THE PERFORMANCE OF NOVEL COMPACT HEAT-EXCHANGERS WITH HIGHLY EXTENDEDSURFACES

The performance of highly extended surface heat exchangers has been ev aluated in two heat pump applications: as the evaporator in a compress ion heat pump and as the absorber in an absorption heat transformer. F ilm heat transfer coefficients based on the equivalent plain tube area (p.t.a.), ranged from 200 W m(-2) K-1, for gas-liquid contact, to 380 0 W m(-2) K-1, in the evaporation of a liquid stream. Another measure of the heat transfer characteristics of the exchangers were the 'UA(o) ' values, which were significantly better than the theoretical values calculated for each operation. The experimental results ranged from 12 W K-1 (gas) to 214 W K-1 (evaporation), while the theoretical values were 1 W K-1 (gas) and 43 K-1 (evaporation).