US1737426A - Refrigerating machine of the absorption type - Google Patents

Description

Nov. 26, 1929. G. MAIURI ET AL REFRIGERATING MACHINE OF THE ABSORPTION TYPE Filed April 25, 1929 I Iiibnl'brs Maid/7'2 30,011; 2? 52mm UM fltzbrnevx.

Patented Nov.26,1929

UNITED STATES PATENT; OFFICE REFRIGERATING MACHINE OF THE ABSORPTION TYPE Application filed April 25, 1929, SerialNo. 358,091, and at Great Britain September 29, 1927.

Our invention relates to improvements in refrigerating machines of the kind in which evaporation and absorption of the refrigerant takeplace into and from an inert gas under pressure to compensate the pressure according to Daltons law.

The object of the invention is to provide an absorption refrigerating machine of the above described kind wherein the inert gas is introduced and sealed in the machine at atmospheric pressure. v

The above object is attained, according to the invention, by arranging that the volumetric capacity of the space in which the inert gas circulates in a closed circuit is less than the volumetric capacity of the vapour space in the boiler and condenser, whereby displacement of inert gas from the boiler by refrigerant vapour increases the pressure of the inert gas to a pressure which, in conjunction with the pressure of the vapour, can eflect the liquefaction of the refrigerant.

In order that our invention may be properly understood and readily carried into cffeet, we have hereunto appended one sheet of drawings, of which Figure 1 is a View of one form of apparatus illustrating our invention.

Figure 2 is a similar view of a slightly modified form of construction.

It is to be understood that the machine can be constructed in different forms to that illustrated. V

In carrying out our invention, and referring to Figural of the drawings, we provide a boiler 1 in the form of a coil or other formation, in which the rich ammonia solution is heated for the purpose of driving off. ammonia vapour; 2 is the space above the boiler in which the hot ammonia vapourpasses before going to the condenser 3. In this condenser 3 the gases are cooled by water which circulates in the annular space 4; therein the ammonia vapour is liquefied and passes therefrom by means of a small siphon tube 5 into the refrigerating coil 6 where it evap orates again, so producing cold.

The ammonia vapour produced in the refrigerating coil becomes absorbed again by the weak solution which passes into the absorber 7 represented in the figure as a horizontal pipe, which can however be constructed as a horizontal or helicoidal coil, as Will be hereinafter described.

In order to render the apparatus operative, it is necessary to compensate the difference of pressure between the pressure necessary for the liquefaction. of the ammonia, which liquefaction takes place at the temperature of the cooling water in the-condenser 3, and the evaporating pressure at low temperature in the refrigerating coil 6.

This iseifected in the following manner The machine is charged with ammonia solution at the density necessary to obtain the best results up to the level 8-8, which is slightly above the level of the bottom surface of the absorber 7. By so doing'the absorber 7 becomes partly occupied by liquid, the upper portion remaining occupied by air. The apparatus is hermetically closed at this stage.

When the heating operation is started the ammonia vapour whichis driven off in the boiler, formed'by the coil 1, ascends in the space 2 and from there passes into the condenser 3, expelling the air through the small pipe 5, and driving same into the pipes 6, 7, 9 and 10; if the spaces 2 and 3 have a capacity six times that of the circuit formed by the pipes enumerated, when the ammonia vapour has expelled all the air from such spaces 2, and 3, the pressure in the whole apparatus will be at 7 atms.

By continuing the heating, the pressure will be continuously augmented until it will be a little superior to the pressure of liquefaction of the ammonia at thetemperature of the cooling water in the condenser 3. If, for instance this pressure is 10 atms., there will be in the circuit of the pipes 6, 7, 9 and 10 7 atms. of air pressure and 3 atms. ammonia vapour pressure.

In this condition the liquid ammonia, which by the inverted siphon or trap 5 is conveyed to the evaporator coil 6, can evaporate at the temperature of 10 C. on the evaporation being rendered possible by effective removal of the ammonia vapour by absorption as soon as formed.

