ABSTRACT
Optimizing the efficiency of energy and thermal systems involving liquid–vapor phase change requires models and correlations based on accurate measurements of wall temperature and liquid–vapor flow parameters (film thickness, void fraction, bubble size, frequency, velocity, etc.). Different optical measurement techniques have successfully been developed and used at CETHIL during the last decades to characterize pool boiling, flow boiling, and/or thermo-capillary phase change heat transfer: high-speed videography for the dynamic tracking of the liquid–vapor interface, confocal microscopy for the measurement of the shape of the meniscus within a capillary structure, and IR thermography for wall temperature measurement along with the flow observation using ITO coating. This chapter not only deals with the techniques, but also advises on the good practices to carry out accurate measurements during liquid–vapor phase change heat transfer.
