US2077865A - Refrigerating system - Google Patents

Description

April 20, 1937. D, D W|| E 2,077,865

REFRIGERATING SYSTEM Filed March l5, 1934 saliti 75;/ lA'TTO EY Patented Apr. 2o, 1937 UNITEDA STATES PATENT' lFFICE REFRIGERATING SYSTEM tion of Michigan Application March 15, 1934, serial No. 715,576

Claims.

My invention relates to a refrigerating system, and more particularly to that part of such a system which comprises the low side unit or evaporator element.

An object of my invention is to provide an evaporator coil so constructed as to retard the flow of refrigerant medium therethrough.

Another object is to provide a refrigerating system having thermostatic means controlled by 10 the temperature of the liquid refrigerant medium supplied to the evaporator for controlling the refrigerating effect of the evaporator.

Another object is to provide means to insure complete refrigeration of the evaporator coil throughout its length prior to closure of the valve controlling admission of refrigerant medium thereto.

Another object is to provide means to shield the bulb element of a thermostatic expansion 2 valve from the cold effect occurring adjacent the inlet to the evaporator coil.

The invention consists in the novel system and the arrangement of the parts embodying the same, to be more fully described hereinafter and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawing, to be taken as a part of this specification, I have fully and clearly illustrated a preferred embodiment of my invention, in which drawing- Figure 1 is a view in front elevation of a casing to be refrigerated, but having a portion of the ouside wall broken away to show my novel evaporator unit, and

Fig. 2 is a view in horizontal section of a portion of the casing showing the evaporator unit in plan view.

Referring to the drawing by characters of reference, I designates a refrigerator casing or box having an outer wall 2 and preferably being substantially rectangular. The casing Ihas a metal liner 3 of heat conducting material which serves as the container for material or goods to be refrigerated. The container 3 is insulated from atmosphere by suitable insulating material 4 which surrounds the sides and bottom of the container and which is positioned between the container and the outer casing wall 2. A cover member 5 is provided to close the top of the container 3 and to effectively seal the chamber 6 formed within the container 3. The container 3 is provided with an evaporator coil 'I which extends externally around the side walls thereof and which is intimately secured and sealed to the liner, as by solder or the like. The coil 'I is of sinuous form composed of a plurality of U-shaped loops designated generally as 8 and each having a downflow leg 9 and an up-flow leg IIJ which terminates at its upper end below the top end of the downflow leg. Each up-fiow leg Ill of one loop is con- 5 nected to the down-flow leg of the next adjacent loop by a straight connecting portion II inclined upwardly in the direction of refrigerant flow from the top of the shorterv up-flow leg to the top of the adjacent longer down-flow leg 9. 10 Each of the loops 8 serves as a trap to retain the refrigerant medium when the compressor o1' the system is not in operation so that the loops act to distribute the refrigerant medium equally around the container. Then when the compressor 15 again starts, there will be uniform refrigeration or cooling of the container walls as each of the loops in effect acts as a separate refrigerating element. The straight upward inclined portions I I cooperate with the loops 8 to retard the trans- 20 fer of the refrigerant medium from one loop to its next adjacent loop in the direction of flow so that refrigeration will take place uniformly and the compressor will not draw liquid refrigerant from the evaporator coil as might occur if the 2 coil were of helical form wrapped around the container 3. This series of interconnected loops preferably extends substantially completely around the container 3 from the inlet I2 of the coil to' its outlet or return line portion I3. 30

Admission of refrigerant medium to the coil I is controlled by a thermostatic expansion valve Id having its outlet I5 connected to the coil inlet I2. The valve IB has an inlet I6 which opens through a valve port I'l into a chamber I8 in the 35 valve body communicating with the outlet I5. The port I1 is controlled by a valve member I9 secured to a pressure responsive diaphragm means 20 such as a metal bellows which closes and seals one side of the chamber I8, being responsive 40 to the pressure of refrigerant medium therein. The operation of the valve member I9 is also controlled by a temperature responsive means 2| such as a bellows chamber having a fixed head 22 rigidly secured to the valve casing and having 45 a movable head 23 which is connected by a thrust rod 24 to` the valve member I9. Expansion of the means 2i or downward movement of the head 23 is opposed by a spring 25 under tension which surrounds the rod 24, being secured at one end 50 to the diaphragm means 20 and at its other end to a partition 26 in the valve casing and through which the rod 24 extends. The responsive means 2| has its internal chamber connected by a tube 2`I to a bulb element 28, the means 2l and bulb 28 55 being charged with a suitable volatile liquid responsive to temperature change. The bulb element 28 is secured by a clamping means or the like 29 to the outlet portion I3 of the evaporator coil closely adjacent the point at which the coil leaves the container wall and also preferably in' substantial contact with the wall of the container or liner 3. The bulb element 28 and its responsive means 2| together comprise a thermostatic means responsive to the temperature of the refrigerant medium adjacent the outlet from the evaporator. The liquid refrigerant medium supply line 30 extends along the outlet portion I3 of the evaporator coil, as at 3|, and is tightly secured thereto, as by clamps 32 or solder, so that the portions 3| and I3 will be in intimate heat conducting relation. 'Ihe portion 3| is secured to the coil outlet portion I3 on the outlet side of the bulb element 28, that is, beyond the bulb element in the direction of flow of the refrigerant medium through the portion I3 so that the bulb element will respond to the temperature of the refrigerant medium in the coil at its outlet end. The liquid supply line 30 also has a portion 33 of its length intermediate the portion 3| and the expansion valve secured preferably by solder to the wall of the liner 3 between the inlet portion of the coil 1 and the bulb element 28, so that the relatively warm liquid refrigerant medi-v um in the supply line 30 will warm the container wall adjacent the bulb element to shield the bulb element from the cold effect at the coil inlet. The outlet end 34 of the supply line or conduit 30 is connected to the expansion valve inlet I6.

