Experimental study of a novel subcooling method based on liquid desiccant dehumidification for vapor-compression refrigeration systems

Refrigerant subcooling could increase the refrigerating capacity and potentially improve the performance of refrigeration systems. In this paper, a novel subcooling method is experimentally studied for the first time in a hybrid vapor compression refrigeration system. In this system, condensation heat (~40 °C) is used to drive an integrated subcooling cycle to subcool the refrigerant leaving the condenser, which significantly increases the system performance. Changes in system performance are measured as functions of the following variables: the mass flow rates of the dehumidification air, ambient air, dehumidification solution, regeneration solution, and spraying water. Comparisons are made between the proposed system and the traditional water-cooled chiller. The proposed system can achieve a larger degree of subcooling (15–20 °C); what’s more, it shows much higher performances than the traditional water-cooled chiller: COP and exergy efficiency of the chiller are improved by 18.6% and 27.9%, respectively. Performance of the integrated subcooling cycle is also evaluated; it has a low COP, with the maximum value of 0.13, due to the low-grade condensation heat; however, it has a pretty high exergy efficiency, with the maximum value of 0.28, which indicates the effective use of the low-grade heat. In addition, an economic analysis of the integrated subcooling cycle is made with a project life cycle of 15 years; the payback period varies from 2.4 to 3.2 years based on different electricity tariffs, and the savings to investment ratio is between 1.3 and 2.1, which indicates that the project is profitable.