Numerical modelling of a multi-stage solar still

This paper reports the development of a mathematical model to predict the p roductivity and the thermal characteristics of a multistage solar still wit h an expansion nozzle and heat recovery in each stage of the still. Further more, this model is used to conduct a parametric investigation of the propo sed solar still. A cost analysis is performed to shed some light on the pot ential of utilizing the proposed still for production of drinking water. It was found that making use of an expansion nozzle and heat recovery techniq ues in the proposed solar still tend to enhance the productivity of the sti ll and the distillation efficiency. The daily solar still productivity can be up to 9 kg/m(2), and the distillation efficiency is 87%. The unit cost f or distilled water of this still is $25.6/1000 gallons. (C) 2000 Elsevier S cience Ltd. All rights reserved.