US2062235A - Refrigeration - Google Patents

Description

A. W. RUFF REFRIGERATION Nov. 24,l 1936.

Filed May 8, 1931 2 Sheets-Sheet 1 MCA Bnvcntor A. W. RUF F REFRIGERATION Filed May 8, 1951 2 Sheets-Sheet 2 [mlm :Snoentor 2s/27 so 55 A9 www.'

Mlll/ Nov. 24, 1936.

perature in the refrigerator fairly uniform, the

Patented Nov. 24, 1936 REFRIGERATION Alonzo W. Ruff, York, Pa., assignor to York Ice Machinery Corporation, York, Pa., a corporation of Delaware Application May s, 1931, serial no. 536,028

(o1. ca -91.5)

9 Claims.

This invention pertains to refrigeration, and more particularly to a method of and means for utilizing solid carbon dioxide in refrigerating units.

` Ordinarily the extremely low temperature of solid CO2 makes its use impracticable for direct cooling of meats and other foodstuis. Even in ice cream cabinets the icecream becomesV very hard, making it difficult to dispense the frozen cream without i'lrst allowing an appreciable rise in' its temperature.

It has heretofore been proposed to employ a secondary convector liquid or gas to act as an intermediary refrigerant between a primary re frigerant having very low temperature characteristcs andpthearticles to be cooled. While the interposition of a secondary refrigerant avoids `heat transfer at extremely low temperatures, efforts to control the temperatures in the refrigerating chamber have met with only partial success., Since it is desirable to maintain the temtemperature control of thes evaporating chamber containing the secondary refrigerant within close limits is important. It is equally important that a secondary refrigerant capable of close regulation be employed. f K

The present invention has for one Vof its objects the control of the temperature of the refrigerating chamber, the specific means adopted in the present Vinstance being a thermostatically actuated valve on the vapor side of an evaporafrlgerant.

tor coil 'containing the secondary refrigerant; A

rise in temperature within the compartment to be refrigerated ,results in Ithe Opening of the valve to permit evaporation of the secondary re- Conversely, the valve actuator responds to a droplin temperature in the compartment to close the valve and interrupt evaporation. y

Another object of the invention is to provide a combined container and condenser, the solid CO2 being deposited in the container in which it liquees and the condenser being so disposed in the container that maximum heat transfer between the liquid CO2' and the secondary refrigerantis effected. l y

A further object of the invention is to effectan -economy'in the use of the primary refrigerant by utilizing cold gas evolved therefrom to supplement the secondary refrigerant and supply other. accessories, such -as 'carbonated water faucets, with CO2 gas where the latter is employed as the primary refrigerant.

Reference to the appended drawings will enable those skilled. in the art clearly-to understand the mode of operation of. apparatus embodying the principles of the invention.

In the drawingst- F'ig. 1 is a schematic arrangement of the con- 5 Vstituent parts of the apparatus, and although their disposition in a refrigerating chamber is not precisely as shown, it is to be understood f lthat the evaporatorv coil and thermostat are so placed in the chamber that effective regulation 10 and desirable temperature conditions are maintained;

Fig. 2 is an elevation, partly in section, of the jacketed holder for the primary refrigerant, the space between the walls servingas a condenser 15 lfor the secondary refrigerant;

Fig. 3 is a top plan view of anice cream cabinet in which a refrigeration system similar to that illustrated 4in Fig. 1 is employed;

Fig. 4 is a front elevation, partly in section, of 20 the cabinet shown in Fig. 3; and

Fig. 5 is a sectional view of the containers for the CO2.

