US2122381A - Refrigerating method and apparatus - Google Patents

Description

June 28, 1938'. J. RAYMOND REFRIGERATING METHOD AND APPARATUS Filed Aug. 3l, 1934 @fase/vfeyzzzond @WMF Patented June v28, 1938 UNITED STATES PATENT OFFICE s l 2,122,381, REFRIGERATmG METHon AND APPARA 'rus Application Augustv31, 1934, Serial No. 742,302

14 Claims.

The present invention relates to a refrigerat ing method and apparatus which utilizes as a refrigerant, solidified carbon dioxide, popularly known as dry ice.

When solidified CO2 is exposed to relatively elevated temperatures, instead of passing through a liquid state, it flashes directly into a gas, this phenomenon being known as sublimation. Such behavior is not restricted to atmospheric pressure, but is experienced at very high pressures as well. Thus when a mass of solidied CO2, optionally in the form of a compacted snow, is placed into a closed container and allowed to absorb heat, it will be transformed to a gas with a resultant rise in pressure, and for all practical purposes, it may be said that the increased pressure will not appreciably impede evaporation.

Another peculiar property of the solidified CO2 is its action when immersed in a body of liquid. Although the dry ice has a low temperature and the liquid la. relatively yhigh one, evaporation of the dry ice will bring about little, if any, reduction of the temperature of the liquid. This may possibly be explained by the poor conductivity of COzgas, which, forming a layer of separation between the solid CO2 and the liquid, prevents the transference of heat. Whatever the explanation, the fact remains, and it is to be clearly understood that the present invention is not to be restricted to any theory, its practical operation being the basis offprotection sought.

Whereas the pressure generated by evaporation of a refrigerant has been utilized in a prior to Gr.` E. Hulse, 1,943,971, granted January 16, 1934, applicant is not aware of a system wherein dry ice is brought into direct'contact with a liquid for causing evaporation of the refrigerant, nor a system combining these two effects. l

While there are many'patents disclosing dry ice as a refrigerant, none of them has described a system of controlling evaporation whereby the cooling effects are economized. Some of the prior systems permit constant evaporation of the refrigerant regardless of cooling demands, using only a small portion of the cooling eect. Such systems are wasteful on the one hand, and not susceptible to close regulation on the other.

The use of water-ice for cooling requires a large refrigerant compartment as compared with the size of the compartment to be cooled. Waterice, moreover, passes to the liquid state and no utilizable pressure is developed during its evaporation.

Mechanical systems of refrigeration are not suitable for many types of installations, and require more space for the same cooling requirements than does the present system.

The present invention is especially suited to the cooling of railway cars, passenger as well `as freight, busses, trucks, private vehicles and boats. It is also intended for the refrigeration of food compartments, rooms, olces, and the various other uses to which mechanical and ice systems would otherwise find application.

It is the object of the present invention to provide a method and apparatus for refrigerating in an economical and well controlled manner, avoiding the faults and limitations inherent to the prior art. By providing a relatively simple apparatus, the initial expense of installation is kept to a minimum, and by virtue of its efficient operation, there is realized a maximum saving during the use lof the apparatus.

In general, the apparatus comprises -a closed container having conducting walls through which the heat may be directly or indirectly transmittedv4 from the body which is ultimately to be cooled. Means is provided for supporting the body of evaporative refrigerant, preferably above the bottom of the container, there being a compartment at the bottom for the reception of the liquid Whose extent of contact with the refrigerant, controls the rate of evaporation of the latter. 'I'he apparatus is equipped with adjustable means to vary the eifective liquid level in accordance with pressure values within the container, which values are preferably those resulting from evaporation of the refrigerant. One or more adjustable lvents are provided for the container to prevent the production of dangerous pressures therein. A storage tank is also contemplated for collection of the CO2 gases, which may be re solidified or put to other. uses, such as carbonating liquids.

Mechanism is contemplated to maintain uniform pressure throughout the container and to insure against freezing of the operating parts. Besides the control in accordance with pressure, auxiliary control is accomplished in accordance with, the temperature conditions of any point under the inuence of thevsystem.

The system is made to operate intermittently with a frequency capable of variation according to the ,rate of cooling required. Continuouoperation is likewise possible, and the system is capable of wide exibility, though close regulation.

Having stated some of the general characteristics of the apparatus, a more complete understanding will follow a study of the detailed structure described in conjunction with the drawing, in which:

' Fig. 1 isa sectional elevation illustrating `one form of the apparatus; and

Fig. 2 is a sectional elevation of a modified form, the adjusting mechanism for the liquid level not appearing in this view.

