US2168438A - Refrigerant circulation - Google Patents

Description

g- 1939- w. H. CARRIER REFRIGERANT CIRCULATION Filed April 8, 1936 [NI EN TOR. MAL/.5 f1 l a A T TORNE Y.

Patented Aug. 8, 1939 UNITED STATES 'PATE'NTOFFI nnmrenm'r CIRCULATION Willis H. Carrier, Essex Fells, N.'J., assignor, by 'mesne assignments, to Carrier Corporation, Newark, N. J., a corporation of Delaware Application April a, 1936, .Serial No. 73,219.

10 Claims. (01. 432-126) This invention relates to refrigeration. I A refrigerating system, in general, includes three essential elements, an evaporator, a com- .pressor and a condenser. In operation, heat is abstracted from a medium in contact withthe evaporator by the vaporization of a volatile re- I irigerant therein. The resulting vapor is withrelatively high pressure are maintained...

In various types of conventional refrigerating systems, it is common practice to recirculate liquid refrigerant through the evaporator by means of a pump. This arrangement is very commonly used in evaporators of theshell andtube type.

Recirculation of refrigerant liquid-in this manner necessitates the provision of a pump, a driving motor therefor, and a control for the driving motor; and entails the supervision, maintenance, repair and replacement of this equipmentl The general object of this invention isto provide an improved method of and means for recirculating liquid through an evaporator.

In practising the invention, advantage is taken of the pressure differential existing between the condenser and evaporator. High pressure refrigerant being fed from the condenser to the evaporatoris passed throughan ejector nozzle and is caused to entrainrefrigerant drawn from the sump of the evaporator. The refrigerant thus entrained is passed 'to the refrigerant supply side of the evaporator without being mechanically pumped thereto.

An object of the invention is to provide an improved refrigerating system in which liquid passing from the condenser to the evaporator entrains refrigerant liquid drawn from the sump of the evaporator and thus recirculates the lastmentioned refrigerant liquid through the evaporator.

Another object of the invention is to provide an improved refrigerating system in which the quantity of refrigerant passed from the condenser to the evaporator and the quantity of refrigerant recirculated through the evaporator are varied in accordance with the load on the system. j q

It is another object of the invention to provide a refrigerating system which is relatively simple and inexpensive to construct and maintain, and which is entirely reliable in operation.

A feature of the invention resides in passing through an ejector nozzle high pressure refrigerant from the condenser of a refrigerating system to entrain refrigerant drawnfrom the sump of the evaporator of the system .forrecirculation of said withdrawn refrigerant through-theevaporator. Y

A feature of the invention vision of a reservoir adapted to receive high presresidesinthepm sure refrigerant liquidfrom a condenser, and an/" ejector in communication with the reservoir andin communication withthe sump of an evaporator, refrigerant liquid from the reservoir and from the sump being supplied to the evaporator.

Another feature of the invention-resides in the provision of a reservoir adapted to receive high pressure refrigerant liquid from a condenser. an ejector in communication with the'reservoir and in communication with the sump of an evaporator, refrigerant liquid from the reservoir and from the sump being supplied to the evaporator,

. and means for controlling the action of the ejector in accordance with variations in load on the evaporator.

A feature of the invention resides in the provision of a refrigerating system including an ejector in the high pressure liquid line for withdrawing refrigerant liquid from and recirculating it .through an evaporator, and an auxiliary line providing communication between the condenser and evaporator, the line being controlled by a valve responsive to variations in conditions of temperature and/or pressure within the evapo- 'rator.- This auxiliary line prevents freezing of the sump being supplied to the evaporator, and

Another feature of the invention resides in the pressure refrigerant liquid from a condenser, an ejector in communication with the reservoir and in communication with the sump of an evaporator, refrigerant liquid from the reservoir and from the sump being supplied to the evaporator, a

float valve in the reservoir for controlling the operation of the ejector responsive to variations in the level of liquid in the reservoir, and means for damping oscillations of the float valve.

Other objects, features and advantages of the invention will be more apparent-from the following description to be read in connection with the accompanying drawing in which- Fig. 1 represents diagrammatically a portion of a refrigerating system embodying the invention; and

Fig. 2 is a sectional view illustrating applicants reservoir and ejector apparatus on an enlarged scale.

