US2257973A - Refrigerator cabinet - Google Patents

Description

Patented Oct. 7, 1941 REFRIGERATOR CABINET Guido Maiuri,

Delaware London, England, vel, Inc., New York, N. Y., a,

assigner to Sercorporation of Application December 29, 1938, Serial No. 248,165

5 Claims.

This invention relates to refrigerator cabinets primarily but not exclusively intended for the preservation, at sub-atmospheric temperatures, of comestibles or other substances, introduced into the cabinet in an already frozen or cooled Condition. For instance already frozen ice cream is preserved in the cabinet at a temperature of from 10 C. to 12 C.

The object of the invention is to provide a refrigerator cabinet which will economically preserve a freezing temperature.

For the above purpose, according to the invention, a refrigerator cabinet is combined with a refrigerating apparatus producing two subatmospheric temperatures, and is provided with a heat-insulated refrigerating chamber cooled by the portion of the apparatus producing the lower of the two temperatures, and the wall of the refrigerating chamber is surrounded by a `region cooled by the portion of the apparatus producing the higher of the two temperatures.

The cooling at the higher temperature between the atmospheric temperature 'and the temperature to be maintained in the refrigerating chamber, of the surrounding region economically intercepts part of the heat leaking in- Wards from the exterior, and thus reduces the `amount of cooling to be effected at the lower temperature. Y

'Ihe surrounding region cooled at the higher temperature should be and preferably is itself externally heat-insulated.

A convenient refrigerating apparatus having two evaporators which can be arranged to produce cold at two different temperatures is described in vUnited States Patent No.' 2,114,602. This apparatus uses dry ice as the original source of cold and converts the extreme low temperature of sublimation of dry ice into a cooling effect at moderate low temperature. This apparatus has two evaporators in one of which refrigerant evaporates from liquid refrigerant into an atmosphere of the refrigerant, and in the other refrigerant evaporates fromy a solution of the refrigerant in an absorption medium into an inert gas atmosphere.

It can, for instan-ce, be arranged that the pure refrigerant, ammonia, evaporates under a pressure of 4,4 atmospheres absolute giving a temperature of 0 C. and, the respective evaporator is used to cool the surrounding frigerant in the other evaporator and which evaporates from the absorption medium, can be arranged to evaporate under a partial pressure of the refrigerant in the inert gas, from 0.25 to region. The re- Great Britain August 4, 1938 -rator f. The metal 0.45 atmosphere absolute, or less accordingto the strength of the aqua-ammonia solution, giving a temperature of 20 C., and this evaporator is used to cool the refrigerating chamber to say 12 C. The inert gas for instance is nitrogen and circulates in contra-110W to the aqua-ammonia solution, `and in being cooled by the dry ice the ammonia condenses until the partial pressure of the ammonia vapour in the stream of nitrogen is about 0.1 atmosphere absolute.

A refrigerating cabinet arranged and embodying a refrigerating apparatus as above described, is illustrated somewhat diagrammatically in sectional elevation on the accompanying drawing,

,in which:

contact with an evaporator e of a refrigeratingapparatus.

The outer metal wall c is in heat-conductive contact with a second evaporator f of the refrigerating apparatus, this second evaporator ,f extending around the inside surface of the wall c.

Refrigerant evaporates in the inner evaporator e at a lower temperature, for instance 20 C., than the temperature, for instance 0 C., at which refrigerant evaporates in the outer evapowall c cooled by the outer evaporator f, consequently intercepts heat leaking through the outside heat-insulation d, and thus reduces the amount of heat which the inner evaporator e must take up from the metal wall a of the refrigerating chamber a1 to maintain the contents of the latter at 'the desired refrigerating temperature. y

The refrigerating apparatus shown on the drawing, is of the kind described in United States Patent No. 2,114,602. In the present apparatus, g is a chamberfor containing a source of intense cold, such as dry ice, i. e. solid carbon dioxide. This dry ice chamber g is surrounded by a jacket h, embedded in the heat-insulation b, and in which is an upstanding partition h1. The jacket h is connected on each side of the partition h1, respectively by pipes e1, e2 with different ends of the inner evaporator e. The jacket h, pipes e1 and e2 and the evaporator e, contain an atmosphere of inert gas, for instance nitrogen. A strong solution of a refrigerant in an absorption medium, such as aqua-ammonia l vent it acting as a gas lift in liquor, circulates through the evaporator e, and from which the refrigerant evaporates under its artial pressure into the inert gas. By convection, the inert gas circulates up the pipe e1 carwith it the vaporised refrigerant, which vapour, returns down the pipe e2 to the other end of the evaporator e. The inert gas ows in the evaporator e in contra-How with the refrigerant liquor, strong liquor being supplied to the evaporator e by a pipe i and impoverished liquor leaving by overowing a Weir lc into a sump l.

The refrigerant liquefied by the cooling effect of the dry ice, ows from the above mentioned sump i by a pipe m into one end of the outer evaporator f. Here the liquid refrigerant is taken up by the capillary action of a metal gauze lining f1, and evaporates.

The refrigerant evaporator f by a pipe n into an external vessel o. The weak liquor from the sump l of the inner evaporator e flows by gravity, along a pipe p, into an external air-cooled vessel q. and q are on the same level pipe p. The liquor thereby becomes enriched before proceeding by the pipe r into the vessel o, so that the refrigerant vapour issuing from the pipe n is not absorbed in the vessel oto such an extent as to prethe pipe s.

The strong liquor raised to the elevated vessel The inner evaporator e and the absorber vessel q are both lined With Wire gauze.

y is a pipe venting the absorber vessel q to the inert gas pipe e1 so that when the apparatus is of the refrigerating chamber a1. By increasing the ratio of the thickness of the outer insulation rators e and f.

The invention can also be carried out with a diffusion refrigerating machine wherein a refrigerant evaporates into an inert gas under different partial pressures of refrigerant in the gas, giving two temperatures. The evaporator is divided and the inner refrigerating chamber is cooled by the portion of the at the lower temperature, whilst the intermediate ature.

I claim: 1. A refrigerator` including a thermally insulated storage compartment,

being arranged element such as 2. In combination, refrigeration apparatus inrelation with said 5. The combination as set forth in claim 2 in which

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