High resolution measurements of wall temperature distribution underneath a single vapour bubble under low gravity conditions

Abstract

Heat transfer performance in nucleate boiling crucially depends on a circular thin film area near the foot of a vapour bubble where high heat fluxes and thus high local evaporation rates occur. The corresponding wall temperature drop close to the tiny thin film area is computed using an existing nucleate boiling model. To verify the predicted temperature distribution, an experiment is designed with a thin electrically heated wall featuring two-dimensional, high resolution temperature measurement using unencapsulated thermochromic liquid crystals. By means of temperature measurements during a parabolic flight under low-g conditions, the validity of the model used to calculate the temperature distribution in the tiny thin film area could be confirmed.