US2512437A

US2512437A - Refrigerator car and method of refrigeration

Info

Publication number: US2512437A
Application number: US740117A
Authority: US
Inventors: Robert D Pike
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-04-08
Filing date: 1947-04-08
Publication date: 1950-06-20
Anticipated expiration: 1967-06-20

Description

June 20, 1950 Filed April 8, 1947 R. D. PIKE 2,512,437 REFRIGERATOR CAR AND METHOD OF REFRIGERATION 2 Sheets-Sheet 1 Fij-Z IN VEN TOR. ROBERT D. Pl/(E R. D. PIKE '2,512,437 REFRIGERATQR CAR AND METHOD oF REFRIGERATION `fune 20, 1950 2 Sheets-Sheet 2 Filed April 8, 1947 l l I .r l l l f 0f ////7//mW////////// L Patented June 20, 1950 UNITED STA-res .PATE-Nr omer.

. 2,512,437 REFRIGERATOR CAR .METHoD oF REFRIGERATroN y Robert D. Pike, Pittsburgh, Pa. Application April s, 1947,!serial 1510. v740,117

vide a railroad refrigerator car that can be,

charged with Dry Ice land water ice at one terminal and which will .be refrigerated for a Iconsiderable period solely by the l.sublimation of the Dry Ice land after the Dry Ice is sublimed, refrigeration will rbe accomplished by waterjice.

Another object of the invention is to provide a railroad refrigerator car in whichrefrigeration is accomplished by sublimation of Dry Ice., means being vprovided to .control the rate of sublimation whereby the temperature in the car can #be con- ,lo

trolled to maintain that desired. A still further object of the invention is to provide a method of refrigerating a car by which Dry Ice may be used and after this ice is suloli mated, water ice will be .available for further refrigeration. f

Other objects and advantages of the invention will be apparent from the following description of a preferred form of the invention, reference being made to the accompanying drawings, wherein: l

Fig. 1 is a `longitudinal section view of Ia railroad refrigerator car, the car Ibeing shown more or less diagrammat'ically, and certain elements of the temperature control system are omitted:

Figa 2 is a view in section taken on line 2 2 of Fig. 1;

Fig. 3 isa view in section taken on linea-3 ofFig.1;and

Fig. 4 isa schematic illustration ofthe temperature control mechanism lfor the railroad car.

.Referring to the drawings, I have shown an insulated railroad refrigerator car I0, suitable for the transportation of food. stuffs, for example, at desired refrigerating temperatures. The car includes a relatively large food storage compartment II, the walls of Which are well insulated in the usual manner. At opposite ends of the car, partitions .I2 are provided, which with the ends of the car. form vertically extending air cooling chambers I3 at each end of the car. The partitions l2 terminate short of the upper and lower walls of the car to form inlet and outf let openingsld and I5, for the' chambers I3 at the lower and upper portions of the .compartment Il, respectively. Preferably, a rack II is 7 claims. (o1. 's2-:915i

2 mounted six inches or so'above the bottom of the car and it forms aperforatedoorfor the compartment 'I I, soth'at'airmay-be withdrawn ffQm 'beneath the rack/l1; through. openings I4 and circulated 4upwardly through'the chambers I3 and back into the ycomparljaneni; through operiings i5, Fans 2li are provided adjacent the vinlets I4 for forcefullycirculating-th'e air as described, andth'ese an's may be driven frornthe carY axles when the car is'movi'ng and driven by electric motors when the 'car is statiIIa'Iy.

