US2252979A - Refrigeration apparatus - Google Patents

Description

Aim- 19,1941.. M REITER mp- REFRIGERATION APPARATUS Filed Oct; 21, 1937 4 Sheets-Sheet '1 2 a mi m wa 4 zmww Rum mmt

Aug. 19, 1941.

A, L. REITE El'AL REFRIGERATION APPARATUS Filed Oct. 21, 1937 4 SheetsShee t 3 I A g-19 1941. A. I. REWER Em 2252919 REFRIGERATIQN APPARATUS Filed Oct. 21, 1937 45Hegts-Sheet 4 'az mard firm OGJM? z z fi s Patented Aug. 19,1941- UNITED STATES PATENT, OFFICE 1 nnrarcnnA'rroN ArrAnA'rUs Alexander L-. Reiter and Leonard P. Traxel, Chi- I cago, Ill., assignors to Mills Novelty Company, Chicago, 111., a corporation of Illinois Application October 21, 193i, Serial No. 170,136

13 Claims.-

f This invention relates to refrigerating systems 7 I and more particularly to that type or refrigerating system which must be adaptable to handle widely varying heat loads, such as, for example, a refrigerating system used in connection with a merchandise-vending machine which is allowed'to stand for long-periods of time while its contained articles of merchandise are gradually dispensed one by one, and then, when nearly empty, is refilled with uncooled articles, imposing a sudden load upon it that is much higher than its normal load after the articles have been cooled to the normal operating temperature of I evaporator for normal-demand operation and a secondary evaporator for peak-load operation. It has been proposed to meet fluctuating demand by arranging two evaporators in series with each other, such arrangement avoiding certain diniculties which arise where-attempt is made to em-v ploy two evaporators in parallel. But a series I arrangement of evaporators is found to be unsuitable for the eflicient handling of loads vary ing as widely as in a refrigerated vending machine. The present invention proposes, therefore, to utilize a parallel arrangement of evaporators.

" .The diflicultiesattendant upon the employment of a parallel relationship are solved in the present invention, and the other objects hereinbefore stated are in general attained by arranging for only one of the evaporators to'be operative at any given time. Accordingly. means are provided for shutting oil one evaporator when the other is in circuit with the compressor, and

vice versa. It will be understood in this connection, of course, that a basic requirement is that the refrigerating demand is comparatively small,

being only that required to compensate for loss of heat from the machine. There will be no frequent opening and closing of the door to the merchandise compartment as in the case of i a domestic or butchers refrigerator, and accordingly, the heat loss in the interim between peak loads will be much less than in the ordinary refrigerator. .The presentinvention aims, there- !ore, to provide a refrigerating system partica single compressor, common to both refrigerating circuits, be employed.

Another important feature in attaining the desired ends is the provision of a hold-over medium (a liquid adapted to congeal during a period of normal demand and to utilize its'latent heat-absorbing capacity during peak-load operation) The hold-over medium is associated with the primary evaporator which handles the normal-demand operation, and cooperates with the V secondary evaporator during peak-load opera- 3 ularly adaptedto-meet a condition wherein the r ratio between peak load and normal demand is unusually high. Since a system large enough to handle a peak load is'ineflicient in the handling of a normal load, it is important. that provision be made. for varying the refrigerating capacity of the system in accordance with the tion. The secondary coil is constructed and arranged so as to have a high heat-transfer capacity per se, so that the combined refrigerating capacity of the hold-over medium and the secondary evaporator is very high.

Another object of the invention is to provide an arrangement in which defrosting will be ,ef-

, fected without shuttingdownthe machine, and

demand; and the present invention provides mechanism designed to achieve such variation in capacity over wide fluctuations of demand.

- Another object of the invention is to provide v an arrangement in which .the refrigerating capacity may be'boosted .to a maximum immediately when the peak demand arises,.and in which the refrigerating effect is quickly lowered to normal when the peak'load has been removed.

These objects .are accomplished, in general,

without raising the temperature within the machine abovethe temperature limits of normal operation.

