Study the Thermal Effect of Ceiling-mounted Light Fixturesfor a Displacement Ventilation System

This paper investigates the thermal effect of ceiling-mounted light fixtures for a displacement ventilation system. The influence of fluorescent lainps on a ceiling is examined by computational fluid dynamics and experimental methods. The test room is a 5.3m X 5.44m X 2.5m height office. Two supply air diffusers and two exhaust grilles are dimensioned bv 0.9m x 0.2ni each. A heat source is instailed at the center of the room. Supply air velocity is treated as a parameter from 0.1 to 0.5 mls. The finite volume method and low-Reynolds number k- ? turbulence model are eniployed for CFD analysis. Thermocouples are installed vertically above floor at the center of the room for the experiments. Temperature data are collected automatically by a data logger every minute. Dimensionless vertical temperature profiles are compared for CFD and experimental results for each supply air velocity. Thermal stratification in the test room is investigated at 8 points of the room by CFD analysis. As a result, dimensionless vertical temperature profiles indicate the similarity for different supply air velocities. Ceiling-mounted light fixtures stabilize thermal stratification as well as heating by ceiling panels according to CFD results. Thermal comfort in the test room is assessed according to IS07730-1994 recommendations for the test room.