US 2001027 A
Description (OCR text may contain errors)
y 1935- w. R. KITZMILLER 2,001,027
v DEFROSTING SYSTEM l Filed Sept. 8; 1931 gwvmtov WIiamR.Kit5miIIer fiiilitllitw nhos'rmd srs'rniw William R. trer, Waynoro, li'a... assignor to Fitch Company, Waynesboro,
tion oil lPeylvania We, a corpora- .dpplication September d, 1931, Serial Ne. 561L804!) 1% Elia.
This inventicn relates to coolers for fluid and especially to the'defrosting of the type having an agitator r blower for circulating the fluid to be cooled overcooling surfaces, which surfaces are d cooled by a fluid of a lower temperature in contact with the cooling surface and further provides means for defrosting or removing the ice on the outside of the cooling surface.
An object of the invention is to provide automatic means of defrosting the cooling unit when ever the frost has accumulated to an objectionable degree.
A further object is to provide means for defrosting cooling surfaces whenever the temperature of the air in the room being cooled has reached the desired low point.
In cooling air or any other gas which contains water vapor it is a well known fact that when the temperature has dropped below the dew point some of the water vapor will condense and freeze on the surfaces of the cooler. This frosting of the cooling surface is objectionable first because the frost is a poor conductor of heat so that when the cooling surfaces are covered with frost the cooler will no longer absorb heat from the surrounding media at the required capacity. Then again the accumulation of frost on the cooling surfaces may restrict the passage of air over these surfaces or through the cooler so that 30 the fan, blower or agitator will no longer deliver the required amount of air so that the capacity of the cooler will be greatly reduced.
From the foregoing it will be apparent that it is desirable and necessary for emcient operation that the frost on the cooling surfaces be removed from time to time to prevent lowering the chiciency of the cooling unit. In describing the invention language will be used which particularly describes the system as applied to cooling air in 40 a room. The system, however, is in no sense limited to this use but may be employed in cooling any kind of gas or for cooling a liquid in which latter case the liquidto be cooled is delivered against the cooling surfaces of the cooler so that the whole liquid is brought into heat exchange contact with the cooling media. In carrying out the invention I show four diflerent applications or modifications of the principle of the invention.
Referring to the accompanying drawing which is made a part hereof and on which similar reference characters indicate similar parts,
Figure l is a view in elevation with certain parts shown diagrammatically of the preferred form of the invention,
Figures 2, 3 and 4 are modifications showing the same principle carried out in a somewhat different structure, and
Figure 5 is a section of a casing housing a circulating fan arranged either for sucking or forcing air through a cooler.
In the drawing numeral it indicates a cooler or heat exchange unit of any suitable construction having an inlet M for the cooling or refrigerant fluid and an outlet it. In the outlet pipe i2 is placed a valve it: which is here shown as controlled by a solenoid it, the solenoid being in circuit with lines it and l 6. Instead of a solenoid as a motor valve. A blower or fan ill operated by a motor it circulates air to be cooled over or through the cooling unit it. The motor it may be any suitable motor, that shown here being a three phase motor operated by current from lines i9, and 25, connected through switch 22 with power lines 23, 2t and 25 from any suitable source of current. Wire i6 is attached to the wire it in advance of the motor it and circuit through the line it is controlled by means of a thermostat switch 26. This may be any suitable thermostatic switch which remains closed so long as the tem- 2 perature in the room is above a predetermined point but opens when the temperature has fallen to a predetermined low point. The wire I5 is connected to the wire 2i through a switch 21 which is operated by any suitable electrical device such for example, as a solenoid 28, the coil of which is in circuit with the wire 2!. Line 2-5 is connected by means of a line 29 and. 30 with a wire 23. A temperature controlled switch at is in circuit with the line 29, at, this switch being opened when the temperature in the room or in the compartment to be cooled drops to a predetermined low degree. Switch 22 is held closed by some suitable electrical means as a solenoid 9 so long as the switch 3! is closed. When switch 3! is opened the solenoid 9 4 is de-energized and switch 22 opened to stop motor it.
In operation when frost has collected to an objectionable degree on the cooler Hi this will impede the passage of air blowing through the cooler. and build up a pressure head in front of the fan. This pressure head will afiect the load. on the motor it. If however the fan is operated to suck air through the cooler the head on the fan will be decreased as the passage of air is impeded. In either case the changed load on the motor it may be caused to control the switch 2? so that this switch will be opened when the pres sure load has reached a certainpredetermined value. When the circuit through the lines it and I6 is interrupted the solenoid It or other motor is de-energized and the valve I3 is closed. This stops circulation of refrigerant through the cooler III. The fan, however, will continue to operate and its operation will soon defrost the cooler. As soon as defrosting has been completed the pressure head on the fan will be removed so that the switch 21 will again be closed, solenoid I4 energized and valve I3 opened so that the circulation of refrigerant may again be started. If the temperature in the room drops to a predetermined low degree temperature con trolled switch 26 will be opened so that circuit through the lines I5 and I6 and solenoid I4 will be interrupted so that valve I3 will again be closed to interrupt circulation of refrigerant through the cooler I6.
