US2275829A - Refrigerating apparatus - Google Patents

Description

March 10, 142. R. TULL 2,275,829

REFRIGERATING APPARATUS Filed May 4, 1939 I 4 i; /9 1- WITNESSES: ,3 lNVENTOR v POBERT 1'72 77/ ATTORNEY Patented Mar. .10, 1942 robs the evaporator of its then too low. If the room application} in which:

- portions of the tube'broken away;

,UNITED STAT S" PATENT OFFICE-f REFmGEnArnvq APPARATUS Robert 11. Tull, Springfield, Mass, assignor to Westinghouse Electric & Manufacturing Company; East Pittsburgh, Pa., a corporation of Pennsylvania Application May 4, 1939, Serial No. 271,636

i 7 Claims. This invention relates to mechanicalrefrig- I crating .apparatus and more especially to means for increasing the efliciency of refrigerating apparatus employing a constantly open flow impediIig-devicer l '1 In mechanical refrigerating apparatus: of the -compressor-condenser-evaporator type employing a constantly open flow-impeding device between the condenser and the evaporator, such as used, for example, in domestic refrigerating apparatus, a 'flooding'of the condenser with liquid refrigerant may occur at abnormally low room temperatures. At such temperatures an abnormally large'amountpf refrigerant is condensed in the condenser and accumulate in the lowerpassages thereof. Ifthe evaporator of such a system is, of relatively small refrigerant-carrying capacity, such as is usually the case when the more expensive refrigerants are used, the accumulation of the refrigerant in the condenser nor'mal content of refrigeranirand starves the evaporator. This pro-- duces an uneconomical operation of the appara tus because the liquidlevel in the evaporatorjis is very cold, the evaporator may be starved completely of liquid re frigerant, in which case the suction of the compressor produces a vaporization of theiiquid refrigerant at or within the restricting device thereby cooling the evaporator.

One object of the invention, therefore, is to control the quantity of liquid refrigerant ilrthe evaporator of a mechanicalrfrigerating system employinga constantly open flow impeding de- 3 vice between the condenser and the evaporator.

Anotherobject is to provide a condenser for refrigerant vapor which condenser'has' a high heat-dissipating value and a low volumetric ca-spacity. A further object is to effect a relatively large change in the vapor condensing area of a .re-'

frigerant condenser", when a relatively small change in the volume of liquid refrigerant in the condenser occurs.

[ Theseand other objects ate effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawing'formin'g apart of this g @Fig. 1 is a. side elevationof a condenser with Fig. 2 is an enlarged section of a porti n of g the condenser tube showlng the restricting rod:

I Fig. 3 is a section taken along the line III-III of Fig. 2; and, I a

Fig. 4 is}. diagrammatic view 31 a refrigerator embodying the condenser of this invention.

-' trance end of the capillary tube adjacent the meral I0 represents a condenser and comprises a trally in the tube I I.

tube l I containing a rod l2 of slightly less diameter than the inside diameter of the tube. The rod. l2 may be formed with pinched-out pro-. trusions l3 on its surface to hold the rod lLcen- The condenser is formed by inserting the rod l2 in the tube"l I, bending the tubell, together with the rod I2, into a sinusoidal configuration, and securing cooling -flns H to the outer surface of the tube. The rod l2,

as shown, cccupies the lower portion of the tube' II and is gradually tapered at its upper half.

1 The rod l2, however, maybe of any length and may be tapered in any manner suited to the operation -of the apparatus. The purpose of the rod I2 is to decrease the volumetric capacity of the tube ll, especially at its lower end without decreasing its esternal diameter upon which depends its heat dissipating effect.

The condenser I0 is of particular application in a refrigerating apparatus of the compressorcondenser, evaporator type employing a con-v stantly open impeding device. betweenthe-condenser and the evaporator. Qne embodiment of restrictor rather than the 30 the electrical conduits 23.

