Effect of water and air flow on concentric tubular solar water desalting system

Abstract

This work reports an innovative design of tubular solar still with a rectangular basin for water desalination with flowing water and air over the cover. The daily distillate output of the system is increased by lowering the temperature of water flowing over it (top cover cooling arrangement). The fresh water production performance of this new still is observed in Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore (11° North, 77° East), India. The water production rate with no cooling flow was 2050ml/day (410ml/trough). However, with cooling air flow, production increased to 3050ml/day, and with cooling water flow, it further increased to 5000ml/day. Despite the increased cost of the water cooling system, the increased output resulted in the cost of distilled water being cut in roughly half. Diurnal variations of a few important parameters are observed during field experiments such as water temperature, cover temperature, air temperature, ambient temperature and distillate output.

Maximized production of water by increasing area of condensation surface for solar distillation

“…Arunkumar et al [17] have concluded two reasons for low productivity of solar stills. Firstly, the difficulty in rejection of the latent heat of condensation to the atmosphere and secondly, the difficulty of raising the evaporation temperature and decreasing the condensation temperature.…”

“…However, solar stills have not been widely applied because of their lower productivity of drinking water [4,[7][8][9][10][11][12][13][14][15][16][17]. Arunkumar et al [17] have concluded two reasons for low productivity of solar stills.…”

“…Firstly, the difficulty in rejection of the latent heat of condensation to the atmosphere and secondly, the difficulty of raising the evaporation temperature and decreasing the condensation temperature. Several other authors [4,[7][8][9][10][11][12][13][14][15][16][17] have evaluated the reasons for the low productivity of water and suggested various solutions. These are (i) achieving a higher basin temperature (lower water level, use of wick, adding black dyes, additional external heating-collector, concentrator, and waste heat recovery), (ii) lowering the cover temperature by using condensation cover cooling, overnight cooling with basin energy storage and use of additional condensers, (iii) large evaporation and condensation surface areas, re-utilization of the latent heat of condensation (multi-effect) and (iv) minimizing heat losses (good side and bottom insulation).…”

Year-round outdoor experiments on a multi-stage active solar still with different numbers of solar collectors

“…Various types of solar stills including single basin passive [3][4][5], single basin active [2,[6][7][8], multi-basin passive [9], multi-basin active [10], tubular [11] and inverted absorber [12] were constructed and studied to date. Moreover, valuable reviews on solar stills can be found in the literature [13][14][15].…”

Experimental Investigation on Modified Solar Still Using Nanoparticles and Water Sprinkler Attachment

“…By contrast, the diffuse solar fraction is only dependent on the geometry of the solar distiller. Arunkumar et al (2013) have concluded cold water and air flow on the glass cover to achieve highest productivity of water. Bhardwaj et al (2013) reported glass is best material as a condensation surface in solar distillation system over any other material.…”