Fundamentals of Heat and Mass Transfer

Chapter 13

Radiation

13.1 Introduction

So far, we considered heat transfer by conduction and convection. In these modes of heat transfer, there was always a medium present for heat transfer to occur. However, radiation mode of heat transfer is radically different in the sense that there is no need for a medium to be present for heat transfer to occur. Just as conduction and convection heat transfers occur when there is a temperature gradient, net radiation heat transfer also occurs from a higher temperature level to a lower temperature level. There are two theories concerning the radiation heat transfer: one, classical electromagnetic wave theory of Maxwell, according to which energy is transferred during radiation by electromagnetic waves, ...