Convective heat transfer studies in macro and mini channels using digital interferometry

Convective heat transfer in micro and mini channels has been recommended as an effective heat removal method for various electronic packages and systems. As the traditional method of temperature measurement in channels using the thermocouple probe disturbs the flow field leading to measurement errors, a non-intrusive measurement technique, such as an optical method is preferable for temperature and heat transfer measurement in mini channels. In the present work, convective heat transfer studies have been performed on water flowing through channels of small cross sections of hydraulic diameter 4 mm and 3 mm, using digital interferometric technique. The channels are fabricated using high quality optical glass and aluminum blocks. Mach-Zehnder Interferometry is used for obtaining the temperature distribution in the channels. The interferograms grabbed using a CCD camera, coupled to a computer and digital image processing technique, has been used for obtaining the temperature distribution from the fringes. The temperature profiles are obtained at different sections of the channels for various values of the average Reynolds number and various heating levels. The local and average heat flux values are obtained from the constructed temperature distributions. Results of parametric studies are compared and contrasted with relevant entry length solutions from the literature.