臺灣博碩士論文加值系統

摘 要
冷凍運輸車在食品冷凍鏈中扮演著極為重要的角色，其主要功能是使車體內裝載之食品在運送及配銷過程中維持在冷藏或凍藏之低溫環境下。隨著國民生活水準之不斷提昇，國內冷凍食品消耗量亦逐年提昇，再加上台灣於2002年成為WTO之會員國，國外農產品開放進口，因此冷凍運輸車需求量將日漸增加。然而冷凍運輸車內所運送食品的保存品質主要受溫度的影響，而溫度場之均勻與否又與車體內氣流場分佈有密切的關係，因此冷凍運輸車內氣流分佈之研究為一重要之課題。
本文首先建立數值模式，用以模擬冷藏庫內食品在冷卻過程之暫態溫度場與流場之變化，並利用冷藏庫進行實測以驗證模式之準確與可用性，結果顯示所得之值與模擬值十分吻合。接著，利用所建立之數值模式研究不同參數對冷凍運輸車內氣流與溫度場之影響，並進一步找尋最佳之氣流分佈方法。所建立之數值模式中輻射熱傳、紊流模式與浮力效應均列入考量。至於探討之參數包含：回風配置、風管配置、出風口位置與風量配置等之影響。結果顯示：回風處安裝檔板將可使溫度場分佈較均勻，但此結果並不能使得所載運的冷凍生鮮食品達到國際冷凍生鮮食品協會的溫度要求，因此有必要在其內部增加風管。在相同風量不同出風位置的模擬方面所得到的結果顯示，當在箱體全長三分之一處出風時其所得之結果最好溫度場較均勻，不過其降溫速率仍然較慢。而在不同風量不同位置出風模擬方面，本研究發現在三分之一、四分之三處安裝兩支風管，風量為3：5：2時其冷卻降溫效果最為佳，不僅降溫速率快，同時產品間的溫差亦最小。使用此種設計方式除了可使冷凍運輸車的氣流場、溫度場分佈較佳外，並且得到良好的溫度控制與貨品品質之維持。

Abstract
A refrigerated semi-trailer plays a very important role in a cold chain. Its main function is to maintain perishable commodities in set conditions of temperature and humidity during the period of transport and delivery. With the progress of the standard of living, the request of refrigerated foods must increase year by year. In the other hand, Taiwan joins WTO in 2002 and imports diversified agricultural products from many countries. Therefore, the requirement of refrigerated semi-trailers must be increased day after day. However, keeping the quality of foods transported by a refrigerated semi-trailer is mainly affected by the uniformity of temperature, which depends on the airflow distribution. Hence, how to obtain even airflow distribution in a refrigerated semi-trailer is a very important issue.
First, this study builds a numerical model to simulate foods cooling process and investigates transient airflow fields, including velocity and temperature distribution in a refrigerated room. In the other hand, modeling accuracy is checked by experiment. It is founds that both simulation and experiment agrees well. Second, to find optimal airflow distribution, the developed model is used to predict the velocity and temperature distribution in a refrigerated semi-trailer, which is affected by different parameters, including return air dispose, air duct dispose, supplying air place and airflow rate dispose. This model considers the effect of radiation, turbulence and buoyancy.
It is found that at returning air place using buffer plate can get uniform temperature distribution, but this result can’t make perishable foods reach ATP request, therefore it must install internal air duct. According to the simulation results of different supply air place, it is found that air duct at 0,1/3 place has the best result, and temperature distribution is more uniform, but temperature drop rate is still slow. The simulating results of different supply air place and airflow rate reveal that air duct at 0,1/3,3/4 place and airflow rate 3:5:2 have a optimization. Using this design not only has uniform velocity and temperature distribution but also has good temperature control and foods quality.

目 次
摘 要
Abstract
誌 謝
目 次
表目錄
圖目錄
第一章　緒論
1.1　研究背景
1.2　文獻回顧
1.2.1　冷凍運輸相關文獻
1.2.2　冷凍冷藏相關文獻
1.3　研究目的
第二章　理論模式與數值方法
2.1　理論模式
2.1.1　流場統御方程式
2.1.2　紊流流場模式
2.2　數值解法
2.2.1　對流-擴散方程式的差分形式
2.2.2　壓力-速度偶合關係的處理
2.3　邊界條件設定及計算方式選用
第三章　冷藏庫內食品冷卻過程之數值模擬
3.1　數值模擬
3.1.1　空庫溫度場模擬
3.1.2　蘋果冷卻模擬
3.2　實驗驗證
3.2.1　實驗系統與設備
3.1.2　實驗方式與步驟
3.3　結果與討論
3.3.1　冷凍庫空庫降溫實驗
3.3.2　蘋果降溫實驗
3.3.3　冷凍庫空庫驗證結果
3.3.4　蘋果冷卻降溫驗證結果
3.4　結論
第四章　冷凍運輸車氣流分佈最佳化之研究
4.1　冷凍車外觀尺寸
4.2　邊界條件
4.3 結果與討論
4.3.1 格點測試
4.3.2　回風檔板之影響
4.3.3　出風口位置之影響
4.3.4　出風口風量之影響
4.4　結論
第五章　結論與建議
5.1　結論
5.2　後續研究建議
參考文獻
符號說明
作者簡介

參考文獻
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