Modelling and Performance Enhancement of Single Slope Solar Still Using CFD

Bibliometric Analysis of Solar Desalination Systems Powered by Solar Energy and CFD Modelled

Solar desalination is a sustainable approach to producing fresh water from saline water. Researchers have tried modifications to solar desalination systems to enhance the distillate output. This survey aims to recognize the characteristics of research work for investigating solar desalination systems. The essential terms to be focused on are computational fluid dynamics (CFD) and solar radiation consideration for the investigation. The data for this bibliometric study was taken from Scopus, with 1932 publications. The characteristics of the research work were analyzed by identifying the research publications, research subject areas, journals, most contributed countries, and data from the authors. The research trend was investigated utilizing yearly research growth, geographical contributions, source quality of publications, and participation of various institutions. VOSviewer software was used for network analysis of essential keywords used in relevant research works and to understand collaborations between the authors and co-authors. About 76% of the total publications belong to the document type articles. It illuminates research tendencies related to the topic under consideration. Results show that desalination research work concerned with CFD or solar radiation was mainly investigated in Engineering and Environmental Science, with their share of more than 50% of the total publications. Further study of relevant research works was assessed using network analysis that helped to link different keywords and authors’ collaborations. This survey helps to spot the increasing research trends and the necessity of further research.

Numerical Investigation of the Double Diffusive Convection in 3D Trapezoidal Solar Still Equipped with Conductive Fins

In this paper a numerical investigation on the double diffusive natural convection in a finned solar still is performed using the finite volume method. The 3D vector potential-vorticity formalism is used to eliminate the gradient pressure terms and due to the complex shape of the cavity the blocked-off-region method is adopted. After getting the dimensionless governing equations, they are written in a generalised form then discretised. The effects of the buoyancy ratio, conductivity ratio and Rayleigh number of the flow structure, temperature field and heat and mass transfer are studied. The results show that the increase of conductivity ratio and Rayleigh number leads to an enhancement of the heat and mass transfer.

Review on performance assessment of solar stills using computational fluid dynamics (CFD)

Environmental pollution and water resource management are some of the biggest challenges for the twenty-first century. The utilization of solar energy for water purification through solar stills is an environmental friendly and sustainable approach. Computational fluid dynamics (CFD) is a valuable and cost-effective tool for the simulation of fluid and thermal phenomena in solar stills as well as for their optimization for maximum productivity. The objective of the current study is to present a comprehensive review of the significance of the CFD tool in analysis, performance estimation, and design improvements of solar still. Various studies in this direction are classified according to the comprehensiveness of the modeling approach employed. The approaches are classified into three categories. The assumptions and governing equations for various approaches are presented. It is highlighted that the relatively simpler CFD modeling of only the humid air zone in the solar still, which relies on the availability of experimental data, the modeling approach has now evolved to an advanced level and can give predictive estimates by using only the ambient atmospheric conditions and solar irradiation as input. Various studies are also classified based on configurations, computational domain, and operational and geometrical parametric range. The key results from various CFD studies are summarized.

Experimental Validation of the Thermal Processes Modeling in a Solar Still

Passive solar distillation is cheap and energy-efficient technology but its main disadvantage is low productivity. Thus, there are many attempts to improve solar stills’ productivity, and one of them is changing the mass of the water. This paper presents the results of validation of the thermal processes modeling in a solar still (SS). In order to validate the model, the experimental studies were conducted in a laboratory to ensure uniform climatic conditions. The studies were carried out for 10 kg, 15 kg, and 20 kg of water under three different solar irradiance conditions. The results show that 10 kg and 20 kg of water ensure the highest and the lowest daily productivity, respectively, independently of solar irradiance. When the water mass is 10 kg, the solar still’s productivity is 800 mL/m2/day, 3732 mL/m2/day, and 9392 mL/m2/day for low, medium, and high solar irradiance, respectively. Additionally, it is found that reducing the water mass from 20 kg to 10 kg can improve solar still’s productivity by a maximum value of 21.6%, which is obtained for low solar irradiance. The proposed mathematical model allows predicting the performance of the SS. The results of the theoretical calculations are in good agreement with the results of the experiments. The minimum and maximum deviation between the actual and theoretical productivity of the SS is 1.1% and 8.3%, respectively.

Experimental Analysis and CFD Modeling for Conventional Basin-Type Solar Still

With the rising population, environmental pollution, and social development, potable water is reducing and being contaminated day by day continually. Thus, several researchers have focused their studies on seas and oceans in order to get potable fresh water by desalination of their saltwater. Solar still of basin type is one of the available technologies to purify water because of free solar energy. The computational fluid dynamic CFD model of the solar still can significantly improve means for optimization of the solar still structure because it reduces the need for conducting large amount of experiments. Therefore, the main purpose of this study is presenting a multi-phase, three-dimensional CFD model, which predicts the performance of the solar still without using any experimental measurements, depending on the CFD solar radiation model. Simulated results are compared with experimental values of water and glass cover temperatures and yield of fresh water in climate conditions of Sheben El-Kom, Egypt (latitude 30.5° N and longitude 31.01° E). The simulation results were found to be in acceptable agreement with the experimental measured data. The results indicated that the daily simulated and experimental accumulated productivities of the single-slope solar still were found to be 1.982 and 1.785 L/m2 at a water depth of 2 cm. In addition, the simulated and experimental daily efficiency were around 16.79% and 15.5%, respectively, for the tested water depth.

Improving the performance of solar still using different heat localization materials

This work aimed to explore a new technique for improving the performance of solar stills (SSs) through utilizing three different types of a new hybrid structure of heat localization materials (HSHLM) floating on the water surface to increase the evaporation rate as well as water production and minimize heat losses. The three types were exfoliated graphite flakes with wick (type A), carbon foam with wick (type B), and exfoliated graphite flakes with wick and carbon foam (type C). These hybrid structures had good features such as high absorption and hydrophilic capillary forces to interconnected pores for fluid flow through the structure. Two identical SSs were designed, fabricated, and investigated to assess SSs' performance with and without HSHLM (modified and conventional SSs). The obtained results showed that the daily productivity was enhanced by 34.5, 28.6, and 51.8% for type A, type B, and type C, respectively, relative to the conventional one. Moreover, the efficiency of the SS reached about 37.6% for type C; while, it reached about 27% for the conventional SS. Contrary to conventional SSs, the use of HSHLM resulted in increasing the productivity proportional to water depth.