Papers by Keyword: Fin

Abstract: Low solid fraction simple rheocasting using Al-25%Si is proposed to cast a product with thin fins. The characteristics of this casting are presented. A conventional die-cast machine was used. The low solid fraction semisolid slurry was made in the sleeve of the die cast machine. Super cooling was used to reduce the casting temperature. The huge latent heat of the Si was utilized because of its excellent flow ability. A model of a heat sink, which was 0.5mm thick, 25mm high with 0.5 mm draft angle, was could be cast by the proposed process.

Abstract: It became clear that semisolid Al-25%Si has excellent flow ability and suitable for thin product die casting thinner than 1mm. Semisolid die casting of thin fin was tried using Al-25%Si. The rheocasting was selected. The pouring temperature of melt was 1103K, and the casting temperature was as same as the liquidus line 1033K. The fine, which thickness was 0.5mm, height was 25mm and draft angle was 0.5 degree, could be cast at the plunger speed of 0.8 m/s. The primary Si was smaller than 0.2mm. The α-aluminum existed by the super cooling.

Abstract: A computational fluid dynamic approach has been utilized to optimize the fin shape inside a circular tube having different shape of fins attached internal circumference of the tube. Total three type shape (rectangular shape, T-Shape, triangular shape) of fins is utilized for this numerical analysis. The tube length is taken 5m and dimeter of 0.07m. For all case volume of fins remains constant factor with Reynolds number 1200 and constant wall heat flux of 200 W/m2. For this analysis a commercial package FLUENT is used. The present paper shows how the fluid temperature, pressure and velocity changes in axial direction for changing the fin shape. Result shows that for triangular fin shape there optimum heat transfer between other configuration of fin.

Abstract: The coach body of the high-speed railway train is required to have a good thermal insulation performance. It can keep a comfort passenger environment and decrease demand for the cooling load of air-conditioning system. The determination of coach body heat transfer coefficient (K-value) is critical for the efficient design of vehicle air-conditioning system. A heat transfer coefficient calculation model is especially proposed for the typical aluminum section thermal insulating wall structure of high-speed trains coach body in china, on the basis of the fin heat transfer mechanism. For the train type of CRH3G, the calculating coach body heat transfer coefficient is in good agreement with the experimental value. So the proposed calculation method can significantly improve the computational efficiency of the K-value for the high-speed railway trains which have the typical aluminum section insulation wall structures, and provide a trustable basis for the coach body structure optimization design.

Abstract: The excellent thermal hydraulic performances of coolers are the foundations of vehicular safety and stability. Structure, material, fin type and arrangement all have important effects on the thermal hydraulic performances. Numerical simulation method was adopted in this paper to investigate the effect of fin arrangement. The fluid flow and heat transfer performances were contrasted and analyzed under two different fin arrangements. It was found that fin arrangement effected thermal hydraulic performances severely and during the design process of a cooler, the performance requirements could be met through adjusting fin arrangements.

Abstract: This study used rectangular fins with constant heat transfer coefficient as material to discuss convective and radiative heat transfer, so as to prove that the hybrid spline difference method proposed in this study is an easy to operate method with high accuracy. According to the computational process described in this paper, the hybrid spline difference method is as simple as finite difference method and is easy to use. The complex computational process of traditional spline method can be simplified by using this method, but the numerical accuracy can be increased to second order. Therefore, the high accuracy numerical method of hybrid spline difference method replacing traditional spline method for future heat transfer analyses is expectable.

Abstract: An experimental study has been carried out to evaluate how fin and copper foam enhance the heat transfer performance of phase change thermal energy storage unit. The thickness of fins is 0.8mm, the porosity of the copper foam is 96% and the phase change material (PCM) is 99% pure eicosane. The samples with fin, copper foam and paraffin (FCFP) or with single copper foam and paraffin (CFP) were processed and their response to temperature variations were tested for vertical placement and horizontal placement under different heat flux conditions. The experimental results show that the use of fin and copper foam can make the sample melt much faster than single copper foam and the effective thermal conductivity of the FCFP composite is 10.83 W/(m∙K), which is 2.7 times as that of the CFP composite. In addition, horizontal placement is more contributive to the heat transfer than vertical placement for high thermal conductivity composite.

Abstract: The article presents a new kind of shell and tube phase change heat storage exchanger using vertical fins. And select paraffin as phase change materials, Fluent6.3 software was used to study the melting process. Some conditions of different fin height, different fin width and different fin numbers of axial direction were investigated. The results show that the higher and the wider of the fins, and the more the fin number of axial direction, the shorter is the melting time, the better is the effect of heat transfer

Abstract: Fin widely used in industrial practice, and the surface heat transfer coefficient is not constant value. In this paper, through appropriate simplification, the mathematical model in Longitudinal Fin of Rectangular Profile has been established, When the surface heat transfer coefficient along the fin in the exponential changes. The exact solution of fin conduction has been get, and derived efficiency and the corresponding fin heat flux formula. And an example has been given to verify. The solution can be applied to engineering practice, and guided theoretical the heat transfer enhancement in the design of fin.

Abstract: This paper presents numerical investigations on melting of phase change material using paraffin wax inside a double pipe heat exchanger. Numerical simulations are performed for melting of phase change material (PCM) in annulus while the inner pipe has two or four longitudinal fins and the results compared with inner bare tube. The aim of this study is to understand the PCM melting behaviors by observing the natural convection currents movement and melting fronts formation. It is concluded that melting performance of PCM can be significantly improved by applying longitudinal fins on the inner tube.