Utilization of Solar Energy for Water Desalination and Purification Using Solar Concentrator

Abstract

This paper focuses on a a solar energy-based project aimed at water desalination and purification. The project's objective is to establish an economically viable and sustainable approach to water heating and desalination, offering benefits to global communities. The project team has devised a solar heating system utilizing a Fresnel array-inspired setup, intended to complement a desalination system employing membrane distillation, which necessitates water heating. The primary focus has been on designing an efficient solar receiver to absorb solar energy for water heating. Moreover, the team has developed equations for concentrator mirror angles across various days, generating charts indicating optimal mirror angles and spacing between mirror rows for different solar times. Project outcomes involve applying heat transfer loss theory via conduction across individual receiver layers, conducting experiments to assess coating efficiency and receiver performance. The team successfully assembled the system with four parallel mirror rows, spaced at 1.5 feet intervals to minimize shadow casting. The solar receiver features two glass tubes, air gaps held by 3D-printed end caps, and an internal mesh turbulator to enhance heat transfer through flow turbulence. The ultimate objective was to heat water sufficiently for membrane distillation (around 40°-70°C). Experimental testing on a windy day with clouds resulted in a final water temperature of 38°C after 3 hours. Receiver efficiency, calculated by comparing solar energy incident on the pipe to energy transferred to water, was 17.5%. While not within the desired range, these promising results, considering surrounding conditions, deem the project successful in creating an efficient heating system for membrane distillation. Recommendations and improvements are possible, confirming the project as a successful proof of concept.