line 28 gives off heat to any liquid collecting at the bottom of the accumulator and causes this liquid to boil. 1

The rate of heat transfer fromthe gas to the liquid in the accumulator 27 can be considered self-compensating. Thus, as the liquid level increases atthebot't'o'r'n of the accumulator, .a greater amount of heat is transferred from the hot gas phase to theliquid phase. As the liquid is boiled off, the level thereof drops and the rate of heat transfer is commensurately reduced.

For extreme low ambient temperatures, the suction accumulator can be equipped with an electric heater blanket 43 or an immersion heater to increase'the heating capacity of the system. It is also possible to obtain this auxiliary heat in other ways, asin transport applications wherein the suction accumulator may be' located adjacent to the .exhaust pipe'and/or mufller of a truck, for example.

If it is desired to remove even'more refrigerant from the receiver and condenser elements-during the heating cycle, an electric heater blanket 38 can be attached to the receiver totincrease the temperature of the liquid therein to a point above the saturation temperature of the compressure suction. This'may be particularly desirable under conditions' of extremelow ambient temperature. i

Another embodiment of the invention comprises the system shown in FIGURE 1 with the omission of the check valve 31 and replacement of valve -13jwith a threeway valve 40 as shown in FIGURE 5. Valve'is connected whereby leftward positioning of spool '41 forms a path connecting ports l l'and 15 and closesoff the hot 17 to permit flow intothe hot gas line 28; Of course, in

this system embodiment, the refrigerant is'not drained from the inactive elements but the other advantages previously noted are retained.

While there have been shown and described and pointed out the fundamental novel features of the inventionas applied to a preferred embodiment, itwill' be understood that various omissions and "substitutions and'changes in the form and details of the system illustratedand in its operation maybe made by those skilled in the artwithout departing from the spirit of the invention It" is the intention, therefore, to be limited only as'indicated by the scope of the following claims.

We claim:

1. In a closed circuit refrigeration system including compressor means having suction and-dischargeconnections, condenser means normally receiving fiuid under pressure fromsaid discharge connection, receiver means in fluid communication'with said condenser mean's, said receiver means having inlet and outlet connections, expansion valvemeans for passing and expanding fluid moving via said outlet connection in a direction'leading'from said receiver. meansand serving to block passage offluid moving ina reverse direction, evaporator means disposed .dischargeconnection to thecondenser so as to direct the.

fluid to flow from said discharge connection to saidevaporator means and bypass said condenser, while further serving to fluid-couple said suction connection to'said condenser in a manner bypassing said evaporator to withdraw fluid from said condenser during the selective dischargeof compressed fluidto said evaporator."

2. A refrigeration system as defined in claim 1 wherein theflow path serving to fluid couple said condenser to said suction connection includes said accumulator.

3. In a closed circuit refrigeration system including compressor means having suction and discharge connections, condenser means, receiver means in fluid cornmunication with said condenser means, said receiver means having inlet and outlet connections, expansion valve means for passing and expanding fluid moving via said outlet connection in a direction leading from said receiver means and serving to block passage of fluid moving in a reverse direction, evaporator means disposed downstream of said expansion valve means, pressure regulating means disposed downstream of said evaporator means for regulating fluid pressure at said suction connection to the compressor, and fluid accumulator means interposed between said pressure regulating means and said suction connection, heating system means comprising a hot gas line having a heat exchange portion disposed in heat exchange relation with respect to said accumulator means, one end of said line being coupled in fluid communication to pass fluid to said evaporator means, and flow path control means operable in one condition to couple the other end of said hot gas line to said compressor discharge connection, and to couple said condenser means to said suction connection via said accumulator to draw refrigerant from said condenser means and said receiver means, said control means being operable in another condition to couple said discharge connection to said condenser and to de-couple said hot gas line whereby heating and cooling by said evaporator is selectively effected.

4. A refrigeration system as defined in claim 3 wherein said control means includes a four-way valve, and said hot gas line includes a check valve disposed and oriented to effect said de'couplin 5. In a closed circuit refrigeration system including compressor means having suction and discharge connections, condenser means, receiver means in fluid communication with said condenser means, said receiver means having inlet and outlet connections, expansion valve means for passing and expanding fluid moving via said outlet connection in a direction leading from said receiver means and serving to block passage of fluid moving in a reverse direction, first heat exchange means disposed downstream of said expansion valve means, pressure regulating means disposed downstream of said first heat exchange means for regulating fluid pressure at said suction connection to the compressor, accumulator means, and second heat exchange means in said accumulator, disposed between said pressure regulating means and said suction connection, flow path control means for selectively heating the first heat exchange means comprising means collectively forming a first fluid path from said discharge connection to said first heat exchange means and by-passing said condenser means and forming a second fluid path serving to fluid-couple the suction connection to the condenser and by-passing said first heat exchange means; to withdraw fluid from said condenser means during discharge of compressed fluid into said first heat exchange means.

