US2478791A - Refrigeration plate cooling unit - Google Patents

Description

9- R. H. SWART 2,478,791

REFRIGERATION PLATE COOLING UNIT Filed March 14, 1946 2 Sheets-Sheet l Aug. 9, 1949. v v R. H. swART 2,478,791

REFRIGERATION PLATE COOLING UNIT I Filed March 14, 1946 2 Sheets- Sheet 2 Patented Aug. 9, 1949 REFRIGERATION PLATE COOLING UNI T Richard H. Swart, Utica, N. Y., assignor to Savage Arms Corporation, Utic New York a, N. Y., a corporation of Application March 14, 1946, Serial No. 654,380

My invention relates to refrigeration plate cooling units, and I declare the following to be a full, complete, concise and exact description thereof sufficient to enable anyone skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings in which like reference characters refer to like parts throughout the specification.

The object of the invention is to provide a refrigerant unit employing two or more refrigerant plates connected in series in such manner that the gaseous portion of the refrigerating mixture is allowed to by-pass the refrigerant circuit in the plates, whereby the refrigerant circulates with negligible pressure drop. It is important that there be negligible pressure drop in the circuit in order to maintain a temperature uniformity throughout the series of refrigeration plates. Furthermore, low pressure drop is conducive also to high thermodynamic efliciency of the complete system.

Heretofore, there has been in use the conventional continuous or serpentine refrigerant circuit similar to continuous pipe coils, and also the trapped or flooded circuit. The continuous type has the advantage of providing positive oil return by avoiding 'a building up of oil concentration in the refrigerant due to the high velocity of the vapor, whereas the flooded or trapped type has the advantage of high heat transfer forthe reason that the interior surfaces of the plates used are covered with almost solid liquid refrigerant. The continuous type has a very low heat transfer due to the small quantity of liquid in contact with the metal of the plate. The flooded type tends to concentrate oil in the refrigerant and portions of the plates tend to become oil logged.

Moreover, in a refrigeration apparatus having a multiple plate circuit comprising a. compressor, condenser and evaporator, the required evaporator surface to effect refrigeration must be relatively great and thereby requires great length of conduit, which causes pressure drop in the expanding refrigerant circuit.

The present invention combines the merits of both the continuous and flooded or trapped types by providing a by-pass in each plate. whereby the vapor in the refrigerant mixture is short circuited and reunited with the refrigerant unevaporated liquid and the mixture allowed to proceed through its course in the refrigerant plates connected in series.

The apparatus is self cleaning in regard to objeotional oil concentration in the refrigerant, for

1 Claim. (Cl. 62-126) the reason that the unevaporated liquid carries the oil in solution through the plates arranged in series.

The object will be understood by referring to the drawings in which:

Fig. 1 is a perspective view of the refrigeration unit.

Fig. 2 is an elevational view of one of the plates in the unit.

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 2.

Referring more particularly to the drawings, the present apparatus employs several refrigerant plates designated l, 2 and 3, which are made preferably by uniting two sheets of metal 4 and 5 and Welding them together at the outer or marginal edges as at 6. Sheet 4 is embossed to form with sheet 5 used as a back wall a continuous passageway in therethrough for the circuit of the refrigerant.

This continuous passageway 10 of each of the several plates I, 2 and 3 has respectively an inlet fitting H, a lower horizontally disposed manifold l5 located near the bottom portion of each of said plates 1 2 and 3 and vertically disposed conduits IS, IT, I8 and I9. Said vertical conduits l1, l8, and I9 are connected at their upper ends with outlet manifold 20 disposed in parallel relation to manifold IS. A fitting 2| is formed or attached to plate I at the location of the outlet of manifold 20 for the attachment of connecting pipe 22. The opposite end of pipe 22 has a similar attachment to plate 2.

A by-pass conduit 24 disposed at an angle and having a predetermined cross sectional area joins the upper part of conduit [6 with the left hand end of the conduit of outlet manifold 20, whereby to allow the vapor in the refrigerant to be short circuited from conduit Hi to manifold 20 without passing down with the refrigerant liquid through conduit l6 to manifold l5.

Manifolds l5 and 20 and vertical pipes or conduits l6, l1, I8 and I9 operate together as a flooded refrigeration circuit for the reason that they are nearly completely liquid filled. They are designed, however, to minimize liquid volume and thus oil concentration in the refrigerant.