A Dry Ice'bunk-er 22 fisio-cated in the lower portion lof each of the chambers i3, and leach bunker includes a metallic bottom wall 2 '3 which projects outwardly from the lower Iedge of the partition |2 and parallel v4tothe Iilciofr of the car and approximately six inches abo-'ve the door. Preferably, the wall '23 `extends the entire width of the 'car and it terminates 4short 1'of the end wall fof the 'car't allow 'air to pass upwardlybetwee'n 4the fend wall of the 'car and an end wall ei the iounk'er;l The lwall 23 may 2be made of l0 gauge sheet steel and the Dry lice rests directly on 'this wall so that heat is transferred to the Dry Ice principally to "the bottom thereof 'through the wall. It will l'be noted that the air 'entering` the 'compartments will flow in ycor'itaetwith `the Wall 23, The end' wall 24 of the bunker-22 Iis formed "of insulating materiali-as arev the 'side walls T26 and top wall 21. Preferably, these wals are lined with sheet-metal; 'and a 'sheet `metal wall 28 is attached to the end Wall 24 and is integral with Wall 23 sof that -heat will be conducted 'to Wall 23, `through wall v28. It will be -noted that the walls -23 and 28, constitute walls of Fan air pas#- sage upwardly through the chambers `I3 and that heat will he transferred from' the air to these walls. The top lof lthe bunkers 22 slope downwardly from the .partition lf2, toward the near end of` the -car to provide for drainage 4of meltedwater ice, as will `melcroug-ht out as the description proceeds. Dry 4Ice is loadedinthe bunkers 22 through two doorways in each bunker formed in the partition I2. These doorways are normallyjclosed -bvinsulating doors 29, The lower portions of the partitions I2 forming the inner walls of the Alounkers 22 are preferably insulated.-` v Y Mounted abovethe bunkers *22W and extending transversely of each, of the `air PvSSagewaysgl'B -is a grill or rack 30, which is adapted to support water ice. The racks 3|.)r are perforatedso that air pa.sfsi1 i,g upwardly `thr'mh the chambers I3 will travel `upwardly;` through the ice supported on the rack. The top of the car is provided with .in the end walls of the car.

areisubstantially coextensive with therespective i.

be raised and lowered relative to the walls 231to.-

decrease and increase, respectively, the cross sectional area of the air passagewaysbetween 'the walls 23 and boards 35. The boards are movable toward and away from the walls 23 by pistons 3B, which reciprocate in pneumatic cylinders 31, mounted in the bottom of the car. Likewise, the eiTective cross sectional area of the air passage-. Ways in heat exchange relation with walls 28 .can be kvaried by insulation boards v38 that are moved toward and away from walls 28 by pistons 39 operating in pneumatic cylinders. 40 mounted Boards and 38 opposite heat exchange. walls. The cylinders 31 and 40 lare connected'in a common air thermostatically controlled air system tobegdescribed presently, so that the boards 35 and 38will be moved gradually toward and: awayl from their respective `heat transfer surfaces simultaneously in accordance with the temperature in compartment In some instances the boards 38 may `be omitted.

Referring nowto Fig. 4, the control systemy forthe cylinders 31 and v40 is shown schematically, and to simplify the explanation only one cylinder 31, is shown. `Air for actuating-the piston in the cylinder supplied from amain pressure tank which may-be supplied with air from ,any suitable source, such as ythe air line of the train. Air is fed tofthe upperend of cylinder 31 from the' tank 45 through pipes "41', 48 and 49, relayvalve and-pipe 5|. Air is fed to the lower yend of cylinder from tank 45 through pipes 41,

48, 48, relay valve53xand pipe 54; The upper and lower end ofA the cylinder 31 may be vented to the atmospherethrough relay'valves 56 and -51, respectively; which are connected to pipes l5| and 54, respectively. v.To move thewpiston up- Wardly for moving board 35 toward the wal123, the upper vpartxofA th'ecylinder 31 is vented throughvalve '5B-and air is fed tolower' end of the cylinder through valve 53. -The piston lis moved in the opposite direction by venting the lower end of the-cylinder and 'feeding air to the `fupper end through valve -50.` l The" relayi'valves`50,f 53,v 56 and 51 'inaybeof :any well known' 'type that are' now available "in "which "a" valve member -is'actuated by a'dialphragrmwhich diaphragm forms a exible wall n-of a'chamber that'is connected with a V'source'oi 'variable pressure.- Whenthe pressure on the dia- 'phragm'decreases' below -a' predetermined value, fthe valve opens to premit'passage of air' through 'the valve"casing and'when the'pressureon*'the diaphragm increases, the valve member isclosed. The operation of relay valves 50 and 51 is effected by connecting the diaphragm sides of these `valves with an auxiliary tank, through pipes -`6| and 62 respectively,v andrela-y'valves 53 and 5B are similarlyconnected with a second auxilfI iary tank 63 by pipes `64 and B5, respectively. Thus, the pressure in 'tank 60 oontrolsoperapipe 15 and port 11. rotated in the opposite direction from its normal 4 tion of valves 50 and 51 and the pressure in tank 03 controls operation of valves 53 and 56.

