噴淋式蒸發器之氣流夾卷液滴現象研究

A study of droplet entrainment phenomenon in Spray-Type evaporator

陳雍仁(Yung-Jen Chen)

指導教授 ： 簡良翰

國立臺北科技大學/機電學院/能源與冷凍空調工程系碩士班/碩士(2013年)

https://doi.org/10.6841/NTUT.2013.00644

摘要

本研究旨在探討噴淋式蒸發器內部流場變化，利用可視化之模擬實驗，觀察冷媒在蒸發器內部噴淋之現象。因噴淋式蒸發器內冷媒與空氣為逆向流動，故液滴飛濺為一重要關鍵之研究。測試風量為192~384CFM，水量為90~180LPM，滴淋管陣高度4.795~1.795公分，吸氣口內徑為23以及30公分，滴淋裝置種類為管式、簡易板狀結構之板式以及傳統三角板狀結構之板式，最後利用計算流體力學模擬軟體ANSYS FLUENT與實驗值相互對照。流場數值分析結果顯示，因流體流動空間越大時，其流動將減速。故本研究以相關實驗與模擬結果而提出預測蒸發器殼側內部最大速度之公式，及其與液滴被氣流夾卷之關係。藉此在設計噴淋式蒸發器時先行估算出流場之速度，以避免氣流夾卷液滴現象。

關鍵字

噴淋式蒸發器 ； 夾卷 ； 可視化流場

並列摘要

In this Study, the flow distribution inside a spray-type evaporator is studied. By the visualization experiment, the droplet entrainment of refrigerant inside an evaporator is simulated. Since the liquid and vapor flow counter currently, the droplet entrainment is an important issue. The experiment was performed with an air duct inlet diameter of either 23cm or 30cm. The airflow varied from 192CFM to 384CFM. The water flow varied from 90LPM to 180LPM. Tube array of height varied from 4.795cm~1.795cm. Three types (tube type, plate type, and triangle type) of fluid distributors were tested. Additionally, the results of CFD (computational fluid dynamics) was compared with the experimental values. The larger flow space results in lower flow velocity, and reduces the possibility of liquid entrainment. The maximum flow velocity is an important parameter to identify the tendency of liquid entrainment. This study developed the equations of maximum velocity, based on its experimental results, to avoid serious droplet entrainment situation.

並列關鍵字

spray-type evaporator ； droplet entrainment ； flow visualization

參考文獻

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