CFD Analysis of different types of single basin solar stills

The current work deals with the numerical and experimental analysis of a solar still of single basin with improved models of stepped, finned, PCM (Phase modification Materials) instrumentation in single slope. The work is additionally extended to double slope solar still of single basin and also the performances were compared with one another. The one slope basin inclinations were compared for 15° and 20°. From the investigations it had been ascertained that single slope with 20° and PCM instrumentation has given the upper productivity compared to different sorts.


Introduction
Solar stills offers a straightforward means produces clinically pure water appropriate for domestic, industrial, medical or agricultural desires. Plenty of technological analysis has been dole out for up the productivity. A simulation and experimental study was conducted to live internal heat transfer rates of the solar still [1]. A thermal analysis of a solar still was conferred with 2 compressing chambers exploitation energy balance equations for parameters like water mass, compressing covers, basin liners and reflective mirror. Numerical and experimental results were compared for the obtained results of temperatures and yield [2]. A numerical computations of yield and temperatures of water and glass cowl was dole out and ascertained that optimum annual yield was obtained once collector's inclination was 20 0 and glass cowl inclinations was 15 0 [3]. A comparative performance analysis was conducted between a double glass and single glass cowl and located that single glass cowl yielded higher compared to double glass cowl [4]. Experimentation was studied regarding the solar still with sponge cubes of various sizes placed within the basin and compared that liquid productivity increased from eighteen to twenty seventh. The results of various parameters like sizes of cube exploit sponge volume, depth, salinity of water and once black coal and black steel was used as cube materials were conjointly investigated [5]. The lumped constant quantity mathematical model was projected to check regarding to analyze the asymmetries that arises in temperature and yield during a solar stills with double slope. The model was compared with the experimental values [6]. The performance of a regenerative 2 basin solar still was sculpturesque, evaluated and compared with the standard still and well-tried that the productivity was increased to twenty additional. The results of insulation, wind speed, thickness of glass cowl, mass flow of water were conjointly studied [7]. The fabrication of single and double basin solar stills was tested and compared the performance throughout the amount of Feb and June month and located that the productivity was regarding 40% over that of single basin still. The very best productivity was obtained within the month of June because of highest incident radiation [8]. The assembly rate was accelerated by desegregation fins, wicks, sponged stills and welltried that the productivity increased by 45.5% for fins, 29.6% for wick and 15.3% for sponges. This paper deals with the theoretical, numerical and experimental study of single basin single slope solar still with steps, fins, PCM instrumentation and compared with the standard sort. This work is additionally extended with double slope and compared.

Solar basin still
Figure1 shows the experimental and schematic model of solar basin still. The still instrumentation is created of steel sheets. The tank fabricated from plastic with the capability of 25 liters was accustomed avoid corrosion. The still basin was painted black and insulated with dielectric for insulation purpose. The condensed water was transferred in to the measuring jar through the versatile piping. This experimental established was designed with inner dimensions of the basin 100X100 cm 2 .The higher glass cowl is tipped at 15 0 and 20 0 with regard to the horizontal that was put in and tested at Sri Venkateswara College Of Engineering and Technology, Chittoor, Andhra Pradesh, India. The experimental setup was placed by facing the North-South direction. The temperatures at totally different positions were measured exploitation copper-constantan thermocouples. The Condenser surface is created of 5mm normal glass plate. Rock bottom of this still is insulated with 50mm. stuffed the water up to ten cm depth. Thermocouples square measure mounted at the subsequent locations as glass plate, Water and out of doors of the glass plate.

Solar basin with PCM
Figure3 shows the experimental and schematic model of the basin still full of Stearic acid at rock bottom of the basin and placed a receptacle to store water. The peak of the PCM instrumentation is of 8cm and also the water is poured to a height of 5cm. Here PCM is employed to store heat within the day time and unharnessed the warmth throughout night which provides continuous production of water.

Meshing
The Steam and collector geometry of different model created are imported to ANSYS ICEMCFD and tetrahedral meshing is generated. Table 1. shows the number of nodes and elements for different domains created for CFD analysis.   Figure 14 (a, b, c) shows the meshed models of the solar still with 15 0 , 20 0 and double slope. Two phase domain is created in Ansys CFX for liquid water and water vapour. The boundary conditions applied are heat flux is applied on the glass cover with free slip boundary; the bottom plate is given with initial temperature of water. The fluid domain created was given with free slip boundary to vapour and no slip boundary to liquid water. Transient Analysis was carried for 8 hours with 1 hour time step. Figure 15 shows the vapour velocity inside the steam which moves in the circular path due to convection of heat and Figure 16 shows the velocity of water which is shown upwards towards the glass plate.  18 shows the fraction of water and vapour within the domain and it's found that water is offered additional below the glass plate which might be condensed into water droplets and picked up within the collector plate. Figure 19 shows the water mass flow within the domain and also the volume fraction of water in Figure 20 shows the amount of water collected in it.

Water Temperature
The theoretical values and also the numerical values obtained were same. From the higher than results water temperature foretold by CFD simulation are compared with obtainable experimental knowledge for 15 0 and 20 0 inclinations shown in Figures 33 to 35. This graph has been drawn with Water temperature as ordinate and time in hours as Cartesian coordinate. Water temperature is in smart agreement with experimental knowledge.

Productivity
From the higher than observations it had been found that solar still with 20 0 angles provides additional output compared to 15 0 angles. And solar still with PCM material provides additional output than all sorts as well as night times once the sunshine isn't obtainable thence it's the simplest potency compared to other sorts. Figures 36 and 37 presents the productivity of distillate in different models of stills.

Conclusions
The temperature distribution of the water and vapour within the totally different form of single slope and double slope is set by exploitation CFD tool and also the results square measure conferred. It's found that 20 0 inclined solar still provide higher results than 15 0 inclined solar still. From the experimental and CFD results, the distillated water production rate is foretold and located that PCM still is best suited that provides additional output compared to different sorts and it will be utilized in the getting dark conjointly Paraffin has higher performance although it's instructed to use Stearic acid in PCM still because it is definitely obtainable and economical.