US2368675A

US2368675A - Refrigerating method

Info

Publication number: US2368675A
Application number: US252292A
Authority: US
Inventors: Muffly Glenn
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-04-05
Filing date: 1939-01-23
Publication date: 1945-02-06
Anticipated expiration: 1962-02-06

Description

Patented Feb. 6, 1945 UNITED STATES PATENT OFFICE REFRIGERATING METHOD Glenn Muflly, Springfield, Ohio Original application April 5, 1934, Serial No. 719,099. Divided and this application Jannary 23. 1939. Serial No. 252.292

3 Claims.

This is a division of application Serial No. 719,099, filed April 5,1934, now Patent No. 2,145.- 774, issued January 31, 1939.

The objects of the invention are the provision of certain methods of operation and of control of apparatus for refrigerating mechanism particularly applicable to such apparatus employed in the artificial production of ice.

The above being among the objects of the present invention, the same consists in certain novel methods of control and operation, to be hereinafter described with reference to the accompanying drawing, and then claimed, having the above and other objects in view. In the accompanying drawing which illustrates one structure capable of carrying out the methods comprising the present invention and in which like numerals refer to like parts, the figure is a more or less diagrammatic, broken, partially sectioned view of a refrigerating apparatus embodying an improved refrigerant flow controlling apparatus, the valve mechanism of which is shown in section and enlarged with respect to the remaining elements.

It will be readily understood by those skilled in the art that certain of the methods and apparatus herein disclosed are applicable for uses other than the production of ice, but, in view of the fact that the present application deals principally with the artificial production of ice, the description and explanation herein, primarily for the purpose of illustration, will be limited entirely to the application of such methods and/or apparatus to their use in the artificial production of ice.

In my previous application above identified means are disclosed for the production of ice by artificial refrigeration and it includes, in certain of the modifications there shown, a refrigerating mechanism including a compressor, condenser and receiver constituting a refrigerant high side, a water tank the bottom of which has associated therewith certain surfaces which, for the simplicity of explanation, will be referred to as cups or cones, exposed to the water within the tank, and each of which has associated with its unwetted surface an evaporating element or refrigerant low side for the purpdse of refrigerating it. The evaporator sections for the ice-making areas are connected in series or in parallel, or as herein described may be connected in a combination of both with the compressor and condenser. Suitable control means are provided in the connection between the high and low sides and between certain series or groups of the cups or cones so that one set or group of cups or cones will be refrigerated so as to cause ice to be formed in or on the same, while the other group of cups or cones will be warmed in order to cause ice previously formed in or on the cups 01' cones of such group to be melted loose therefrom whereby their natural buoyancy in the water within the tank will cause them to be removed from the surfaces upon which the ice was formed. The control means therein provided, particularly in certain modifications there shown, were such as to cause periodic reversal of flow of the refrigerant through the two sets or groups of evaporator sections so as to effect a constant and continuous production of ice.

The present invention deals primarily with the same type of construction as disclosed in said copending application above identified, now Patent No. 2,145,773, but relates to'certain improvements therein. Accordingly, there is illustrated a refrigerating mechanism including a high side indicated generally at III, a low side indicated generally at l2 and a control mechanism connecting them. The highside includes the usual motor driven compressor 12, condenser 13 and receiver ll. The low side includes two groups of evaporating units in the form of rings 3| connected in series through the dual expansion valve 36, each series being subdivided into two smaller groups, the individual rings of which are connected in parallel. Each ring 3| of the groups 21 and 28 of rings 3| is thermally associated with a corresponding ice making surface arranged in a water tank 9, the groups 21 and 28 are preferably being arranged at opposite ends of'the tank 9 or otherwise spaced apart to minimize heat transfer between them. The control unit includes suitable valves for controlling the direction of flow of refrigerant from the high side ill to the low side I? together with thermal responsive means in the form of bellows I12, the entire control unit being such that the direction of flow of refrigerant through the low side I! may be periodically reversed.

Any refrigerant may be employed in connection with this refrigerating system, but it is preferable to use one having a high ratio of specific heat of liquid to latent heat of vaporization, such as dichlorodifluoromethane, for instance, so that ample heat is available for melting the ice free from the refrigerated surfaces.

It will be understood that any desired and/ or conventional form of control means may be employed in connection with the refrigerating system as a whole for effecting cyclic operation of orator without dumping any of the liquid into' suction line.

