EN Analysis of temperature modes and temperature differences in heat exchangers of solar-powered absorption refrigeration systems

Abstract

Solar cooling technologies include a solar power plant as a heat source and heat-using refrigeration machine as a cooling production. The article presents the analysis of temperature regimes and temperature differences in heat exchange devices of absorption refrigeration systems from the standpoint of ensuring the workability and high efficiency of processes. The analysis was performed on the example of a single-effect water-ammonia absorption machine. The analysis is based on the following conditions: the presence of the system limit cycle. That is, the interdependence of the temperature potentials of three heat sources, two of which are chosen arbitrarily, the third is a function of the first two; temperature regimes and temperature differences in the heat exchangers are given in interaction with the temperatures of external energy sources .The presence of a system total temperature differences, consistent with the limit cycle at known temperature levels of the heat sources, was established. The total head takes into account: the generator temperature range, the temperature at the generator hot edge, the temperature at the solution heat exchanger cold edge, the temperature differences at the absorber cold edge, at the condenser smallest temperature differences, water heating in the condenser. The issue of optimizing temperature differences in system elements is proposed to be solved by considering the variable component of capital costs associated with the cost of each heat exchanger depending on the temperature differences. For the practical implementation of cycles with the considered temperature regimes and solar powered generator on the basis of energy saving, cycles of absorption systems "with an extended degassing zone" are proposed. The cycles are implemented under conditions of different nature of temperature changes of energy sources and working fluid in the heat exchange processes between them. Solving problems is recommended by creating complex schemes and cycles of hybrid water-ammonia refrigeration systems

Keywords

• solar cooling technology
• water-ammonia absorption system
• heat exchanger
• temperature difference
• degassing zone