In conventional refrigerating systems, it is customary to effect defrosting by permitting a temperature rise above the normal temperature limits of the refrigeratedspace. The present invention accomplishes defrosting without exceed- 7 ing the normal limits of the machine, first by a by the provision of two independehtly-functionin: refrigerating elgrnents, including a'primary V I adopting a temperature range just above the freezing point of water (both maximum and minimum limits being above -32" Fahrenheit), by. employing water as thehold-over medium,

one evaporator at a time is in operation. The invention in this respect embodies the discovery that the hold-over casing w'ill,'when the primary evaporator is out out, assume an exterior tern perature thatis sufllciently higher than that of the ice it contains (which, of course, will atv a maximum, be 32 Fahrenheit) so that the frost on its exterior surface will melt; T'his-temperature, while ice remains in thehold-over casing,

' will approximate 33 Fahrenheit.

The invention further accomplishes the change-over from'one evaporator to the other,

without the'use of a two-way valve.

The last two mentioned objects are accomplished by employing a resistance valve in the lineleading to the auxiliary evaporator, which valve normally shunts the refrigerant fiowthrough the primary evaporator, and employing a control valve for cutting off the flow to thelatter, whereby theflow will be forced to travel through the auxiliary evaporator. The resistance valve also serves to reduce the operating pressure in the auxiliary evaporator below that in the primary evaporator, so that the operating temperature of the auxiliary evaporator may be lower than that.

of the primary evaporator.

, Another object of the invention is to provide means for maintaining a constant supply of water in the hold-over casing, without employingan external source of supply. To this end, the condensate from the auxiliary evaporator, and-the water produced by the defrosting of said evaporator, is led into the hold-over casing. 'We find that this provides an adequate supply so that the hold-over casing is automatically kept full, without attention on the part of the operator.

'tion between these areas.

and by the aforesaid arrangement whereby only vention comprises acabinet including a front wall wall l2, side walls II.

l0, a'rearxwall -l I, a bottom and a top H- in which the refrigerant compressing and air-circulating mechanism is contained.)

return passage IS, a refrigerating element assembly, designated generally at ILservlng as a parti ment assembly v metal or the like, extending the fullwidth of the space between the side walls of the cabinet, a wall l9 upwardly bentv from the lower end extends to the front wall ll) of the cabinet 'and.

from one to the other vofthe side walls i3; At-

'tachedj to the wall 23 and communicating with. anopeningu therein,'is ablowercasingjl in which is rotatably mounted a blower-impeller 2.

The blower 25, 26' pulls air from the horizontal A further object is to provide a novel refrig crating element comprising a flat coil and a narrow casing or' tank in which the coil is embedded in a hold-over liquid contained therein, the arrangement being such that the casing will be unaffected by freezing of its contained water, and maximum emciency of heat transfer'will be bad. This object may be accomplished-by employinga casing that has side walls diverging upwardly. embedding-the lower bends of the coil in a substance that is solid at all temperatures to which the coil may be subjected, and soldering the reaches of the coil to one side of the casing, or by applying the coil tothe exterior of the sidewall, or by extending the return bends 'beyond the bottom of the casing.

Other objects and advantages of the invention will become apparent from the following detailed description, which, taken in connection with the bodiment thereof;

Referring to the drawings: 4 Figure 1 is a diagrammatical view of a refrigerator embodying the invention;

Figure 2 is a partial vertical, sectional view through such refrigerator;

Figure 3 is a'detailed sectional view of the primary'heat transfer unit; v

Figure 4 is a detailed sectional view of a portionofthesame; a

Figure 51s a detailed s'ectional'vlew of a portion of a modification of the heat transfer unit:

Figure 6 is a detailed sectional view of the control valve; ahd

Figure '1 is a a modification of the invention.

Referring first to Figure 2, a

" accompanying drawings, discloses a preferred emview similar to Figure 1, showing bottle-dispensing' machine constructed in accordance with the inspace 21 extending laterally, from the-upper end of return passage l6, and'formed between the top H, the wall 23, andthe side walls I, and blows it through the opening 24 into the merchandise storage andvending compartment II. From the compartment l5, the air travels through a space 28 between the lower 'end'of-the casing!" and the bottom wall l2, into the return passage Ii.

