An Investigation of the Passive Cooling of Table Model Television Receivers

Economic and reliability considerations lead to the adoption of passive techniques for cooling by a combination of natural convection and radiation heat transfer. In order to facilitate the cooling by natural convection, thermal design engineers commonly incorporate vent openings in the walls of a receiver cabinet. Unfortunately, natural convection flows in complex, vented enclosures are presently not well understood and designers must employ “cut and try” methodologies to determine the sizes and locations of vent openings. Since vent openings are expensive to incorporate in consumer electronic products, it was decided to develop the techniques that would enable thermal designers to minimize the number of vent openings in a TV cabinet and maximize the effectiveness of those vents that are employed. Thus, the present study represents the first step in a rational program to develop the tools that will enable engineers to optimize the thermal design of a table model television receiver. In this initial work, experiments were performed to determine the effects of vent size and location on component cooling in a representative table model receiver. Vents were systematically blocked until the set was operated in a completely sealed condition. Measurements of component, air, and cabinet wall temperatures and the results of flow visualization experiments were used to assess the effects of various combinations of vent openings on the natural convection cooling of the receiver. Results indicate that: (1) the present design of the vent system of a representative, commercially available table model television receiver is adequate, but has not been optimized, and (2) significant improvements in the design of the vent could be achieved; that is, improved component cooling could be obtained with fewer vent openings. The results of this work, which should be directly applicable by thermal designers, will also serve to experimentally verify numerical models of the natural convection flows through television receivers that are currently under development.