Parametric study of an active and passive solar distillation system: Energy and exergy analysis

Abstract

This paper presents the parametric study of passive and active solar stills integrated with a flat plate collector based on the computer based thermal models. These models are developed based on mass and energy balance equations. The effect of inner and outer glass cover temperatures on the performance of the solar stills is studied which lacks in the present literature. Hence, this paper aims to compare the daily yield values from the thermal models based on both assumptions, (a) inner and outer glass cover temperatures are equal ( T gi = T go) and (b) inner and outer glass cover temperatures are not equal ( T gi ≠ T go). In this paper, the comparison is made between active and passive solar stills based on the hourly yield values for the two assumptions. The thermal performance of the active solar still is affected by design parameters like water depth, thickness of glass cover, insulation thickness, condensing cover material, type of solar collector, number of collectors, and also affected by a change in climatic parameters like ambient air temperature, solar intensity and wind velocity. The effect of design parameters and wind velocity on the daily yield of both passive and active solar stills is presented in this paper. The results of the thermal model of the active solar still integrated with a flat plate collector show that the daily yield values are 3.08 L and 2.85 L for the two conditions T gi = T go and T gi ≠ T go respectively. Similarly, in the case of the passive solar still, the daily yield values are 1.14 L and 1.09 L for T gi = T go and T gi ≠ T go respectively. The effect of the number of collectors and water depth on exergy and thermal efficiency of the active solar still is also obtained and presented. At the end, the comparison is made between the types of solar collectors and their effect on daily yield of the active solar still.