HT2008-56478 HEAT TRANSFER ENHANCEMENT IN TRIANGULAR FIN

ABSTRACT Fins are widely utilized in many industrial applications for example, fins are used in air cooled finned tube heat exchangers like car radiators, heat rejection devices, refrigeration systems and in condensing central heat exchangers. In this paper, heat transfer inside the fin system composed of a primary rectangular fin with a number of rectangular fins (secondary fins), which are attached on its surface, is modeled and analyzed numerically. The length of the secondary fins decreases linearly from the base of the primary fin to its tip. This modified triangular fin is a kind of improved tree fin networks. The effectiveness of the modified triangular fin is compared with the effectiveness of triangular fin which is calculated analytically. The results show that adding secondary fins increases the effectiveness of triangular fin significantly. Also, it is found that increasing the number of secondary fins in a constant length of primary fin will increase the effectiveness. In addition, by comparing the results it can be concluded that by shortening the length of the primary fin in modified triangular fin, the effectiveness will increase significantly to the contrary of the triangular fin, so smaller heat exchangers can be built by using the modified triangular fin. It is found that in a constant length of primary fin, there is an optimum thickness of secondary fins which maximize the effectiveness of the fin. INTRODUCTION The principle goal in improving the performance of existing thermal systems or in the design of new ones is to enhance heat transfer between hot or cold surfaces and the transport fluid. As such, several methods were proposed in the literature to achieve this task. These methods can be classifie

Sama: A Scalable Group Communication Mechanism for Mobile Agents

Abstract. Provision of fast and scalable group communication for mobile agents can considerably improve their efficiency. Unfortunately, most of the existing approaches do not scale well when the number of agents grows. In this paper, we propose Sama, a new group communication mechanism, to speed up message delivery to a group of mobile agents. The main contribution of Sama is distribution and parallelization of message propagation in an efficient way to achieve scalability and speed up message delivery to the group members. Sama uses Message Dispatcher Objects (MDOs), which are stationary agents on each host, to propagate messages in a parallel manner. The proposed mechanism is independent of agent locations and transparently delivers messages to the group using a constant number of remote messages. Experimental results show that message delivery time is significantly reduced in Sama compared to the previously proposed methods

DETC2005-84021 FREE VIBRATION ANALYSIS OF CIRCULAR FGM PLATE HAVING VARIABLE THICKNESS UNDER AXISYMMETRIC CONDITION BY FINITE ELEMENT METHOD

ABSTRACT This study presents the free vibration analysis of circular plate having variable thickness made of functionally-graded material. The boundary conditions of the plate is either simply supported or clamped. Dynamic equations were obtained using energy method based on Love-Kichhoff hypothesis and Sander's non-linear strain-displacement relation for thin plates. The finite element method is used to determine the natural frequencies. The results obtained show good agreement with known analytical data. The effects of thickness variation and Poisson's ratio are investigated by calculating the natural frequencies. These effects are found not to be the same for simply supported and clamped plates