The tanks 60 and 03 are connected to the main air tank 45, by pipes 41, 48 and 61. Check valves 68 and 69 are placed in pipe 61 to prevent the flow of air from one tank to the other. Also, gate valves 'v -'v are located in pipe 48. The main tank thus normally maintains the auxiliary tanks undera predetermined head of air, v,such as 70 per square inch k-for example. Preferably, a check valve 10 is located in pipe 41 and this valve is set to deliver air at a relatively slow rate to the cylinders and tanks. The pressure in the auxiliary tanks may be reduced to cause operation of the relay valves in the proper sequence to control the pistons by a thermostatically controlled two Way valve, 1|. The valve includes a casing having a cylindrical chamber divided by a valve blade or gate 12, pivotally mounted in the chamber at 13. One side of the chamber is connected with tank 60 through pipe 15 and the other side of the valve chamber is connected with tank 03, by pipe 1E. Either side of the chamber may be vented to the atmospherethrough port v11. When the valvegate 12 is in its normal or intermediate position, as shown in full lines, port "11 is closed and pressure is 4maintained in both tanks E0 and 63. When valve gate 12 is rotated clockwise to the position shown in dotted lines A, port 11 is opened and tank 60 is vented through When the valve gate is position, las shown in dotted lines B, tank 63 is vented through pipe 16 and port 11. The valve gate is turned by an arm 18 connected thereto, which arm is normally retained in the position `vshown in full lines by two oppositely arranged tension springs and 8|. One end of the arm l18 is connected to an armature 82 of an electro- 'magnet 83 and the opposite end of the arm is connected to an armature'84 of second electromagnet 85.

`, The electromagnets are energized by a suitable source of current, such as a dry battery 81. 4The circuit for magnet 83 includes mainswitch 88, Wire 83, a thermostatic switch 90, wire 9|, limitswitch 92, wire 93, pressure switch 94, wire 95, to the magnet winding and

wires

The thermostatic switch may be any well known commercial type having a bimetal element |00 connected at one end to wire 83, and the opposite end carrying a contact |01. The contact |01 is moved by the bimetal to the left, to engagea xed contact |08 when the temperature of the 'bimetal increases above a predetermined value, and it is moved to the right against a fixed contact |09, when the temperature of the bimetal decreases below the predetermined value. The

'usual means not shown, may be provided for ad- 'justing the bimetal to cause engagement of the 'contacts at the temperatures desired. The contact |08 is connected to wire 9| and contact |09 'isconnected to wire |00, so that when the conftacts |01 and |08 are engaged the electromagnet 83 will be energized and when contacts |01 and `|00 are engaged the electromagnet 85 will be energized, providing the limit switches and pressure switches of the respective circuits are closed.

The limit switch 92 is normally closed and 1t :will ber opened by the board 35 when the board is moved to its position most remote from .wall 23. Limit switch |01 is normally closed and it will be .opened by the board 35 when the board is .against or close to the .wall 23. Thus, the .limit ,switches .will prevent yoperation of valve k1| when the-control boards 3.5 are at their extreme posiltions and the thermostat switch 90 continues to indicate control in the direction .in effect. For example, if the thermostat calls for colder air and board 35 is moved tolowermost position, the valve 1| will not be operated until the thermostat calls for warmer air.

Pressure switches -94 and .|03 are .connected in

pipes

15 and 15 respectively, and are arranged to open the circuit therethrough when the pressure in these respective pipesdecrease to say `o50 p. s. i. caused -by the opening of valve 1| and they will not reclose the circuits until the air pressure returns to approximately nor-mal.

The thermostatic switch is placed in any suitable location in the food `compartment |I, to be sensitive tochanges in temperature in the `compartment. In the event the temperature increases above that desired, the electromagnet .is ener gized which .operates valve 1| to vent `tank B0. The decrease in pressure in this tank causes relay valves 56 and 51 to open, admitting air through pipe 5| to the top of cylinder 31 and venting the lower end of the cylinder. This ,slowly moves the .board away from wall 23, thus increasing the air exposed to the wall '23, thereby increasing the rate of heat exchange between the air and Dry Ice. It will be understood that all of the cylinders 31 and 40 will be actuated simultaneously, being connected to pipes 5| and 54 as indicated at the pipes C, so that

boards

35 and 38 will be withdrawn from

walls

23 and 28. As soon as the tank 80 is vented to some predetermined vpressure, usually about 20 p. s. i., below the storage pressure, or to about p. s. i., .pressure switch 04 opens the magnet circuit .so-that valve 1| closes the vent port 11 and bleeding of the pneumatic system will cease with a minimum of loss -of air. When the temperature decreases below that desired, electromagnet `85 will be energized to 'actuate valve 1| to. vent tank 63. The reduction kin pressure in the tank causes relay valves'53 and 51 to open, admitting air to the lower end of the cylinders 31 and 40 and ventingthe upper ends. The boards .35 and `-v38 are thus moved toward their respective heat transfer surfaces lto reduce the volume of air passing in contact `with the

walls

23 and 28 so that the rate of heat eX change between the air and Dry Ice will decrease. When the pressure in tank 63 decreases by about 20 p. s. i., or to about .50 p. s. i., the'switch '|03 is opened to break the circuit to magnet .85 so that valve 1| closes the vent port 11 and pressure will be restored in tank B3. i Y