As the air passes through the compartment ll,

' it will absorb heat fromthe bottles 20 carried therein by the endless carrier 30. The conveyor and dispensingmechanism arepreferabiy as;

shown in United States PatcntNo. 2,189,740, is-

sued February 6, 1940. As it travels downward ly,-the air will give up some'of this heatto the; wall 18, and as it passes upwardly through return passageli" it will be further cooled by the wall I9.

e The element at a weldedor soldered directly to the wall It so that heat will be readily conducted through the wall H to said element II. The casing 20; which, in effect, forms a verythln, dee'p' tank. is filled with water il which acts as a hold:

over liquid and which also serves to conduct heat from'the wall it to the evaporator II during nor-' mal operation. A

The compressor 32 is shown diagrammatically in Figure 1. From its high side; the compressed refrigerant is conveyed through the conventional condenser coil 33 into a receiver 34 from which it passes through the feed tube" to an expansion valve '38 and thence to a Tuni'on 31. From the 1' union 31, tubes 30 and 39 lead to the evaporator-s 2| and 22, respectively. Froni the evaporators 2| and 1!, tubes 40 and, respectively, lead to a T union 2, from which a return-or vapor tube 44 leadsback to the compressor. 1 4

'It-will 'thusbe seen that rater circuits are provided, a circuit inchidingthe compressing and. condensing mechanism I2; 33, 84, the tube llthe expansion valve 38., the line ".the primary evaporator II, the tube, andthe return tube ll leading back to the compressor, and the other circuit-comprising the compressing and condensing mechanism II,

as, u, the tube 35, theexpanslon valve ".thci

This enclosure is divided into amerchandise' storage" and dispensing chamber II and anair The refrigerating ele-' llv includes a wall IQ of sheet 2 of the wall l8 on the rear side thereof and forming; and evaporating" two parallelevapotube 35, thesecondary evaporator 2 4i, and the return tube 44,

1 rator 2|.

the casing 20 from the circulating air. .theairV-has beencooled to a temperature at -75 A resistance valve 451s interposed inthe tube 39 leading to the secondary evaporator 22. This cient to maintain it closed against the pressure normally existing in the system when the primary circuit is open; c

A control valve 451s insertedin the line 40 in.

2,252,979 2, the tube f valve offers a'resistanc'e to opening which is sufli- 5 which it can no longer give up sufilcient heat to the hold-over casing 25 to keep thehold-over water 3i at -;a temperature above freezing, the latter will commence to' congeal. When fully frozen, it will under normal conditions allow the temperature of the circulating air to drop to the lower limit of the operating range, whereupon the switch will again open, shutting oh the comthe primary circuit and functions, when opened, 10

to circulate through the evaporator 2| for normaloperation. The operator may manually close the valve' 45 when he refills the machine. The closing of the valve cuts oil communication bei tween the lines '40 and 44, thus shutting off the primary circuit, and causing the secondary circuit to open. I The compressor, overcoming. the resistance of valve 43, will then scnd the refriger .ant through the evaporator 22 instead of the evaporator 2 l ,and the refrigerant in the primary evaporatorv will ball 01! through. the valve .43 into the secondary evaporator. The water 3| in' the hold-over casing,.which has been frozen to ice by the preceding extended period'of normal op-;25

eratiom will thence commence to absorb the heat load which has been imposed upon the machine by the fresh charge of bottles. The air will, after having been preliminarily'cooled by. the holdover casinggpass over the secondary refrigerat- '3 ing element which comprises an open coil of -many turns, and will be further cooled thereby.

As the peak load is gradually absorbed, the ice in the hold-over casing will melt and utilize its latent heat-absorbing capacity.-

-. Before the ice has completely melted, the tem perature within the enclosure will, under normal conditions, be reduced to 33 Fahrenheit, which is the-lower limit of the'operating range of the to open the primary circuit and allow refrigerant 'pressor. Should this happen, a subsequent raise to the upper limit of the operating range, will have no eflect on the control valve 45 since the latter will .be already open, but will simply cause the compressor to again go into operation.

