| DEVELOPMENT OF A FLOW NETWORK SIMULATION PROGRAM PART II – THERMAL ANALYSIS |
| J. LIM, K. Y. YANG |
| Hyundai Motor Company |
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| ABSTRACT |
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An in-house simulation program is developed that can conveniently be utilized to predict flow and thermal characteristics such as velocity, pressure and temperature in any flow network systems comprising multiple flow components such as pipe, pump, heat exchanger, valves, etc. The program consists of two parts, the flow analysis for computing velocity and pressure and thermal analysis for temperature. The flow analysis portion of the program was dealt with in the Part I of the paper. Here, the thermal analysis part of the program is discussed. For the thermal analysis, first the flow analysis should be carried out to find out velocity and pressure in the network system, since this flow information is used as the input data for the thermal analysis. The mathematical and numerical formulations in the thermal analysis are very similar to those in the flow analysis. A thermal energy balance equation is applied to each thermal element with the unknown temperatures at nodes, while in the flow analysis both energy and mass conservation equation are applied to each flow element with two unknowns, velocity and pressure, at each node, so as to establish a set of non-linear algebraic equations that is to be iteratively solved by the Newton-Raphson scheme. In the program, five different flow and thermal elements respectively are treated, and believed to represent a variety of the network flow system in many practical engineering applications. However, the program can easily be extended to incorporate additional elements if necessary. In order to demonstrate the validity and applicability of the program, a comprehensive example of the engineering problems encountered in the vehicle development is introduced, and the solution process as well as accuracy of obtained results are discussed. Throughout the study, it is found that the program can most efficiently be used to find an optimal design concept among many potential design options in an early conceptual design phase of the vehicle development. |
| Key Words:
Flow network, Thermal analysis, Simulation code, Newton-raphson method, Flow components |
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