SU382667A1 - WORKING BODY VACUUM-ABSORPTION REFRIGERATING - Google Patents

Description

one

The invention relates to refrigeration engineering and relates to the selection of a working fluid from vacuum absorption chillers designed to produce a cold of moderate potential.

Working bodies are known which are solutions of lithium bromide, lithium chloride, lithium iodide, zinc bromide, zinc chloride in water or in methyl alcohol (anhydrous).

The use of such working fluids has a number of operational difficulties. When using aqueous solutions of lithium salts or zinc, it is not possible to obtain evaporation temperatures below ± 2 ° C. The use of methyl alcohol as a solvent in some modes leads to disruption of the normal operation of the refrigerating machine due to the precipitation of salts from the solution. Due to the fact that the solubility of lithium salts and zinc in methyl alcohol is less than their solubility in water, the degassing zone is significantly reduced and thereby increases the circulation ratio of a strong solution. Consequently, this leads to an increase in energy costs and a decrease in the thermal coefficient of the vacuum-absorption chiller.

The purpose of the invention is to reduce the rate of circulation of the solution.

This is achieved by using lithium bromide, lithium chloride, lithium iodide, zinc bromide, zinc chloride, or mixtures of these salts, dissolved in watered methyl alcohol, as a working medium. Use as a solvent of a binary mixture of methyl alcohol - water prevents salt from falling out of solution. In a water-alcohol solution, the weight content of salts is greater than the salt content in anhydrous methyl alcohol; The boiling point of the binary solvent is higher than the boiling point of methyl alcohol - all this, with the same parameters, provides a lower temperature in the evaporator, an increase in the degassing zone and the thermal coefficient of the machine.

The drawing shows a diagram of a vacuum absorption chiller.

By supplying heat to the boiler, methyl alcohol is distilled from the aqueous-alcoholic salt solution. In a reflux condenser, 2 water vapors are condensed and then returned to the boiler. The vaporized methyl alcohol is passed through the condenser 3 to the evaporator 4. In the evaporator, the refrigerant is evaporated and sent to the absorber 5. A strong solution, for example, an aqueous solution of lithium bromide saturated with methyl alcohol, is returned through the heat exchanger 7 to the boil tilter /.

In tab. 1 shows the vapor pressure over

solutions of different salt concentrations in water and in methyl alcohol, and in table. 2 - the multiplicity of circulation of a strong solution but proposed and known methods.

Table 1

Note.

Concentration of weak solution, kg / kg Note.

Example. In the vacuum absorption chiller machine, the working fluids used are: methyl alcohol-coolant, a solution of lithium bromide in water — an absorbent.

Temperature of a strong solution

leaving the boiler, ° С +35

The temperature of the solution leaving the absorber, ° C + 40

Temperature in the evaporator, 0 ° С

Multiplicity of strong circulation

solution, kg / kg

on the proposed method3,12

table 2

3.5

By a known method (water-ammonia machine)

Subject invention

The working fluid of vacuum absorption chillers based on alkaline and alkaline earth metal salts of halogen-hydrogen acids, in which methyl alcohol is used as a refrigerant, is characterized in that, in order to reduce the circulation ratio of the solution, water-methyl mixture is used as a solvent alcohol. The table shows the pressure above the LlBr solution in methyl alcohol, water and water-alcohol solution with a weight ratio of water and methyl alcohol 1: 1. Concentration of a strong solution is 0.66 kg / kg, condensation temperature IK. 2. Figures expressed by fractions mean the ratio of the multiplicity of circulation according to the proposed method to the multiplicity of circulation by a known method (water-ammonia machine).