6. In a closed circuit refrigeration system including compressor means having suction and discharge connections, condenser means, heat exchange means disposed downstream of said condenser means, fluid expansion means interposed in fluid communication between said condenser means and said heat exchange means, pressure regulating means disposed downstream of said heat exchange means for regulating fluid pressure at said suction connection of said compressor, and means interposed between said pressure regulating means and said suction connection serving to protect said compressor against entry of liquid thereto, flow path control means serving to selectively heat said heat exchange means, said control means comprising means selectively conditionable to form a first fluid path from said discharge connection to said heat exchange means and by-passing said condenser means and to form a second fluid path from said condenser means to said suction connection and by-passing said heat exchange means; whereby fluid is withdrawn from said condenser means during discharge of compressed fluid into said first heat exchange means.

7. A closed circuit refrigeration system including compressor means having suction and discharge connections, condenser means, evaporator means disposed downstream of said condenser means, expansion means interposed in fluid communication between said condenser means and said evaporator means, pressure regulating means and fluid accumulator means disposed downstream of said evaporator means for regulating fluid pressure at said suction connection to the compressor, heating and cooling system means comprising means selectively operable between first and second positions, said first position serving to condition the last named means to form a first fluid path from said discharge connection to said evaporator and by-passing said condenser, fluid check means serv ing to pass fluid along said path and substantially block fluid flow in a reverse direction along said path, said second position serving to condition the penultimate named means and operable in another condition to form a second fluid path from said discharge connection to said condenser whereby heating or cooling via said evaporator can be selectively eflected.

8. A closed circuit refrigeration system as defined in claim 7 wherein said first fluid path includes a hot gas line having a heat exchange portion disposed in heat exchange relation with respect to said accumulator means whereby the rate of heat transfer from said hot gas line to liquid in said accumulator varies with the amount of liquid in said accumulator.

9. A closed circuit refrigeration system as defined in claim 7 further including an auxiliary heat source disposed in heat exchange relation with respect to said accumulator.

References (Iited in the file of this patent UNITED STATES PATENTS

Claims

1. IN A CLOSED CIRCUIT REFRIGERATION SYSTEM INCLUDING COMPRESSER MEANS HAVING SUCTION AND DISCHARGE CONNECTIONS, CONDENSER MEANS NORMALLY RECEIVING FLUID UNDER PRESSURE FROM SAID DISCHARGE CONNECTION, RECEIVER MEANS IN FLUID COMMUNICATION WITH SAID CONDENSER MEANS, SAID RECEIVER MEANS HAVING INLET AND OUTLET CONNECTION, EXPANSION VALVE MEANS FOR PASSING AND EXPANDING FLUID MOVING VIE SAID OUTLET CONNECTION IN A DIRECTION LEADING FROM SAID RECEIVER MEANS AND SERVING TO BLOCK PASSAGE OF FLUID MOVING IN A REVERSE DIRECTION, EVAPORATOR MEANS DISPOSED DOWNSTREAM OF SAID EXPANSION VALVE MEANS, PRESSURE REGULATING MEANS AND FLUID ACCUMULATOR MEANS DISPOSED DOWNSTREAM OF SAID EVAPORATOR MEANS FOR REGULATING FLUID PRESSURE AT SAID SUCTION CONNECTION TO THE COMPRESSOR, FLOW PATH CONTROL MEANS OPERABLE TO SELECTIVELY HEAT THE EVAPORATOR MEANS, SAID FLOW CONTROL MEANS SERVING TO SELECTIVELY DIVERT THE FLUID NORMALLY FLOWING FROM SAID DISCHARGE CONNECTION TO THE CONDENSER SO AS TO DIRECT THE FLUID TO FLOW FROM SAID DISCHARGE CONNECTION TO SAID EVAPORATOR MEANS AND BYPASS SAID CONDENSER, WHILE FURTHER SERVING TO FLUID-COUPLE SAID SUCTION CONNECTION TO SAID CONDENSER IN A MANNER BYPASSING SAID EVAPORATOR TO WITHDRAW FLUID FROM SAID CONDENSER DURING THE SELECTIVE DISCHARGE OF COMPRESSED FLUID TO SAID EVAPORATOR.