Experimental investigation of dedicated desiccant wheel outdoor air cooling systems for nearly zero energy buildings

In high-temperature and high-humidity environments, a large amount of energy is consumed to cool and dehumidify outdoor air by dedicated outdoor air systems in nearly zero energy buildings. Desiccant wheels have the advantages of large moisture removal capacities and continuous regeneration. However, the application of desiccant wheels in nearly zero energy buildings is limited by their large regeneration heat capacity and high temperature after dehumidification. A dedicated desiccant wheel outdoor air cooling system is thus proposed. An experimental setup is built and used to test the performances of three modes for dedicated desiccant wheel outdoor air cooling systems. The results show that mode I (wet membrane humidifier downstream evaporation section of heat pipe heat exchanger) has a higher performance coefficient and higher exergy efficiency compared to other modes. The thermodynamic and exergy performances of the proposed mode I system are determined. The results show that the thermodynamic coefficient decreases from 1.3 to 0.52 and the exergy efficiency decreases from 0.76 to 0.18 when the regeneration temperature increases from 60 degrees C to 110 degrees C.