Experimental investigation of conjugate forced convection heat transfer in a horizontal circular pipe

In this thesis, conjugated heat transfer in the thermal development region of laminar flow inside a pipe was investigated experimentally by considering the axial wall conduction. The test pipes used in the study consisted of three regions, namely inlet, heating and outlet. In the experiments, pipes with wall thickness ratios δwf = 0.06, 0.3 and 0.6, which are used in engineering applications, were used. The conjugated heat transfer problem that occurs when a constant heat flux is applied externally to the heating region of the pipe under the conditions of hydrodynamic development in the inlet region and thermal development in the heating region of the pipe was investigated experimentally. Heat conduction in the wall was taken into account in the inlet and outlet regions of the test pipe. The parameters of the problem are the wall thickness ratio, Reynolds number and external surface heat flux. The effects of these parameters on the axial changes of the pipe's interface temperature, fluid bulk temperature and interface heat flux were investigated. In macro pipes, especially in low Reynolds number laminar flows, the effects of axial wall conduction should be taken into account. The most significant effects of wall axial heat conduction in the entrance and outlet region of the pipe are obtained for wall thickness ratio δwf =0.6, external surface heat flux qwo=350 W/m2 and Reynolds number Re=500.