Performance of absorption heat pump using fine particle slurry of LIBR crystal

Abstract

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.

Absorption heat pump systems (AHP) are one candidate of attractive technologies to upgrade and utilize exhaust heat of low temperature level for refrigeration or heating up without emitting global warming gas. This work is to propose the method to form fine-particle slurry of LiBr crystal and to evaluate the effectiveness of the slurry for advancement of the absorption performance in LiBr/water AHP. It was found that the fine particle slurry of LiBr crystal is formed stably in the solution under a super saturation condition when zeolite powder is suspended. This phenomenon is considered to take place since the crystal grows around the zeolite particles by a function as nucleus. Then almost saturated concentration is maintained due to dissolution of the crystal even if the solution is diluted by absorption of water vapor in the absorber. The theoretical analysis based on heat and mass transfer model predicted that the output power of AHP was improved up to twice when compared with the conventional solution in lower concentration than saturation solubility without containing any fine powder of adsorbent or crystal. The measurement of the slurry properties and experiment on heat transfer of slurry film flowing on a heat transfer plate was carried out, and the effectiveness of the slurry as well as the reasonability of the modeling was confirmed.