The relations between the capacities are calculated so as to obtain the best functioning of the apparatus in relation to the temperature of the cooling water available and in relation to the minimum temperature which is r uired in the refrigerating coil.

As descfibed in the specification of Patent No. 1,725,658, granted-August 20, 1929, of which we are co-patentees, to promote the removal of the ammonia vapour by absorption, mixture of inert gas and ammonia vapour which fills the pipes 6, 7 9 and 10 is forced to circulate sufficiently by the thermosiphonic action which is obtained by heating the mixture in the vertical pipe 9 bycontact of the hot ammonia vapour from the boiler, and by cooling the same in the inclined pipe 10 in contact with the water of the condenser. By suitably dimensioning the length of this pipe 10, this circulation can be accelerated as required.

This forced circulation is suflicient to obtain a good evaporation in the refrigerating coil because therein the ammonia vapour is generated at a pressure which-tends to make it mix with the other gas, but such forced circulation is not normally sufficient in the absorber where the weak liquor absorbs obviously only the ammonia which comes into.

contact with it.

To render the forced circulation eflicient as regards the absorption, it is necessary that the gases should circulate in the absorber in a turbulent manner, in order to increase their contact with the weak liquor.

The desired turbulence is set up in the pipe 7 forming the absorber, by the gases flowing in the upper space thereof above the liquor in a direction opposite to that in which the weak li uor which flows along the bottom, the resdlting fluid friction sets the gas mixture in turbulence and causes more thereof to come into contact with the liquid, which latter absorbs the ammonia and rejects the air. The near] horizontal position of the pipe 7 tends to eep the gas mixture in contact with the liquid as long as possible, whilst however assuring a continuous flow.

In our apparatus the circulation of the liquid takes place by thermosiphonic action in the ordinary way by the heat produced in the boiler and the cooling exchanger, which is in an inclined sition and in which in the part 11 the hquid is cooled and descends whilst in the-tube 12 itis heated and ascends.

The liquid circulation passes through, the pipe 13 which leads the weak liquor intothe absorber 'i'. This pi' e 13 extends'througgh the casin 14, in whic water circulates; thus complete y coolin the liquid before entering into the absor er.

The absorber 7 which we represent as a simple pipe can also have the form of a horizontal coil.

obtained in the by a helicoidal coil and the condenser 3 is also formed by a helicoidal coil. The exchanger, instead of being formed of two concentric pipes is formed by a pipe 11 in which is contained a helicoidal coil 12, and in which the liquor is heated in ascending and is cooled and descends in the tube 11.

The apparatus represented in Figure 2 is intended or being worked by electric heating by an electric resistance 19 wound round the vertical boiler 1. The apparatus is also: designed to work by air cooling and so no' water jackets are provided as in Figure 1. There is also provided an exchanger of temperature 1516, in the circuit of the inert gas, as described in our said patent and a circulation by reverse flow of the liquid ammonia in the refrigerating coil 6, which descends by gravity whilst the inert gas moves in the opposite direction, ascending. This is only possible by the forced circulation obtained by the heating device.

The evaporation will occur with perfect efiiciency with this counterflow disposition. The siphon 18, eliminates any excess of liquid ammonia which may tend to accumulate in the coil and also the water carried by the ammonia vapour.

From the exchanger, the inert gas, rich with ammonia vapour, passes through the pi e 17, into the absorber 7.

aving now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is 1. An absorption refrigerating machine of the kind in which evaporation and absorption of the refrigerant take place into and from an inert gas, in which the inert gas is sealed in the machine at atmospheric pressure, comprising a generator, a condenser, an evaporator, an absorber and conduits therebetween having the volumetric capacity .of said evaporator, absorber and connecting conduits 1n whlch the inert gas clrculates of char ing. the a paratus with liquid. GUf

DO MAIURI. RAOUL FELICE BOSSINI.

The apparatus shown in Figure 1 is dia-

Images