Referring to Fig. 1, a metallic container I0 is provided with a closure I I, shown as of the manhole type commonly employed in boilers. A gasket I2 and fastening means l3 are provided for the closure, whereby a fluid tight joint is achieved. As is usual with such a joint, the seal improves as the internal pressure increases.

Spaced from the bottom of the container Ill and suitably suspended from its vertical walls, there is a perforated refrigerant support I4 dividing the container into a refrigerant compartment I5 and a liquid compartment I6. Communicating with the liquid compartment, there is a pipe I1 provided with branch pipes I8 and I9, joined by a T-tting 20. Branch pipe I8 leads into the bottom of a pressure dome or tank 2|, closed at its upper end. 'I'he branch pipe I9 leads to the upper portion of the container I0 for a purpose to be described.

A valve 22 is inserted in the pipe I1 and is adjusted, by means of a screw 23 or similar element,

-to open when it is subjected to a predetermined fluid pressure. Thus until the pressure in ques-'- tion assumes the predetermined value, the valve .will remain closed. Pressures equal to or exceeding the preset'value will cause the valve to open and remain open until the pressure again drops below that for which the setting has been made, whereupon the valve closes until a new elevated pressure reopens it.Y By adjustment of the screw, this predetermined value may vary over a wide range, and for all practical purposes, is limited only by the operating conditions of the system.

The tank 2| contains a body of air or gas 24 which will be compressed as the column of liquid 25 rises, and thus, will tend to stabilize the height of the liquid column'. A valve 26 is provided at the closed end of the tank 2 I, by which additional liquid and/ or gas may be introduced through the pipe 21 projecting therefrom.

Surrounding the container I l), there is a jacket 28 containing a pipe 'coil 29 having an inlet end 30 and an outlet end 3l. The jacket is shown` as provided with bimetallic elements 32 and 33 which close the jacket to the atmosphere when the temperature of uid within the coil 29 is too high, but open when this temperature is reduced excessively, and thus prevent solidiflcation of such fluid .or undesirable cooling thereof.

Leading from the top of container II), is a pipe 34 through which excess gases resulting from evaporation may be withdrawn. Tapped from pipe 34, there is a conduit 35 leading to a gas storage tank 36 from which CO2 gas may be Withdrawn through a pipe line 31 leading to a closed system diagrammatically shown at A, which may be a carbonator, compressor, or other apparatus utilizing such gas. Optionally, if no such system is contemplated, the pipe line 31 may be capped. A check valve 38 in the pipe 34 prevents gas in the storage tank` 36 from reentering the container I6. A blow-olf valve 39 on.the storage tank may be set to any desired value of storage pressure. A valve 48 in the pipe 34 is used to control the operation of the system as will appear hereinafter.

A thermostatic bulb 4I, -shown as in contact 4 any reason, and the temperature withinthe coil 29 continue to increase, increased pressure within the container I0 will force liquid up through pipe I9 and its valve 44, adjusted by its adjusting screw 45 to a yielding pressure somewhat in excess of the opening point of valve 22, and deliver such liquid over the body of solidified refrigerant 46 in the container, causing further evaporation thereof.

Should the dry ice or solidified refrigerant 46 freeze against the walls and divide the container Into two compartments, liquid will be forced by Athe resultant pressure at the lower end, up through a tube 41 suitably mounted on the container wall, and cause suiicient evaporation of the refrigerant to again equalize pressures throughout the container and clear the walls thereof.

Upon the generation of pressures within the container exceeding those whichare safe or necessary for the operation of the system, a safety valve 48 provided in the closure will vent the container and reduce the pressure to a normal and safe value. In lieu of such a valve, a disk may be employed which will become ruptured and lrequire replacement.

In operation, if an operating pressure of 50 lbs. per square inch is desired, the valve 22 is set to this value by its adjusting screw 23. Assuming that the desired storage pressure is l5 lbs. per square inch, the blow-off valve 39 is set to this value. Valve 44 will be set to open at some pressure slightly in excess of the Setting of valve 22, and valve 48 set to blow off at a pressure assuring safe operation.

The closure II will be removed from the container I0, and a charge of solidified CO2 Will be lowered to rest upon its support I4. The liquid level in the lower part of the container will be above the perforated support, the actual height depending upon the amount of liquid in the system and the pressure of the fluid body 24. The liquid contacting the refrigerant 48 will cause the latterto start evaporating and upon bolting the closure in fluid tight relation with the container, this evaporation will begin to build up a pressure within the container.

