US2683360A

US2683360A - Refrigeration system

Info

Publication number: US2683360A
Application number: US293284A
Authority: US
Inventors: Ragnar A Norbom
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-06-13
Filing date: 1952-06-13
Publication date: 1954-07-13
Anticipated expiration: 1971-07-13

Description

July 13, 1954 R. A. N ORBOM 2,683,360

REFRIGERATION SYSTEM Filed June 15, 1952 2 Sheets-Sheet 1 INVENTOR RAGNAR A. NORBOM V BY (4/ Q ATTORNEY R. A. NORBOM REFRIGERATION SYSTEM July 13, 1954 2 Shets-Sheet 2 Filed June 13, 1952 INVENTOR RA GNAR A. A/o/wo/v ATTORNEY Patented July 13, I954 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to refrigeration systems and, although useful to cool any chamber, has special application to refrigeration systems adapted for use upon vehicles for the transportation of perishable commodities such as foods, drugs, etc.

To date, there is no known system of mechanical refrigeration devised for railroad cars which has enjoyed any substantial degree of commercial success. As a result, even today, the largest users of refrigerating equipment for railroad cars continue to depend for cooling, upon ice stored in space-consuming bunkers, positioned at various locations within a refrigerator car. The problems involved in adapting mechanical refrigeration systems to the needs of this industry are many. Quite frequently refrigerator cars must stand for long periods in locations where the ambient temperature places a heavy demand on the refrigerating system. Obviously, such devices as compressors driven either directly from the axles of the cars or through electric energy supplied by generators driven from the axles, are not well suited for use on standing cars where other electricity is unavailable.

Absorption type refrigeration systems have been tried, but with very limited success. The drawbacks to these systems apparently include the fire hazard due to the flame and the problem of keeping a burner flame lighted in a closed or drafty moving vehicle. Other attempts at solving the instant problem have included refrigeration systems of the type in which a high pressure tank of refrigerant has been allowed to expand slowly into an evaporator coil placed within the car, and then been exhausted to the atmosphere. Such systems are expensive in view of the waste of refrigerant and are impractical because of the large quantity of refrigerant'which must be carried to maintain desired temperatures on long hauls where renewals are not purchasable.

This invention embodies an entirely novel ap- In conventional mechanical refrigeration systems, the heat abstracted from the lading space is wasted. In a domestic type refrigerator, for example, the condenser is simply exposed to the ambient air so that the heat content of the refrigerant due to heat pickup in the lading space plus the heat of compression is dissipated through the condenser to the ambient air.

It is a primary object of this invention to pro vide a means for converting this otherwise wasted heat into useful energy to assist in the circulation of refrigerant through the system.

It is a further object of this invention to eliminate from the system apparatus which would serve to function as a conventional condenser, at least insofar as from such condenser the heat absorbed by the refrigerant in the evaporator would be lost to atmosphere.

A further object of the invention is to utilize a direct heat exchange between liquid refrigerant which has by-passed the evaporator and gaseous refrigerant which is withdrawn from the evaporator to effect condensation of the gaseous re-' frigerant and thus retain the heat (which other Wise would be wasted) to effect a saving in the required energy input to the system as a whole."

Another object of this invention is to provide pressure booster means, operating automatically when and as occasioned by Waning pressure of the refrigerant vapor, by which means another gas, under pressure independent of and not in contact with the refrigerant vapor, will move a piston to compress, and augment the pressure of such vapor and restore thereto the energy lost through friction or otherwise, so that such refrigerant vapor will continue to cause the liquid refrigerant to circulate throughout the system.

This invention will be fully understood from the following description read in conjunction with the attached drawings in which:

Figure 1 is a diagrammatic showing of the overall system, and

proach to many problems in all kinds of mechanical refrigeration systems. In part,'this invention utilizes the heat (energy) extracted from the lading space to reduce the. power input necessary to operate the system. In addition, this invention also utilizes the kinetic energy of the liquid refrigerant circulating in the system to' Figure 2 is a detailed sectional side elevation of the gas operated pressure booster which supplies, automatically when from time. to time required, such additional energy as becomes nec--- essary to keep the system operating.