Referring now to the drawing, 5 represents a condenser in which refrigerant is liquefied by a condensing medium flowing through pipes 6. Condensed refrigerant passes through pipe I to reservoir chamber 8. Chamber 8 is provided with adomed-portion 9 into which the refrigerant liquid is discharged. Projecting into the reservoir chamber 8 is an ejector nozzle 9a. The outlet of nozzle 9a is positioned proximate the opening of pipe l0, which supplies refrigerant to perforated refrigerant distributor plate I I of the evaporator l3. Fluid passed through pipes l2 of the evaporator I3 is cooled by the evaporation of refrigerant. The refrigerant vapors are drawn off to a compressor (not shown) and are then supplied in compressed condition to the condenser 5. Refrigerant from the distributor 'plate II which is not evaporated, passes to the sump H of the evaporator, which communicates through pipe I5 with the inlet to pipe I0. Within the domed section 9 of reservoir chamber 8 is positioned a float l6 carried on and pivotally connected to a pair of arms I1. Arms l1 are carried on pins l8 extending from a suitable support l9 within the reservoir chamber 8. Arms ll pivotally support a needle valve 20' positioned proximate the throat of ejector nozzle 9a and adapted to control the flow of refrigerant liquid therethrough. V

In operation, high pressure refrigerant liquid passed to the reservoir chamber 8 through pipe '1 is forced through the ejector nozzle 9a and entrains liquid from pipe l5. Thus, there is passed through pipe in to the distributing plate II a mixture of liquid refrigerant from the condenser and liquid refrigerant from the sump of the evaporator. In practice it has been found that these are in the ratio of approximately 1 to 4, or, in other words, that the quantity ofrefrigerant liquid passingthrough pipe l0 approximates five times the quantity of refrigerant liquid passed through ejector nozzle So.

its will be understood, the level of refrigerant liquid in the high pressure side of the system varies in accordance with changes in heat load on the system. When theload decreases, the liquid level in. the domed portion 9 of the reservoir falls. This results in a lowering of the float I6 and increased restriction of the throat of ejector nozzle So by needle valve 20. Accordingly, less refrigerant passes through the ejector nozzle 9a and less refrigerant-is drawn from pipe l5 by ejector action for recirculation when the load is low. Conversely, when there is an increase in heat load on the refrigerating system, the liquid commodation for variations in load.

Preferably a ballle 2! is positioned in the reservoir chamber 0 in front of the opening of pipe 1, to

. minimize disturbance within the reservoir chamber due to the admission of refrigerant liquid and thus provide against unduly great oscillation of the float IS. A plate 22, carried on the float I6 is provided to stabilize operation of the float to prevent surging of refrigerant.

The dual arrangement of bars I! assures straight line motion of the needle valve 20 in the center of nozzle 9a.

A pipe 23 provides communication between the evaporator" l3 and the condenser 5. Pipe 23 enters the bottom of the condenser and enters the evaporator l3 above the normal refrigerant liquid level. Flow through the pipe is controlled by a valve 24 under the control of pressurestat 25 disposed within the evaporator. Connection 23 serves two purposes. There is a tendency for refrigerant in a refrigerating system to return to the condenser when the system has been shut down, leaving insufficient liquid in the evaporator to be circulated over the tubes l2 when operation is resumed. Hence, it is necessary to provide'some means for supplying liquid to the evaporator when operation is resumed. Moreover, it is desirable to provide against the freezing of liquid circulated through the tubes I2. .Line 23, with its associated valve and pressurestat 25, serves in both of these capacities. When operation of the system is resumed after an interruption, the pressure in the evaporator becomes abnormally low. Pressurestat 25, responsive to the abnormally low pressure, opens valve 24. Since the liquid in the condenser is at a pressure considerably higher than the pressure in the evaporator, refrigerant from the condenser is blown through pipe 23 to the evaporator until normal operating conditions prevail. Since freezing occurs when evaporator pressures are abnormally low, this arrangement also prevents freezing of liquid in the tubes l2. If desired, the control device designated 25 may constitute a thermostat instead of a pressurestat as above described, such thermostat being arranged and adapted, in a manner well known in the art and therefore requiring no detailed description herein, to open the valve 24 when the temperature in the evaporator drops below a desired point. j To" prevent cavitation, the entire ejector nozzle is positioned below the level of liquid refrigerant. While in the embodiment of the invention herein described, the float control is on the highpressure side of the refrigerating system, a float control responsive to variations in the level of liquid refrigerant on the low'side of the system may be used instead. It will be understood that the refrigerant passing from the condenser and from the evap-.

Although valves of all types for controlling refrigerant flow through nozzle 9a may be used and are deemed within-the purview hereof, needle valves are to be preferred, since they reduce flow without reducing the energy per weight unit of the primary refrigerant.

" Since many modifications may be made in the invention without departing from the scope thereof, it is intended that the foregoing description and the accompanying drawing shall be regarded as illustrative only, applicant limiting himself only as indicated in the accompanying claims.