Temperature controlled switch 3| is placed in circuit with lines 28 and 30 so that when the temperature in the room or chamber to be cooled reaches the desired low degree switch 22 will. be opened to stop operation of the fan motor I8. This will also break-the circuit through the lines I5 and I6 so that the valve I3 will be closed to stop circulation of refrigerant to the cooler. Should the fan ll be stopped with refrigerant still circulating through the cooler, the cooler might freeze up. It is necessary therefore to stop operation of the refrigerating fluid when the fan is stopped.
Figure 2 shows a cooler in which the refrigerant inlet 32 is controlled by a valve 33 operated by solenoid or other motor 34. The outlet from the cooler 35 is controlled by a valve 36 .operated by solenoid or other motor 31. A pipe 38 is attached into the outlet connection 39 and a valve 46, controlled by solenoid or other motor 4 I, controls passage of fluid through the pipe 38. A pipe 42 connects to the inlet pipe 82 and is controlled by a valve 48 which is operated by a solenoid or other motor ll. Solenoid 31 is operated by current from lines 45, 48, 49 and 52, when switch 86 is in the position shown in Figure 2. A wire 417 passes through a solenoid ll to operate it and is attached to wire 86 which in turn is attached to wire 88 which is a lead-in wire to a motor 58. The motor 58 is operated by current of the three phase type received through lines it, 59 and 52.
In operation when a pressure or suction head has been built up in the cooler, loading or unloading the fan lit, the load on the motor 58 will be affected so that solenoid 58 will be operated to break connection between lines 52 and 85 so that solenoid 31 will be deenergized and valve 36 allowed to close. As is obvious, valve 33 will also be closed. This will stop circulation of refrigerant through the line 39, allowing the fan 53 to continue to operate to defrost the cooler. Simultaneously with closing the valve 36 current will be passed from line 52 through line 41 and through solenoid 4| so that this solenoid will be energized to open valve 40. Solenoid 44 is likewise in circuit with line 41 and 48 so that solenoid I may likewise be energized to open valve 43. Valves 33 and 36 will remain closed so that warm refrigerant may now be circulated through the lines 42 and 38 and the cooler to quickly warm the cooling unit to assist in quickly defrosting this vunit. The defrosting is more quickly accomplished than could be'done by circulating the air in the chamber from the cooler with no auxiliary heat radiating means.
In the form shown in Figure 3 the cooler 55 is supplied with refrigerant flow lines 56 and 51, the line 51 being controlled by a valve 58 which is operated by solenoid or motor 59. The solenoid 59 in turn is in circuit through lines 66 and 6| with lead-in wires 62 and 63. A switch 64 operated by solenoid or other motor 55 is in circuit with lines 6|. Lines 62, 63 and 66 are the usual three-phase lines to a motor 61 for operating a fan 68. In this form of the invention when the cooler 55 becomes covered with frost the load on the fan 68 changes and this load in turn affects the current through the solenoid 65, so that the switch 64 is allowed to open. When switch opens, circuit through the lines and 6| is broken, so that the solenoid 59 is de-energized thus permitting the valve 58 to close. This interrupts circulation so that further operation of the fan 68 forcing or drawing air rapidly through the cooling unit will quickly defrost the cooling unit.
In the form shown in Figure 4 the cooling unit 69 has inlet and outlet refrigerant connections, the latter of which is controlled by valve I6 operated by solenoid or other motor II. Fan I2 is operated by motor I3 which motor receives its M current through lines I4, I5, I6 connected to lead-in lines I8, I9 and 86 by which 11. A wire 8| is attached to the line I8 and 82 is attached through coil 88 to the line 88. Wires 8| and 82 are in series with a thermostatic switch 83 placed in the chamber, the temperature of which is to be regulated, so that when the temperature falls to the desired low degree switch 83 is-energized to open the switch I1 which'controls the motor I3 so that the fan will be stopped. A temperature controlled switch 89 is placed in circuit with leadin lines 85 and 86 which latter lines are incircuit with a solenoid II. When the temperature in the chamber to be cooled reaches a predetermined low degree, switch 89 is closed, closing the circuit through lines 85 and 86 to energize the solenoid II to close the valve III. This will interrupt circulation of the refrigerant so that the cooling of the unit 69 will cease simultaneously with circulation of the refrigerant past the cooler. If desired, the solenoid valve I6 may be omitted and a signal used to warn the operator that he should defrost the cooler. This signal may be a light, a bell or any other suitable signal. The valve and the lamp are shown in series in Figure 4.
While the fan, blower or pump is described in the foregoing as forcing the fluid to be cooled through the cooler, the fiuid is frequently sucked through coolers of this type. Whetherthe fluid is forced or sucked through the cooler does not affect the operation of my invention, and I therefore do not limit myself to forcing the fluid through the cooler.
