US2001697A - Absorption refrigerating machine - Google Patents

Description

May 21, 1935. E. ALTENKIRCH ABSORPTION REFRIGERATING MACHINE Filed Aug. 14, 1930 2 Sheets-Sheet 1 Fig. I

. Era- May 21, 1935. E. ALTENKIRCH 2,001,697

k v ABSORPTION REFRIGERATING MACHINE F'ile d' Au 14, 1950 2 Sheets-Sheet 2 Patented May 121, 1935 2,001,697 ABSORPTION asrarcsaa'rme moms Edmund Altenkirch, Neuenhagen, near Berlin, Germany, assignor, by mesne assignments, to The Hoover Company, North Canton, Ohio, a

corporation of Ohio Application August 14, 1930, Serial No. 475,206

In Germany August 20, 19 29 4 Claims. (01. 62-1195) My invention relates to an absorption refrigerating machine with a working medium which condenses at atmospheric pressure at a tempera- 'ture of about 10 to 20 degrees centigrade above the highest room temperature practically occurring. This is, for example, the case with ethylene dichloride. An absorption refrigerating machine of this kind has a number of important advantages. The pressure at which the pure working medium condenses in an air-cooled condenser, even under unfavorable cooling condi tions is just below the atmospheric pressure, whereas in the absorption refrigerating machines known up to the present the condensing pressure was as a rule either considerably higher or considerably lower than the atmospheric pressure' With the subject-matter of the invention, both disadvantages, existing if the internal pressure of the machine is above atmospheric, for instance, the possibility of the working medium escaping into the surrounding space, and the difficulties caused if a high vacuum is to be maintained, are eliminated.

Owing to the comparatively low pressure in the whole machine, the difference in pressure between the evaporator and the liquefier is also small. If water cooling is employed, the difference inv pressure can therefore, be equalized by columns of liquid, in order to be able to operate without pumps or valves. The liquid columns need in this case only be made moderately high, so that the machine is very suitable for household purposes. If air cooling is employed, the height can be maintained within the desired limits by admixing a neutral gas.

Among the organic substances possessing the property mentioned at the beginning, the said ethylene dichloride is, according to the invention, employed to great advantage as a working medium. Its condensation point'is (at atmospheric pressure) at +55 degrees centigrade, its solidifying point lower than -70 degrees centigrade i. e. lower than the necessary evaporating temperature practically required for most purposes.

As a solvent for ethylene dichloride, according to the further invention, paraflin oil is to be employed. Paraflin oil has a very high boiling point, about 360 to 390 degrees centigrade. This fact makes it possible to raise the temperature for heating the expeller to a considerably higher degree than is possible for example with aqueous ammonia solutions even at high pressures. Now, large differences between the expelling temperature and the condensation temperature mean corresponding low temperatures in the production of cold. Moreover, when ethylene dichloride is being expelled from a solution in paraffin oil, an evaporation of considerable quantities of the solvent need not be reckoned with.

' The specific gravity of paramn oil is lower than that of ethylene dichloride, and this fact influences favorably an automatic circulation of i the liquid between the generator and the. absorber, disposed at a higher level.

If cold is not produced by evaporating the condensate but by expelling gas from a strong absorption solution of ethylene dichloride in parafiin oil, the mentioned working medium is also suitable for absorption refrigerating machines op-' erating with air cooling and without an indifferent gas. The diiierences in pressure can in this case also be maintained by means of columns of liquid of a small height.

If water cooling is preferred, then one obtains,-

for operation with ethylene dichloride, a very simple construction of the absorption machine, since the admixture of indifierent auxiliary gas is in that case not necessary. Thermically, the manner in which a machine of that kind operates is so favorable, that it is suitable for being built for very large refrigeration outputs. v

In the drawings, the invention is diagrammatically illustrated in two modifications.

Figure 1 shows a continuously acting absorption refrigerating machine operating with condensation, in which an indifferent auxiliary gas (air) is mixed with the gaseous working medium (ethylene dichloride) in the evaporator and absorber, whereas Figure 2 illustrates an absorption refrigerating machine operating on the re-absorption principle and withoutan auxiliary gas.

In the arrangement according to Fig. 1, liquid ethylene dichloride flows from an air cooled condenser I5 through a pipe 2 into the evaporator I.

By falling in drops over the baffle plates 3 in the evaporator, it evaporates into the mixture of air and ethylene dichloride, which is weak as to its co'ntent of working medium, and which passes through the evaporator from the bottom to .the top. The gas mixture streaming into the bottom of the evaporator I through the pipe 4, leaves the evaporator, after having enriched itself with ethylene dichloride, at the top through the pipe 5, and then passes through the pipe 6 into the bottom of the air cooled absorber 1, provided with ribs i8. 'Inside the absorber, weak absorption solution, conveyed into same through the pipe 8 andconsisting of parafiin oil and ethylene dichloride, falls in drops over the bailie plates l9 fittedin the absorber; it gathers at the bottom and flows off again through the pipe 9. The pipes 8 and 9 are so arranged as to exchange heat with each other. In the absorber, the solution absorbs a great part of the working medium from the gas mixture, so that the latter only retains a small content of ethylene dichloride, when it leaves the absorber through the pipe 4. The enriched solution flows from the absorber through the pipe 9 into the generator I!) which is heated ride gas is conveyed through the pipe l4 into the condenser l5. Here it is condensed, the heat of condensation being given up to the surrounding air. From the pipe I, a pipe l6 branches off, which ends in a nozzle l1 arranged in pipe 6 conveying gas mixture. The ethylene dichloride gas discharged through this nozzle imparts a motion to the gas mixture, causing it to move in an upward direction through the absorber and the evaporator. The circulation of the gas mixture through .the evaporator and the absorber takes place in the direction indicated by arrows, i. e. in the contrary direction to the flow of the liquids.