I claim:

1. A method of operating a refrigerating system including an evaporator and a condenser, which consists in passing refrigerant from the condenser to the evaporator through a first path, causing refrigerant passed through said first path to entrain by ejector action other refrigerant withdrawn from the evaporator, whereby the other refrigerant is supplied to the evaporator with refrigerant passing from the condenser, and passing refrigerant from the condenser to the evaporator through a second path whenever the pressure in the evaporator drops below a predetermined point.

2. A method of operating a refrigerating system including an evaporator and a condenser, which consists in passing refrigerant from the condenser to the evaporator through a first path, causing refrigerant passed through said first path to entrain by ejector action other refrigerant withdrawn from the evaporator, whereby the other refrigerant is supplied to the evaporator with refrigerant passing from the condenser, and passing refrigerant from the condenser to the evaporator through a second path whenever the temperature in the evaporator drops below a predetermined point.

3. In a refrigerating system, a condenser, an

, evaporator, an ejector, the primary intake of the ejector being in communication with the condenser, the secondary intake of the ejectorbeing ln communication with the evaporator, whereby primary refrigerant passing to the evaporator from the condenser through the ejector will entrain secondary refrigerant withdrawn from the evaporator, and means in said ejector adapted to throttle the flow of primary refrigerant in accordance with variations in the level of liquid refrigerant at a point in the system( 4. In a refrigerating system including a condenser and an evaporator having a sump, means including an ejector means for supplying to the evaporator refrigerant from the condenser and refrigerant withdrawn from the sump of the evaporator, a needle valve within the ejector, and means for varying the position of the needle valve in accordance with variations in the level of refrigerant liquid at a point in the system.

5. In a refrigerating system, a condenser, means forming a zone in which refrigerant is adapted to be evaporated an ejector, means providing communication between the primary intake of the ejector and the condenser, means providing communication between the secondary intake of the ejector and the evaporator zone, whereby refrigerant passing to the evaporator refrigerant. supply means.

zone from the condenser through the ejector will entrain refrigerant withdrawnfrom the evaporator zone, an auxiliary refrigerant liquid supply conduit connecting said evaporator zone and said condenser in a course bypassing said ejector, and means responsive to variations in evaporator zone operating conditions for controlling refrigerant fiow through said conduit in such manner that flow therethrough is permitted only when refrigerant passing through the primary and secondary intakes of said ejector is insufiicient to satisfy the heat load on said evaporator.

6. In a refrigerating system, a condenser, an

' evaporator, an ejector having a primary intake and a secondary intake, means providing communication between theprimary intake of the ejector and the condenser, means providing communication between the secondary intake of tlie ejector and the evaporator, whereby refrigerant passing to the evaporator from the condenser through the ejector will entrain refrigerant withdrawn from the evaporator, a valve member positioned at said ejector and adapted to control refrigerant flow therethrough and means for varying the position of said valve member in accordance with variations in the heat load on said evaporator. p

' 7. In a refrigerating system, a condenser, an evaporator, an ejector having a primary intake and a secondary intake, means providing communication between the primary intake of the ejector and the condenser, means providing communication between the secondary intake of the ejector and the evaporator, whereby refrigerant passing to the evaporator from the condenser through the ejector will entrain refrigerant withdrawn from the evaporator, a needle valve member adjustably poistioned within said ejectorand means for controlling the poistion of said needle valve member in accordance with changes in heat load on said evaporator.

8. In a refrigerating system, a condenser, an evaporator, an'ejector having a primary intake and a secondary intake, means providing communication between the primary intake of the ejector and the condenser, means providing communication between the secondary intake of the ejector and evaporator, whereby refrigerant passing to the evaporator through the ejector will entrainrefrigerant withdrawn from the evaporator, a valve member positioned at said ejector and adapted to control refrigerant flow therethrough, and means for varying the position of said valve member in accordance with variations in the level of liquid refrigerant at a point in the system. i

9. In a refrigerating system of the compression type including an evaporator, a compressor and a condenser, the combination of means for supplying refrigerant under relatively high pressure from said condenser to said evaporator, means for utilizing the energy of said high pressure refrigerant for effecting recirculation of refrigerant liquid through said evaporator, and auxiliary supply means for supplying refrigerant liquid from said condenser to said evaporator in a course tioned means, said auxiliary refrigerant liquid supply means normally being inoperative, and means for rendering operative said auxiliary supply means in response to demand for refrigerant liquid which is not met by said first-mentioned 10. In 'a refrigerating system, a condenser, means forming a zone in' which refrigerant is adapted to be evaporated, an ejector, means providing communication between the primary intake of the ejector and the condenser, means providing communication between the secondary intake of the ejector and the evaporator zone,.

whereby refrigerant passing to the evaporator zone from the condenser through the ejector will entrain refrigerant withdrawn from the evaporator zone, an auxiliary refrigerant liquid supply

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