US2641908A

US2641908A - Refrigerator defrosting means

Info

Publication number: US2641908A
Application number: US182971A
Authority: US
Inventors: Porte Louis F La
Original assignee: FRANCIS L LA PORTE
Current assignee: FRANCIS L LA PORTE
Priority date: 1950-09-02
Filing date: 1950-09-02
Publication date: 1953-06-16
Anticipated expiration: 1970-06-16

Description

June 16, 1953 1 F. LA PORTE 2,641,908

REFRIGERATOR DEFROSTING MEANS Filed Sept. 2, 1950 A Z- 34 HEAT-HoLo/Ne Empa/mmf? 46 6,6 4@ f MED/UMLEVEL 24 E 70 72 82 fell BY- P555 l/HL VE CONO E11/SER SHUT- OFF VA L VE j; 74 64 74 az Patented June 16, 1953 n 2,641,908 REFRIGERATOR DEFROSTIG vMEAN S Louis F. La Porte, Wellston, Mo., assigner to Francis L. La Porte, Burlingame, Calif.

Application September 2, 195i), Serial No. 182,971

10 Claims. (Cl. 62--115) The present invention pertains generally to mechanical refrigeration, and more particularly to improved means adapted to defrost evaporators, or cooling units of refrigerator systems. Y

The defrosting problem has plagued the refrigeration industry for a longtime, and numerous attempts have been made to solve this problem in the past.

A few of the prior art methods and apparatus have achieved a measure of success. vMost of them however, have been tried and then discarded for one reason or another, the principal reasons being that the defrosting operations required too much time, or that the apparatus provided proved too complicated and so on.

The primary obj ect of this invention is to provide a method whereby the defrosting of evaporators, whether of the iinned typaplate type, or bare pipe coil construction, can be accomf plished rapidly and efficiently. l

A further object is to provide simple, rather than complicated means for attaining the primary object aforesaid.

Another object is to provide means for defrosting a drain pan simultaneously with the defrosting of an evaporator, so that water which drips from the latter may ow freely from the refrigerated space, as is understood.

Broadly, the instant invention contemplates the incorporation in a conventional refrigeration system, of a novel heat storage unit interposed between the compressor and the evaporator; a liquid new retarding device enclosed within said unit.; a by-pass valve in the discharge line of the compressor for diverting the gasses passing therethrough to the evaporator in a preheated condition during a defrosting operation; and other novel features associated with these elements for attaining the objects of the invention, as will appear.

The invention is partly diagrammatically, and partly structurally illustrated in the accompanying drawing, and the arrangement of the various partsY which are combinedfto attain the objectives thereof `will be more clearly understood from the description to follow with reference to said drawing, in which:

Fig. 1 is a diagrammatical illustration of a conventional refrigeration system incorporating Athe preferred embodiment'of the present invenvention Fig. .3 is a'horizontal sectional view, on an en- A larged scale, taken on line 3--3 in Fig. 2, and particularly illustrating details of a liquid flow retarding device enclosed within the said heat storage unit;

' Fig. 4 is a vertical sectionalfview, on a further enlarged scale, through said retarding device, the view taken on line 4-4 of Fig. 3;

Fig. 5 is a fragmentary view, similar to Fig. 2 wherein Vis illustrated an additional feature that may be included in the liquid flow retarding device; and y Fig. 6 is a fragmentary view similar to Fig. '1, portraying an alternate arrangement.

With particular reference now to Fig. 1, fthe conventional refrigeration system shown includes a compressor lil, a condenser I2, a liquid receiver I4, an expansion valve It, and an evaporator I8. The latter is of the finned type coil construction, although itis to be understood as previously pointed out, that the invention is applicable to other evaporator types.

Numeral 2 indicates a drain pan with which is associated a discharge conduit 22. The evaporator coil is designated by numeral 24, the suction or intake line of the compressor by numeral 25, and the compressor discharge line by numeral 28. n

The liquid line leading from the receiver tank to the expansion valve is indicated by numeral 3d. The usual shut-off valve is designated 32.

Usually as well known, the assembly including the evaporator, drain pan, and expansion valve is mounted in the space to be cooled, whereas the assembly including the compressor, condenser, and receiver is located remotely therefrom.

While it is taken forv granted that the operation of the conventional system illustrated and thus far described is well understood,` a brief summary is not believed to be objectionable prolix at this point.

. Thus, assuming that the temperature of the space to be cooled has risen above a predeter- `mined degree, "any of the well known thermal responsive devices will cause the compressor to start. As a result, refrigerant in vapor form is withdrawn from the evaporator via line 26,

- compressed, thereupon delivered to the condenser i2 still in vapor form, and thence to receiver I4 in liquid form, via line 23.