Referring now to Figure l, the basic refrigerant circuit includes a tank IQ, for the storage of at least such quantity of refrigerant as the sys tem requires, leaving space thereabove, substan tially as shown. While several known refrigerants would operate satisfactorily in this system, it is contemplated that use will be made primarily of Freon 12 or its equivalent. From the lower portion of the tank Ill, a conduit H, for liquid refrigerant, connects to the high pressure inlet of an ejector device i2. interposed in this conduit H are a filter and a valve i i. The purpose of the latter will be described hereinafter. From the Venturi outlet of the ejector device it, a conduit i5 conducts refrigerant to a coil iii and a further conduit i! connects the other side of the coil through a check valve it to a nozzle it which enters the tank Li; An: evaporator lading space to be cooled, is connected in parallel with conduit ll. The inlet to the evaporator is through a conduit 2i and an expansion valve 22 The outlet or" the evaporator is connected to. the suction inlet of the ejector I2.

Liquid refrigerant is caused to circulate inthe' system by pressure of its own vapor in tank Iii. It will flow from tank It through" the conduit i l and the valve i l. When the refrigerant. reaches:

the junction point of conduits I l and 2i the flow will. divide, and part will pass through the expansion valve 22- into the evaporator where it becomes a vapor, such change of phase absorbing heat from the lading space. The remainder of. theretrigerant liquid will continue through conduit I l to the ejector. The liquid refrigerant flowing. through the ejector will then serve to withdraw and. entrain cold gaseous refrigerant fromthe evaporator, and the mixture will be returned through. the conduit l5, coil 16, conduit [1, check. valve l3 and nozzle ii) to the. tank is. In its passage from the ejector i2, to the. tank H), the vapor component of the mixture will revert to liquid phase. as next described.

Important reactions in this refrigerant cycle are those which take place between the ejector devicev l2 and the check valve It. The liquid refrigerant leaving the ejector will be at substantially' ambient temperature, but the gaseous refrigerant will be at a much lower temperature. Initially, therefore, the gaseous phase is warmed to: some extent by its direct contact with the liquid: refrigerant, and the latter is cooled, so-

that. the temperatures of the two phases tend to approach a common intermediate degree with relatively reduced pressure. The latter temperature, of course. will be determined by the relative proportions of liquid refrigerant fed through the conduit l i to the ejector l2 and of that portion which flows through the conduit 2! into the evaporator. The rapidly moving stream of liquid refrigerant leaving the ejector l2 develops kinetic energy due to its mass and velocity. This creates a build-up of pressure in the coil i6 because the flow backs up from the check valve 18, held: by the opposing vapor pressure in tank iii. The. immediate and instantaneous result of this pressure. build-up is that the gaseous phase of the. refrigerant in the mixture is quickly raised in temperature while the temperature of theliquid. portion of the refrigerant in the mixture remains substantially constant. With a temperature differential thus: created between the gaseous and liquid phases. of the refrigerant and with both phases in mutual contact, the gaseous phase will entirely condense. In so doing the gaseous phase gives up its latent heat of. condensation to the liquid phase, increasing the temperature. of and: energy in the liquid. The resulting total pressure now accumulated in coil will overbalance the pressure of refrigerant vapor in tank m and: open check valve l8, through which and-I through nozzle It the liquid will rc-enter tank f6; completing the operating cycle.

The remainder of the apparatus shown in Fig ure 1' is: entirely for the purpose of maintaining in the a predetermined pressure Within the tank In. The source of additional pressure therefor, as will be apparent from an examination of the drawing, is the high pressure cylinder 23 which may contain an inert gas such as carbon dioxide or helium. A pressure booster 2 operates automatically, partly by pressure from the cylinder 23, to increase the pressure of gaseous refrigerant inthe top of tank it.