After either tank or 63, has been vented to about 50 p. s. i. and the valve 1| has been closed by action of the pressure switches', 94 or |03 opening, as described, the tanks will immediately but slowly begin to recover their pressure of .about 70 p. s. i. through the pipe 41 and check valve B8 or 69 respectively, but this pipe and these valves are so proportioned that several minutes will elapse, preferably about 10 minutes, before the pressure in 60 or 63, as the case may be, shall have been restored to the full storage pressure. Also, the valves 94 and |03 are so vdesigned that they will open their switches at about 50 p. s. i. when the pressure is being reduced, but will not close their switches when the pressure is being increased until about 70 p. s. i. Thus, a con- Cil siderable time lag occurs between deenergizingof one of the relays 583 ior `by pressure switches 84 or |03, and its ree-energizing by the lsame switch upon `restoration of the pressure in tank 60 `or V63. This time lag is benecial in that it minimizes both the use of air and electric current from the battery. When the pressure has been restored in the tank 60 or 63 and the pressure switch which .had'been open is again closed, the corresponding circuit through relay 83 or 85 again becomes energized and the system is restored to the dictates of the thermostat.

ThusJ the pressure switches 94 and |03 cause the boards 35 and 40 to be moved in short steps so that these boards will generally float within the extremities of their range of movement, thereby maintaining an even temperature with a minimum consumption of current and air.

The system shown for moving the

control boards

35 and 38 is not necessarily the only one which .may be used, but it provides accurate control with a minimum of expenditure of electric current and air pressure. The various control elements may be of conventional design and f readily available as commercial products.

In use, the -car is loaded at a terminal and prior to loading, the bunkers arelled with Dry Ice blocksand water ice is placed on the racks. Depending on the temperatures to be maintained, salt is added to the water ice, :the lower the temperature, the greater the proportion of Vsalt will be used. The thermostat is set to maintain a temperature in the car several degrees below that at 4which the Water ice and salt mixturev is capable of producing.

v'The Afans v20A vare operated and' air is 'drawn from compartment and 4circulated upwardly along the walls .23 and 28 .of the Dry' Ice bunkers, and upwardly through thewater ice and then into the upper part of the compartment, as indicated by the arrows'. The air cooled by the Dry Ice will maintain the water ice intact since the fair will be chilled below the melting point of the ice bythe .Dry Ice, it being understood that the water ice and salt mixture is adjusted so that its melting point will be a few degrees above the temperature of the air passing from contact with the Dry Ice bunker. After the Dry Ice has been entirely sublimed, the water ice will be available for chilling the air circulated to the .compartment il.

'The advantage of my invention is that the car can be charged with a considerable quantity of Dry Ice at most terminals, which ice will provide considerable more refrigeration per pound than water ice. 'In the event that the Dry Ice is used up before the car reaches its destination, suilicient Water ice can be loadedin the `car to last fori periods of several days. The supply depots of Water ice `is more wide spread than that of Dry Ice and the supply of water ice is therefore assured.

It will be understood, however, that my invention may be practiced with the entire elimination of water ice and with a corresponding increasein the size of the Dry Ice bunker. 'In the-design -s'hown in the vdrawings I will ordinarily store at the start, 11,000 pounds Dry Ice and 1500 pounds of the water ice salt mixture.'

Under usual summer conditions this Dry Ice will last about8.5 days and the water ice about 2.5 days when using an insulated refrigerator car. This Will necessitate a rst re-icing in about 10 days as it would not be safeto allow all of the water ice to melt. However, if the water ice be I7 entirely omittedfrom my'de'sigm additional Dry Ice may be stored to give a running tim-'e of about l days' before the Dry Ice is completely confsumed., Either condition represents an immense improvement over present practice when water ice alone is used 4requiring re-icing every one to two days.` If Dry Ice alone were used it would be preferable to install the doors to the Dry Ice bunkers in the sides of the car so that additional Dry Ice could be added before the car was unloaded.

