Convection Heat Transfer Due to Protruded Heat Sources in an Enclosure

An experimental study of convective heat transfer in a rectangular enclosure with 10 protruding heaters from one vertical wall has been performed. The top surface of the enclosure was a heat exchanger maintained isothermally as the heat sink. All of the other Surfaces, except the heater locations, were unheated. Distilled water and ethylene glycol were used as working fluids. The heaters were numbered sequentially from bottom to top, and experimental results show that the bottom heater (heater 1), except for high Rayleigh number runs, has the highest heat transfer coefficient. The heat transfer coefficients at heaters 7, 8, and 9 are nearly the same and present the lowest values among the heaters. It is shown that the heat transfer coefficient decreases with increasing vertical position up to heater 7. At high Rayleigh numbers, the top heater (10) exhibited the highest heat transfer coefficients. Flow visualization experiments were also performed. Photographs Of the flow patterns under several power inputs with glycol as the working fluid indicate the existence of a core flow within the enclosure and a recirculating cell in the gap between heaters. These pictures provide a clear basis for improved understanding of the flow mechanisms in an enclosure of the type used in the present study.