Referring now to Figure 2 for details of the pressure booster 2d it will be seen that it comprises essentially a cylinder 25 and a piston 26 slidably mounted therein. Assuming that all valves in the entire circulatory system (Figure 1) areclosed and that a charge of liquid refrigerant under the pressure of its own vapor has been placed in the" tanlr Hl, a small amount of such liquid will pass from the tank it through the conduit 35 and the check valve 38 into the chamber. Where it will expandand evaporate. Valve 3.3. serves to permit flow only from the tank to the expansion chamber. This vapor then passes through the conduit 39 into the cylinder 25 and forces the. piston 26' toits extreme right-hand position shown in Figure 1. The piston '26 in moving. to:- its extreme right-hand position forces the plug 32 to the right opening the valve 2.9 and, Whenshutwff valve 46. andpressure-control valve 47- have been. opened, admits, through conduits 27:. and 25v and. valve 29 tov the right-hand side of they iston 26, inert gas from cylinder 23 under pressure predetermined by regulating valve 41. This gas, when the pressure of refrigerant vapor in. tank l0. and in cylinder 25 has become less than that of the inert gas from 23. against the right side ofsaid piston, will force the piston to the left and in so doing will compress said vapor through the conduit 53 and check valve ll (see Figure 1) into the upper portion of tank It] above the liquid. Valve ll serves to permit flow only from the cylinder '2 5 to the tank it. Every time, therefore, that the piston 2c is moved from right to left under the influence of the inert gas from the cylinder 2.3, it compresses a volume of refrigerant vapor and returns it to the upper portion' of the tank: It. Thiscompressed refrigerant vapor, expanding in the tank it to a volume greatly exceeding that of the liquid which had flowed from said tank through conduit 36, augm nts the vapor pressure in tank It suficiently to-force liquid therefrom, via conduit i i, throughout the system.

When the piston 26 reaches its most leftward position, shown in dotted line in Figure l, the guide. rod 43- (Figure' 2) is withdrawn sufiiciently far from its cylinder 3% to enable the inert gas to; enter thev space 3| by way of cylinder 3 2- and passageway 35. While guide rod 13 has been withdrawn from its cylinder. 34, guide rod t l, which is slightlylonger than guide rod 43', is still partly within itscylinder. This serves to'prevent rotation of: the piston 25, thus assuring that guide rod. 4 3: will re-enterits'cylindcr 34 when the piston 25 isreturnedtoitsright-hand position. Zhe pressure of the inert gas in the space 31 exerts a forcecagainst the plug" 32 forcing it to the left. This results iirclosing valve 29 and opening valve 42; The latter valve. permits the inert gas to escapetotheatmosphere under'the control of an adjustable pressure relief valve it. On the next rightwardstroke therefore of piston the piston may return to its extreme right-hand position shown in Figure l, again.simultaneously opening.

valve 29 and closing. valve 42 (Figure 2:). Ad.-

5. and/or the flow control valve 49 will serve to regulate the speed of the pressure booster device.

In order to provide a path of escape for the inert gas on the right side of the piston 28 as the latter is moved from left to right by the force of expanding refrigerant gas from chamber 31. a number of passageways are drilled or otherwise formed in the body of the pressure booster device. The first of these, bearing reference number 5!, extends from the space to the right of piston 26 in a direction parallel to the axis of the piston. A second passageway 52 connects 5! to the passageway 53 which leads to valve 49. As the piston 26 is forced from left to right therefore, the inert gas will enter passageway 5|, as indicated by the arrows in Figure 2. and thence through 52 and 53 to valve 49 which controls its release to the atmosphere.

The foregoing description of the operation assumes that initially all valves are closed and that the piston 26 is in its left-hand (dotted line) position (Figure l), but such situation is not es-' sential. If said piston stand initially in its righthand position, valve 253 will be open and valves c6 and t? may be opened initially to admit gas under pressure from cylinder 23 through valve 29 and cause the piston 26 to move leftward, increasing the pressure in tank If! with the same effect as described above at page 7, lines 14 et seq. It is contemplated that use of the inert gas from cylinder is will be sufiiciently infrequent that such cylinders readily may be replaced before they become completely exhausted, from supplies maintained either at suitable intervals or spare cylinders carried on or within the vehicle.

, ther features of the system shown in the attached drawings are a dual purpose valve 45 connected to the interior of tank If]; and the pressure regulating valve 41 provided with a gauge 43. Before the system is filled with refrigerant, a pump is first attached to the valve 45 to withdraw air from the system. Then a refrigerant suppl container is attached to valve 45 and the system is thereby charged with an adequate supply of refrigerant. A cap may also be provided to cover the inlet to valve 45 at all other times. In addition to the filling valve 45, a safety valve 56 is also provided which serves to vent the tank it in the event of pressure rise therein beyond a predetermined level.

Refrigeration is accomplished by opening valve 54- and expansion valve 22 to allow part of the liquid refrigerant to flow from conduit ll through the evaporator as more fully stated above at page lines 12 et seq. By adjusting expansion valve 22 this system is adaptable to produce any of the wide range of temperatures from those below zero Fahrenheit required for frozen foods to those above freezing for fresh fruits, bananas, vegetables, and berries. Adjustingthe pressure regulating valve 47 or the flowcontrol valve 69. either or both of which will affeet the speed of the pressure booster 24, will adapt the system to meet any of the varying refrigeration loads occasioned by climate or by the varying temperatures of lading placed in the space to be cooled.