. -In the form of the invention illustrated in Figs. 1 and 2, the primary refrigerant is solid 25 CO2 having initially a temperature of approximately 109 F. at atmospheric pressure, while the secondary refrigerant circulating in a closed cycle, which includes an evaporator coil within the space to be refrigerated, is ammonia or methyl chloride. There are "other secondary refrigerants, however, which are suitable for use in the present system. l The solid C02 is placed in a jacketed container Il, the details of which are illustrated in Fig. 2. 35 This container comprises an inner drum I2 surrounded by a jacket I3 spaced therefrom, .the inner drum being supported by a leg I4. The container is suitably heat insulated, as indicated at I5, and a cover Il) adapted to be bolted or 40 otherwise secured to the'drum forms a tight closure therefor.

outlet for the CO2 gas evolved in the drum shown at I6, and this outlet connects with a discharge pipe I1 having therein a pressure regu- '45' -lator I8. The pressure regulator is preferably jacket, indicated at I9, is connected with an evaporator 20 in a refrigerator chamber 2| vthrough pipes 22, 23, nipples 24, 25 on the jacket being 55 secondary refrigerant, is contained in chamber I9l` and in the lower coils of the evaporator, the pressure of the secondary refrigerant being fixed when the evaporatoris originally charged to maintain atemperature of approximately 25 F. in the evaporator and about 0 F. in chamber 2|. A suitable valved inlet 26 is provided to ll the circuit with the secondary refrigerant.

It will be understood that the secondary refrigerant in the evaporator will be vaporized when subjected to the relatively high temperature of the refrigerator chamber and pass in a gaseous state to the chamber I9. As the gaseous secondary refrigerant comes in contact with thecold surface of drum I2 it will be condensed. The liqueed secondary refrigerant then flows by gravity through pipe 22 and liquidtrap 30 to the lower coil of the evaporator in which it is again 1 vaporized. The secondary refrigerant circuit thus acts automatically to effect heat transfer between the evaporator and the refrigerating chamber on the one hand, and between the condenser chamber I9 and the carbon dioxide on the other.

'I'he means for regulating the temperature of the evaporator comprises, in the present instance, an electrically actuated valve 21 disposed in the pipe connection 23, i. e., the return line, between the evaporator andthe condensing chamber I9. The electrical actuator maybe, and preferably is, arfsolenoid adapted to be energized to open or close valve 21 upon closing of a thermostatically controlled switch 28 responsive to the temperature of the refrigerator chamber 2I.

A suitable source of current, as a battery 29, supplies the necessary energy for actuating the valve. So long as the temperature of the refrigerating chamber is below a predetermined value, the valve 21 remains closed to retard evaporation of the liquefied secondary refrigerant inthe evaporator, the pressure of the vaporized secondary refrigerant backing up the liquid refrigerant into the condenser chamber I9, reducing the effective area of the evaporator, thus retarding evaporation. When, however, the temperature. rises sufficiently to operate the thermostatically controlled switch 28, the valve will be opened to permit more rapid evaporation of the secondary refrigerant, incidentally increasing the rate of heat exchange between the CO2 and the secondary refrigerant. Due to the limited .space in the condenser, it is inadvisable to load the. circuit with more refrigerant in its liquid form than can be contained in the condenser chamber during this last-mentioned stage of operation.

For the purpose of properly observing pressure and temperature conditions in the secondary circuit, there are provided a pressure gage 3I and thermometer well 32 in the pipes 23 and 22, respectively. There is also provided a lamp 39 in the solenoid circuit to indicate whether the lvalve is opened or closed. This latter signal may be used as indication of the supply of CO2 in the container, it being obvious that abnormally long periods of evaporation indicate the necessity for replenishment of the charge of CO2.

It is customary in refrigerating installations employing solid CO2 to permit the gas evolved during sublimation to pass tothe atmosphere. Suitable means are provided by the present invention for utilizing the gas thus wasted before its passage to the outer air.

As shown in Fig. 1, pipe I1 has an extension 33 directed to enter the refrigerator 2| and lie in proximity to the evaporator 20, the Waste gas passing through this extension before being vented to the atmosphere. A branch pipe 34 is also connected to pipe I1 as well as to a mixing valve or faucet 35 of the type common to soda fountains, so that the CO2 gas may be used for carbonating water. A check valve 36 to prevent backflow of lgas from the extension when the drum is open forl loading is also provided; likewise, a pressure gage 31 and valved outlet 38 areconnected to .pipe I1. K The operation will be apparent from the previously described arrangement of the apparatus and the functions of its various elements. The drum is rst loaded with solid CO2, usually supplied as compressed blocks of snow-like carbon dioxide. The blocks are, of course, extremely cold and tend to sublime at normal atmospheric temperatures and pressures. The drum is, therefore,.supplied with an air-tight cover and provided with gaskets to preventl escape of the CO2 gas except through pipe I1.

