US2199463A - Refrigerating apparatus - Google Patents

Description

Patented May 7, 1940 UNITED STATES PATENT OFFICE REFRIGERATING APPARATUS Application March 2, 1937, Serial No. 128,570

5 Claims.

This invention relates to refrigerating apparatus, and particularly to refrigerating apparatus of the type wherein a liquid refrigerant is cooled in an evaporator by exposure to the action of a vacuum.

More specifically, the invention has reference to refrigerating apparatus employing evacuators through which the discharged fluid can surge and break back into the evaporator to efiect undue heating of its contents. Such breaking back occurs when the evacuator is shut down, or under certain abnormal conditions when the evacuator is unable to assume its load.

Accordingly, it is an object of the invention to avoid subjecting the refrigerant to undue heating effects.

Another object is to maintain the refrigerating effect of the refrigerant for the longest possible time with a minimum expenditure of power.

Other objects will be apparent or pointed out hereinafter.

The accompanying drawing shows an elevation, partly in section, of refrigerating apparatus constructed in accordance with the practice of the invention.

Referring more particularly to the drawing, the invention is shown embodied in refrigerating apparatus comprising an evaporator tank I, an evacuator 2, a condenser 3 and a refrigerant piping system having a cooling coil 4 therein.

The tank I defines a refrigerant vaporization and cooling chamber 5 from which an open passage 6 leads to and through the evacuator 2 into the condenser 3. The evacuator, as illustrated, comprises an ejector having nozzles I positioned in the passage 6 to discharge to the condenser, and a supply pipe 8 having a valve 9 therein serves to convey suitable power fluid, such as steam, to the nozzles l.

The condenser has the usual connections I for cooling water, and may be provided with an air-removal device (not shown).

The refrigerant piping system for the coil 4 comprises pipes II and I2, pipe II leading out of the chamber 2 through a leg 30 to a pump I3 and thence to the coil 4, and pipe I2 leading from the coil to the tank I and having interposed therein a. diaphragm-actuated valve I5 of well known make arranged to be maintained in open position by the operation of the pump I3.

A make-up pipe I 6 may also be provided for replenishing refrigerant losses, and a float-actuated valve IT in the pipe I6 may serve to maintain a desired quantity of refrigerant in the system.

The structure thus far described is of a conventional type in which, as long as the pump I3 operates, refrigerant flows through the chamber 5 to be exposed to whatever temperature and pressure condition may exist therein.

In accordance with the practice of the invention, means are provided for preventing the admission of refrigerant to the evaporator when the conditions therein are such that heating rather than cooling of the refrigerant may occur. Within the tank I and depending from the top thereof is a partition I8 which cooperates with a side wall I9 and the end walls of the tank to form a chamber 20. Another partition 2I extends upwardly from the bottom of the tank between the partion I8 and the side wall opposite to the wall I9 and cooperates with the partition I8 and the end walls of the tank to form an inlet well 22 leading to the chamber 5. Between the chamber and the well 22 is a passage 23, and a port 24 in the wall I9 opens from the return pipe I2 into the chamber 20.

The partition 2I terminates below the top of the tank to form over-flow means into the chamber 5, or openings 25 may be positioned near the top of the partition to communicate between the well 22 and the chamber 5.

In the wall I9 of the tank two ports 26 and 21 are shown. From the upper port 26, which is preferably disposed near the top of the chamber 20, a pipe 28 leads into the condenser 3 near the top thereof. This pipe might instead open into the passage 6 at a point along the discharge path of the power fluid from the nozzles 1. The port 21 is positioned at a somewhat lower elevation than the openings 25 in the partition 2I and has connected thereto a constantly open bypass conduit 29 which leads directly from the chamber 20 into the discharge pipe II and the intake of the pump I3. The by-pass conduit has a capacity at least as great as the capacity of the return pipe I2.

The operation of the apparatus is as follows:

During normal operation, the refrigerant flows from the pipe I2 into the chamber 20 and well 22 and thence into the chamber 5. The evacuator 2 maintains a high vacuum in this chamber under the action of which part of the refrigerant, which may be water, boils, removing heat from the remainder and chilling it. Chilled refrigerant fiOWs through the pipe II under the impulse of the pump I3 to the coil 4 where its refrigerating effect may be utilized.

Vapor formed in the chamber 5 is removed through the passage 6, compressed by power fluid issuing from the nozzles 1 and delivered to the condenser 3. The pressure in the condenser is normally higher than the pressure in the chamber and is communicated through the pipe 28 to the chamber 20 to depress refrigerant therein below the refrigerant level in the well 22 and also below the port 21 leading into the by-pass 23. Thus during normal operation, the pressure difference maintained between the vaporization chamber and the condenser prevents the admission of refrigerant to the by-pass, and all refrigerant flows into the chamber 5 to be exposed to vaporizing action therein.

The term normal operation as herein used. refers to any set of conditions in the evaporator and condenser which will enable continuous evacuation of the chamber 5 to be effected and a difference in pressure between chamber 5 and condenser 3 to be maintained.

However, when an evacuator of the non-positive displacement type is employed, there are times when the load may surge in the system and condenser fluid break back through the evacuator into the vaporization chamber and effect heating of the contents of the evaporator. Such a condition will occur if the evacuator is deliberately shut down, as at low refrigerating load for example. This may be done by manual operation of the valve 9, or the valve may be thermostatically controlled, as in accordance with a temperature condition of the refrigerant at the coil 4 or in the chamber 5, for example. In this connection, the evacuator may be active intermittently to create some refrigeration while at the same time saving power and preventing excessive cooling of the refrigerant.