It will be obvious to those skilled in the art that various changes may be made in my device without departing from the spirit of the invention and therefore I do not limit myself to what is shown in the drawing and described in the specification, but only as indicated by'the appended claims.
Having thus fully described my said invention, what I claim as new and desire to secure by Letters Patent, is:
1. A cooler having means for circulating a refrigerant therethrough with a valve for controlling circulation of the refrigerant and a fan for moving a fluid to be cooled over refrigerating surfaces of the cooler, a motor for operating said fan, the load on said motor varying directly in response to a pressure head built up through the cooler due to an impeding of the passage of the fluid to be cooled by an accumulation of frost on the said cooling unit, said variation of the load on the motor being in control of the said valve whereby the said valve willbe closed when frost has covered the cooler to a predetermined degree, the fan continuing to operate after closing of the valve to thaw out the frost on the cooler, substantially as set-forth.
2. In a cooling system for a chamber, a refrigerating unit in said chamber, means for circulating air in the chamber over said refrigerating unit to cool the said air, a refrigerant circuit through said unit having a valvefor controlling the flow of refrigerant therethrough, means responsive to variations in the load on the motor due to a pressure head built up through the cooler due to frost on the cooler for controlling the said valve, substantially as set forth.
3. In a cooling system for a chamber, a refrigerating unit in said chamber, means for circulating air in the chamber over said refrigerating unit to cool the said air, a refrigerant circuit through said unit having a valve for controlling,
the flow of refrigerant there-through, means responsive to variations in the load on the motor due to a pressure head built up through the cooler ,due to frost on the cooler for controlling the said valve, and means controlled by the temperature in the chamber for stopping operation of the fan when the temperature in the chamber has reached a predetermined low limit, substantially as set forth.
4. A device for removing frozen substance from a fluid cooler through which a refrigerating fluid is circulated comprising a fan for circulating fluid to be cooled into contact with the cooler, a motor for operating said fan, and means for interrupting the flow of refrigerant through said cooler, said means being responsive to change in the load on the motor due to accumulation of frozen substance on the cooler which resists the passage through the cooler of the fluid being cooled, substantially as set forth.
5. A device for removing frozen substance from a fiuid cooler comprising means for circulating fluid to be cooled in heat exchange relation with the .cooler, a motor for operating said means, means for causing the circulation of refrigerant through said cooler, and means responsive to variation in the load on the motor due to the formation of frozen substance on the cooler which resists the passage of air through the cooler in control of means for interrupting the circulation of refrigerant through the cooler, substantially as set forth.
6. A device for removing frozen substance from a fluid cooler comprising in combination with a fluid cooler, an agitator for forcing fluid to be cooled into heat exchange relation with the cooler and means for circulating refrigerant through the cooler of means for interrupting the flow of refrigerant comprising a motor for operating said agitator, the load on said motor being increased by the formation of frozen substance on the cooler which impedes the passage of fluid to be cooled through the cooler, means for stopping the said motor and for simultaneously interrupting the circulation of refrigerant through the cooler, said last named means operating in response to an increased load on the motor due to the formation of excessive frozen moisture on the said cooler, substantially as set forth.
7. In a device for cooling air in a chamber having a heat exchange unit therein and means for circulating a refrigerant fluid through the unit, an agitator for circulating the air to be cooled in heat exchange relation with the unit, a motor for operating said agitator, a signal for indicating when a substance has frozen on the surfaces of the heat exchange unit to an objectionable degree, said signal being operative in response to variation in the load on the motor as the formation of the frozen substance on the heat exchanger impedes circulation of the fluid to be cooled in contact with the heat exchange unit, substantially as set forth.
8. In a cooling system for a chamber, a heat absorbing unit having means for circulating a refrigerant therethrough and a valve controlling the flow of refrigerant through the circulating means, means for circulating a heating fluid through the unit and a valve for controlling the passage of the heating fluid therethrough, an agitator for circulating fluid to be cooled into heat exchange relation with the said heat absorbing unit an air confining chamber surrounding said agitator, a motor for operating said agitator, variation in the load on the motor being caused by variation in the obstruction of the passage of the fluid to be cooled about the coolingunit due to the formation of frozen substance on the said unit, the circulation of the cooling fluid and the heating fluid being responsive to the said variation of the load on the motor which drives the said agitator, substantially as set forth.
9. The method of defrosting a fluid cooler which comprises controlling the circulation of refrigerant fluid through the cooler in response to the formation in excess of a predetermined amount of frozen substance on the cooler, the said control being effected by variation in the load on the power means for circulating the fluid to be cooled in heat exchange relation with the cooler, substantially as set forth.
10. The method of controlling the formation of frozen substance on a cooler which comprises using the impeding effect of the frozen substance as it forms on the cooler to vary the load on the power means for circulating the fluid to be cooled and causing variation of the load on the power means to vary the circulation of the refrigerant by means of which the cooling unit is cooled, substantially as set forth.
WILLIAM R. KI'IZMILIER.