machine. At this temperature, the compressor will be shut on by the opening of compressor control switch III, which in turn is controlled through s a tube H, by a thermostatic bulb 12 located in the dispensing compartment [5 near the bottle-delivery opening 15 in the front wall ill of the machine (the warmest region of the machine during the idling period 01 the refrigerating nie'chanism) t k After the compressor has ceased operating, the

temperature in the machine .will again begin'to 50 rise, until "it approaches the upper limit of the operating'range, which preferably is in the neighborhood of 38. Before it reaches this limit,

however, the pressure in the refrigerant circulating system will have increased to such an extent that the control valve, which is constructed to react to such pressure increase, as will hereinafter be more fully set forth.if"it is not locked in closed position, will open, so as to open the The control valve (Figure:li).=comprises a casing 46 in which is housed a bellows 41 positioned above a hollow cylindrical neck portion 45 ber- 55 onthe end of the plunger 54 having upper and lower conical surfaces 55a and55b, respectively, engagesbetween rollers 55' mounted on spring arms 51 attached to the .skirt 53. The head 55 of the bellows." is rigidly attached to the plunger 54, and a coil spring 59, engaged between the cap ofthe casing 45 and the head 58, urges the plunger in a downward direction when the valve is positioned as in Fig. 6. The plunger 54 hasa button 54* on the outer end thereof adapted to be engaged by a hinged wire 54, the ends ofwhich, indicated by the reference numerals 54, are turned inwardly and pass through openings ,(not shown) in the casing 45,

to provide a hinged connection therewith. A

transverse outer portion 54 has a crimp 54 therein, adapted to enter a depression (not shown) in the button 54 to hold said parts in interlockedrelation for'suchperiod as it may be desired to lock the valve 52 in closed position.

By pushing in the plunger 54, the valve ele- 'ment 52 iscaused'to seat against the valve seat 5| as a result ofthe rollers 55 riding against the- [upper conical surface 55a. The spring arms .51 urge the rollers 55 toward-each other, and in seeking to' embrace the narrowest portion of the head 55, the'rollers 56 will, when riding against the upper conical surface 55a. lift the valve relative to the plunger, while when riding against thelower conical surface 5'5b,.the rollers 55 will I cause the valve to move downwardly relative to the plunger. .Pushing in the plunger 54 when the valveis open causes the head 55 to force its way primary circuit and allow the secondary circuit 9 to close. i I

The system will then ber'eady foranother 'cycleof normal operation, and when the upper temperature limit is reached, the thermostatic 6 switch III will close and complete the electric circuit 14 which supplies power; to the compressor motor 15, and the compressor will commence to circulate the refrigerant through the evapo- 7 The primary evaporator will then again begin toabstract heat from the hold-over water a,

and the latter will in tum abstract heat through when o cluced when the door of the machine is open for 1 between the rollers until the latter have passed the major diameter of the head 55 whereupon the rollers will react withtheupper conical surface to move the valve upwardly relative tothe plunger. a a

As above indicated, the valve may be heldclosed for so long as desired by means orthe locking wire 54", the purpose of so locking it in closed position being ordinarily to provide for removal of any excessive frost ,in and about the primary evaporator 2i, in case the heat introrenlling is not sufllcientior eifecting satisfactory defrosting. Normally the wire 54 is allowed to vhang at the side of. the casing 45, and is primarily for the purpose of iacilitating defrosting fin the manner above described, although it ob I machine is open, and when the. conditions are such that it is no longer desired to lock the valve closed, said wire ,may be removed from engagement with the button 54, leaving the valve free to be opened by the bellows 47." y

The pressure in the system is communicatedto the bellows 41 through the cylinder t8 (the skirt 53 allowing the gas to pass)... When thecritical temperature is reached, the pressure, will have overcome the resistance of the spring 59-to such an'extent that the plunger 55 will have arrived at a position in which the major diameter of the head 55 will have passed between the rollers in an upward direction whereupon the rollers 56 will ride downwardly against the surface to move the valve element 52 away from the seat 5|, thus opening the control valve Q5 and causing the resistance valve 43 to close.

The control valve dis is designed for manual operation so that the operator may immediately close the valve when he opens the machine. However, the'invention also contemplates fully automatic operation in which, as shown in Figure 7, the valve 35 is closed thermostatically "by a thermostatic control element It locatedin the upper region of the storage and dispensing compartment and adapted to exert through the line 11 sufiicient pressure against the top of the bellows M so as to overcome the pressure Within the bellows, when a peaklo'ad is imposed upon the system, to such anextent as to cause the valve to close. It will be understood that for this purpose a pressure sensitive element might beplaced adjacent the top of the bellows in place of the plunger 54 and in communication with a temperature-controlled pressure medium contained in the line H.