The operation of my system is as follows: When the compressor, connected in the usual manner together with a condenser to the outlet or return line I3 and the supply line 30, is started, the reduction in pressure transmitted through coil 'I to chamber I8 will act on diaphragm means 20 to 40 open the valve I9. The liquid refrigerant medium entering the supply line 30 will iiow through the portion 3| and since the liquid is relatively warm,

it will heat the coil outlet portion I3 which will conduct the heat of the liquid to the bulb element l5 2B. The heat of the refrigerant liquid conducted to the element 28 will expand the volatile liquid therein creating pressure in the responsive means 2| to move the head 23 downward to hold the valve member I9 open against the force ot'- spring 5^ 25 until the coil is completely refrigerated. 'I'he liquid refrigerant medium passing through the valve portv Il will expand into the coil 1 and cool the inlet portion of the coil and its adjacent container wall to a very low degree of temperature, 55 which would result in the bulb element 28 being subjected by conduction through the container wall to this extremely low temperature at the coil inlet. This would cause contraction of the volatile liquid in the element 28 with a consequent prema- 60 ture throttling or closing of valve I9. In order to prevent 'this cold effect at the coil inlet from affecting the operation of the thermostatlc expansion valve by chilling of the bulb element 28, the supply line 30 is secured to the liner wall be- 65 tween the bulb element and the inlet portion of the evaporator coil so that the relatively Warm vliquid refrigerant in the supply conduit will heat an interposed area of the liner wall and offset transmission of cold from the coil inlet through 70 the liner wall to the bulb element. While the compressor is in operation, the Valve member I9 will be held open by the responsive means 2| against the force of spring and back pressure of the expanded refrigerant in chamber I8 and 75 coil 1 acting on the diaphragm means 20. when the coil has been completely refrigerated and the cold refrigerant medium has passed through the coil to the point at which the bulb element 28 is connected to the coil, then the volatile liquid in the bulb element will be cooled and contract to permit closing movement of the valve member I9 to reduce flow of refrigerant medium to the coil 1. When the outlet end portion of the coil 1 on the container side of the bulb element warms up due to lack of refrigeration in response to closing movement of valve member I9, then the responsive means 2| will move the valve member I9 toward open position to again cause complete refrigeration of the coil 'I. The heat of the relatively warm liquid refrigerant in portion 3| is transmitted through the evaporator coil and the liner wall to the bulb element so that the bulb element responds to the temperature of the liner or the coil at its position only and is not affected by transmission of cold through the liner wall or the evaporator coil until refrigeration actually reaches the bulb element. The heating of the bulb element by the relatively warm refrigerant liquid in the inlet portion 3| also results in a quick response of the bulb element to lack of refrigerant in the outlet end portion of the evaporator coil so that there is a balanced operation of the valve member 9 during compressor operation and only sufficient refrigerant medium will be admitted to the coil by the differential operation on valve member I8 of the responsive means 2| and diaphragm means 20 to maintain the coil refrigerated throughout its length. When the compressor is stopped by the usual automatic compressor switch or by any other means, the flow of yliquid refrigerant medium through the supply line 30 will cease, and the bulb element 28 being no longer heated thereby, the valve member I9 will quickly close the port Il under the force of spring 25 and the back pressure in the coil 'I acting on diaphragm means 20. While the cornpressor is not in operation, the valve member I9 will remain closed as the evaporator coil warms up, since the back pressure of refrigerant medium acting on diaphragm means 20 plus the force of spring 25 is greater than the pressure exerted by the responsive means 2| on the plunger rod 24.

From the foregoing description, it will be apparent that I have provided a thermostatic control means which although shown as cooperating with an expansion valve to control the refrigerating effect of an evaporator, can readily be adapted for controlling the refrigerating effect of the evaporator by direct control of the usual compressor switch.

