Study of factors affecting warm air spreading distance in impinging jet ventilation rooms using multiple regression analysis

Factors influencing the warm jet spreading distance of an impinging jet ventilation (IJV) system, which is operated in heating mode, are studied and multiple regression analysis is used to develop multivariate regression models for the estimation of the spreading distance. The factors considered are jet discharge height, nozzle area (i.e., nozzle configuration), supply airflow rate and temperature difference between the supply and indoor air (i.e., supply condition). CFD techniques are employed to conduct a set of required numerical experiments, and each simulation condition is determined by the Box-Behnken design (BBD) method. The developed equation suggests that the warm air spreading distance in IJV has a maxima and will not exceed 12 m for any nozzle configuration and supply condition. Moreover, the supply airflow rate should be greater than a threshold and the height and area of the nozzle should also be within particular ranges in order to meet the special requirements of the spreading distance. The larger the required spreading distance there is, the more restrictions there are on the studied variables. With the regression models established for the warm air spreading distance, the optimized combination of these variables for satisfying the design requirement is determined.