劣化およびレトロフィットを伴うヒートポンプシステムのサイクルシミュレーション(熱工学,内燃機関,動力など)

抄録

This paper shows numerical simulation to predict how a heat-pump system behaves in a variety of conditions and specifications. A model of heat-pump system, which consisted of a constant rotational speed compressor, a condenser, an evaporator, a decompression device and connecting tubes, was employed. Steady state governing equations for refrigerant flows and the state of refrigerant given by REFPROP 8.0 was solved by iterations. Characteristics of a heat-pump system with different heat transfer coefficients of condenser caused by degradation, different ambient temperatures and different specifications due to retrofit by installing an additional condenser and replacing refrigerant were predicted by the simulation. As a result, a decreased heat transfer coefficient (from 600W/m^2/K to 450W/m^2/K) reduced COP by 7%, and an increased ambient temperature (from 35℃ to 40℃) reduced COP by 10%. Installing an additional condenser to the degraded condenser reduced the work of compression by 5% and recovered COP to the rated value. Moreover replacing the refrigerant R22 with R134 a reduced the work of compression by 35% and increased COP by 15% while the cooling capacity became 75% of a rated value.