From the above it will be seen that the energy required to be supplied to this system via the pressure booster 2d driven by the high pressure gas from cylinder 23 will be much less than that which would be required in a system wherefrom the heat absorbed from the lading space is thrown away. The consumption of energy and Lil) 6 need for its replenishing are at a minimum; operation does not depend upon electricity or electrical connections being available nor require any supply of running water; the apparatus is unusually compact and simple, having few working parts; and there is no fire hazard present as would be the case in one or another of the conventional refrigeration systems known and in use today. Hence, the system is admirably suited for use in transportation conditions.

It should be further noted that operation of the pressure booster 24 is entirely automatic and the pressure in the system is maintained at a predetermined operation level by boosting the pressure in tank 10.

In practice it is preferable that all the apparatus of the system, save the evaporator, will be positioned below the floor of the car for which the apparatus is to be used. This saving in lading space, plus the lowering of the center of gravity of the car, are marked advantages.

It will be apparent that the apparatus of this invention will find widespread use wherever low temperature refrigeration with a minimum en ergy input is required.

The drawings serve to illustrate only a preferred embodiment of this invention and obvious variations within the scope of the appended claims will be apparent to those skilled in the art.

I claim:

1. A refrigeration system comprising in com bination: a pressure storage tank for refrigerant having space in the lower portion thereof for liquid refrigerant and space thereabove for gaseous refrigerant; means for automatically maintaining a predetermined pressure within said tank said means including a high pressure gas cylinder, a pressure regulating valve connected to the outlet of said cylinder, and a pump the cylinder of which is connected to said valve and to the said tank; an ejector of the jet pump type; a first conduit means connected to carry liquid refrigerant from the lower portion of said tank to the high pressure inlet of said ejector; an evaporator connected at its inlet end to the said first conduit means by means including a valve, and at the outlet end to the suction inlet of said ejector; and means including an elongated conduit for connecting the outlet of said ejector to the upper portion of said storage tank.

2. A refrigeration system comprising in combination: a pressure storage tank for refrigerant having space in the lower portion thereof for liquid refrigerant and space thereabove for gaseous refrigerant; means for automatically maintaining a predetermined pressure within said tank said means including a source of high pressure gas; a pump witha cylinder having a free piston slideably mounted therein, a refrigerant expansion chamber, means including a check valve connecting the lower portion of the refrigerant storage tank to said chamber permitting flow only from the tank to the chamber, conduit means connecting said chamber to said cylinder on one side of said piston, means including a conduit and a check valve connecting the same side of said piston to the upper portion of said storage tank permitting fiow only from said cylinder to said tank, means connecting said source of high pressure gas to said cylinder on the other side of said piston, said means including a valve within said cylinder, means carried by said piston for opening said last mentioned valve when said piston is forced to one end of the cylinder by expanded refrigerant from said chamber, and

meansfor closing said last mentioned valve when said piston is forced to the opposite end of said cylinder by expanding gas from said source; an ejector of the jet pump type; a first conduit means connected; to carry liquid refrigerant fromwhich a refrigerant evaporator is supplied with liquid refrigerant from a refrigerant storage tank, means for maintaining pressure on the sys-- tem comprising: a source of high pressure inert gas; a pump with cylinder having a piston slidably mounted therein; a refrigerant expansion chamber; means including a. check valve con necting the lower portion of the refrigerant storage tank to said chamber permitting flow only from the tank to the chamber; conduit means connecting said chamber to said cylinder on one 8 side of said: piston; and a check valve connecting the. same side of said piston to the upper portion of said storage tank permitting flow only from said cylinder to said tank; means connecting said source of high pressure inert. gas to said cylinder on the other side of said piston, said means including a valve within said cylinder; means carried by said piston for opening saidlast mentioned valve when said piston is forced to one end of the cylinder by expanded refrigerant from said chamber; and means for closing said valve when said piston is forced to the opposite end of said cylinder by expanding inert gas from said source.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,0 %,811 Randel June 23, 1936 2,088,609 Randel Aug. 8, 1937 FOREIGN PATENTS Number Country Date 930352 France a- Aug. 4, 1947 means including aconduit