Liquid-liquid direct contact heat exchange using a perfluorocarbon liquid for waste heat recovery (Heat transfer characteristics obtained with perfluorocarbon droplets descending in a hot water medium)

This paper has dealt with the heat transfer characteristics of a liquid-liq uid direct contact operation in which a Perfluorocarbon (PFC) liquid was re leased in a hot water stream, which was a low-grade heat source such as urb an sewage, for the purpose of heat recovery from it. The paper reported on a set of experiments in which a PFC liquid (1 800 kg/m(3) at 20 degrees C) was continuously injected from a downward-facing single nozzle into a slow and upward flow of hot water and it was disintegrated into a lot of droplet s and then they were heated from the ascending hot water. The experimental results revealed that the size distribution and flow behavior of the drople t ensembles exerted an influence on the coefficient of overall heat transfe r between the droplet ensembles and hot water and also the temperature effe ctiveness for the droplet ensembles.