Energy saving potential of an innovative membrane contactor hybrid system for vehicles’ climate control

In this paper an innovative Membrane Contactor Hybrid System (MCHS) for automotive air conditioning is presented and its energy needs are evaluated and compared with those of a traditional system for internal combustion engine vehicles and hybrid ones. The proposed system joints a Vapor Compression Cycle (VCC) with a Liquid Desiccant Cycle (LDC) provided with innovative Three-Fluid Membrane Contactors (3F-MCs). These components are crossed by air, liquid desiccant and a third fluid operating as an internal heat source/sink to control the desiccant temperature. The VCC refrigerant undergoes a two-stage compression process: the lower level is used in a conventional evaporator for cooling the air, and the higher level in an absorption 3F-MC to dehumidify the renewal air. A second 3F-MC (desorber) is heated (by means of hot water derived from the vehicle's engine) in order to reconcentrate the desiccant by discharging water vapor to the environment. Air temperatures between 26 and 32 degrees C and relative humidity in the range 40-80% are considered to perform the comparisons between the two systems. Results show that energy savings can exceed 40% in the case of the most severe external conditions.