ISSN: 2277-3754 ISO 9001:2008 Certified International Journal of Engineering and Innovative Technology (IJEIT) Volume 4, Issue 1, July 2014 Computation of Optimal Structural and Technical Parameters of Solar Dryer K. M. Khazimov; G. C. Bora; B. A. Urmashev; M. Z. Khazimov; Z. M. Khazimov ABSTRACT: -determination of the geometrical measurement and technological parameters of a heliodryer are very important. This study engaged computational modeling using known mathematical relationship and new boundary statements of the problem in relation to the object. The movement of air was acting as drying agent in the dryer and the common heat conductivity equation was considered. According to the presented algorithm in this study, the differential equation was solved with taking into account dimensionless magnitudes (Grasgof, Reynolds and Prandtl).The results were identified as is olines, the function of an isotherm and an isobar current were found at various values of Grasgof, Reynolds and Prandtl numbers. Most efficient heat exchanges zones were recognized by various Nusselt's various values. The effective zone of drying was described graphically ina vicinity of the camera of the dryer, where the passive zone near site of the dryer camera was identified and it was presented also as a graph. KEYWORDS: Computational Modeling, Grashof Numbers, Nusselt numbers, Optimization, Solar Drying. I. INTRODUCTION Computational modeling for justification of technological and structural parameters of solar dryer allows reducing costs of experimental studies during its design. The laws of transfer of energy and mass in wet materials in the process of dehydration are very complex and have not been studied at sufficient level. Main provisions of the theories of drying were developed by A.V.Lykov, P.A.Rebinder, A.S.Ginzburg, V.V Krasnikov and other researchers [1- 4]. Wet material subjects to drying represents multiphase and multi component environment. During the passage of drying agent the complex process takes place which is accompanies by heat and mass transfer between different phases and components of the system. Depending on the set task, the system is studied at different levels of complexity. In accordance with the technology, regularity of heat and mass exchange in the system of solar dryer - wet material - the environment must be described in the appropriate equations, qualitatively and quantitatively satisfying the real process. There are many mathematical models of free convection. The case of thermo-gravitational convection has been most studied, when the equations of fluid motion are solved together with the heat equation. Changing of density is taking into consideration in the equations of motion through the approximation of Boussinesk.During last three decades a considerable amount of publications were devoted to the research of free (natural) convection. Such interest to a phenomenon of thermal convection is mainly explained by its important role in various processes, such as air flow in the street canyons, a cooling tower, spread of smoke and fire in building, movement of blood in vessels, operation of solar collectors etc.The objective of this study is to find out the optimum technological parameters and structural measurements of a heliodryer. II. MATERIALS AND METHODS The proposed construction of solar dryer relates to mine types, which includes air heating element from solar energy, vertical drying chamber, heat accumulator, air passage (Figure 1a&b). The device is made with possibility of rotat able by means of supporting wheels 12, which are arranged at the basis of the device. On the outer surface of the drying chamber 6 there is coating which is made of heat isolating material. The proposed system works like this. In the daytime, sun rays pass through the screen 8, through a layer of greenhouse protection, heat the air in the heater of drying chamber 10 and heat accumulator 11. Warm air enters the drying chamber 6, which is used for drying of raw material, and the exhaust air enters the air ductwork 3, and is expelled out of the umbrella 1. There are many mathematical models of free convection. The most studied is the case of thermo- gravitational convection, when the equations of fluid motion are solved together with thermal conductivity equation. Changing of density is taken into consideration in the equations of the motion through the approximation of Boussinesk. The system of equations of free convection in the Boussinesk approximation is as follows [5]. , ] ) ( [ ρθ β µ ρ g u p u u t u      − ∆ = ∇ + ∇ + ∂ ∂ (1) , 0 = u div  (2) , ] ) ( [ θ χ θ θ ρ ∆ = ∇ + ∂ ∂ u t с  (3) The system of equations (1) - (3) takes into account the assumption of Boussinesk, which applies to the density, assuming that the change of density฀฀ (฀฀ ) can be taken into account only for. Practice shows that this system is a good description of a wide range of free convection. The solution of (1) - (3) depends on initial and boundary conditions. 258