The inaccuracy of heat transfer characteristics for an insulated sphere neglecting the influence of heat radiation

• Main Authors: Jun-Bin Lin, 林俊斌
• Other Authors: 黃景良
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/92wy66

碩士 === 崑山科技大學 === 機械工程研究所 === 97 === Heat radiation equation contains 4th exponential order of temperature which makes heat equation calculation become very troublesome. Thus, in conventional application, the heat radiation effect was ignored in situations of small temperature difference between insulated surfaces and surrounding. In this investigation, the differences heat transfer characteristics of an insulated spherical container between considering and neglecting the influence of heat radiation is studied by the simulations in some practical situations. It is found that even in situations of very low temperature-difference between outer surface and surrounding (such as 1℃), the heat radiation effect can’t be ignored in situations of lower ambient convection heat coefficients and greater surface emissivities. In most situations, ignoring the heat radiation will generate quite a big errors (especially in surface temperature) and affect the design quality. It is also proved that using smaller surface emissivity can greatly improve the performance of insulation.