Evaporation continues as long as the liquid contacts the refrigerant. Thus until the container pressure reaches the setting of the valve 22, evaporation continues at an undiminished rate. `As soon as the pressure reaches 50 lbs. per square inch, valve 22 opens and the gas pressure tends to force the liquid from the container into the tank 2|, compressing the fluid body 24. When contact between the liquid and refrigerant is broken, evaporation stops, and as long as the pressure within the container is sufficient to` maintain this condition, there will be no further evaporation. However, when the pressure reaches a value corresponding to the setting of valve 44, the latter will open and permit some of the liquid to ow over the refrigerant and set up some further evaporation. Should the presf to internal pressures.

sure continue to build up in this manner, safety valve 48 will ultimately open and vent the container to avoid dangerous consequences.

'I'he actual'operating cycle however, depends upon the adjustment of valve 40. When this valve is opened a small amount, the CO2 gas will escape slowly, whereby there will be alternate periods of contact between the refrigerant and liquid, with relatively long periods of no such contact. A greater opening of the valve 40 causes the intermittent contactsvto occur with greater frequency, with a correspondingly greater rate of evaporation. Increased opening of the valve increases the contact periods, until finally, continuous evaporation may be achieved by allowing the gas to escape as rapidly as it is generated. The escaping gas may be discharged to the atmosphere and wasted, or, it may be stored in a tank such as 36 from which it may be drawn oil as needed for desired purposes.

If the valve 40 has not been opened sumciently to cool the fluid in the coil 29 to a proper degree, thermostatic uid in the bulb 4| willV expand and vent the container by opening the valve 42, bringing about an increased evaporation and a corresponding increase in cooling effect.

With regard to the structure and operation set out above, it should be borne in mind that the structure considered is illustrative only and not restrictive. For example, in lieu of the tank 2| and valve 22 together with their appurtenances, the bottom of the container I0 could be formed of aflexible diaphragm for allowing the liquid to break its contact with the refrigerant in response Such a diaphragm could be given an adjustable responding value by backing it with a spring of variable tension or a balance beam with a sliding weight. As a matter of fact, the apparatus as shown would be operative without the pipe I9 and its valve 44. yThe thermal control could well be accomplished electrically according to known methods of thermally controlling valves. The bulb 4| yor other temperature sensitive device could be located at any point under the influence of the system instead of on the outlet end of the coil.

The apparatus is by no means confined toits use in conjunction with a coil. i In Fig. 2 another use is depicted, namely, cooling a fluid body such as air or gas. The container l0 is in this instance surrounded by a duct 49, both of which will be suitably7 supported in a manner not shown since Athe drawings are diagrammatic to a large degree'.

The duct may convey air or gas of any kind,

with or without suspended solids, such as dusts employed for industrial purposes. The inlet opening V50 may be providedwith a fan or blower 5I for circulating the fluid to be cooled. The coextensive walls of the container I0 and the duct 49 are shown as carrying bailles or vanes 52 for exposing the ilowing iuid to a maximum cooling surface, and for this purpose, the bales carried by the duct may have metallic contact with the container wall.

A thermostatic bulb 53 is shown in the outlet end 54 of the duct 49, suitably supported thereby. As in the preceding case, when the temperature of the delivered uid is too high, the fluid expansion within the bulb and its tube ES-.opens a valve 56 and vents the container Ill, bringing about an increased evaporation. This valve may discharge to the atmosphere or into theduct itself, as desired. The actual operating mechanism has not been shown in this ilgure, but it may assume any of the 'forms contemplated for the preceding illustration. The gas discharged from the apparatus may-be used to produce an in- Jector or ejector action in the ductlto promote increased circulation of the fluid to be cooled. For charging the container of Fig. 2 with refrigerant, a manhole 51 in the duct 49 has been indicated in dotted lines to show one operative means.-

The' thermostatically operated valves are preferably of an adjustable type, so that they may come into play at any desired temperature.

The liquid used to cause evaporation of the refrigerant will have such a low freezing point that the conduction by the container Walls will not cause it to solidify.

The various valves may be immersed in a similar liquid if it is necessary to provide an assurance against their freezing.

The valve 22 will remain open as long as pressure on either side thereof exceeds the pressure for which it is set. 'I'he claims should be construed to include a condition where the refrigerant itself assumes various levels and the body of liquid-has a fixed height. Y d

Where employed for cooling air, the apparatus may be vcombined with dehumidifying apparatus to prevent the formation of rime on the container and its bailies.