Plate 2 is made similar to plate I and is disposed in reverse relation thereto with its inlet at the end opposite to that of plate I. It has an inlet header 25, a lower manifold 28, vertical risers or conduits 21, 28, 28 and 30, an outlet manifold 3|, and a by-pass conduit 32, whereby to allow for the short circuit of the vapor. It has also a nipple 33 for the attachment of connecting pipe 22.

Likewise plate 3 is similar to plate I and is disposed in the same position with respect thereto, it has an inlet header 35, a lower manifold 36, vertical risers or conduits 31, 38, 39 and 40, an upper outlet manifold 41 and a by-pass conduit 42 connecting the upper portion of conduit 3'! with outlet manifold 4| It is attached to plate 2 by connecting pipe 43 at the end opposite to connecting pipe 22.

Plate 3 is joined to accumulator plate 45, made similar to plates 2 and 3, except it has no bypass conduit. It is bent atzright angles to itself at 45. There is an inlet manifold 4"; a lower manifold 48 and connecting conduits 50. Manifold 41 is connected to compressor 5lby a pipe 52, which in turn is connected by a pipe 53 of much smaller diameter than pipes 22, 43% and 52 to condenser 55 and thence to high side float valve 561' Valve 55- is connected to dehydrator 5-t by pipe 58 of the same diameter as pipe 53; Said dehydrator 57 is connected to plate t by pipe Gil-which has a very small calibrated diameter to restrict the liquid flow to a predetermined degree Pipe 60 is attached to the coiled part iii of suction pipev 52, whereby to aid in cooling the refrigerant passing therethrough, thereby utilizing the sensible cooling. effect of the cold suction vapor passing through said pipe 6|.

The: operation of the apparatus is effected by compressor 5i forcing the refrigerant through the system. From compressor 5|, the refrigerant passes through pipe 53 to condenser 55- where the refrigerant is liquefied. A far- .5.4 will aid in. cooling condenser 55 which is. kept warm due to the liberation. of heat of the refrigerant,- returning to a liquid body. From condenser 55 the refrigerant will pass to high side float, valve 56- which admits the condensed refrigerant liquid to the dehydrator 5i. Said dehydrator- 5'Iv absorbs any water from the refrigerant and thence it passes on through restrictor pipe 60' to coil. 5]... The high pressure warm refrigerant liquid in. pipe 60. will be cooled .bythe returning. cold vapor in pipe 52 at coil 61. In passing through restrictor. pipe 63-, the pressure is reduced and a portion of. the liquid evaporates, whereby the refrigerant. becomes a mixture of liquid and vapor.

This refrigerant mixture of liquid and. vapor will enter fitting ii of plate I. The liquid pore; tion of the refrigerant mixture will flow down by its own velocity aided by gravity through conduit I6 past by-pass conduit 24' into lower manifold whence it will rise. through vertical conduits IT, !8 and IE! to outlet manifold As said refrigerant rises in conduits. I'll. 18' and I9 it will partially evaporate thereby absorbing heat to cause refrigeration. V

In the meantime, while the refrigerant liquid and the vapor generated from the boiling liquid is passing upwards through conduits i1, i8; and I9} the vapor portion entering plate I will have escaped through by-pass 24 to outlet manifold 20: and rejoin the vapor generated. in conduits Ill; l8. and Li at manifold outlet 20. This mixture of vapor and liquid passes on to plate: 2.

This same process will-happen asthe refrigerant. passes through plates 2 and 3. When the refrigerant mixture, however, comes; to accumulator plate 45, the refrigerant liquid willbe sep arated. from; the vapor which will be sucked through pipe 6i back to compressor. 51.

By thus allowing the vapor to escape through the several icy-passes 24, 32 and 42 of the system, the pressure drop throughout the apparatus or unit as a whole will be negligible. This is extremely important in maintaining temperature uniformity throughout the system as well as conducive to good thermodynamic efiiciency due to; low pressure drop in plates i, 2 and 3 or the unit as a whole. i

In order to effect the above mentioned uniiormity of temperature throughout the system, it is necessary to prevent the accumulation of oil in the vertical conduits in plates 1, 2 and 3.

