Multiple-effect diffusion solar still coupled with a vacuum-tube collector and heat pipe

The present study develops a multiple-effect diffusion solar still (MEDS) with a bended-plate design in multiple-effect diffusion unit (MDU) to solve the peel-off problem of wick material. The MW is coupled with a vacuum-tube solar collector to produce a high temperature gradient for high productivity. A heat pipe is used to transfer the solar heat to the MDU. A prototype MEDS-1L was built and tested outdoors. Four performance indexes are proposed for the performance evaluation of MEDS, including daily pure water production per unit area of glass cover, solar absorber, and evaporating surface (M-cov, M-sol, M-evp, respectively), and solar distillation efficiency R-cov,. The outdoor test results of MEDS-1L show that the solar collector supply temperature T-h reaches 100 degrees C at solar radiation 800 W m(-2). The highest M-cov is 23.9 kg m(-2) d(-1) which is about 29% higher than the basin-type MEDS [11]. The highest value is 25.9 kg m-2 d-1 for M-sol and 2.79 kg m(-2) d(-1) for M. The measured R-cov is 1.5-2.44, higher than the basin-type MEDS (1.45-1.88). The M-cov, M-sol, M-evp and R-cov of MEDS-1L are all higher than the theoretical calculation of a MEDS with a flat-plate solar collector coupled with a heat pipe (MEDS-FHP) [17]. (C) 2014 Elsevier B.V. All rights reserved.