One manner in which this may be accomplished I loading of the machine by arranging the mechanism so that the temperature above the warm is to allow an interval of time to occur between thecutting in of the compressor and the changeover from the primary to the secondary evaporator. Normally the pressure at which the belapproximately 20 pounds. With the temperature in the enclosure at 33, and the evaporating coils having remained inactive over a period of time normally necessary for the temperatureto have raised from 33 to 38, the temperature within the evaporators will be sufflciently high so as to produce in the neighborhood of 20 to 22 pounds pressure therein.

However, after the compressor has been cut in, the temperature within the evaporators will rapidly drop so as to pull down the pressure to the normal operating pressure of about 9 pounds,

while the temperature within the enclosure still remains in the neighborhood of 38 or more under the fresh charge of warm bottles. The control lows 41 will cause the control valve to close, is

element 16,'located preferably in the region most heated by the warm bottles (in the upper region normal operating pressure .of 9 pounds.

The operationof the automatic control may be made practically simultaneous with the rebottles may reach 40 to 42 (2 to 4 above the temperature at which the compressor cuts in) whereby the thermostat 16 may overcome the pressure within the bellows 41 while the latter still remains in. the vicinity of the 20 pounds at" which the valve opens. In any event, the operation of the valve in both directions is assured by the fact that the valve opens during a period when the compressor is not in operation and when it is possible for the temperature within the evaporators to approach that of the air in the enclosure, whereas the valve is closed at a time when the compressor is operating, causing the temperature within the evaporators to be pulled down so as to remove the high pressure from within the bellows.

, One of the requirements in a machine of this kind is that the bottles be kept dry. This is accomplished by locating the refrigerating unit in the return passageway l6 and allowing the condensate which collects on the hold-over. casing to drip from the lower edge thereof directly onto the bottom ill from which it may be collected by suitable collecting means. The condensate from the secondary evaporator 22 is usefully embottom of the casing with a solid material which I will hold its position, such as wax or some type of cement. This filling material is indicated in Figure 1 at 61; It covers the lower bends 68 of the evaporator coil 2i so as to avoid the occurrence of the conditionillustrated in' Figure 4.

Where the water fills the casing to thebottonf thereof, thegra'dual building up of ice layers along the bends of the coil 2| will ultimately result in the imprisonment of a wedge-shaped region of water 69. The subsequent freezing of this region 69 will cause a tank to bulge and ultimately to burst.

The filling in ofv the bottom of the tank above the level of the bends 68, causes the ice to form only in vertical layers, so that there is no opportunity for water pockets to form. The same result can be achieved by extending the tubes 2! through the bottom of the tank 20, as shown in Fig. 7; or by attaching the reache of. the coil to the outside of said tank, as shown in Fig. 5. An added advantage is possible in this arrangement; namely, the use of an extended heat transfer surface 18, which serves to carry heat to the hold-over medium much more rapidly than is possible through the medium of just the walls of the hold-over casing.

While it is necessary for the pressure in the line 35 to raise slightly above the normal operating pressure in the primary circuit in order to open the valve 43, the pressure drop through the valve 43 is sufficient so that the refrigerant will circulate through the secondary circuit at a pressure considerably less than that in the primary circuit. Thus the secondary refrigerating elementoperates at a lower temperature than the primary refrigerating element, and air coming off the primary element, even though cooled to the temperature of the primary element, will be further cooled by passing over the secondary element.

While the thermostat I6 is set to cut out the compressor at 33, the temperature of the refrigerating units will drop below this level, which is determined in the warmest region-i. e., near the discharge opening. Accordingly, the refrigstatic type, controlled by a thermostatic bulb 80,, acting through a tube 8|, as shown in Figure 7.

The bulb 80 will be arranged to react to mean temperatures of the two evaporators 2| and 22, being connected in thermal contact therewith by a clip 82.