With the valve positions as shown, the refrigerant enters from tube I1 and follows the solid arrows through valve port I8, the valve '2I being lifted by piston 24 at itsextreme travel to the left, and from there the liquid flows through tube I! to the lefthand evaporator section 21. It is reduced in pressure by the dual expansion valve 38, evaporated in group 28 of the evaporator the two cooperating notches in member I92 to 'guard against accidental movement by vibration.

closed and the vapor valves left as at the start. a

The result is that liquid refrigerant in section 21 of the evaporator is stlll'supplled to the section 28 through the expansion valve as before, until such time as the pressure upon the liquid falls to a point that allows it to evaporate in section 21 before going through the expansion valve. i-his will stop the refrigeration of section 28 and start the refrigeration of section 21, b1 the pressure in section 21 will remain appreciably higher than in section 28 because of the fact that vapor cannot pass the restricted opening ir the expansion valve as rapidly as liquid did measured in weight of refrigerant). This causes a further rings 3| and returns through tube I4 to the open vapor valve I94 and through chamber "I to the outlet port 88 leading to tube 1 I 1 The housing I10 is open to allow the vapor to flow through the entire chamber I H and over the bellows I12 at all times. This bellows is urged to expand by the spring I19 andthe vapor pressure of volatile fluid I14 with which it is charged. It will be understood that a more volatile fluid I14 would require that the spring I18 be under tension or placed outside of the bellows to assist in compressing it.

When the temperature of the vapor in chamber I" is lowered by the reduction of heat transfer rate in the evaporator section or group 28, due to ice having been frozen to the desired thickness, the temperature of fluid I14 will be lowered and bellows I12 will contract, moving its "head I15 downward, which pulls the rod I18 and pin I11 downward. The pin I11 engages the slot in rocker I18 which is pivoted to the housing I10 at I19. This causes contact point I80, which is integral with rocker I18 to depress the plunger I8I against the action of the spring I82, disengaging the plunger from the notch I83 in piston 24', which has been thereby held at its extreme leftward position.

The piston 24', upon being so released, moves to the right under the force exerted upon its left end by the high pressure liquid refrigerant. This movement of the piston allows valve 2| to close under force of spring 28 and it is thereafter held against its seat I9 by this spring plus the pressure of liquid refrigerant in tube I1. The movement of piston 24' to the right is then stopped by the righthand plunger I88, which is urged upwardly by spring I81 and engages notch I84 on its left side.

Pin I88 in the piston 24' has meantime moved member I89 to the right, compressing spring I90 between the shoulders on members I89 and I 9I, the latter being pivoted at 200 at a point midway of the extreme positions of movement of pin I89. This moves the upper end of member I9I to the left, so that it no longer bears against the right hand shoulder on part I92, but the movement is not enough to cause IN to contact the lefthand shoulder of part I 92, hence valves I93 and I94 are not moved. Since the pressure against I93 tending to hold it closed is greater than the pres sure acting upon I94, there is nothing to move either valve. but as a safety measure I prefer to employ a snap-over device as indicated by ball I88, which engages one and then the other of drop of pressure in chamber Ill and allows bellows I12 to expand under the combined effect of a lower surrounding pressure and a higher internal pressure. stoppage of refrigeration in evaporator section 28 which allows a greater degree of superheat in the refrigerant in chamber I1I than existed befor during the refrigeration of section 28.

The expansion of bellows I12 pushes upwardly on rocker I18, causing its point I91 to .push downwardly on the righthand plunger I 88, compressing spring I81 and releasing the piston to a move farther to the right under the'combined influence of pressure difference between the two ends of the piston 24' and the force of spring I which was compressed in the previous movementand stoppedjust beyond its maximum compression, in which position it is urging the piston to the right. This movement of the pistonopens valve 20 by direct push and opens valve I 93,,

simultaneously closing valve I94, by the contact of member I9l upon the left shoulder of ISL This brings the valves into positions. to ,make evaporator group 21 active, but there is little no liquid refrigerant to spill into chambe and thence into thesuction, line. 1 Warm;;li

refrigerant entering section 28. of the ev apora 13 which has been substantially evacuated and allowed to warm up somewhat, ill;,rap,idl y. melt free the ice that remains on-th sso'ciated-freesing surfaces in this section. 1

When the freezing of ice by evaporator section 21 has progressed to the point Of again causing bellows I12 to contract, the leftplunger I8I, which is now engaged in notch I85.,and holding the piston at its extreme right position, will be withdrawn from this notch and thepiston will move to the left under pressure of the liquid refrigerant which now acts upon its righthand end and the righthand plunger I86 will engage the righthandside of notch I84, holding the piston from further movement until the liquid is substantially exhausted from section 28 and the bellows expands as before, to release the piston for completion of its travel, which in this case takes it Q back to the position shown in the drawing;