'such an apparatus is shown in Fig. 4, and comprises the condenser lllreceiving hot compressed refrigerantvapor at its upper end through a tube I 5 from a. compressor 6, which compressor withdraws vaporized refrigerant through-a suction tube l-l from an evaporator It! in an insulated chamber l9. liquid refrigerant from the lower portion of the condenser I0 through a capillary impedance'tube 2|. A Lscreening device 22 is located at the encondenser Ill. The compressor I6 is drivenby an electric motor 20 which receives power through It will be apparentthat the insulated chamber I9 is refrigerated by the vaporization of liquid refrigerant in' the evaporator l8;

The refrigerating apparatus is controlled by a temperature sensitive device 24 actuated by a bulb 26 containing an expansible fluid, which bulb 26 sis in contact with a side-wall of the evaporator 18. This device 24 controls the temperature of the evaporator 18 between predetermined limits. The volumetric capacity of the condenser I 9 is preferably smallerthan the volumetric capacity of. the, space normally 0 upied by the liquid refrigerantin the evapora r I8. 7 i

The action of -the condenser. Ill on there-'- frigerant-during normal operation can be divided into three distinct steps, These steps take place in-the respective zones A, B, and C, as indicated in Fig. 1. Zone A comprises the upper portion of the condenseradjacent the inlet endthereof in which portion the sensible heat of the superheated-refrigerant'is removed.

Zone B comprises the lower central portion of The evaporator is supplied with duced to a liquid.

. normal level.

. cooling capacity of the condenser.

the condenser adj acent zone A in which the latent heat of vaporization of the refrigerant vapor is removed and the refrigerant vapor thereby re- The upper portion of zone B will contain wet refrigerant vapor and very little 5 liquid refrigerant, the proportion of liquid to vapor will increase as the refrigerant passes through this zone and the refrigerant will be entirely liquefied when it reaches the bottom of the 1 zone.

Zone C is the portion of the condenser containing liquid refrigerant which is being subcooled below its vaporizing temperature. If this apparatus is operated in an abnormally cold room, the areas of zone A and zone B will decrease because the sensible and latent heat is more actively removed than formerly. Zone C containing liquid refrigerant, therefore, will increase in size to occupy the remainder of the condenser Ill. 'The rate at which the refrigerant is forced through the capillary tube 2| into the condenser l8 will also decrease because of the decreased pressure of the refrigerant vapor'in zones A and B. This decreased pressure is caused by the decreased temperature of .the condenser. l0. This decreased flow of refrigerant into the evaporator l8 will also aid in increasing the zone C of the condenser. Because of the insertion of the tapered rod I2 in the lower portion of the condenser, the volume of refrigerant in this portion will be relatively small and comparatively little liquid refrigerant will be takenfrom the evaporator It! so that the liquid refrigerant in the evaporator I8 is moren'early at its Y i as It will be observed that the rod I: in the lower portion of the condenser [0 does not decrease the Neither does it substantially impede the flow of liquid refrigerant therethrough because the linear velocity 40 of the liquid'refrigerant through the tube II is very much less than the linear velocity of refrigerant vapor because of the greater density of the liquid. A very beneficial effect also occurs if the, refrigerating apparatus is operated in an abnor-' mally warm room. In this case, zones A and B will increase in width and zone C will decrease and may disappear entirely. The liquid refrigerant normally in zone C is forced into the evap- 5 orator Ill, but since the volume of liquid in zone C is small because of the presence of the thick end of the rod I! in this portion of the tube II,- the level of the refrigerant liquid. in the evaporator ID will rise but little., At the same time a portion of cooling surface which is disproportionately large as compared to the quantity of refrigerant liquid displaced in zone C is added to zones A and Blwhich added cooling surface aids in condensing the refrigerant vapor in the tube II.

From the above it will be apparent that this invention provides a more eflicient refrigerating apparatus of the-constantly open restrictor type and a means for maintaining the liquid levc of G5 the refrigerant in an. evaporator more nearly constant.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of T0 various changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in 7 the appended claims.