In the modification shown in Figure 7, a check valve 84 is incorporated in the intake tube 38 of theprimary evaporator 2|. The purpose of'this valve is to prevent the escape of refrigerant from the primary evaporator when the latter is cutoff by the control valve 45 and the secondary evapo rator 22 is in operation. By completely closing off both the inlet and the outlet of the evaporator 2|, and thus maintaining the latter full of refrigerant, the efliciency of the evaporator in transferring heat from the extended surface 18 into the hold-over 3|, is materially increased. The refrigerant in the lower regions of the evaporator, vaporizing under the effect of the heat being absorbed through the extended surface 18, will rise into the upper regions of the evaporator,

where it will be condensed by the loss of heat into the hold-over and, becoming aliquid,will move downwardly to displace the vaporized refrigerant rising from the lower regions. The tendency of the refrigerant to completely vaporize as the tem-- perature in the hold-over raises above the boiling point of the refrigerant under normal pressures, will be retarded by the increase in pressure developed in the evaporator by the imprisoned vapor so that a certain amount of circulation of the refrigerant' will continue to take place even as the temperature of the hold-over. melting point. v e

In the showing of the modified form in Figure 7, the compressor and itsassociated members are illustrated only roughlyby the rectangle 32a.

The upper evaporator 22 preferably incorporates an extended heat transfer surface 83, as indicated in both Figures 1 and 7. v

The foregoing detailedv description has been given forclearness of illustration only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

We claim as our invention:

approaches the A built up by the closing of the primary circuit and to thereupon open said secondary circuit; and a hold-over medium in heat transfer association with said primary evaporator including a liquid adapted to congeal when said primary evaporator is in operation and to cooperate with the secondary evaporator in handling peak loads when said primary evaporator is not operating.

' 2. In a refrigerating system, an enclosure to be refrigerated; a compressor; a primary refrigerant circuit, including said compressor, a primary evaporator, and a control valve for opening and closing said circuit; a secondarrcircuit, including said compressor, a secondary evaporator and a resistance valve adapted to close said secondary circuit when said primary circuit is'open and to open under pressure built up by the closing of the primary circuit and to thereupon open said sec ondarycircuit; and means responsive to pressure built up in the system as a result of vaporization during a' period of inactivity of said compressor for causing said control valve to open so as to open said primary circuit.

3. In arefrigerating system, an enclosure to be refrigerated: a compressor; a primary refrigerant circuit, including said compressor, a primaryevaporator, and a control valve for opening and closing said circuit; a secondary circuit, including said compressor, a secondary evaporator and aresistance valve adapted to close said secondary circuit when said primary circuit is open and to open under pressure built up by the closing of the primary circuit and to thereupon open said secondary circuit; thermostatic means responsive to temperatures in the enclosure for starting and stopping said compressor, and means responsive to pressure built up in the system after a period of inactivity of said compressor for causing said control valve to circuit.

4. In a refrigerating system, a compressor, primary and secondary refrigerant circuits, each including said compressor and an evaporator, said circuits being in parallel with each other, means for controlling said circuits so that one and only one thereof will be open at any given time, thermostatic means responsive to temperatures in the enclosure for starting and stopping said compressor, and means responsive to predetermined pressure built up in the system after a period of mary and secondary refrigerant circuits, each in- 1. In a refrigerating system, an enclosure tobe refrigerated, a compressor; a primary -rei'rigerant circuit, including saidcompressor, a

primary evaporator, and a control valve for opening'and closing said circuit; a secondary circuit,

. including 'said compressor, a secondary evaporator and a resistance valve adapted to close said secondary circuit when said primary circuit is cluding said compressor and anevaporaton-said circuits being in parallel with each other, means for controlling said circuits so that one and only one thereof will be open at any given time, thermostatic means responsive to temperatures in the enclosure for starting. and stopping said compressor, means responsive to pressure built up in the system after a period of inactivity of said compressorl for causing said circuit controlling means to open the primary circuit and close the secondary circuit, and thermostatic means for closing said control valve at the beginning of a period of peak-load operation.

means for controlling .said circuits ,so that one and only one thereof will be open at any given open and to open under predetermined pressure open so as to open said primary .dling peak loads when said time, thermostatic meansresponsive to temperatures in the enclosure for starting and stopping said compressor, means responsive to pressure built up in the system after a period of inactivity i of said compressor for causing said circuit controllingmetins toopen the primary circuit and a close the secondary circuit, and manually operable means for closing said control valve at the beginning of a period of peak-load operation.

