US2614393A

US2614393A - Art of refrigeration

Info

Publication number: US2614393A
Application number: US645183A
Authority: US
Inventors: Edward L Schulz; Edward A Bailey
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 1946-02-02
Filing date: 1946-02-02
Publication date: 1952-10-21
Anticipated expiration: 1969-10-21

Description

1952 E. L. SCHULZ ETA].

ART OF REFRIGERATION- 3 Sheets-Sheet 1 Filed Feb. 2, 1946 FIG. 7

IN VEN TOR. 4 $4M -s Oct. 21, 1952 Filed Feb. 2, 1946 FIG.3

E. L. SCHULZ ET AL ART OF REFRIGERATION FIGJO 3 Sheets-Sheet 2 Oct. 21, 1952 E. SCHULZ ETAL. 2,614,393

ART OF REFRIGERATION Filed Feb. 2, 1946 s Sheets-Sheet s FIG.5

trating modifications of the system, shown in Figure 3; and

Figures 11 and 12 are fragmentary views'illustrating modifications of the system shown in.

Figure 5.

Referring to the drawings there isshown a compressor 2 of the reciprocating type, although it may be of any desired type, adapted to discharge compressed refrigerant gas through line 3 to a condenser 4. Condenser 4 may be air or water cooled as desired; condenser 4 is illustrated as air cooled by means of fan 5. Condensed refrigerant enters receiver 6 and then proceeds through discharge line I to control valve 8, expansion valve 9 and evaporator Iii, returning to compressor 2 through suction line i l. Expansion valve 9 operates in the usual manner under control of bulb l2 attached to the discharge side of evaporator ill to maintain a predetermined super-heat in the refrigerant discharged from evaporator Iii. As is customary, an equalizerline connects expansion valve 9 with suction line H to provide a pressure under the diaphragmof the expansion valve equal to the pressure atthe discharge end of the evaporator.

When the system operates normally and the condenser pressure as reflected in line 1 remains below a predetermined upper limit of 200 pounds, for example, valve 8 remains fully open and the system operates as if valve 8 were omitted therefrom.

Assuming that the system becomes overloaded due, for example, to the break-down of fan 5, used for cooling the condenser (or due to the break-down of the water supply if the condenser depends upon water for refrigerant cooling purposes), then the pressure in condenser 4, receiver 6 and line i rises. If the failure to provide con-' denser cooling becomes'so serious as to cause the pressure to rise above the predetermined maxi mum limit of ZOOpounds in the example given, then damage to the system would result'unl ess operation was stopped or the capacity of the system effectively reduced so that only that amount of refrigerant was handled which could be condensed effectively.

When the pressure in discharge line i (the condensing pressure) exceeds the predetermined maximum of 200 pounds, control'valve 8 will operate responsive to a rise in pressure abovethe set figure to decrease progressively'the amount of refrigerant permitted to enter evaporator l-ll through expansion valve 9; The-volume of re frigerant admitted to evaporator Iii will'decrease as the condensing pressure increases above the predetermined maximumof 200 pounds. If the fault in the system causing the increase in condensing pressure is due to impaired condensing action, but assuming some condensing action does take place, then valve 8 will permit a reduced quantity of refrigerant to be admitted to evaporator it, such reduced volume being the maximum which the system can handle without a fur? ther increase in condensing pressure.

Assuming that a pressure of 200 pounds, for example, which is below the danger point would not be exceeded if only a portion of the normal volume of refrigerant is permitted to be circulated in the system, then control valve 8 will constri'ct the flow leading to expansion valve 9 and evapo- 4 rator lil so that only such percentage of the normal amount of refrigerant will be delivered by the system.

Since such operation at reduced efficiency is undesirable, suitable means may be provided for informing the operator of the abnormal conditions. A relay may be provided operative responsive to a rise in temperature in discharge line 1 above an upper limit which will cause a suitable alarm to function; the alarm may take the form of a bell, flashing light or other signal device.

