US2896422A

US2896422A - Refrigerant control means

Info

Publication number: US2896422A
Application number: US722181A
Authority: US
Inventors: Leonard W Atchison
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1958-03-18
Filing date: 1958-03-18
Publication date: 1959-07-28
Anticipated expiration: 1976-07-28

Description

' July 28, 1959 Filed March 18. 1958 INVENTOR. LEONARD w. ATCH :sow

' HIS ATTORNEY UnitedStates Patent REFRIGERANT CONTROL Leonard W. Atchison, Louisville, Ky., assignor to General Electric Company, a corporation of New York Application March 18, 1958, Serial No. 722,181

'1 Claim. (c1. 62-197 improved arrangement for reducing the quantity of re frigerant pumped by the compressor when the pressure on the high pressure side of the system exceeds a predetermined value.

It is an object of the present invention to provide, for a refrigerating system using a capillary expansion means between the high and low pressure sides of the system, an improved arrangement for automatically modulating the flow of refrigerant through the system when the pressure on the high side of the system exceeds a predetermined maximum. t

It is afurther object of the present invention to provide, in a refrigeration system using a capillary expansion means between the high and low pressure sides of the system and utilizing outdoor air for coolingthe condenser of the system, a liquid refrigerant flow control and storing arrangementfor automatically reducing the amount of refrigerant flowing through the system as the outdoor temperature increases and reduces the amount of refrigerant gas that can be effectively liquified in the condenser of the system.

Further objects and advantages of the invention will" become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed outwith particularity in the claim annexed to and forming a part of this specification.

In accordance with the present invention there is provided a closed refrigerant. circuit in which are arranged a compressor, a condensing means, and an evaporator. A flow control restrictor between the condensing means and the evaporator is provided in the form of first and second capillaries connected in series relationship and having an intermediate chamber arranged therebetween.

In order to vary the flow of refrigerant through the system, a bypass conduit is connected between the .condensing means and the intermediate chamber for introducing gaseous refrigerant from the condensing means into the intermediate chamber and thereby into the second capillary. A pressure responsive means associated compressor 3 and a condensing means which condenses and stores liquid refrigerant. In the illustrated embodi 2,89%,422 Patented July 28, 1959 ice ment of the invention, the condensing means includes a condenser 4 and a receiver 8 for storing refrigerant liquified in the condenser. However, it is possible with a condenser of proper proportions to provide this storing function in the later stages'of the condenser.

The operation of the compressor withdraws gaseous refrigerant from the evaporator through a suction line 6 and delivers hot compressed gaseous refrigerant to the condenser 4 through a discharge line 7. The hot compressed refrigerant in the condenser 4 is cooled by circulating a cooling medium, such as air, over the surface of the condenser thus liquifying the refrigerant within the condenser which then flows into a liquid receiver 8 where it is stored prior to passing through the remaining components of the system.

Liquid refrigerant is. delivered from. the receiver 8 through a capillary expansion means to the evaporator 2. Where the liquid refrigerant evaporates under reduced pressure. More specifically, the capillary expansion means of the present invention includes a first capillary 9 and a second capillary 11 connected in series circuit between the lower portion of the receiver 8 and the end of the evaporator 2. Obviously, if the storing of liquid refrigerant is performed by the later stages of the condenser 4, then the capillary 9 would connect directly to the condenser 4. The capillaries 9 and 11 are separated by a small intermediate chamber 12 which, in the illustrated embodiment of the invention, is formed as an integral portion of the main receiver body 8. This intermediate chamber 12 could be remotely disposed or separated from the receiver 8 or from the condenser as long as the chamber is connected between the first and second capillaries in the manner explained above. During normal. operation of the system, the refrigerant liquid flows from the lower portion of the receiver 8 through the capillary 9, and enters the chamber 12 which is of relatively small dimensions. Normally, the refrigerant passing through chamber 12 is largely in the liquified phase. Liquid refrigerant then enters the capillary 11 whereupon it is delivered to the end of the evaporator 2. A pressure drop caused by the capillary 9 exists under normal conditions of operation, between the receiver 8 and the intermediate chamber 12 as well as between the chamber 12 and the evaporator 2.

