Applicability of an organic Rankine cycle for a liquid desiccant-assisted dedicated outdoor air system in apartments

Abstract

This study investigates the dehumidification and energy performance of central ventilation systems based on a liquid desiccant-assisted dedicated outdoor air system applied to an apartment residential building. This heat-driven central ventilation system should receive heat energy because of regenerating the liquid desiccant. An organic Rankine cycle (ORC) consists of the central ventilation system proposed in this study to provide heat to the regeneration of the desiccant solution. The overall configuration of the ventilation system consists of three main devices, a liquid type of desiccant system, an evaporative cooler driven indirectly to utilize free cooling energy, and the electric heating coil to supply the process air at a neutral temperature condition. The size of the ORC is determined to provide the base electricity demand of community facilities in the apartment selected in this study. The evaluation of the size and energy performance is conducted through a detailed simulation. The results of the energy simulation are compared with heat-driven desiccant wheel and conventional energy recovery ventilation systems. The proposed system demonstrates 4%–24% lower annual primary energy consumption than two existing ventilation systems. This result can be expected that the proposed liquid desiccant-based central ventilation system incorporating ORC is possible to contribute to the achievement of the zero-energy building by using both electricity and heat energy.