'Inusual refrigeration systems, a small quantity of oil. pumped through the compressor 5| circulates with the liquid refrigerant. This oil is non-volatile and therefore tends to accumulate in any part of the refrigeration evaporator plates I, 2 and 3 which is not swept through, either by positively circulated liquid refrigerant or by highveloeity vapor. A vertical conduit, sealed at its. lower end is particularly liable to become oil-logged for the above reasons. Special means of preventing this condition, herein described will prevent this accumulation of oil,

which obviously result in that portion of the evaporator plates I, 2 or, 3, warming above the desired temperature due to lack of refrigerating liquid feed. If, however, a multiplicity, of vertical conduits are provided with a horizontalconduit connecting them at their lower ends, the incoming liquid refrigerant, being heavier than theoil, will displace the oil upwardly, bothby reason of the greater density of the refrigerant, and also by the boiling action-,; and Vapor generation of the refrigerant. If each conduit were fed. a sufficiency of liquid refrigerant to completely vaporize it, it should be necessary depend upon the vapor velocity alone tore move the accumulation of oil in the. conduit, and it might be possible to build up an accumulation of a high. percentage of oil in the liquid refrigerant lowerin the vertical conduit. It has been found, however,v that if each verticalconduit is provided with an ex'ces's of liquid refrig erant over and above that, required for cooling; that section of the plate, there is no tendency of oil to either increase appreciable in concen-- tration in the liquid refrigerant, or to completely oil log the conduit.

More specifically as the refrigerant liquid, passes downwardly in conduit iii of plate I by the. vapor. lay-pass 24,. it establishes an essenti'al'l'y. static head of solid refrigerant liquid in conduit l6" of plate I, whereas any vapor formed insaid conduit l6 bubbles upward through one d'uit l5" and passes out through by-pass 24, conduit 2'0 and pipe 22 to the next plate 2.

The refrigerant liquid passing downwardly in conduit I6. continuously replaces, the evaporating liquid in conduits ll, [8 and i9. Moreover, the refrigerant liquid is supplied to the conduits in plate I in excess of that required for complete vaporization and for this reason the surplus liquid together withv the lily-passed vapor, and. the vapor formed by evaporation in conduits ll, l8 and i9 ofpl'atel passes upwardly and out through: conduit 28- and pipe 22 to the next plate 2.

This excess liquid refrigerant carried with it in solution the circulatin oil. Anytendency. of the oilto concentrate locally in any of theconduits of plate I is overcome by the constant renewal of refrigerant. liquid of high density and low in oil concentration fed into the bottom of- 5 conduits l1, l8 and IQ of plate I, and by the rapid upward velocity of the combined refri erant liquid and vapor in said conduits.

The mixture of excess liquid and vapor passes out through conduit 20 of plate I and pipe 22 to plate 2 where the same process is repeated. A considerable number of such plates as I may be refrigerated in series in this manner without excessive pressure drop, and without building up oil concentrations in any of the plates I, 2 and 3.

A wire 65 of predetermined diameter is inserted in tubing or pipe 60 at fitting 66, whereby to compensate for variation in the internal diameter of said pipe 60. Furthermore, varying the length of wire 65 in pipe 60 will permit of adjustment of the restrictive efiect of said pipe 69. Placing the major portion of the restrictive effect near the outlet of pipe 60 increases the thermal efilciency thereof by preventing the vaporization of any of the refrigerant liquid throughout the major portion of tube 60.

It will be observed that plate 3 and accumu-' lator plate 45 are connected by pipe 49.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is as follows: 7

In a refrigeration plate cooling unit, an evaporator plate comprising a flat plate, an embossed plate superimposed on and secured to said flat plate for forming conduits therebetween, one of said embossments forming an outlet manifold,

an outlet fitting for the outlet manifold positioned adjacent an edge of the evaporator plate, another of said embossments forming a manifold parallel to and spaced from the outlet manifold, still other of said embossments forming parallel conduits some of which connect the second mentioned manifold to the outlet manifold, an inlet fitting positioned adjacent said edge, one of said parallel conduits connecting said inlet fitting with the second mentioned manifold, a by-pass formed by certain of said embossments, said by-pass extending obliquely from said one conduit and connecting the same with the discharge portion of the adjacent parallel conduit, whereby when the evaporator plate is in a vertical operating position the by-pass will operate to permit refrigerant vapors to pass from the upper part of said one parallel conduit to the outlet manifold.

RICHARD H. SWART.

REFERENCES. CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,156,544 Raskin May 2, 1939 2,166,161 Kleist July 18, 1939 2,349,695 Beane May 23, 1944 2,398,262 Swart Apr. 9, 1946

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