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

1. In a refrigerating system, a container having a conduit for ow of refrigerant medium in heat exchange relation to said container, said conduit having its inlet and outlet closely adjacent each other, an expansion valve controlling admission of refrigerant medium to said conduit, temperature responsive means controlling said valve and having a bulb element responsive to temperature adjacent the outlet from said conduit, said bulb element being so positioned that it is subject to the cold effect at said inlet, and a refrigerant medium supply conduit leading to said expansion valve, said supply conduit having a portion thereof positioned adjacent said bulb element so that the relatively warm refrigerant medium in said supply conduit will shield said bulb element from the cold refrigerant medium leaving said expansion valve.

2. In a refrigerating system, a casing to be refrigerated having a liner of heat conducting material, a refrigerant medium conveying conduit secured to said liner, a thermostatic expansion valve controlling thejadmission of refrigerant medium to said conduit and having a bulb element responsive to temperature of the refrigerant medium adjacent the outlet from said conduit, and a refrigerant medium supply conduit leading to said expansion valve and secured to said liner intermediate the inlet of said first-named conduit and said bulb element whereby to shield said bulb element from the cold refrigerant medium leaving said expansion valve.

3. In a refrigerating system, a casing to be refrigerated having a liner of heat conducting material, a refrigerant medium conveying conduit secured to and extending around the side walls of said liner, a thermostatic expansion valve controlling the admission of refrigerant medium to said conduit and having a bulb element responsive to temperature of the refrigerant medium adjacent the outlet from said conduit, said conduit being of sinuous form having vertically extending loop portions, and a refrigerant medium supply conduit leading to said expansion valve and secured to said liner intermediate the inlet of said first-named conduit and said bulb element whereby to shield said bulb element from the cold refrigerant medium leaving said expansion valve.

4. In a refrigerating system, an evaporator coil comprising a plurality of U-shaped loops having down-flow and up-ow legs, the up-flow leg of one loop having connection to the down-ow leg of the next adjacent loop .to provide a sinuous passageway, said up-ow legsbeing shorter than said down-flow legs, and said connection comprising means to retard the flow-of refrigerant medium. y l

5. In a refrigerating system, an evaporator coil comprising aplurality of U-shaped loops having down-ow and up-flow legs, the up-flow leg of one loop having connection to the down-flow leg of the next adjacent loop to provide a sinuous passageway, said up-iiow legs being shorter than said down-flow legs, and said connection comprising a conduit portion inclined upward in thedirection of iiow to retard the ow of refrigerant medium.

6. In a refrigerating system, an elongated tubu- 450 lar evaporator having an inlet and an outlet, an

tor adjacent said supply conduit such that saidr bulb element is heated by conduction through said evaporator from said supply conduit.

7. In a refrigerating system, a heat transfer member, a tubular evaporator having an inlet portion and an outlet portion secured to said member, a thermostatic expansion valve controlling .admission of refrigerant medium to said inlet portion and having a bulb element secured to said outlet portion, and a refrigerant medium supply conduit leading to said valve and secured to said outlet portion to influence the operation of said valve, said conduit also being secured to said member intermediate said portions such that said bulb element is shielded from the cold refrigerant medium leaving said valve.

8. In a refrigerating system, an evaporator including a heat absorbing wall and having a refrigerant passageway with an inlet and an outlet in adjacent relation to each other, an expansion valve controlling admission of refrigerant medium to said inlet, temperature responsive means controlling the operation of said valve and having a bulb element responsiveto refrigerant medium temperature adjacent said outlet, and a refrigerprising an elongated pipe having one end deiining an inlet and its other end defining an outlet, an expansion valve controlling admission of refrigerant to said pipe inlet, a pipe for supplying liquid refrigerant to said expansion valve,

temperature responsive means controlling the operation of said valve, means tightly clamping said responsive means to said evaporator pipe adjacent said outlet, said liquid supply pipe having a portion of its length extending longitudinally of said evaporator pipe and positioned between said responsive means and the evaporator pipe outlet, and means tightly clamping said supply pipe portion externally to said evaporator pipe in intimate heat exchange relation so that the relatively warm liquid refrigerant in said supply pipe'will by conduction through the wall of said evaporator pipe act to heat said responsive means.

10. In a refrigerating system, an evaporator comprising an elongated pipe, a pipe for supplying liquid refrigerant to .said evaporator pipe, said supply pipe having a portion of its length extending parallel to a portion of said evaporator pipe adjacent the evaporator outlet, means clamping said pipe portions tightly in intimate heat exchange relation to each other such that the relatively warm refrigerant in said supply pipe will heat said evaporator pipe portion, a thermostatic expansion valve controlling admission of refrigerant from said supply pipe to said evaporator, said valve having a temperature responsive bulb element, and means securing said bulb element in intimate heat. exchange relation to said evaporator pipe on the evaporator side of said portion such that said bulb element will be heated by conduction through said evaporator pipe from lthe relatively warm liquid refrigerant in said supply pipe.

DANIEL D. WILE.

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