Vertical Distribution of Temperature and Contaminant Concentration in a Room with Impinging Jet Ventilation System

The impinging jet ventilation system (hereinafter referred to as IJV) has been proposed as a new air conditioning ventilation system. Properties of indoor environment with this system using impinging jet are complicated. The present paper reports fundamental properties of indoor air with distributed interior heat generation load assuming an office. The experiment was conducted in the climate chamber of which floor area was 27.0 m2, and basic properties of temperature and CO2 distributions were investigated. Heat load within a room was simulated by black lamps (incandescent bulb covered with dark purple glass) distributed uniformly. As for contaminant, CO2 was generated from 4 locations. The temperature and CO2 concentration were measured by changing the combination of supply air temperature and supply air flow rate, and four cases were studied. In addition, the number of IJV supply terminals was also changed as a parameter to understand the effect of supply air momentum. Two cases (1 or 2 terminals) were studied without changing total supply airflow rate, i.e., only supply momentum was changed. In total eight cases were studied in the experiment. The specific Archimedes number was defined and evaluated based on experimental results, and relationship between temperature/concentration stratification and Archimedes number was investigated. It was shown that the  temperature/concentration stratification become clear when the supply airflow momentum is small. Moreover, a correlation between Archimedes number and vertical temperature difference was shown. To propose a simplified calculation model, further parametric study is required, and CFD analysis seems to be beneficial because it enables numerical experiment easily. To do this, however, CFD calculation method for IJV system needs to be validated. Therefore, one case of full-scale experiment was simulated. Here, the effect of turbulence model was evaluated, and three turbulence models (standard k-ε model, RNG k-ε model, and SST k-ω model) were studied, and the accuracy of CFD analysis is finally verified.