Assuming that valve 32 is open, the refrigerant in liquid form is metered or fed through the expansion valve it vand into the evaporator coil 2li. VThe ambient warmth or heat about the evap- -.-orator being absorbed by the refrigerant asis understood, the latter is vaporized, and in that form returned to the compressor via suction line 26 to repeat the cycle until the temperature of the space to be cooled causes the thermal responsive device to shut off the compressor. The circuit described is indicated by the broken line arrows in Fig. 1.

During these cycles of normal compressor operation, the moisture prevalent in the ambient atmosphere settles upon and is gradually transformed into a layer or layers of frost, which increasingly accumulate on the external portions of the evaporator.

As is well understood, unless these layers of frost are removed from time to time, the eiliciency of any refrigeration system will eventually be reduced to a point where its operation is noneffective.

The present invention contemplates no change in the normal refrigeration system thus far considered. It does contemplate however, the incorporation in such system of novel means whereby the normally employed refrigerant or cooling agent may also serve, selectively as the defrosting agent, without requiring cessation of normal compressor operations.

Referring again to Fig. l, numeral 34 indicates generally a heat storage unit, 36 a by-pass valve, 38 a vapor line, and 40 a loop portion formed in the latter. The upper end of the vapor line is in communication with the inlet portion 4| of the evaporator coil by means of a T fitting 42, as shown. f

The incorporation of the non-conventional elements `just enumerated will, when necessary or desired, cause the refrigeration system to supply preheated gas vapors to the evaporator for defrosting the same in a manner to be explained later.

With particular reference now tov Figs. 2 and 3, the heat storage unit 34 includes a tank 44 f containing a heat holding uid .the upper level of which is indicated at 4S. It may be water or other selected medium.

submerged in said fluid medium, and mounted in any suitable manner within container 44, is a liquid flow retarding device generally indicated by numeral 48. Also submerged, and disposed beneath said device, is a loop or coil portion 56 formed in suction line 26. Preferably but not necessarily, coil portion 50 is provided with a plurality of heat transfer fins 52 as shown. For descriptive purposes, coil 58 will sometimes be termed Vthe suction coil hereinafter.

Also submerged, and disposed in said container below suction coil 56, is a coil portion 54 formed in discharge line 28. This coil portion is also preferably provided with heat transfer ns designated 56. For descriptive purposes, coil 54 will sometimes be termed the discharge coil hereinafter.

A suitable electric heating device 58 submerged in the lowerniost region of the tank. This device may be controlled by manual or automatic means, as suggested by switch 65 in Fig. 1.

rIfhe liquid flow retarding device 4B, as will appear, is of prime importance. As shown in the drawing it comprises a cylinder 62, closed at either end, and interposed in suction line 26 between coil 56 and that portion of said line extending from the tank 44 to the evaporator.

In horizontally spaced relation to the inlet end wall 64 of cylinder 62, is an upper baille plate 66 which, as seen to best advantage in Fig. 4, extends downwardly to .a plane slightly above the horizontal centerline of the cylinder` In horizontally spaced relation to the outlet end wall 68 of cylinder 62, is a lower baille plate 'ES which, as also seen to best advantage in Fig. fi, extends upwardly to a plane slightly below the horizontal centerline of the cylinder.

Interposed between these two bailes, and in spaced relation thereto and to one another, is a plurality of lower baille plates l2, two being shown in the drawing. The intermediate baffles are identical with the baffle lil', and each of the lower baffles is provided with a small orifice or bleeder T4, preferably formed therein adjacent the low ermost portion thereof.

As portrayed in Fig. 2, delivery portion i6 of suction line 25 enters the device 43 through wall 64, in a plane above the bottom marginal edge i8 of non-perforate baiiie 66. Near the outlet end of the device, portion B9 of said suction line depends from the lowermost region of cylinder 62, between end wall 68 and perforate baffle l0.

It is noted that by opening valve 36, the compressor discharge gases may be directed into line 38'. It `is also noted that said valve may be manual'ly, mechanically or electrically operated.

In normal refrigerating operation, said valve is closed so that the high pressure refrigerant discharged from the compressor passes through the discharge coil portion 54 of line 28, thence on to condenser l2.

In this manner, most of the heat inherent in the compressed discharged refrigerant is absorbed bythe fluid heat holding medium in tank 44. The transfer of heatr from coil 54 to the liquid is abetted by the ns 56, as is understood.

Thus, it should be manifest that during each compressor operation, heat extracted from the discharge line is stored, or accumulated, within the tank 44. It is noted that in such normal operation, the heating device 58 is inoperative.