The term high pressure side as employed in this specification has reference to what is commonly called a highside and which comprises the components of the system in the refrigerant circuit from the compressor to the flow restrictor means, or more specifically to the capillary 9, in the illustrated embodiment of the invention. In order to control the pressure in the high side of the system and thereby to maintain the load on the compressor 3 under a predetermined maximum, the present invention is provided with an arrangement for introducing gaseous refrigerant into the second capillary when the pressure Within the high pressure side of the system, as indicated by the pressure within the receiver exceeds a predetermined maximum. By the introduction of gaseous refrigerant into the second capillary 11, the flow of liquid refrigerant through the capillary is greatly reduced or restricted. For injecting gaseous. refrigerant into the second capillary, there is provided a bypass conduit 13 connecting the intermediate chamber 12 with the upper portion of the receiver 8 where high pressure refrigerant gas not liquified in the condenser normally accumulates. If the receiver 8 is eliminated and the storing of liquid refrigerant is performed by the last few coils of the condenser 4, then the bypass conduit 13 connects with the condenser at some point ahead of the stored liquid refrigerant, such as ata point in the first few coils of the condenser. chamber 12 through an opening or port 14 in the bottom The bypass conduit 13 connects with the the pressure on the high side of the system exceeds a predetermined amount. In the illustrated embodiment of the invention, the pressure responsive means includes a valve 16 seated in the port 14 and biased into the closed position to prevent the flow of gas into. the chamber. A weight 17, which is arranged to ride in piston-like fashion withinthe cylinder-like chamber 18, arranged above the intermediate. chamber 12, biases the valve 16 into the closed position; The weight, of course, is just sufiicient to prevent opening of. the port by the gas pressure exerted on the face of the valve 16 until such pressure reaches a predetermined maximum. I Other types of flow restrictor valve arrangements could be used for controlling the flow of gaseous refrigerant through the conduit 13 according to pressures within the receiver 8. For example, a pressure responsive bellows could be arranged within thethe control arrangement on the total refrigerant flow inthe system may be more clearly understood when the operation of the system is considered under the temperature conditions encountered during utilization of the system in an air conditioning device. ment outdoor air is sometimes blown for cooling purposes over the condenser 4, and the temperature of the outdoor air, since it fluctuates greatly during the summer cooling period, causes the pressure within the condenser and the high pressure side of the system to vary over a wide range. If some arrangement is not provided for maintaining load conditions below a certain predetermined amount, it is necessary to provide the refrigeration system of the air conditionerwith a compressor motor of sufiicient power to operate the compressor under the maximum load conditions which would result from the extreme temperatures encountered in any part of the country inwhich the conditioner might possibly be used. Thus, the load conditions resulting from an outdoor temperature of 120 F., which occurs at times in some Southwestern areas of the country, would require the utilization of a much more powerful motor in relation to compressor displacement, than would be necessary if the system never had to be operated under load conditions greater than those existing when the outdoor temperature is 100 F. or below.

Also, if such a powerful motor is utilized to drive the.

compressor, then, at all temperatures below 120 F. the motor is unloaded and the potential refrigerating capacity of the system is not made available during most of'the time that it is used. a

In the system of the present invention the valve 16 and weight 17 are designed to permit gas into the intermediate chamber when the high side pressure reaches a predetermined. maximum, such as 300 psi. That is, when the gas pressure in the receiver equals 300 p.s.i., there is exerted against the area of the valve sufficient pressure to overcome the imposed weight 17 thereby opening the valve to permit flow of gas into the intermediate chamber 12 at the same pressure as that of the receiver 8. Flow of high pressure gas into the intermediate chamber raises the pressure of the intermediate chamber 12 to that of Or, for example, a spring loaded valve.

In such an arrangethe amount of compressed gas fed to the condenser with a corresponding build-up of the liquid refrigerant stored in the receiver 8, or in the latter stages of the condenser 4 when no receiver is used, which rapidly reduces the pressure in the high pressure side of the system. When the pressure in the receiver is reduced below 300 psi, or any desirable predetermined maximum pressure'as determinedby thedesign of the valve 16 and weight 17, then thevalve '16 closes'the port 14 and the liquid refrigerant again begins to flow in the normal manner through the system.

'From the foregoing, it is apparent that there is provideda control arrangement for a refrigeration system, such as those employed'in air cooledair conditioning systems, which automatically maintains the high side pressure and the resultant load conditions on the compressor below a predetermined maximum regardless of the temperatureof the air blown over the condenser of the system.

While in accordance with the patent statutes there has been described what at present is considered to be the preferred embodiment of the invention, it will be obvious to'those skilled in the art thatvarious changes and modifi'cations may be made therein without departing from the invention and it is, therefore, the aim of the appended claim to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I' claim as new and desire to secure by Letters Patent of the United States is:

A refrigeration system comprising a compressor, a condenser and an evaporator connected in refrigerant flow relationship, a receiver in said system between said condenser-and said evaporator for storing liquid refrigerant from said condenser, an intermediate chamber in said system between said receiver and said evaporator, a first capillary for conducting liquid refrigerant from said receiver to said intermediate chamber and for creating a pressure drop between said receiver and said intermediate chamber, a second'capillary for conducting refrigerant from said intermediate chamber to said evaporator and gas-to flow into said intermediate chamber in response to an increase in pressure in said receiver above a predetermined amount whereby gaseous refrigerant is introduced into said intermediate chamber and thence into said second capillary to restrict the flow of liquid refrigerant through said second capillary thereby reducing the total refrigerant flow through the system.

References Cited in the file of this patent UNITED STATES PATENTS 2,807,940 'Urban O ct. ,1, 1957 Hubbard Nov. 9', 1942'