Obviously, under conditions of serious impairment, such as when fan 5 breaks down or when force is exerted against diaphragm I5, flexing it- For purposes of illustration, control valve 8'- may take-the form shown in'Figure 2." Considering'Figure 2,controlvalve8 includes a housing l4 containing a diaphragm l5 disposed in position therein; A-spring i5 is disposed adjacent one side of the diaphragm and is adapted to apply a predetermined force thereto. A' stem 1''! carrying valve member I 8 is adapted'to close a port [9 within'housing l6. Under normal conditions spring [6 flexes diaphragm I5 downward moving stem I! downward thus moving valve member l8 away from port [9, permitting free flow of refrigerant through entrance port 20 intothe housing, through port I9 and through discharge'port As pressure increases in discharge line I,

in the opposite direction and raising stem l1 carrying valve member !8 to closeport l9 to the required extent. As the condenser pressure again decreases, spring 16 'flexes diaphragm 15 to move valve member l8 away from port I9 to open port 19 to the free passage of refrigerant.

If desired, in the system illustrated in Figure 1, control means'rnaybe provided as shown in'Figure 7 for regulating theflow of refrigerant responsive to variations in load in an area served by the system. Such means may comprise a suitable diaphragm Z2 incorporated in a control valve 8, which is actuated by a bulb 23 disposed preferably in the area beingserved. In such case a decrease in th temperature of "the area being served will tend to move control valve 8' toward aclosed position thus reducing the flow of refrigerant to evaporator l6. The decrease in tempera-, tune in the area being. conditioned is reflected by bulb 23 which servesto applypressure to diaphragm 22 to urge control valve 8 toward a'closed position.

' In a structure of'th'e type contemplated, control valve 8 normally functions to restrict the flow of refrigerant in order to take care of conditions of overload. It may be actuated, however, as described above 'to compensate for conditions of underload; in such case, control valve 8" may be employed and actuated to compensate for a reduction in load as reflected by a reduction in temperature within the area being conditioned.

if desired, a second control valve 24 as shown inFigure 8 maybe disposed in line .1 which .may beactuated by a bulb 25 disposed in the area beingserved. Such-valve operates similarly to reflected by bulb 25, urges control valvel ktoward-1 a closed position to compensate for the reduction in load, thus decreasing; the; amount. ofi refrigerant forwarded to. evaporatory-tfl.

In'Figure 3, we have illustrated, a, modifiedyform of; our; invention in, which the functions,performed ,byi expansion valve 9, and. controlyalve E 35 system f t e pe ShOMlILiI-l F gure. lwax'e combined .ir1---a single valve,.,2;.6. Refem'zinaio Figured, control valve 26 is responsive to-.a.bulb attached to the dischargeside-of evaporator nt maintain a p et rmined.sup rwheatrin the refrigerant discharged. fromgevaporator; I 0. Valve 26,15 designed to mover toward aaolosed position. inr ponse to anf-inerease in condense press re bove a pr et rmine maximu thereby decreasing the amount of refrigerant passing to evaporator The structure of a suitable, valve for use in the system illustrated in Figure 3 is show diagrammatically in Figure 4. As shown in Figure 4, a.

housing 28 contains a diaphragm 29 disposed Within a chamber 30 therein. Diaphragm 29 separates chamber 30 into two compartments 3| and 32. Pressure in compartment 3| is controlled by bulb 21 while pressure in compartment 32 is controlled by suction pressure through equalizer line 33. .A stem 34 is secured to diaphragm 29 and carries a valve member 35 adapted to close port 36 within the valve. Expansion valves of this type are well known in the art.

In the structure shown in Figure 4, a bellows 31 is added which carries a lever 38 connected toa continuation 34' of stem 34. Lever 38 is hinged at point 39. An increase in pressure in discharge line '1 extends bellows 31 forcing lever 38 to pivot about point 39 and moving valve member 35 upwardly to close port 36.

If desired, a valve 26 generally similar to valve 26 but designed to also be responsive to a decrease in temperature in an area being conditioned to decrease the amount of refrigerant passing to evaporator ID as shown in Figure 9 may be employed. Likewise, as pointed out in connection with Figure 1, an additional control valve 24 as shown in Figure 10 responsive to room temperature as reflected by bulb 25 may be disposed in line to govern the amount of refrigerant flowing through the evaporator in accordance with a decrease in temperature in an area oeing served.