What I claim is:

1. In a closed mechanical refrigerating system, the combination of a cooling unit'adapted .to evaporate liquid refrigerant, a compressor for withdrawing refrigerant vapor from said cooling unit and compressing said vapor, a condenser for cooling and liquefying said compressed vapor, a

conduit including a fixed flow-impeding orifice for conducting the liquid refrigerant from the 0 condenser to the cooling unit, said condenser comprising a refrigerant-carrying tube structure having an entrance and an exit, a substantial portion of said tube structure adjacent its exit end'being of relatively small refrigerant-conducting cross-sectional area, and means for cooling the surface of .said tube structure, the system being arranged to locate the refrigerant level in said tub; structure adjacent its exit end during normal operation, said-condenser being formed to have greater heat-abstracting effectiveness per unit of refrigerant-conducting cross-sectional area of the tube structure at the portion adjacent the exit endthan at the portion adjacent the entrance end of the tube structure, whereby a small change in the volume of liquid refrigerant in the portion of the tube structure adjacent the exit end thereof causes a large change .in the effectiveness of heat abstraction from the refrigerant vapor in the tube structure, .thereby maintaining the level of the refrigerant liquid in the cooling unit more nearly constant.

2. In a closed mechanical refrigerating system,

the combination of a cooling unit adapted to evaporate liquid refrigerant, a compressor for withdrawing refrigerant vapor from said cooling unit and compressing said vapor, a condenser for cooling and liquefying said compressed vapor, a conduit including a fixed flow-impeding orifice for conducting the liquid refrigerant from the condenser to the evaporator, said condenser comprising a refrigerant-carrying tube structure having an entrance and an exit, a substantial portion of said 'tube structure adjacent its exit end being of smaller refrigerant-conducting cross-sectional area than the portion of said tube structure adjacent its entrance end, and means for cooling the surface of said tube structure, the system being arranged to locate the refrigerant level in said tube structure adjacent its exit end during normal operation, said condenser being formed to have greater heat-abstracting effectiveness per unit of refrigerant-conducting cross-sectional area of the tube structure at theportion adjacent the exit end than at the portion adjacent the entrance end of the tube structure, whereby a-small change in the volume of -liquid refrigerant in the portion 'of the tube structure adjacent the exitend thereof causes a large change in the effectiveness of heat abstraction from the refrigerant vapor in the tube structure,'thereby maintaining the levelof the refrigerant liquid in the cooling unit more nearly constant.

3. In a closed mechanical refrigerating system, the combination of a cooling unit adapted to evaporate liquid refrigerant, a compressor for withdrawing refrigerant vapor from said cooling unit and compressing said vapor, a condenser for cooling and liquefying said compressed vapor, a conduit including a fixed flow-impeding orifice 'for conducting the liquid refrigerant from the condenser to the cooling unit, said condenser comprising a refrigerant-carrying tube of uniform cross-sectional area and having an entrance and an exit, a rod in said tube adjacent 2,275,829 its exit end, and means for cooling the surface of said tube, the system being arranged to cate the refrigerant levelin said tube adjacent its exit end during normal operation, said condenser being formed to have greater heat-abstracting effectiveness per unit of refrigerantof=the tube adjacent the exit end thereof causes a large change in the effectiveness of heat abconducting cross-sectional area of the tube at the portion containing the rod than at the portion adjacent the entrance end of the tube, whereby a small change in the volume of liquid refrigerant in theportion of the tube adjacent the exit end thereof causes a large change in the effectiveness of heat abstraction from therei'rigerant vapor in the tube, thereby maintaining the level of the liquid refrigerant in the cooling unit more nearly constant.

straction from the refrigerant vapor in the tube} thereby maintaining the level of the refrigerant liquid in the cooling unit more. nearly constant.

