三維空間環境控制室之熱流場分析

Abstract

環境控制室是冷凍空間系統提供冷氣機量測其性能效率能力環境 的庫體結構。本文以其室內側房為模擬對象，用數值方法探討該三維 空間的氣流和溫度場的分佈情形，並將其結果做為環探室設計依據。 本研究考慮的介質為不可壓縮之穩態空氣流，對論具有非等溫熱 傳的紊流流場，以k-紊流模式、SIMPLE演算法及混合差分法求解。第 一部份主要分析矩形空間內，改變氣流入口位置而固定氣流出口位置， 並在上下兩壁面均給予高溫邊界，而氣流入口為較低溫冷空氣時室內冷 卻的情形；第二部份則在符合環控室精度要求之下，提供不同數量、 位置、及大小的熱源熱傳量，以尋求供試機測試口附近均溫、低流速 的最佳設計。 結論顯示，當氣流入口位置愈接近邊側，則室內中間的風速、溫 度愈均勻。但同時也因磨擦黏滯的影響，氣流動能會損耗較快；就環 控室來說，其熱源表面熱傳的散逸能力是受到熱對流效應的強弱來決 定，當流場內部局部干擾升高時，散熱也較佳，相對地流速較緩的地 方，特別亦發生熱量的囤積，使得該處溫度升高。

The environment control room is used for measuring the performance and efficiency of air conditioners in the refrigeration system. The three-dimensional distributed outline of airflow in velocity and temperature fields in the indoor-side room is studied numerically by the computer program FLOW3D. This airflow field is assumed as incompressible, steady, non-isothermal the turbulent. The k-ε turbulence model, SIMPLE algorithm as well as hybrid scheme are utilized to solve these problems. The effect of inlet locations on flowfield with two different high temperature of ceiling and floor and fixed outlet are discussed in this analysis. Under environment control standard, a optimal design is developed by changing the numbers, the locations and the values of heat sources. The results show that the nearer inlet location is to corners, the more uniform velocity as well as temperature distributions will become. However, airflow kinetic energy will decay seriously due to the influence of friction. As for environment control room, the capability of diffusion on heat sources should be decided by thermal convection effect. When this effect arised, diffusion happenned. If airflow velocity is slow, its local temperature would become high.