HEAT AND MASS TRANSFER DURING DESORPTION OF AMMONIA- WATER IN MINI-CHANNELS

摘要

The performance of mini-channels during desorption of ammonia-water mixtures in mini-channels has been experimentally investigated. Measurements have been done in four different lengths of channels (namely 0.2, 0.4, 0.6 and 0.8 m) and three different diameters (0.5, 1.1 and 2.0 mm). These different lengths are used to determine the heat transfer coefficient and pressure drop during desorption for different vapor fractions along the channels. Results were set out against ammonia concentration, mass flux and vapor quality in order to investigate the dependency of transfer coefficients on the given variables. Mass flow is directly measured; vapor quality is obtained from equations of state with pressure and temperature at in- and outlet of each channel as input, assuming equilibrium conditions. The experimental results are used for the validation of a phenomenological model of the desorber which will also shortly be introduced.