The thermal behaviour of solar energy systems using heat pipe absorbers is analysed and compared with systems using conventional solar collectors. The mathematical model employed is based on the Hottel-Whillier-Bliss formalism for solar collectors. The heat transfer ratio (γ) is found to be a very useful parameter in predicting the thermal performance of a heat pipe absorber. For solar heating applications, the heat removal factor (Fr) of the heat pipe system is apparently lower than that of an equivalent conventional system because of the extra heat transfer surface in the heat pipe system. This penalty, however, can be minimized by proper design at the heat pipe condenser and system manifold. In solar cooling applications, the heat pipe absorber manifests better heat transfer characteristics than the flow-through absorber because it attains very high values of γ.
Solar & Wind Technology 01/1990; 7(4-7):349-354. DOI:10.1016/0741-983X(90)90020-3