In this paper, the airlfow and temperature distributions in a commercial kitchen are simulated based on the k- E model, and the ventilation efficiency is investigated for three types of ventilation systems. The result of this simulation shows that the suitable supply method of the outdoor air and the conditioned air can give high ventilation efficiency, and thus the kitchen can be kept comfortable with relatively low energy consumption.
There are many indices to evaluate the ventilation characteristics of the ventilated rooms. These indices are classified into air change efficiency and contaminant removal effectiveness. In order to know how to use many indjces for a good understanding of the characteristics of the concerned ventilation system, the values of various efficiencies under some typical air flow conditions with isothermal condition are compared. The local mean age distributions and local contaminant concentrations are measured with tracer gas technique in a scaled model of the room ventilated mechanically.
Several new scales have been developed to quantify fresh air diffusion and contaminant dispersion in ventilated spaces. The local purging effectiveness is proposed for analyzing the individual contribution of each supply opening for a multi-inlet system. The local specific contaminant-accumulating index is defined to indicate the tolerance of a ventilation flow to contaminants. Furthermore, the regional purging flow rate, Up, is re-embodied in a simple expression different from the previous description.
A Computational. Fluid Dynamics technique is employed to predict the two dimensional turbulent air flow which is created by an Aaberg slot exhaust hood reinforced by a two-dimensional wall jet flow. The standard turbulent k-e model, control volume method and SIMPLE algorithm are tised to simulate the air flow. The numerical results for the effect of the Aaberg slot exhaust hood on the air flow pattern, shape of the capture region and the velocity distribution of the capture region in the system are presented.
The results of various numerical simulations of wind induced flows through large openings in a room are presented. The study is parametric on the sizes and relative positions of the openings and the wind direction. Various grid densities have been used. Grid independency for the presented results is demonstrated. Validation of the numerical approach is performed using measurements on a test cell with a single opening. The influence of the inflow wind profile is studied. It is shown that different flow patterns are induced within the dwelling when different profiles are assumed.
The performance of a ventilation system, particularly that which is incorporated in centralised air-conditioning system, can be evaluated in several ways. The "ventilation efficiency and ventilation effectiveness" and "air exchange efficiency" are two of the most commonly employed methods in ventilation analysis.
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