Wall-temperature distributions of nucleate pool boiling surfaces vs. boiling curves: A new approach

• Nucleate pool boiling was performed on surfaces with different wettabilities.
• Transient wall-temperature fields were measured with high-speed IR thermography.
• Boiling performance was evaluated by novel approach: wall-temperature distributions.
• Compared to boiling curves, presented distributions provide spectra of information.
• This method reveals the stability of the boiling process.

Boiling is one of the most effective heat transfer mechanisms and has a great potential in applications where superior thermal energy management capability is required. During nucleate boiling the fluid vaporises on a surface heated above the fluid’s saturation temperature and the latent heat of vaporisation allows dissipating large heat flux. The boiling performance is usually represented by a boiling curve that plots the spatio-temporal averaged heat flux versus the wall superheat. Here, we show a new approach to evaluating the process on the basis of wall-temperature distributions, calculated from spatio-temporal thermographs of the boiling surface. Instead of a single data point on the boiling curve, the presented distributions provide spectra of information, such as the maximum, minimum and mean wall superheat and the standard deviation of the wall temperature. These parameters are all associated with the nucleation frequencies and the nucleation site densities. The experimental results from various state-of-the-art surfaces suggest that the distributions reveal the stability of the boiling process, which opens a new path towards a better understanding and the development of heat transfer technology.