Analysis of cooling characteristics of discrete heaters attached with horizontal fins in a tall vertical enclosure

An analysis is made of cooling characteristics of four two-dimensional discrete flush-mounted heaters, each attached centrally with a horizontal fin, in an air-filled vertical rectangular enclosure of aspect ratio 10. Parametric simulations via a finite difference method are first carried out to reflect the effects of fin conductivity (k* = 0.1 to 10⁴) and modified Rayleigh number (Ra* = 10³ to 10⁸) on cooling of the enclosed discrete heaters fully attached with the fins. Attached with fins of k*≥10 the temperature of the discrete heaters can be greatly reduced in comparison with that without the fin attachment. The temperature non-uniformity over the heater surface as well as the temperature disparity among the heaters can be effectively minimized by the attachment of highly conductive fin. Contribution of natural convection in air-filled subenclosures to cooling of the discretely heated enclosure is greatly degraded with the increase of k*. The numerical results of the heater temperature as well as the heat transfer rate through fin-attached portion of the cold endwall for k* = 10⁴ are found to be very close to those predicted by a simplified one-dimensional fin conduction analysis. The influence of the fin thickness is also investigated for the case of aluminum fin.