Assessing the accuracy of the heat flux measurement for the study of boiling phenomena

Abstract

The present work quantifies numerically the systematic errors present in experimental infrared heat flux studies of boiling surfaces. A transient conduction model for multilayer structures is proposed to describe the periodic heat fluxes encountered on boiling surfaces. The results of the current work show that the systematic error behavior of the infrared method is not uniform but dependent on the frequency of the heat flux signal of the boiling surface; which is a novel finding. As the frequency of the heat flux signal increases, the errors in the measured phase of heat flux signals are expected to increase. The errors in the amplitude of heat flux signals sharply increase at low frequencies (1-10 Hz) and decrease as the frequency increases.The maximum errors in the phase and amplitude of heat flux signals are 9% and 23%, respectively in the frequency range of nucleate boiling (10-80 Hz). Based on the current analysis, it is concluded that the systematic errors found arise from assuming that thermal contact resistances of such systems are negligible. This is an assumption universally adopted

Comprehensive simulations of boiling with a resolved microlayer: validation and sensitivity study

“…Although modern, high-resolution experimental techniques can provide detailed information on the actual microlayer dynamics, several limitations and deficiencies in the approach can be identified. Measurements of microlayer thickness are often indirect and/or rely either on assumptions, such as zero flow in the microlayer (Utaka et al 2013;Yabuki & Nakabeppu 2014), or on indirect numerical techniques (Bucci et al 2016), the uncertainties of which need to be carefully evaluated (Kim et al 2020).…”

“…2016), the uncertainties of which need to be carefully evaluated (Kim et al. 2020). Furthermore, an experimental set-up can accommodate only a limited number of diagnostic systems, reducing the amount of information that can be obtained in a synchronous way.…”

Experimental and Numerical Investigation of Temperature Development of Ohmic Heating Cured Nonmass Concrete under Subzero Temperature

“…where J is the current density vector (A/m 2 ); Q j,v represents the general current source (A/m 3 ); E represents the intensity of the electric field (N/C); σ represents the conductivity (S/M); V is the electric potential; and D represents the relative dielectric constant (C^2). e features provided by the solid heating transfer module interface have been utilized to simulate the process of conduction convection and radiation heat transfer through heat flux and the surface settings of environmental radiation, in which, heat flux is defined as convection heat flux, and its expression [22,23] is shown as follows:…”