In the arrangement according to Fig. 2, gaseous ethylene dichloride is developed in the generator 2|, heated by an electric heating element 22, from a solution of ethylene dichloride in paraffin oil. The gas expelled through the supply of heat rises, in mixture with the absorption solution, in the upwardly extending pipe 26 up into the gas separation chamber 2|, the absorption liquid separate. Whilst the liquid passes through the U-shaped pipe 25 into the air-cooled absorber 26, the gas is conveyed through a pipe 28, opening into a rising pipe 33, filled with solution, to a re-absorber 29, also air cooled, which is connected, by means of a pipe 36, with the gas space of the evaporator 3|, at a higher elevation. Through a pipe 62 connected to the liquid space of the evaporator 3|, and forming a heat exchanger with the pipe 36, absorption liquid ethylene dichloride in paramn oil) flows from the evaporator ll into the abovementioned rising pipe 36. The gaseous working medum flowing from the pipe 26 into the pipe 33 rises with this solution into the re-absorber 26. Here it is absorbed by the solution and gives up heat to the surroundings. The ethylene dichloride vapor evaporated from the absorption solution in the evaporator ll, for which process heat is taken from the surroundings, passes through a pipe 36 into the absorber 26, where it enriches the weak solution entering through the pipe 26. The enriched solution flows through a pipe 21, which'forms a heat-exchanger with the pipe 26, to the generator 2|. The gas space of the absorber 26 is provided with an air discharging device 34 by the means of which gaseous parts, which may have penetrated into the absorber and are not absorbable, may be removed from the refrigerating machine.

In the refrigerating machine last described, two completely separate circulations of absorption liquid take place. In both systems (generator 2 I gas separation chamber 24, absorber 26 on the one hand, and re-absorber 29, evaporator 3| on the other hand), the circulation of the liquid is maintained by the absorption liquid being lifted by the gaseous ethylene dichloride developed in the generator 2i. The circulation'of the liquid between the generator and the absorber, situated at a higher level, is facilitated by the fact that the strong solution containing much ethylene dichloride and therefore having a higher specific where the gas and gravity moves mostly downwards in the pipe 21, whereas a specifically lighter solution rises inthe pipe 23.

I claim as my invention:-

1. In a continuous absorption refrigerating system using ethylene dichloride as a refrigerant and parafiln oil as an absorbent, an absorber, a generator located below said absorber, conduits connecting the generator and the absorber for circulating the paraflln oil between and through the same, means for causing the ethylene dichloride to evaporate from a liquid to produce a cooling eflect, means for conveying the ethylene dichloride vapor into the absorber to cause it tobe absorbed by the paraflln oil therein and be conveyed to the generator, means for appiyi'ng heat to the generator to expel the ethylene dichloride from the paraffin oil and means for condensing the expelled ethylene dichloride and conducting it into the evaporating means, the arrangement being such that as the ethylene dichloride is supplied to the paramn oil in the absorber, conducted downwardly from the absorber to the generator in solution in the parafiln oil and expelled from the paraffin oil in the generator the circulation of the paraflin oil is favorably influenced due to the fact that the density of the solution of ethylene dichloride and paraflln oil is greater than the density of the paraflln oil per se.

2. A continuous absorption refrigerating system including an absorber, a generator located below the absorber, conduit means for conveying an absorption liquid downwardly from the absorber to the generator, conduit means for conveying the absorption liquid from the generator back to the absorber, means for adding a refrigerant to the absorption liquid in the absorber and for removing the refrigerant from-the absorption liquid in the generator, said refrigerant having a greater'speciflc gravity than the absorption liquid whereby the density of the liquid is increased in the absorber and decreased in the generator due to the addition and removal of refrigerant to foster circulation of the absorption liquid under the influence of gravity.

3. A continuous absorption refrigerating system including an absorber, a generator, a conduit for conveying a liquid from the absorber to the generator, a conduit for conveying a liquid from the generator to the absorber and an arrangement causing circulation of said liquid'through said conduits including means for adding a fluid to the liquid in an absorber and removing the fluid from the liquid in the generator, the fluid having a greater specific gravity than the liquid thereby increasing the density of the liquid in the absorber and decreasing the density of the liquid in the generator whereby circulation may be fostered by the action of gravity on the portions of the liquid of different density.

4. The method of causing the circulation of an absorption liquid in a circuit between the absorber and the generator of a continuous absorp tion refrigerating system which includes the steps of causing the liquid to absorb a gas, in the absorber to thereby increase the density of the absorption liquid and expelling, the absorbed gas in the generator to decrease the density of the absorption liquid, and fostering circulation of the liquid under the influence of gravity action on the portions of the absorption liquid of diflerent density.

EDMUND ALTENKIR-CH.

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