Effectiveness Of Supply Air By Impinging Jet Ventilation System Combined With Bathroom Heater

Impinging jet ventilation(IJV)is considered to be a new type of ventilation that can create a good indoor thermal environment,improve indoor air quality,and reduce energy consumption.It has been successfully applied in the large-height space.The bathroom heater with top diffuser is widely used,but it has problems such as high noise,draught discomfort,temperature stratification,etc.This study tries to combine the impinging jet ventilation with the bathroom heater to warm the bathroom efficiently.Full-scale experiments and CFD simulations were conducted to explore the effectiveness of supply air by impinging jet ventilation system combined with bathroom heater.A standard laboratory of bathroom heater was established to test the air temperature and velocity distribution of two types of air-heating system combined with bathroom heater.The experimental results show that when warm air is supplied from the top diffuser of bathroom heater,indoor thermal comfort is not good since the temperature difference between the head and the foot is as high as 32.4? and draught discomfort is obvious.The thermal comfort produced by the IJV system combined with bathroom heater is better than that produced by the bathroom heater with top diffuser.As the jet discharge height decreases,air temperature rises quickly.But the jet discharge height has less influence on the vertical temperature distribution.The power of the PTC in the bathroom heater decreases slowly with time.The AIRPAK software was used to simulate the typical experimental cases corresponding to the two types of air-heating system,and the simulation results were compared with the experimental data.The results show that the indoor vertical temperature distribution characteristics are basically consistent with the experimental results,which indicates that CFD simulation is reasonable and reliable.The numerical model of was modified to consider the thermal performance of building envelope,human body and outdoor meteorological parameters.Indoor temperature field and velocity field for 36 cases of the two types of air-heating system were then simulated.The effects of airflow rate,jet discharge height and heating power on the thermal environment were discussed according to the thermal comfort index and energy efficiency in the occupied zone.As for the case of warm air supplied from the top diffuser of bathroom heater,the thermal comfort is poor because the draught discomfort in the occupied zone is obvious,and energy efficiency is low to the extent that the average value is less than 72%.As for the IJV system combined with bathroom heater,indoor air can be warmed up quickly if the power increases,but the bathroom may be hotter than need.As the airflow rate increases,the influences of the jet discharge height on the indoor thermal environment and thermal comfort decreases gradually.Among the 33 cases studied,indoor thermal comfort is shown to be good when the heating power is 11.5 kW or 1.4 kW,jet discharge height is 300 mm and airflow rate is 120 m3/h.The experimental results and CFD simulations indicate that the effectiveness of supply air by the IJV system combined with bathroom heater is significantly better than that by the top diffuser of bathroom heater,and the former system can produce more comfortable and stable thermal environment indoors,and can save energy by 25%?30%.