A novel method to improve the efficiency of a cooking device via thermal insulation

Abstract

We propose a method of finding the transient temperature variation in an insulated cooking device. We also report a means of optimising the thickness of insulation. The cooking device is a double walled cylindrical vessel with spacing of 5-20mm between the vertical walls (width) and spacing of 560 or 870mm between top and bottom surfaces (height). The height to width ratio (H/L) is between 28 and 174 and Rayleigh number (Ra) is between 907 and 2.61×10 5. First, an energy balance for the cooking device is established. A correlation is developed to predict the heat transfer coefficient (HTC) as a function of Ra and H/L. The method developed for finding the transient variation in temperature has been tested on two cooking device volumes: 120 and 700lit. Using the optimised parameters, a reduction in heat loss of 22% and 30%, respectively, is observed. © 2011 Canadian Society for Chemical Engineering.