From coil 54, the thus partially liquefied refrigerant proceeds to the condenser I2, thence to receiver I4, and thereafter, via cold liquid line 3D and metering valve I6, to the coil 24 as is understood, -but on its return to the compressor via suction line 26, it again travels through the heat storage unit 34.

In other words, the refrigerant, in mingled vapor andliquid form, passing from the evaporator first enters the liquid ow retarding device 48, then travels through suction coil 59, whence it continues on to the compressor lil in completely vaporized form, as will now be explained with particular reference to Figs. 2 to 4.

As previously noted, the liquid flow retarding device 48 is immersed within container 44 in the uppermost region thereof.

As the mingled vapor and liquid body of refrigerant is drawn into device 48 through portion 'i6 of suction conduit 26, it impinges upon the baffie 66. The vapors pass quickly beneath the bottom marginal edge 'i8 of said baille into coil 5G as indicated by the Fig. 2 broken line arrows, thence to compressor I6 in the usual manner.

The non-vaporized or liquid portion of the refrigerant however, is either deflected downwardly from the baiiie 66, or drops by gravity from portion 16 of the suction line into compartment 82 dened longitudinally of cylinder 62 by end wall 64, and right hand intermediate lower baille 72.

Bearing in mind that cylinder S2 is immersed in a body of heated fluid, a considerable quantity of this non-vaporized refrigerant is quickly transferred into vapor form to rise and proceed onwardly through coil 59 to the compressor. The

.5 residue simultaneously flows into compartment 84 via orifice 'M in the right hand baille 12.

As the residue of non-vaporized refrigerantl flows through compartment 84, a considerabler baffle 12, rthence to the suction coil 59 via orifice 'M in baffle l0, and on to compressor lil in a now vaporized state. l

From the foregoing, it should be evident that the device 48, in conjunction with the coil t, pro vides for the complete vaporization of the refrigerant enroute to the compressor from the evaporator. The orifices I4 prevent the flow of any liquid slugs to the compressor, the orice in the baffle 1B preferably being of a more minute diam* eter than the others.

Assuming now that the evaporator requires de frosting, valve 36 is opened whereby gases from both the compressor and the condenser will flow into line 38. Opening of valve 35, starts the defrosting cycle, which continues as long as said valve is open.

That is to say, the cycle continues uninter ruptedly until defrosting is complete, whereupon closing of valve 36 will again place the system in condition to resume normal refrigeration operation.

The defrosting circuit is indicated by. full line arrows in Fig. l, and will be further described with reference also to Fig. 2. After manipulation of valve 36 to open or defrost position, the high pressure gases from the compressor pass through the heat storage unit via line 28, coil 515, valve 3G,

line 38, loop 4t, 'l' 42 and into the evaporatorr .coil 24. o

As the preheated'gas circulates through the from and into coil 54 contain comparatively little heat. As these vapors continue to advance through said coil toward the evaporator, addiloop 40 and coil 24, it is partially condensed. That is to say, the heat inherent in the vapors is transferred to the evaporator and the drain pan whereby to melt frost which had accumulated thereon.

`As a result, the refrigerant leaves the coil in a v v partially liquid state and proceeds via suction line 2t to the device A8 in the heat storage unit.

j As previously explained in detail, passage of the refrigerant through heat storage unit 34 cornpletely reevap-orates the same. Thus it leaves said vunit and proceeds via line 26 to the compressor in the form of vapors, to repeat the cycle until the defrosting operation is brought to an end. Should it be desired to accelerate the defrostn ing operation, additional heat may be supplied to y the liquid in container 44 by the electrical heating device 58. In that event, switch 6D may be closed prior to manipulating the valve 35 to defrost position.

It is notedthat discharge coil 54 has a dual role. In other words, during normal refrigerating cycles, said coil serves to supply heat to the storage tank; during defrosticycles, said coil servesto extract heat therefrom and transfer same to the vapors enroute to the evaporator from the compressor. v y

That is to say, when theesystem is operating normally, each time the compressor goes on, refrigerant vapor is compressed and in passing through said coil on its Way to the condenser, it supplies heat to the luid within tank d'3.

. However, immediately following the opening oi by-pass valve 36, pressures within the entire sys,-

tem tend to equalize. As a result, the compressor at such time functions in themanner of a circulating pump, so that the gases discharged theretional heat is absorbed by them from-the previously stored heat in the tank, augmented if desired, by heat generated by the device 58.

In other Words, during normal refrigerating cycles, coil 513 supplies heat to the tank for storage; during defrosting cycles, said coil withdraws previously stored heat fromv the tank.

