Вдосконалення енергетичних характеристик генераторів абсорбційних холодильних агрегатів

Abstract

Based on the original method of calculating the thermodynamic parameters of the generator of the absorption refrigeration unit (ARU), the analysis of its operating parameters is performed taking into account the results of experimental studies of typical production analogues. The results of the theoretical study allowed us to draw the following conclusions. First, in contrast to pure substances, when operating the generator on binary mixtures, in particular, on watert-ammonia solution (WAS), the supply coefficients of the generator depend on the magnitude of the applied heat load. Thus, when increasing the heat load from 40 to 80 W, the numerical values of the supply factors are reduced by about 3 times. Second, the dependence of the specific amount of supplied heat has an optimum (minimum) in the range of heat loads from 40 to 80 W and end-boiling temperatures from 145 to 170 °C. The main significant result of the calculated research can be considered the found criticality of energy efficiency and temperature of the end of vaporization (boiling) of WAS in the generator. It is shown that the operation of a typical ARU with air cooling of heat-dissipating elements at an ambient temperature of 25 °C is most effective in the temperature range of the end of boiling from 147 to 155 °C. The decrease and increase of this temperature outside the optimal range leads to an increase in the specific energy consumption during the operation of ARU, up to 9%, and in the first case it is due to unreasonably high heating of the liquid phase, and in the second – with increasing absorbent (water) in steam mixture. It is also shown that the presence of a minimum of energy consumption during the operation of the ARU generator is explained by the fact that in the studied range of mode parameters of the thermosyphon (temperature at the generator inlet from 87 to 112 °C, at the outlet from 145 to 170 °C, system pressure 9 bar, mass fraction of ammonia in WAS 0,34) the optimal ratio of the composition of the liquid and vapor phases at the output of the generator. A detailed study of the physical nature of this effect should be carried out on the basis of joint modeling of thermal and hydraulic characteristics of generators