Investigation of a high-efficient hybrid adsorption refrigeration system using desiccant coated heat exchangers

Abstract

To extract as much energy as possible from a low-grade heat source in the range of 50–95 °C, a hybrid adsorption refrigeration system using desiccant coated heat exchangers is proposed and investigated in this study. This hybrid system can be operated in three working modes to satisfy various demands for cooling capacity output forms and system performance. Models of the adsorption refrigeration system and desiccant coated heat exchangers are integrated to match the two separate systems and evaluate the system performance. The results indicate that 24 °C is the optimal chilled water temperature to establish circulation between the two systems. Mode 1 exhibits the best cooling capacity output, which is 24% and 32% higher than that of Mode 2 and Mode 3, respectively. Mode 2 ranks first in exergetic efficiency with a heat source of 50 °C and reaches a maximum thermal coefficient of performance (COPth) of 11.09% and 0.998, respectively. Mode 3 provides the highest exergetic efficiency at a heat source of 55–95 °C and a cold-water supply. Finally, the performance of the hybrid system is compared with that of a traditional adsorption system to verify the improved efficiency and wider operable heat source range of the proposed system. The hybrid system can operate effectively with a heat source range of 50–95 °C, while the traditional system cannot work below 65 °C. The COPth of Mode 2 is superior to that of the traditional system, and the heat source of 50–65 °C results in a better COPth of Mode 1, while the traditional mode shows higher COPth than that of Mode 3 at a heat source of 65–95 °C. The three modes outperform than the traditional mode in terms of exergetic efficiency. The proposed hybrid system can thus effectively exploit a low-grade heat source with high efficiency, providing a promising solution for efficient energy utilization.