| Popis: |
Optimum design of any thermal system requires detailed and experimentally verifiable knowledge of spatio-temporal heat transfer rates. Several techniques are available to estimate the heat flux and hence the heat transfer coefficient, including surface mountable sensors and thermocouple-based methods. Commercially available thermopile heat flux sensors are found to be unsuitable for measurement of condensation fluxes, mainly due to: (a) intrusion of the sensor with the ensuing condensation process, and (b) inherent measurement lag when the sensor is mounted away from the surface of interest. Thus, a noninvasive measurement system becomes highly desirable for surface textured-dependent phenomena such as condensation heat transfer. Use of inverse heat transfer technique, where temperature measurement at internal location(s) in the substrate is utilized to estimate the conditions prevailing at its boundary, is quite attractive for such heat transfer processes. Two case studies are presented in this chapter for measurement of filmwise and dropwise mode of condensation heat transfer to demonstrate its efficiency. Use of inverse heat transfer technique for well-designed experiments is found to be a very attractive and versatile technique to measure heat transfer rate for both modes of the condensation. The experiments on dropwise condensation of pure steam are also performed at different inclination angles, including limiting bounds of sessile and pendant mode, and high-quality experimental data are reported. |