This invention is not to be limited to the specific embodiments shown since it covers a large number of alternatives, a few of which have been suggested. The scope of the invention is measured by the following claims: l

1. A method of refrigerating comprising bringing a solid refrigerant and a relatively warm liquid into contact in a substantially closed container, progressively' decreasing the mutual contact, between said refrigerant and said liquid under operating conditions as the vapor pressure resulting from sublimation of the refrigerant increases above a predetermined value, and venting -said container when the vapor pressure exceeds another predetermined value.

2. A method of. refrigerating comprising placing a solid refrigerant into a substantially closed container in the presence of a body of liquid which directly contacts the refrigerant below a predetermined pressure in.the container, under operating conditions causing the liquid to recede from i contact with the refrigerant as the pressure with-v in the container increases, and venting said container upon further increase of pressure beyond a predetermined value.

3. A method of refrigeration comprising placing a solid refrigerant into a substantially closed container in the presence of a body of. liquid, causing the liquid to. remain in contact with the refrigerant below a predetermined pressure, under operating conditions breaking the contact between the liquid and refrigerant when the pressure exceeds lthe predetermined value, and venting said container at a pressure exceedinga second predetermined value.

4. A method of refrigerating comprising placing a solid refrigerant into a substantially closed container in the presence of a body of liquid, causing the liquid to remain in -contact with the refrigerant below a predetermined pressure, under operating conditions breaking the contact between the liquid and refrigerant when the pressure exceeds the predetermined value, and venting the container when the pressure exceeds a Y second predetermined value, the pressure values resulting from sublimation of the refrigerant.

5. A method of refrigerating comprising placpressures within the container below a predetermined value, breaking the contact between the liquid and refrigerant at pressures within the container above the predetermined value, venting the container at pressures above a second pre-r determined value, and transferring heat through the container wall.

6. A method of refrigerating comprising placing a solid refrigerant into a substantially closed container in the presence of a body of liquid, causing the liquid to contact the refrigerant at pressures within the container below a predetermined value, breaking the contact between the liquid and refrigerant at pressures within the container above the. predetermined value, and venting the container at pressures exceeding a second'predetermined Value.

7. A method of refrigerating comprising placing a body of dry ice into a substantially closed container in spaced relation with the bottom thereof, providing a body of liquid in the space below the dry ice under operating conditions varying the effective liquid level for intermittent and varying extent of direct contact with the dry ice in accordance with instantaneous pressures within the container and venting said container at a predetermined pressure.

8. A method of refrigerating comprising controlling the ratel of evaporation of a refrigerant in a substantially closed container by ldirectly contacting said refrigerant with a body of liquid whose effective level may be varied, varying the effective level of said liquid by the joint effects of pressure within the container and the temperature at a point under the influence ofthe system and venting said container at a predetermined pressure.

9. Refrigerating apparatus comprising a contai 'er having conductive walls, means supporting a b dy of evaporative refrigerant in direct contact with a body of liquid in said container, means responsive to pressure within the container for adjusting the extent of contact between said refrigerant and said liquid and means for venting said container at a pressure in excess of a p redetermined value.

10. Refrigerating apparatus comprising a container having conductive walls, means supporting a body yof evaporative refrigerant in direct contact with la body of liquid, means responsive to pressure within the container for adjusting the extent of contact between said refrigerant and said liquid, means responsive to temperature at a point under the influence of the apparatus for adjusting the extent of contact between said refrigerant and said liquid and means for venting said container at a pressure in excess of a' predetermined value.

' 11. Refrigerating apparatus comprising a container having conductive Walls, means supporting a body of evaporative refrigerant in direct contact with a body of liquidin said container, means responsive to pressure'within the container for adjusting the extent of contact between said refrigerant and said liquid, means insuring uniform pressure throughout the container, and means for venting said container at a pressure in excess -of a predetermined value.

12. Refrigerating apparatus comprising a container having conductive walls, means supporting a body of evaporative refrigerant above the bottom of saidcontainer, a liquid compartment in the bottom of said container, means automatically adjusting the liquid'level in said compartment responsive to pressure within the container, means for varying the automatic adjusting means and means for venting the container at a pressure in excess ofja predetermined value.

13. Refrigerating apparatus comprising a container having conductive walls, means supporting a body of evaporative refrigerant for direct contact with a body of liquid in said container, means for adjusting the rate of evaporation of said 'refrigerant under operating conditions, and

means for venting said container at a pressure in excess of a predetermined value.

14. Refrigerating apparatus comprising a container having conductive walls, means supporting a body of evaporative refrigerant for direct contact with a body of liquid in said container, `means for adjusting the rate of evaporation of said refrigerant, and means for venting said container at a pressure in excess of a predetermined value.

JOSEPH RAYMOND. 5o

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