中 文 摘 要 應用熱傳遞原理來設計一個可應用的儀器裝置而完成一特定工程目標是非常重要的。在設計時我們必須以經濟利益為首要目標來考量。因此熱交換器(heat exchanger)的設計，經濟因素扮演一個非常重要的角色。譬如：為了達到經濟原則，我們需考量熱交換器裝置的大小、重量、材質、能量回收效率和熱交換器操作的費用等，而這些因素必需依靠熱交換器的熱分析為依據。 熱交換器以冷熱兩流體的流動方式可區分為平行流(parallel-flow)、逆流(counterflow)和交叉流(crossflow)三種形式。在一般的文獻中大部份探討穩定性(steady state)熱交換器，而討論時間非穩性(unsteady state)熱交換器的文獻卻非常少。因此本篇論文研究主要目的是分析和討論在時間非穩定性的平板(plane)逆流熱交換器和時間非穩定性圓管(cylinder)逆流熱交換器的基本原理和模式。並且以數值分析之有限差分法(finite-difference)來計算非穩態與穩態熱交換器內的兩流體和分隔板的溫度分佈情形。這個問題我們由數值分析方法來分析造成龐大的聯立方程式組，因此我們必需用電腦和程式語言來做輔助計算。 ABSTRACT It is important to apply the principle of heat transfer to design an engineering system of heat exchanger. In an engineering design, the economical considerations are very important. For example in a heat exchanger design, we have to consider the size and weight, the material of the construction, the cost of the operation and the efficiency performance of the equipment. These factors are depended on the thermal analysis of heat exchanger. Based on the flow direction, the heat exchanger may be cataloged as three types; parallel-flow, counterflow and crossflow heat exchanger. Most part of the technical literature and textbook discuss steady state of heat exchanger only. The main objective of this study is to analyze the unsteady state of plane-type and cylindrical type counterflow heat exchanger. We apply finite difference numerical method to calculate unsteady and steady state temperature distributions of two fluids and partition wall in counter-flow-heat exchanges. The method of calculation developed in this study can be applied to reduce the size of the matrices and used to compute the solution of a tremendous set of simultaneous equations.