Vapor may also break back under certain abnormal conditions while the evacuator is still in action. Such abnormal conditions may occur at extremely light loads or under excessive back pressure in the condenser, and the breaking back is then due to the creation of an excessive pressure differential between the chamber 5 and condenser 3 which is too great for the evacuator to overcome.

When breaking back occurs, vapor from the evacuator discharge fills the chamber 5, and were refrigerant circulation through the chamber 5 to continue, the vapor would be condensed by the refrigerant, the refrigerant absorbing heat and thereby losing its refrigerating efiect.

To avoid such heating of the refrigerant in order to extend its refrigerating effect to the greatest possible length, the refrigerant is automatically by-passed around the chamber 5 when breaking back occurs. Thus the evacuator may be shut down at low loads for the maximum length of time and a minimum amount of power expended for refrigerating purposes.

Under breaking back conditions, the pressure. differential between chamber 5 and condenser 3 is destroyed and an equalization in the pressures occurs. Such equalization causes ref'rigerant to seek a common level in the well 22 and chamber 20. The refrigerant rises until it flows through the port 21 and by-pass 29 directly into the pipe H, and since the by-pass has a capacity at least as great as that of the pipe l2, all of the refrigerant is discharged through the by-pass and none can rise sufficiently in the well 22 to flow into the chamber 5. Thus, so long as there is breaking back of the load on the evacuator 2 refrigerant is diverted from its normal course into the evaporator to prevent intimate contact between the refrigerant and the fluid contents of the vaporization chamber.

In the practice of this invention no valves are required for controlling the by-pass 29, the action thereof being automatic and the flow of refrigerant therethrough being dependent only upon the absence of a pressure differential between the chamber 5 and the condenser 3. An added advantage is that when breaking back occurs, the accompanying increase of pressure in the chamber 5 forces refrigerant out of the chamber into the leg 30 of the pipe II and the chamber will be drained to effectively avoid any heating of the refrigerant therein.

While the invention has been described herein in connection with refrigerating apparatus embodying a closed coil 4 and an ejector evacuator, it will be understood that the invention is equally applicable to open types of systems, for example those having air washers, or with systems employing other types of non-positive displacement evacuators, such as centrifugal compressors, for example.

It will be also understood that the foregoing disclosure is illustrative only and that various changes may be made within the scope of the invention as defined in the hereinafter appended claims.

I claim:

l. Refrigerating apparatus comprising an evaporator, evacuator means for removing vapor from the evaporator, inlet means in the evaporator to admit refrigerant to the evaporator, means to divide the inlet means into two chambers, one chamber being subject to evaporator pressure and the second chamber being constantly subjected to evacuator discharge pressure, outlet means to discharge refrigerant from the evaporator, and an open by-pass between said second chamber and outlet means to divert incoming refrigerant from the first said chamber when the evaporator pressure approaches the evacuator discharge pressure and prevent the entry of refrigerant to the evaporator.

2. In a refrigerating apparatus comprising an evaporator and a condenser, evacuator means to remove vapor from the evaporator and to discharge it to the condenser, a well in the evaporator, means defining two intercommunicating chambers in the well, one of said chambers being subjected to the evaporating pressure and a second chamber being subjected to condenser pressure, inlet means to admit refrigerant to the well to be discharged from the top portion of the chamber subject to evaporator pressure, outlet means to discharge refrigerant in the evaporator, and by-pass means from the chamber subject to condenser pressure to the outlet to prevent admission of refrigerant to the evaporator when the pressure in the evaporator approaches the condenser pressure.

3. The method of refrigeration which consists of va gr lging and chilling a refrigerant, removing an compressing va or thus formed, removing chillefiFfl'igerintfi use, introducing refrigerant to the place of vaporization, subjecting a portion of the refrigerant being introduced to the vaporization pressure of the refrigerant and constantly subjecting another portion to the pressure of the compressed vapors, by-passing the refrigerant along a path free of the vaporization pressure around the place of vaporization and removing the refrigerant when the vaporization pressure approaches the pressure of the compressed vapor. and causing the difference between the vaporization pressure of the refrigerant and the pressure of the compressed vapor to prevent by-passing of refrigerant during the removal of vapor from the refrigerant.

4. A refrigerating apparatus comprising an evaporator having a single evaporating chamber, evacuator means to reduce the pressure and remove and compress vapor from the evaporator, inlet means to admit refrigerant to the evaporator, outlet means for the vaporator, means to supply refrigerant to the inlet means, means to always subject refrigerant supplied to the inlet means to evacuator discharge pressure, and means to divert refrigerant from the inlet means to the outlet means along a path free of evaporator pressure in response to the approach of the evaporator pressure toward the evacuator discharge pressure.

5. A refrigerating apparatus comprising an evaporator having a single evaporating chamber, evacuator means to reduce the pressure in and remove and compress vapor from the evaporator, inlet means to admit refrigerant to the evaporator, outlet means to discharge refrigerant from the evaporator, by-pass means free of evaporator pressure between said inlet and said outlet means, and means to always subject refrigerant supplied to the inlet means to the evacuator pressure to direct the refrigerant to the by-pass in response to a substantial equalization of the evaporator pressure and the evacuator discharge pressure.

ALFRED D. KARR.

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