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Correlations for nucleate boiling heat transfer should be improved, or in the long term possibly be replaced, by the development of mechanistic simulations that include the non-uniform spacing and variable characteristics of the nucleation sites and non-linear interactions between the sites. This paper discusses the interactions that should be included in simulations and some lessons from a first attempt to validate a particular simulation against experimental spatio-temporal data for wall temperature. Input data for nucleation site positions and characteristics are a particular problem and the prospects for obtaining this data from measurements that are independent of boiling are discussed.

This paper investigates the relationship between the neutral height for air distribution and the ventilation load in a room with displacement ventilation. An environmental chamber equipped with a displacement ventilation system has been used to carry out the neutral height measurements with the presence of a heated mannequin and other heat sources in the chamber. The total room load used was varied from 104 to 502 W , i.e., corresponding to a ventilation load from 10 to 60 W / m 2 . The prediction of the neutral height was based on plume theory. Comparison between the experimental data and the predictions showed good agreement. The prediction also showed that human body could draw uncontaminated fresh air from the lower zone, which improves the air quality in breathing zone.

Simple models of nucleate boiling consider nucleation sites in isolation. In practice, they interact in ways that depend on the distance between them. In this paper, statistical evidence of interactions is obtained for a large number of non-uniformly distributed sites with different activation superheats during pool boiling of water on a thin plate at a heat flux of 51 kW/m2. By analysis of spatio-temporal data for wall temperature obtained by liquid crystal thermography over a period of 30 s, the timing, position, activation superheat and radius of cooled region are obtained for every nucleation event, without need for direct observations of the bubbles. For each event, the number of subsequent events at all other sites during different delayed time intervals is obtained as a function of distance from the original site. The number is compared with a null hypothesis obtained by assigning random times to all events: a higher number indicates promotion, a lower number inhibition. It is found that there is promotion during very short time delays of the order of the bubble growth time at distances less than the bubble radius and inhibition for slightly longer delays and shorter distances. There is no statistically significant effect at distances greater than the bubble radius. This finding may be influenced by the low bubble frequencies characteristic of these particular experiments.