A new validated model of dropwise condensation of vapor in humid air flow

Vapor condensation from humid air can occur as dropwise condensation (DWC). Accurate modeling of DWC is crucial not only to predict heat transfer, but also to understand the underlying mechanisms. The increasing availability of computing resources has led to development of sophisticated numerical models to determine dropsize distribution and heat exchanged, eliminating the need for statistical assumptions. This paper introduces a novel individual-based model (IBM) to perform simulations of DWC with non-condensable gases (NCG). In the developed IBM, the droplet growth rate model and the accommodation coefficient are critical input parameters. Here, we use droplet growth rate measurements (which are rare in the literature) to infer the value of accommodation coefficient and select the best growth rate model for predicting DWC with humid air. Then, the developed simulation tool is successfully validated (within 6%) against an experimental database obtained by varying air humidity (relative humidity 50-90%, specific humidity 0.012-0.022 kgv/kgdryair) and dew-to-wall temperature difference (7-13 K). After validation, the model is used to study the effect of main input parameters on droplet population and condensation heat flux. Interestingly, the small droplet population is not affected by the accommodation coefficient or air conditions, but instead depends on surface wettability.