An adjustment for the lowerbellows head I98 is provided by screw I99, by means of which the bellows may be positioned to give the spring I13 the required degree of compression or expansion to properly balance the contraction and expansion of the bellows so that the division of time between two adiacentportions' of the cycl'e'will be satisfactory. By changing springs I82and;., I81, orlby providing adjustments for "changingv-fi their working lengths independently, such'as-by The rise of temperature is due--to asoaevs providing adjustable stops for them at their lower extremities, it is possible to control the cycling of the system still further, prolonging or shortening the time of the piston at its two extreme positions by means of spring I82 and the time of the piston at its two intermediate positions by means of spring I81. Y

Assuming that the bellows I12 is charged with the same fluid used as t refrigerant in the system, containing some vapor and some liquid, and assuming that the suction chamber "I is filled with refrigerant vapor at a constant saturated temv perature condition, it will be seen that the fluid pressure acting externally upon the bellows will be exactly the same as that acting internally upon it. This, however, is a condition which, if it exists at all, is maintained only momentarily in the cycling of the system as described.

There is actually a varying amount of superheat in the vapor surrounding bellows I12 and there is a certain time lag in the temperaturewithin the bellows as compared with the temperature surrounding it, toward which latter temperature the fluid in the bellows is always being heated or cooled.

With methyl chloride at five pounds suction pressure, under control of an expansion valve, the pressure surrounding the bellows will be practically constant during a constant operation part of the cycle. The temperature of the vapor around the bellows will gradually be reduced as the refrigerating process progresses. Assuming now that the bellows is charged with sulfur dioxide, the bellows and its charge will be cooled by the methyl chloride vapor, resulting in the vapor pressure of sulfur dioxide in the bellows dropping. The vapor pressure within the bellows will thus be caused to drop to a pressure lower than that of the methyl chloride vapor surrounding it, whereas it started well above the five pound suction pressure.

This cooling effect upon the bellows during the first stage of operation causes it to contract, actuating the mechanism as described and releasing the piston 24', thus causing valve 2| to close. Soon after this valve is closed the suction pressure will begin to drop, and at the same time the temperature of vapor surrounding bellows I12 will rise, causing an increase of the sulfur dioxide vapor pressure within the bellows. This actuates the mechanism which opens valves 20 and I93 and closes valve I94, thus initiating another cooling period, but refrigerating the other evaporator section.

The bellows is now affected in the same manner as at the beginning. The fresh supply of liquid methyl chloride brings the suction pressure back up to the five pound setting of the expansion valve, while the temperature of the vaporized methyl chloride surrounding the bellows drops. cooling the bellows so that its internal vapor pressure of sulfur dioxide drops. This causes the bellows to contract again and trip the mechanism which closes valve 20.

With valve 20 closed, the supply of liquid methyl chloride is stopped and the suction pressure drops while the suction temperature rises. This causes the bellows to expand, opening valves 2| and I94 and closing valve I93. Valve 20' remains closed, which brings us back to the start.

Should the refrigerant in the system be sulfur dioxide, the same as the charge in the bellows, it will be noted that the pressures do not cross, hence for this combination of the same gas inside and out of the bellows, it would be necessary to place a spring or weight so that it tends to compress the bellows. By assuming the spring I18 to be under tension instead of compression this condition is met.

For convenience in assembly, it is desirable to have a rather low vapor pressure fluid in the bellows as for instance ethyl chloride (Cal-RC1).

Should it be desired to employ methyl chloride as the refrigerant and ethyl chloride as the charge in the bellows,- it will be seen that the pressures cross to only a slight degree at the end of the evacuating portion of the cycle (when both liquid valves are closed). The use of this combination is, however, quite practicable when the spring I13 is used under compression to help .the ethyl chloride expand the bellows.

Adjustments of the compression of spring I82 and of spring I81 independently, together with adjustment of spring I13 to vary its te ion or compression, will accommodate the cont 1 to a wide variety of refrigerants and bellows, charges. The design may be modified to use a spring external of bellows I12, tending to compress it if desired.

It is to be understood that formal changes may be made in the specific embodiment of the invention disclosed without departing from the spirit and substance of the broad invention, the scope of which is commensurate with the appended claims. i

What is claimed is:

1. The method of heating and cooling a submerged surface for the purpose of alternately Y said means and introducing relatively warm liquid refrigerant under reiativelyhigh pressure to said means.

2. The method of heating and cooling a submerged surface for the .purpose of alternately forming separate pieces of ice on and freeing ice from said surface comprising, operating a heat exchange means in thermal relation to said surface as an evaporator with liquid refrigerant supplied thereto and vapor removed therefrom, stopping said supply of liquid, refrigerant to said means while continuing said removal of vapor therefrom, stopping said removal of vapor from said means and circulating relatively warm liquid refrigerant under relatively high pressure to said means. a

3. The method of heating and cooling-separated areas of a submerged surface for the purthe last mentioned refrigerant through a pressure reducing device to another evaporating means.

GLENN MUFFLY.