A novel analytical performance investigation of varying water depth in an active multi-stage basin solar still in addition to optimization of water depth in a single stage basin still

In the present research, active solar basin stills are studied and the effect of water depth on output productivity is evaluated analytically. In order to validate the reliability of the results of the proposed model, they have been compared with the available Karimi’s experimental data with an acceptable accuracy. Then, the temperature distribution of the basin, covers, the water in the basin and heat transfer coefficients between the water as well as covers in all stages are calculated. Then, the amount of fresh water as an output are derived for one and multistage units. With increasing the number of stages from one to four, the amount of fresh water was increased by 42%, 72% and 94%, respectively. In addition, the amount of yield water for the ratio of three stages to two stages and four stages to three stages was increased 20% and 13%, respectively. Moreover, in this article, a new approach is adapted based on the variation of water depth instead of considering it constant and because of this methodology, there is an optimum value for water depth, which leads to the maximum productivity. Due to the storage of energy in water as a function of water depth, with an increase in the amount of water in the basin of solar stills more than the optimum value, or even decreasing the water depth below the optimum value, one should expect to get the basin without water at the end of day. This may lead to have less fresh water in the output at the end of the day. Finally, a correlation has been provided to calculate the productivity of a single basin still based on the water depth in the basin

Heat transfer analysis of lateral perforated fin heat sinks

In this article fluid flow and conjugate conduction-convective heat transfer from a three-dimensional array of rectangular perforated fins with square windows that are arranged in lateral surface of fins are studied numerically. For investigation, Navier-Stokes equations and RNG based k - [epsilon] turbulent model are used. Finite volume procedure with SIMPLE algorithm is applied to coupled differential equations for both solid and gas phases. Computations are carried out for Reynolds numbers of 2000-5000 based on the fin thickness and Pr = 0.71. Numerical model is first validated with previous experimental studies and good agreement were observed. Based on a valid numerical model, numerical solution is made to find fluid flow and temperature distribution for various arrangements. For each type, fin efficiency of perforated fins is determined and compared with the equivalent solid fin. Results show that new perforated fins have higher total heat transfer and considerable weight reduction in comparison with solid fins.Rectangular perforated fins Turbulent flow Convection heat transfer Fin weight