' '7. In-a refrigerating system, an enclosure to be refrigerated; a compressor; a primary refrigerant circuit, including said compressor, a primary evaporator, and a control valve for opening and closing said circuit; a secondarycircuit, including said compressor, a secondary evaporator and a resistance valve adapted to close said secmaximum and minimum limits for respectively starting and stopping said compressor; and means responsive to pressure inthe system at a temperature intermediate said limits, for causing said control valve to open so as to open said primary circuit.

10. In a refrigerating system, an enclosure, to be refrigerated; a compressor, a primary refrigerant circuit, including said compressor, a primary evaporator, and acontrol valve for opening and closing said circuit; a secondary circuit, including said compremor, a secondary evaporator and a resistance valve adapted to close said secondary circuit when said primary circuit is open and to open under pressure built up by the closing oi the primary circuit and to thereupon open o'ndary circuit when said primary circuit is open and to open under pressure built up by closing of the primary circuit and to thereupon open said secondary circuit, said control valve being adapted to reopen under pressure built up in the primary circuit by theraising of the temperature therein above a predetermined'limit; and a holdover medium in heat transfer association with evaporator, and 'a control valve for opening and,

closing said circuit; a secondary circuit, including said compressor, a secondary evaporator and said secondary circuit; thermostatic means responsive to temperatures in the enclosure at maximum and minimum limits for respectively starting and stopping said compressor; means responsive to pressure in the system at a temperature intermediate said limits forcausing said control valve to open so as to open said primary circuit; and thermostatic means for causing said control valve to close when a peak load is imposed'upon the system.

11. In a refrigerating apparatus for a bottle vending. machine, a cabinet having an interior a resistance valve adapted to close said secondary circuit when said primary circuit is open'and to open under pressure built up by the closing of the primary circuit and to thereupon open said secondary circuit; thermostatic means responsive to temperatures in the enclosure at maximum and minimumlimits for respectively starting and stopping'said compressor; means responsive to pressure built up in the system as a result of the raising of the temperature in the enclosure to a level beneath the maximum limit for causing said control valve to open so as to open said primary circuit; and a hold-over medium in heat transfer association'with said primary evaporator adapted to congeal when said primary evaporator is in operation and to cooperate with the secondary evaporator in handling peak. loads hen said primary evaporator is inoperative.

9. In a refrigerating system, an enclosure to be refrigerated; a compressor; a primary refrigerant circuit, including said compressor, a primary evaporator, and a control valve for opening and closing said circuit; a secondary circuit, including said compressor, a secondary evaporator and a resistance valve adapted to close said secondary circuit when said primary circuit is open and to openunder pressure built up by the space forming a bottle storage compartment and a return air passage,-each extending from top to bottom of said space, a refrigerating element forming the dividing wall between said passage and compartment, and air circulating means disposed inthe cabinet above said spacefor causing air to travel downwardly through said bottle compartment to be initially cooled by contact witln said refrigerating element during said downward travel, to thence pass upwardly through said passage, to be finally cooled therein,

,and to then return tosaidbottle storage compartment, said element extending from side to side and to the top of said space and being spaced from the bottom of the cabinet to form an opening through which air may pass from said compartment into said passage, but arranged so as .to discharge its collected condensate directly upon said bottom.

12. In a refrigeration system, a refrigerating evaporator comprising a coil of tubing having vertically disposed portions and return bends Joining the lower ends of said portions,'a tank .0! water in which said coil is immersed, said bends being near the bottom oi the tank, and

means excluding the water from the region of said bends.

13. In a refrigeration system, a pair of refrigcrating. evaporators, one abovethe other, a tank closing 0! the primary circuit and to thereupon open saidsecondary circuit; thermostatic means responsive to temperatures in the enclosure at of hold-over water inwhich the lower evaporator is immersed, and means for replenishing said water-comprising means for collecting condensate fiom the upper evaporator and draining the same into thelower evaporator.

.Eannnmm' LE NARDR'I'RAXEL.

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