噴流捲入率對開放式冷藏櫃氣簾效率之影響

Jet Entrainment Rates of Air Curtain to Open-Type Refrigeration Display Cabinet Efficiency

李金堂(Jin-Tang Li)

指導教授 ： 蔡瑞益

中原大學/工學院/機械工程學系/碩士(2008年)

https://doi.org/10.6840/cycu200800474

摘要

本研究主要討論到開放式冷藏櫃的出風速度、紊流強度、出風角度及背板開孔出風以達到維持氣簾效率減少整體開放櫃溫度梯度的效果。出風口速度以 來比較討論速度對於氣簾效率之影響，提出幾組適合本文所使用之開放櫃原型機的速度後，再作捲入率的討論。選用出風速度 ，搭配紊流強度5-25％、出風角度-20°-20°，及背板開孔來作討論。計算過程採用CFDRC計算流體力學套裝軟體，計算結果包括速度場及溫度場分佈情形，流體狀態為紊流模式。本文經模擬分析後，得知此型開放櫃原型機所使用出風風速約在 最為恰當，出風紊流強度可有效減低捲入率。出風角度大約在外翻15°-20°間可連結回風口並降低捲入率。在開啟背板方面本文以開啟5、6兩層作比較，開啟5或6單層的確有明顯的冷卻效果在A及B截面的溫度上都有降低2-3K，但5或6沒開背板其層板的溫度就會較高，不如開啟5、6兩層雖然在A截面其冷卻效果不明顯但是在第5、6的B截面上溫度都降了約在3K左右，且可讓擺放空間更多。

關鍵字

冷藏 ； 展示櫃 ； 模擬

並列摘要

ABSTRACT
The present work is to discuss the discharge of flow velocity, turbulent intensity, discharging angles and back panel flow inlet to sustain the efficiency of air curtain and reduce the temperature gradient of the cabinet. We set the flow inlet velocity in a range of to research the influence of air curtain efficiency and select several suitable parameter of velocity to test the entrainment rate. We discuss the correlation among the discharging velocity of , turbulence intensity of 5~25％ and discharging angles of -20°~20° accompanied with whether the back panel flow inlet is existing or not. The commercial code of CFDRC is adopted to simulate and the results depict the velocity and temperature distributions.
After simulation and analysis, we can figure that the optimum velocities are in a range of and the entrainment rate can be decreased by the weaker turbulence intensity efficiently. The optimum discharging angle is between 15°and 20° which the flow could be linked to the return air grill and decrease the entrainment rate. In other respects, to compare the results of opening the level of 5 and 6, it could be seen the cooling effects on both A and B sections and the temperature decrease is about 2~3K. The temperature would increase if the level of 5or 6 is not opening. The cooling performance is not so obviously on section A, whereas the temperature decrease is about 3K on section B, thus a lot of free space could be released.

並列關鍵字

cabinet ； Refrigeration ； Simulation

參考文獻

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