It will be understood that a car could be operated in accordance with my invention but'without the useiof the insulating

boards

35 and 38 andvftheir accompanying automatic controls. However, a car operated in such marmer would be uneconomical in the use of Dry Ice because, in order to assure that the cartemperature should not rise over `0 which is desirable with frozen foods, it will be necessary to everrefrigerate, subliming Dry Ice at agreater rate than need be' and lowering the temperature of the ca'r at times as low as -20 F. This is not only uneconomical in the use of Dry Ice but will also require more frequent re-icing.

The COzfrom the Dry Ice may be ventedA to the' atmosphere so that it will not enterv into the car compartment as is shown at lr6. .'Although I have described but one form of my invention, it is to be understood that other forms might be adopted, -all falling within the scope of the claims which follow.

1. A refrigerator comprising a storage compartment; Walls forming an air cooling chamber having spaced openings into the vcompartment to provide an air circulation system through the compartment and chamber; a Dry vIce bunker in the lower portion of the chamber, said bunker `having a bottom wall for supporting Dry Ice and forming a heat conductor between air passing therealong and the Dry Ice; an air pervious water ice support in said chamber above the bunker; and means for circulating air from the compartment into the bottom of the cham-y ber and upwardly through the Ichamber and into the compartment. e

2. A refrigerator comprising a storage compartment; walls forming an air cooling chamber 'hav ing openings into the compartment at the bottom and top of the compartment to provide an air circulation passageway through the chamber to and from the compartment; a Dry Ice bunker in said passageway, said bunker having a bottom wall for supporting Dry Ice and an end wall, Said walls forming a heat conductor between the air inthe passage and vthe Dry Ice; an air pervous Waterice support in said chamber and yextending transl versely thereof; and means for circulating air4 from the compartment through said chamber in a direction tocause the air to pass iirst in heat exchange relation with said walls of the bunker and then into contact with ice carried by said support and then into the compartment.

3. A refrigerator comprising. a storage, compartment; walls forming an aircooling chamber having spaced openings into the compartment to provide an air circulating passageway through the chamber; a Dry Ice bunker in the passageway, said bunker having a boittomwall and anv end wall forming heat exchange mediums be,- tween the air in the passageway and the Dry Ice;

ineansfor lcirculating air from the storage compartment through the chamber whereby the air passes said 'walls and then returns to the compartment; two insulating plates in the chamber,`

vone of said plates beingsubstantially coextensive with said' bottomwall and the other of said plates being substantially coextensive with the end wall;4 and means vfor moving said plates toward a'nd away from4 therespective walls in response to I,predetermined temperatures.

4. The method of refrigerating anstorage compartment, which consists in circulating air from the storage compartment into heat exchange relation with Dry Ice, then into contact with water ice, and then back to the compartment; and controlling the rate of heat exchange .between the air and Dry Ice f or maintaining, the temperature of the air circulated over the water ice below the melting point of the water ice Auntil the Dry Ice is entirely sublimed.' 5. The method of refrigerating a storage compartment, which consists in lcirculating air from the storage compartment into heat exchange relation with Dry Ice, theninto Contact with water ice, and then back to the compartment; and controlling'the rate of heatexchange `between the air and Dry Ice' by varying the` volume of air flowing intoheat exchange relation with the Dry Ice for maintaining the temperature of the air circulated over vthewater Yice below the melting point of the water ice until the Dry Ice is entirely sublimed. y A

6. A refrigerator car 4having a storage compartment intermediate the', ends and air cooling chambers at the Aends, said chambers being connected by openings with the storage compartment at the top and bottom ofthe chambers; means for circulating air from the compartment through the chambers and back to the compartment; vbunkers for containing Dry Ice in the chambers, said bunkers having heat conducting Walls for Supporting theDry Ice and being exposed to the air passing through the respective chambers; and'a water ice support in each of said chambers andv located in the path of air ilowing through thev respective chambers after passing said walls. f y

7. The method of refrigerating a storage compartment which consists in circulating air from the storage compartment through a passage, one wall of which forms a heat exchange between the air and Dry Ice'; and controllingthe rate of heat exchange between the air eand Dry Ice by interposingan insulating plate in the passage parallel to said one wall, and moving the A'plate toward and awayl'from said one wall in accordance with temperature "changes in the compartment for varying the depth of the air stream passing in directcontact with said one wall.

ROBERT D. PIKE.

. `RFJIR'ENGES' CITED v v The followingreferences are of` record in the rile of this patent:

UNITED STATES PATENTS Number Name" Date 1,796,907 Josephson et al. Mar. 17, 1931 2,012,892 Rice Aug. 27, 1935 2,109,310 Cordrey Feb. 22, 1938 Wieden July 20, 19413`