Figure 5 illustrates a further modification of Jur invention in which a bypass line 40 is pro- 'Iided connecting discharge line 1 with suction ine The point of juncture of bypass 40 with abova- A; decrease in enigma il'ar, tether-valve shownin. F gure: zrexceptrthat" n' nerease inrcondenser pressure excrtsqfoma against: diaphragm L5 to openztheyalye andzthatr a decrease in condenser I pressure-permits.valve;

. member 8=to bemoyccl toward-a positionclosing:

Itrwil l baunderstood the system shown inlil'gz ure 5 may also be :responsive to the temperature of' the area beingserved' by: means of an-addiftionald-iaphragm-w added'tovalve 4|" as: shown iii-Figure l1 which is-actuated, by-a bulb disse posed in the-areabeing served If desired, a suitable valve -45-may be di'sposed inlineflt as: shown in-Fig=ure --12', valve '45 being actuated by a -bulb-4i6 disposed in-thearea being served; todecrease the amount of' refrigerant passing' to theevaporaton The present inventionprovidesca ready-andi simplecontrol arrangement for regulating the production of refrigeration effect in. response to variations in lea-d conditions. Thesystem so providedcoinpensates for overload' conditions arising-fromunforeseen causes. It provides a simple and efiective control for regulating the operation of an expansion valve to compensate automatically for conditions resulting in undesirable condenser pressures. The control arrangement so provided is responsive to the pressure of the system, and if desired, may also be responsive to the temperature of the area being conditioned, thus assuring satisfactory results in operation. The control arrangement operates effectively to throttle the flow of refrigerant to an evaporator When condenser temperature rises above a predetermined maximum. The control arrangement provided effectively regulates operation of the system in response to conditions of overload or partial load.

While we have described and illustrated a preferred embodiment of our invention, it will be understood our invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

We claim:

1. In a refrigeration system, the combination of a compressor, a condenser, an expansion valve and an evaporator disposed in a closed circuit, means disposed adjacent the suction line for controlling the operation of said expansion valve, a bypass extending from the discharge line to the suction line, the juncture of said bypass with the suction line being disposed between the discharge end of the evaporator and line H is located between the discharge end of refrigerant passing into the suction line cools bulb |2 thus urging expansion valve 9 toward a closed position and decreasing the amount of refrigerant passing to evaporator ID.

A suitable control valve 4| for this purpose is shown in Figure 6. Such valve is generally simthe control means for the expansion valve, a second valve in said bypass, said bypass having an orifice therein adapted to regulate the quantity of refrigerant passing therethrough, said second valve being responsive to an increase in condenser pressure above a predetermined level to move toward an open position permitting refrigerant to pass through said bypass, passage of refrigerant through the bypass into the suction line actuating said control means to operate the expansion valve.

2. A refrigeration system according to claim 1 in which a control valve is provided in the discharge line to meter the quantity of refrigerant passing to the expansion valve, and means are provided to actuate said control valve in response to a decrease in room temperature below a predetermined level to decrease the quantity of refrigerant passing to the expansion valve.

3. In a refrigeration system, the combination of a compressor, a condenser connected to the compressor, an evaporator, a dischargelli-ne connecting the condenser and the evaporator;

anexpansion valve in said line, a suction line connecting the evaporator and the compressor, a thermal bulb disposed adjacent the suction line adapted to control operation of said expansion valve, a bypass connecting the discharge line and'the suction line, the juncture of the bypass with the suction line being placed-between the discharge end of the evaporator and the thermal bulb, a valve in said bypass, an orifice in said bypass, said valve under normal conditions of operation remaining in a substantially closed position and being adapted in response to an increase in condenser pressure above a predetermined level to tend to open to permit liquid refrigerant to enter the bypass,

passage of liquid refrigerant through the bypass to the suction line actuating said thermal bulb thereby tending to move the expansion valve toward a closed position to decrease the quantity of refrigerant passing to the evaporator.

EDWARD L. SCHU'LZ. EDWARD A. BAILEY.

8, REFERENCES CITED.

The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,591,302 Franklin July 6, 1926 1,782,687 Hoffman Nov. 25, 1930 2,080,358 Kucher May 11, 1937 2 ,091,787 Locke Aug. 31, 1937 2,183,343 Alsing 'Dec. 12, 1939 2,196,777 Otto Apr. 9, 1940 2,196,778 Dodge Apr. 9, 1940 2,258,458 Lange Oct. 7, 1941 2,344,215 Soling et a1 Mar. 14, 1944 2,415,338 Carter Feb. 4, 1947 2,434,593 Schulz et a1 Jan. 13, 1948 2,453,439 Hubbard Nov. 9, 194,8,