NUMERICAL INVESTIGATION OF THE INTERACTION BETWEEN THE ROUGHNESS AND THE TRIANGULAR OBSTRUCTIONS IN A RECTANGULAR CHANNEL

Abstract

The study is conducted around a heat exchanger, its channel is horizontal rect-angular, its upper wall is isothermal, while its lower wall is thermally insulated, containing extended surfaces in the form of triangular obstacles attached in a stag-gered manner periodically. Four models of the channel with various roughnesses were compared in this study. Square, triangular Type 1, triangular Type 2, and triangular Type 3 roughnesses, which are positioned on the hot top part of the channel (absorber), downstream of the last obstacle, are examined to promote heat transfer between the absorber and the heat transfer fluid. The case of triangular roughness (Type 3) is the optimal case in terms of improved heat transfer. More-over, it shows a significant decrease in terms of friction values.