Research on thermodynamic performance of a novel building cooling system integrating dew point evaporative cooling, air-carrying energy radiant air conditioning and vacuum membrane-based dehumidification (DAV-cooling system)

In this work, a novel building cooling system is proposed, namely DAV-cooling system, which integrates dew point evaporative cooling, air-carrying energy radiant air conditioning and vacuum membrane-based dehumidification. The DAV-cooling system does not use any organic refrigerants, and can naturally provide fresh air indoors to prevent managers from arbitrarily reducing fresh air, and can be flexibly adjusted to meet different cooling requirements. In addition, the thermodynamic model of the DAV-cooling system is established, and some systematical analysis of parameters of the DAV-cooling system is carried out. The results indicate that there is an optimal ratio of fresh air to primary air for the DAV-cooling system, and the optimal value of this ratio should be in the range of 0.2–0.4. When the DAV-cooling system operates under the condition of a higher flow of primary air, the requirements for the dehumidification efficiency of the vacuum membrane-based dehumidification device can be reduced. Moreover, the relationship between COP and cooling capacity ratio is revealed, and it is found that COP decreases as the cooling capacity ratio increases, but they are not in an absolutely one-to-one relationship. Outdoor temperature and humidity also have a greater impact on the performance of the DAV-cooling system. For Singapore and Changsha in the period from June to August, the COP of the DAV-cooling system is about 5–7 and 4.5–9 respectively when the permeate side pressure is 20 kPa. Finally, the engineering design methods of the DAV-cooling system are discussed, and it is found that the DAV-cooling system can be designed as a temperature and humidity independent control air conditioning system through the proposed design method and the established model. This work can provide a complete solution reference and some new insights for the application of next-generation HVAC systems.