Determination of local convection heat transfer coefficients inside a circular pipe using pulsed laser

The determination of local convection heat transfer coefficients of pipe flow using pulsed laser heating (PLH) from a combination of experimental and numerical study is presented in this paper. The method is advantageous because it is fluid-independent, contact-free and high in spatial and temporal resolution. For simplicity, the experiment used water at different temperatures and flow rates inside two long circular tubes which were subject to radiation heating using a finite size (20 mm in diameter) pulsed laser beam. An infrared camera was used to image and measure its surface temperatures. Two correlations for convection heat transfer coefficient in the thermal/combined entry length region were used in this paper for comparison with the experimental results. The experimental results using the thermal circuit method processed by MATLAB® agree well with both correlations. To gain better insight and quantify the uncertainty, a 3-D conjugated heat transfer simulation was carried out using Fluent CFD. The implication of the accuracy and limitation of the PLH method on the determination of local heat transfer coefficients are also discussed in the analysis.Copyright © 2015 by ASME