Journal of Flow Visualization and Image Processing

ISSN for PRINT: 1065-3090

For Online Access

Best Paper Award Selection - Editorial Board Site

2008, Volume15

Issue 2

95 pages

Issue price - $175.00

Jr-Ming Miao
Department of Mechatronic, Energy and Aerospace Engineering, Chung Cheng Institute of Technology, National Defense University, Taoyuan, Taiwan 335, R.O.C.

Hou-Chei Chang
Graduate School of Defense Science Studies, Chung Cheng Institute of Technology National Defense University, Taoyuan, 335, Taiwan, R.O.C.

The interior of mobile communication vehicles is relatively compact, and various collocated communication equipment producing heat in the compartment should be effectively distributed. If the air outlets of air-conditioning systems are not designed with a proper location, operators will feel uncomfortable in those working environments. In this investigation, the computational fluid dynamics (CFD) method was used to simulate the flow field and the temperature distribution inside the compartment of a mobile communication vehicle under different configurations of air-conditioning units.
The three-dimensional thermal-flow field was solved by steady incompressible Reynolds-averaged Navier-Stokes equations (RANS) with the control volume method. The buoyancy effect was assumed with the Boussinesq hypothesis, and the turbulent model was the standard k−ε turbulence model. The indices such as predicted mean vote (PMV), predicted percentage of dissatisfied (PPD), percentage of dissatisfied due to draught (PD), and mean air age were studied to analyze the comfort level and indoor air quality (IAQ) inside the compartment.
Before the numerical simulations, the velocities of air outlets and the temperatures of air-conditioning units were measured to serve as prescribed boundary conditions for the simulations. Three cases with different layouts of air outlets were simulated to study their influence on the uniformity of thermal comfort distributions. The simulation results revealed the PMV and PPD indices of all three cases conformed to the standard value, but all PD indices exceeded or approached the critical value of the standard value. All PD indices of the three cases were up to 45% at the abdomen of sitting operators, which will obviously lead to discomfort. This result agrees with the response of operators. The reason for this discomfort was the cold airflow with high velocity from the outlets in the floor beneath the control platform.
The simulation also showed the cold air supply on floor could efficiently exchange heat production from equipment, especially when the fresh air inlet was located at the upper-backside or front-top of the compartment. Further, the air age in the upper area of compartment was low when the fresh air inlet was located at the upper backside or front top of the compartment.

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