From theiforegoing, it should be manifest that the present inventionV provides a simple, highly eflicient method and means for rapid defrosting operations without turning off the compressor.

It should also be evident, that the incorporation A in a conventional refrigerating system of the heat storage unit 34, and particularly the liquid ow retarding device d8 thereof, will increase the eiciency of the system in normal operation.

The invention obviously admits of modifican tions without departing from the principles there of. For example, in some installations, the coil 4B beneath the drain pan may be eliminated.

And, as shown in Fig. 5, the device d8 may be provided'with a vapor tube 88, one end of which enters cylinder 62 at a high level, the other end being connected into suction line 2S by T fitting Sli outside the tank.

With this arrangement, some of the vapors will by-pass coil 59. It may also not be necessary to immerse the liquid flow retarder 48 in the heatholding medium, as this View indicates.

The invention also contemplates heating the fluid in tank de by means other than the dircharge line.' In that case, and with reference to Fig. 6, Vit is noted that compressor discharge line ZSleads both to coil 54 and t0 condenser l2, there being a T fitting 92 interposed in the line shown.

Numeral 9d indicates diagrammatically a coil submerged in the heat-holding medium. Either steam or hot water may vbe circulated through this coil to maintain the uid Within tank da at desired temperature.

Again, coil 94 may be dispensed with, and the medium heated entirely by one or more electrical heating devices 5E, The invention also conter-.iu plates, assuming the iluid in tank 4l! to be watery that heat may be supplied by providing Jfor a constant or intermittent flow of hot water into and thereafter outl of the tank.

, Except for the'slight differences pointed out, vthe system illustrated in Fig. e is identical' with shown in Fig. l, and the same reference numerals'have been appliedto corresponding parts. 'Obviously however with this arrangement, the sole purpose of coil 54! is to preheat the gas vapors enroute to the evaporator coil during a defrost operation.

In normal operation the discharge gas travels directly to the condenser, and thence through the system and back to the compressor as in the l embodiment. Y

During a defrost cycle, with valve 36 open to line 33, the discharge gas travels onward to the evaporator coil 24 and thence through the system and back to the compressor in the identical manner described at lengthhereinbefore with respect maintaining said liquid at a high temperature, a :rst coil submerged in the liquid and formed in the discharge line of said compressor, a second coil submerged in the liquid and formed in the suction line of said compressor, a flow retarding device of the character described interposed in the suction line within the container-.between the second coil and the evaporator for vaporizing the refrigerant passing therethrough from said evaporator, a vapor line in communication at one end with the inlet portion of the evaporator coil, and a normally closed valve on the other end of the vapor line and in communication with the compressor discharge line for diverting the normal flow of discharge gases into said vapor line.

2. In combination with a refrigeration system including a compressor, a condenser, and an evaporator, means for defrosting said evaporator without turning oil the compressor, said means including a container at least partially lilled with a quantity of liquid, heatsupplying means for maintaining said liquid at a high temperature, a first coil submerged in the liquid and formed in the discharge line of said compressor, a second coil submerged in the liquid and formed in the suction line of said compressor, a flow retarding device of the character described intern posed in the suction line within the container between `the second coil and the evaporator for vaporizing the refrigerant passing therethrough from said evaporator, and a valve for divertingv the normal flow of discharge gases from said compressor to a vapor line in communication at its lower' end with said valve, and at its upper end with the inlet portion of the evaporator coil.

3. In combination with a refrigeration system including a compressor, a condenser, and an evaporator, means for defro'sting said evaporator without turning off the compressor, said -means including a container at least partially filled with a quantity of liquid, heat-supplying means for maintaining said liquid at a high temperature, a first coil submerged in the liquid and formed in the discharge line of said compressor, a plurality of heat transfer fins on said coil, a second coil submerged in the liquid and formed in the suction line of said system, a plurality of heat transfer fins thereon, a flow retarding device of the character described interposed in the suction line within the container between the second coil and the evaporator for vaporizing the refrigerant passing therethrough from said evaporator, and a valve for diverting the normal flow of discharge gases from said compressor to a vapor line in communication at its lower end with said valve, and at its upper end with the inlet portion of the evaporator coil.