As stated hereinbefore, the regulator I8 maintains a pressure in the drinn corresponding with a liquid temperature of 50 F. for CO2. The secondary refrigerant in the evaporator 20 vaporizes to produce a temperature therein of about 25 F. and in so doing extracts heat from the refrigerating chamber. As the vaporized secondary refrigerant contacts the surface of the CO2 drum, it is condensed thereon and flows in liquid form either by gravity or by suitable pumping means back to the evaporator. Except when the flow of secondary refrigerant is interrupted by thermostatic actuation of valve 21, the refrigerating cycle is continuous and automatic.

In Figs. 3, 4 and 5, there is illustrated a practical application of the invention to an ice cream cabinet. Similar reference charactersare employed wherever the parts correspond with those shown in Fig. 1. TheCOz containers I2, I2', of which there are two connected by pipes 4I, 42, at the top and bottom respectively, are each provided with a closure Ill. Each closure is elliptical and cooperates with a similarly shaped opening 43 in the top of the. container. The closuresand openings may be square or any other shape to permit insertion of the closure so that it will seal the .container on the inner side of the top. thereof. The closures are clamped in position to seal the container by yokes 44.

As distinguished from the jacket surrounding the container in Fig. 1,-the condenser chamber shown in Figs. 4 and 5 is a U-shaped channel-like chamber 45 welded on the inner walls of. the container some distance above the bottom thereof and connected by upper and lower pipes 46, 41. Connections 24, 25 provide for communication between the condenser chamber and the evaporator .20 through the liquid line 22 and return pipe 23. As in Fig. 1, a trap 30 and thermostatically controlled solenoid valve 21, supplied with energy by a source of electrical energy 29, are disposed in the liquid and return lines, respectively. Thermostat 28 and indicator lamp 39 are shown as being in series with the valve actuating solenoid.

Regulating valves I8 and a charging valve 26 are also shown. Although not illustrated, it is to be understood that means are provided for drawing olf CO2 gas from the container and that the necessary blow-off valves are connected to the containers.

The particular disposition of the condensing chambers 45 within the containers is intended to obviate certain disadvantages inherent in condensers wherein the condensing surface is in contact with solid CO2. As has been heretofore explained, the CO2 is permitted to liquefy in the container after charging thereof by maintaining a pressure of about 100 pounds gage in the container. That portion of the CO2 that has not liqueed will sink to the bottom of the container.

Were the condensing surface in contact with the crystalline CO2, the effective heat transfer area would be less than that in which only liquid CO is in Contact with the condensing surface. By placing the condensing chamber at a height somewhat above the bottom of the container, it

will be in heat exchanging relation with only liquid CO2 until the level ofthe liquid falls below the condenser and thereafter suicient heat will be conducted through the container wall tocondense gas in the condenser.

AStill another advantage in spacing the condenser from the surface on which the solid CO2 rests is that, when the container is being blown leakage of heat from the exterior of the cabinet,

and removable covers 49 are placed over the several openings 5| provided for access to the cans of ice cream and to the CO2 container. 'Ihe levaporator comprises coils 54 adjacent opposite side walls of the cabinet, each of said coils being welded to plates 55 to provide for large radiating surfaces. 'Ihe coils are connected to vapor line 22 at the regulating valve and to liquid line 23 at trap130.

By controlling the evaporator in the manner set forth, extremely close regulation of the cabinet temperature is possible. Tests have indicated that, if properly charged and replenished with CO2, theevaporator will maintain a temperature varying less than 1 over a period of 24 hours even though the load fluctuations b e relatively severe. Another advantage of the system is that the CO2 is evaporated or used only as required to maintain the desired temperature in the refrigerator cabinet. Y l

Another characteristic of the apparatus is uniform transfer of heat. Since no ice, oil or -water are present in the system, 'and moving parts are unnecessary, the operation of the apparatus. is unaffected by the usual factors common to other refrigeration systems. Furthermore, the CO2 gas maybe withdrawn for other purposes so that it is not entirely wasted.

