Thermodynamic Study of Solar-Assisted Hybrid Cooling Systems with Consideration of Duration in Heat-Driven Processes

Solar-assisted hybrid cooling systems are promising for the energy saving of refrigeration systems. In most cases, the solar thermal gain is only able to power the heat-driven process of facilities during part of the working period. Therefore, the reduction of compressor power strongly depends upon the duration of heat-driven processes, which has not been addressed properly. Motivated by such a knowledge gap, the thermodynamic understanding of solar-assisted hybrid cooling systems is deepened through considering the duration in heat-driven processes. Three absorption–compression-integrated cooling cycles were taken as examples. It was found that optimal parameters, e.g., inter-stage pressure and temperature, corresponding to various performance indicators tend to be identical, as the duration of heat-driven processes is taken into account. Furthermore, the optimal parameter for different working conditions was obtained. The dimensionless optimal intermediate temperature of layout with the cascade condensation process varies slightly, e.g., 4%, for different conditions. Moreover, the fall of compressor power in the entire working period was nearly independent upon the intermediate temperature. The paper is favorable for the efficient design and operation of solar-assisted hybrid cooling systems.