Exergoeconomic design criterion of solar absorption-subcooled compression hybrid cooling system based on the variable working conditions

Abstract

The solar absorption-subcooled compression hybrid cooling system (SASCHCS) is subjected to the off-design operation due to the variation of solar irradiance and cooling load. Therefore, the recent design based on the specific condition is difficult to make the system cost-effective in the entire working range. This paper mainly deals with the exergoeconomic design criterion of hybrid system based on the variable working conditions to access the trade-off of investment cost and performance in the whole working condition. The SASCHCS employed in the low-rise building and the high-rise building is considered. Besides, twenty-four cases with different important parameters, i.e., the size of absorption subsystem, condenser and evaporator of compression subsystem as well as isentropic efficiency of compressor, are analyzed in detail. The product cost flow rate and relative cost difference are taken as the decision variables. The exergoeconomic off-design model is developed at first. Subsequently, the decision variables for different temperatures of hot water and cooling water as well as load level is obtained and analyzed. It is found that the difference of the design guideline for the system used in the low-rise building and high-rise building lies in the size of absorption subsystem and condenser, i.e., the lowest scale of absorption chiller is appropriate when the temperature of hot water is less than 75 °C for the facility applied in the low-rise building, but the largest size of absorption subsystem is attractive in the entire range of hot water temperature as the hybrid system is used in the high-rise building. This paper is positive for the development of design theory and helpful to design the cost-effective SASCHCS under the entire working range.