Since ammonia and methyl chloride are readily responsive to temperature control and are kwithout departing from the invention. It is i immaterial, for instance, whether the solenoid on the valve be energized to open or close the valve. If the refrigerating load is low, it may be advisable to energize the solenoid to open the valve, whereas when the load is relatively high entire charge of secondary refrigerant; means in said circuit for controlling ow of the secondary refrigerant from said evaporator to said condensing chamber; and means responsive to temperature in said refrigerated chamber for actuating said dow-controlling means.'

2. A refrigeration system comprising a refrigerated chamber; a container having a primary refrigerant therein; a circuit having a secondary refrigerant therein, said circuit including a condensing chamber in heat exchanging relation with said container and an evaporator in heat exchanging relation with said refrigerated chamber, said condensing chamber being of volume suilcient to contain substantially the entire charge of secondary refrigerant; and means responsive to a predetermined temperature in said circuit to cause displacement of liquid refrigerant from saidY evaporator into said condensing chamber.

3. A refrigeration system comprising a refrigerated chamber; a container having carbon dioxide therein, said carbon dioxide having a temperature substantially lower than that to be maintained in the refrigerated chamber; a circuit having a secondary refrigerant therein, said secondary refrigerant being in heat exchanging relation with said container and said refrigerated chamber; a mixing valve; and means connecting said mixing valve with said container.

4. A refrigeration system comprising a refrigerated chamber; a container having a primary volatile refrigerant therein; pressure regulating means controlling the venting of primary refrigerant from said container and arranged to maintain in said container a pressure at which the primaryI refrigerant will liquefy; and a circuit having' a secondary refrigerant therein, said circuit including a condensing chamber in heat exchanging relation with said container, an evaporator in said refrigerated chamber, said condensupper portion of said evaporator and said condensing chamber. Y

5. A refrigeration system comprising a refrigerated chamber; a container having a primary volatile refrigerantv therein; pressure regulating means controlling the venting of primary refrigerant from said container and arranged to maintain in said container a pressure at which the primary refrigerant will liquefy; and a circuit having a secondary refrigerant therein, said circuit including a condensing chamber in heat exchanging relation with said container and an evaporator in said refrigerated chamber, said cono of said circuit in heat exchange relation with the evaporator in said refrigerated chamber, said condensing chamber comprising a channelshaped member secured to the interior of said container above the bottom thereof.

7. That method of utilizing carbon dioxide for refrigerating a chamber which comprises partly filling a container with solid carbon dioxide; so regulating the pressure in the container that the carbon dioxide will liquefy; circulating a volatile refrigerant in a closed circuit: evaporating the said refrigerant in a portion of the circuit in heat exchange relation with the chamber; and condensing said refrigerant in another portion liquefied carbon dioxide.

8. That method of utilizing carbon dioxide for refrigerating a chamber which comprises partly filling a container with solid carbon dioxide; so regulating the pressure in the container that the carbon dioxide will liquefy; circulating a volatile refrigerant in a closed circuit; evaporating the' said refrigerant in a portionof the circuit in heat exchange relation with the chamber; and condensing said refrigerant in another portion of said circuit in heat exchange relation with a portion of the container intermediate the top and bottom thereof.

9. The method of utilizing carbon dioxide for refrigerating a chamber which comprises partly filling a container With solid carbon dioxide; maintaining a pressure of substantially one hundred pounds gage in the container whereby the carbon dioxide will be liquefied; circulating a volatile refrigerant in a closed circuit; evaporating the said refrigerant in a portion of the circuit in heat exchange relation with said chamber; condensing said refrigerant in another portion of the circuit in heat exchange relation with the liquefied carbon dioxide; and regulating the flow of vaporized refrigerant to said condensing portion to maintain a temperature of approximately

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