4. In combination with a refrigeration system including a compressor, a condenser, and an evaporator, means for defrosting said evaporator without turning off the compressor, said means including a container at least partially filled with a quantity of liquid, heat-supplying means for maintaining said liquid at a high temperature, a first coil submerged in the liquid and formed in the discharge line of said compressor, a plurality of heat transfer fins on said coil, a second coil Y submerged in the liquid and formed in the suction line of said system, a plurality of heat transfer fins thereon, a now retarding device of the character described interposed in the suction line within the container between the second coil and the evaporator for vaporzing the. refrigerant passing therethrough from said evaporaton a valve for diverting the normal flow of discharge gases from said compressor to a vapor line in communication at its lower end with said valve, and at its upper end with the inlet portion of the evaporator coil, and an auxiliary electrical heating device submerged in the liquid beneath the rst coil aforesaid.

5. In combination with a refrigeration system including a compressor, a condenser, and an evaporator with associated drain pan, means for defrosting said evaporator and pan without turning off the compressor, said means including a container at least partially filled with a quantity of liquid, heat-supplying means for maintaining said liquid at a high temperature, a rst coil submerged in the liquid and formed in the discharge line of said compressor, a plurality of heat transfer ns on said coil, a second coil submerged in the liquid and formed in the suction line of said compressor, a plurality of heat transfer fins thereon, a flow retardingvdevice of the charac ter described interposed in the suction line within the container between the second coil and evaporator for vaporizing the refrigerant passing therethrough from said evaporator, and a valve for diverting the normal fiow of discharge gases from said compressor to a vapor line in communication at its lower end with said valve, and at its upper end with the inlet portion of the evaporator coil, said vapor line having formed therein a loop portion adapted to engage a portion of said drain pan.

6. In combination with a refrigeration system including a compressor, a condenser, and an evaporator, means for temporarily converting a portion of said system into a defrosting system, said means including a heat storage unit in the form of a sealed container at least partially filled with a quantity of liquid maintained at a high temperature, a first finned coil formed in the compressor discharge line and submerged in said liquid, a second finned coil formed in the compressor suction line and submerged in the liquid, a flow retarding device of the character described interposed in the suction line aforesaid between the second coil and the evaporator also submerged in the liquid for vaporizing the refrigerant passing through said device from said evaporator, and a valve in communication with the compressor discharge line for diverting the discharge gases which normally flow from the compresor via said line toward the condenser into a conduit leading from said valve to the inlet portion of the evaporator coil.

7. In combination with a refrigeration system including a compressor, a condenser, and an evaporator, means for temporarily converting a portion of said system into a defrosting system, said means including a heat storage unit in the form of a sealed container at least partially filled with a quantity of liquid, a first finned coil formed in the compressor discharge line and submerged in said liquid for normally transferring thereto the heat inherent in the hot gases passing through the coil, an auxiliary electrical heating device submerged in the liquid below said coil to further heat said liquid when desirable, a second finned coil formed in the compressor suction line and submerged in the liquid, a flow retarding device of the character described interposed in the suction line aforesaid between the second coil and the evaporator also submerged in the liquid for vaporizing the refrigerant passing through said device from said evaporator, and a valve in communication with the compressor discharge line for diverting the discharge gases which nor- 9. The defrosting means set forth inl claim 1 l wherein the heat-supplying means for maintaining said liquid at a high temperature includes a coil submerged in said liquid, said coil having an inlet portion and an outlet portion each projecting through and beyond said container whereby hot water may be circulated through said coil.

10.v In combination with a refrigeration system including a compressor, a condenser, and an evaporator, means for defrosting said evaporator without turning off the compressor, said means including a container at least partially filled with a quantity of liquid, heat-supplying means for maintaining said liquid at a high temperature, a first coil submerged in the liquid and formed in the discharge line of said compressor, a second coil submerged in the liquid and formed in the suction line of said compressor, a flow retarding device of the character described interl0 posed inthe suction line within the container between the second coil and the evaporator for vaporizing the refrigerant passing therethrough from said evaporator, a vapor tubefthe upper end of which is in iiuid communication with said flow retarding device above the horizontal centerline of the latter and the lower end of which is connected into the suction line outside the container, and a Valve for diverting the normal flow of discharge gases from said compressor to a vapor line in communication at itsl lower end with said valve, and at its upper end with the inlet portion of the evaporator coil.

Louis F. LA PORTE.

References Cited in the le of .this patent UNITED STATES PATENTS Number Name Date 1,196,546r Jacobson Aug. 29, 1916` 1,816,159 Smith July 28, 1931 2,042,462 Hahn June 2, 1936 2,196,707 Nelson et al l- Apr. 9, 1940 2,351,140 McCloy June 13, 1944 2,452,102 Cocanour Oct. 26, 1948 2,481,469 Brown Sept. 6, 1949 2,516,093 Rui July 18, 1950 1 2,526,032 La Porte Oct. 17, 1950 2,530,440 Nussbaum Nov. 21, 1950