' 6. In a closed mechanical refrigerating system, the combination of a cooling unit adapted to evaporate liquid refrigerant, a compressor-for withdrawing refrigerant vapor from said cooling unit and compressing said vapor, a condenser for cooling and liquefying said compressed v apor, a

4. In a closed mechanical refrigerating system,

, the large end of said rod being adjacent the exit end of the tube, andmeans for cooling the surface of said tube, the system being arranged to locate the'refrigerant level in said tube adjacent its exit end during normal operation, said condenser being formed to have greater heat-abstracting effectiveness per unit of refrigerantconducting cross-sectional area of the tube at the portion adjacent the exit end than at the portion adjacent the entrance end of the tube. whereby a small change in the volume of liquid refrigerant in the portion of the tube adjacent the exit end thereof causes a large change in the eflectiveness of heat abstraction from the refrigerant vapor in the tube, thereby maintaining the the cooling unit level of the refrigerant liquid in more nearly constant. a

5. In a closed mechanical refrigerating system, the combination of a cooling unit adapted to evaporate liquid refrigerant, a compressor for withdrawing refrigerant vapor from said cooling unit and compressing said vapor, a condenser for cooling and liquefying said compressed vapor,

a conduit including a fixed flow-impeding orifice for conducting the liquid refrigerant from the condenser to the cooling unit,,said condenser comprising a refrigerant-carrying tube of uniform cross-sectional area and having. an entrance and an exit, a rod irr only a portion of said tube adjacent its exit end, and means for cooling the surface of said tube, the volume in said tube available to the refrigerant being less than-the volume of refrigerant liquid normally in the cooling unit, the system beingarranged to locate the refrigerant level in saidtube adjacent its exit end during normal operation, said condenser being formed to have greater heat-abstracting effectiveness per unit of refrigerant-conductingcross- 1 sectional area at theportion ofthe tube containing the .rod than at the portion of the tube ad jacent the entrance end, whereby a small change in the volume of liquid refrigerant in the portion conduit including a fixed flow-impeding orifice for conducting the liquid refrigerant from the condenser to the cooling unit, said condensercomprising a refrigerant-carrying tube'ofsub- 'stantially uniform cross-sectional area and having an entrance and an exit, a tapered rod in the 1 tube, the large end of said rod being located near the -,exit end of the tube, the volumetric capacity of said condenser being'lessthan the volume of refrigerant liquid normally in the cooling unit, and means for cooling the surface of I said tube, the system being arranged to locate the refrigerant level in said tube adjacent its constant.

exit end during normal operation, said'condenser being formed to have greater heat-abstracting efiectiveness per unit of refrigerant-conducting cross-sectional area of the tube at the portion adjacent the exitend than at theportion adja-' cent the entrance end of the tube, whereby a small change in the volume of liquid refrigerant in the portion of the tube adjacentthe exit end thereof causes a large change in the effectiveness of heat abstraction from the refrigerant vapor in the tube, thereby maintaining the level of the refrigerant liquid'inthe'cooling unit more nearly 7. In ,a closed mechaiiical refrigerating system,

"the combination of a, cooling unit adapted to evaporate liquid refri erant, a compressor for withdrawing refrigeran vapor from said cooling unit and compressing said vapor, a condenser for cooling and liquefying said compressed vapor, a capillary flow-impeding conduit for conducting the liquid refrigerant from the condenser to the cooling unit, said condenser comprising a refrigerant-carrying tube of substantially uniform cross-sectional area, said tube having an entrance/and an exit,a tapered rod in said tube,

the large end of said rod being located near the exit end of the tube, and means for cooling the surface of said tube, the volumetric capacity of said tube available to the refrigerant therein being lessthan the volume of refrigerant liquid normally in the cooling unit, the system bein arranged to locate the refrigerant level in said 7 tube adjacent its exit end during normal operation, said condenser being formed to have greater heat-abstractingeffectiveness per unit of refrigerant-conducting'cross-sectional area of the tube at the portion'ad'jacent the exit end than at the portion adjacent the entrance end of the tube structure, whereby a small ch ein theivolume of liquid refrigerant in the on of the tube adjacent the exit endthereof causes a' large change in the effectiveness of heat abstraction from the refrigerant vapor in the tube, thereby maintaining the level of the refrigerant liquid in the cooling, unit more nearlyconstant;

. v nonna'rn'r'um

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