Pulsating impinging jet ventilation with floor cooling to improve thermal comfort at enhanced system performance

In light of global warming and increasing outdoor temperatures under future climate conditions, solutions for reducing energy consumption are needed for heating, ventilation and air-conditioning (HVAC) systems. The impinging ventilation system (IJV) is known as low energy consumption system compared to conventional HVAC. There is significant potential to improve performance of IJV when it is combined with cooled floor to increase cooling capacity and operated with pulsating flow to reduce energy consumption. This work investigates the performance of the PIJV system coupled with radiative cooling floor (RCF) in terms of meeting the occupant's thermal comfort and sensation requirements. The study aims to investigate the PIJV-RCF system for improving thermal comfort while considering the pulsating frequency of the PIJV airflow and its temperature. A 3-D computational fluid dynamics (CFD) model of the airflow and heat transfer was developed and validated with experimental measurements of the temperature field. Moreover, a robust bioheat and comfort model was used to predict the transient and overall thermal comfort due to the pulsating jet compared to a steady IJV system. The validated CFD model and the bioheat model are then used to simulate the PIJV-RCF conditioned room and the cooled floor to predict the thermal comfort at different frequencies for a typical office space. The PIJV system resulted in improved thermal comfort compared to the steady non-pulsating IJV at the same average flow rate. The pulsating frequency of 60s ON followed by 60s OFF resulted in the best thermal comfort.