Investigation on thermal performance of the wall-mounted attached ventilation for night cooling under hot summer conditions

• Published in: Building and environment 2018-12, Vol.146, p.268-279
• Main Authors: Ji, Wenhui, Luo, Qing, Zhang, Zili, Wang, Houhua, Du, Tao, Heiselberg, Per Kvols
• Format: Article
• Language: English
• Subjects: Air flow; Convective heat transfer; Cooling; Cooling effects; Energy management; Heat removal; Heat transfer; Heat transfer coefficients; Mechanical ventilation; Night; Night ventilation; Performance indices; Summer; Surface cooling; Temperature; Temperature efficiency; Test chambers; Thermal analysis; Ventilation; Wall-attached jet
• ISSN: 0360-1323; 1873-684X
• DOI: 10.1016/j.buildenv.2018.10.002

In Hot Summer and Cold Winter Climate Zone, the cooling potential of natural/passive night ventilation is limited during summer due to the insignificant difference between the outdoor and indoor temperatures. Therefore, a novel mechanical ventilation strategy, the wall-mounted attached ventilation (WAV) system, is proposed in the present paper to improve ventilation efficiency of night cooling. The idea is that WAV can produce a downward airflow over the internal wall surface that is somewhat similar to a sidewall jet, so as to achieve enhanced heat transfer in the room. This paper starts with a series of experiments in a test chamber, and continues with thermal analysis of the heat transfer characteristics and heat removal performance of WAV. The performance of night ventilation with WAV is further evaluated in terms of ventilation efficiency index and energy performance index. It is shown that the overall average value of the convective heat transfer coefficient at the internal wall surface with WAV is 10.79 W m−2 °C−1. With WAV, the amount of heat removed from the ventilated wall is about five times that in the natural night ventilation case, and the total amount of heat removed from the whole chamber is twice as much. The average value of the surface cooling effectiveness of WAV is 1.48, and the overall coefficient of performance (COP) of WAV turns out to be 26.8. As a night ventilation strategy, WAV is capable to achieve good cooling performance under hot summer conditions. •A novel wall-mounted attached ventilation (WAV) night cooling system proposed.•Experiments carried out to understand the temperature decreasing effect of WAV.•Transient heat transfer models established to analyse the thermal performance of WAV.•WAV has much better performance on surface cooling and heat removal than natural ventilation.