Direct Contact Evaporation Process for Recovery of Waste Heat

回收废热的直接接触蒸发工艺

• 批准号: 60850041
• 负责人: FUJITA Yasunobu
• 金额: $ 3.2万
• 依托单位: Kyushu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Developmental Scientific Research
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1986
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-60850041/
• 关键词: Direct Contact Evaporation; Phase Change; Boiling Heat Transfer; Waste Heat; 熱回収; 直接接触式蒸発器; 廃熱回収; 性能評価法; 沸騰蒸発過程; 沸騰形態; 流動伝熱特性; 二相流伝熱; 高性能熱交換器

The direct contact evaporation process of dispersed low boiling-point liquid within immiscible hot water is prospective for industrial use to recover waste heat from hot water. This study aims at pursuing heat transfer characteristics in a direct contact evaporation column.Boiling characteristics of refrigerant R113 injected as the dispersed phase into hot water flowing upwards in a vertical test column at atmospheric pressure are investigated by photographic observation of the flow pattern and by measurement of the local flow and heat transfer behavior with the aid of the multi probe void meter developed for this work.Heat transfer characteristics are strongly influenced by the boiling regime just near the nozzle. An increase in the inlet temperature of water and R113, and an increase in the nozzle Reynolds number promote the rate of evaporation and the bubble coalescence. As a result, the boiling regime near the nozzle changes from the unstable, stable, to column-like ones and the heat transfer is improved in this order. In the column-like regime where the highest performance is attained, heat transfer coefficient is influenced by the mass velocity of liquid R113 and the temperature driving force and not by the inlet temperature of R113 and the nozzle Reynolds number. Volumetric heat transfer coefficients, local and also average over the column, are correlated in terms of those two influencing parameters.

分散的低沸点液体在非混相热水中直接接触蒸发是回收热水余热的一种很有应用前景的方法。本研究旨在研究直接接触蒸发塔的传热特性。在常压垂直试验塔中，通过摄影观察流动模式，并借助为此研制的多探头空隙计测量了局部流动和传热行为，研究了制冷剂R113作为分散相注入到向上流动的热水中的沸腾特性。热传递特性受到喷嘴附近沸腾状态的强烈影响。水和R113入口温度的升高以及喷嘴雷诺数的增大均促进了气泡的蒸发速率和气泡的聚并。因此，喷嘴附近的沸腾状态由不稳定的、稳定的转变为柱状的，换热效果也随之改善。在获得最高性能的柱状区，传热系数受液体R113的质量速度和温度驱动力的影响，而不受R113进口温度和喷嘴雷诺数的影响。根据这两个影响参数，局部传热系数和柱上的平均传热系数是相关的。

项目成果

Fujita, Yasunobu: "Heat Transfer Process in Direct Contact Evaporation (2nd Rep., Boiling Regime and Heat Transfer Characteristics)" Transactions of Japan Society of Mechanical Engineers. 52. 1379-1386 (1986)

Fujita, Yasunobu：“直接接触蒸发中的传热过程（第二次报告，沸腾状态和传热特性）”日本机械工程师学会汇刊。

日本機械学会論文集. 52-475. (1986)

日本机械工程师学会会刊 52-475 (1986)。

藤田恭伸: 日本機械学会論文集. 52. 1379-1386 (1986)

Yasunobu Fujita：日本机械工程师学会会议记录 52. 1379-1386 (1986)。

Shiina,Kohji: "Evaluating Method of Heat Transfer Performance in Direct Contact Evaporator (2nd Rep., Flow Regime and Heat Transfer Correlation)" Proceedings of 22th Japan National Heat Transfer Symposium. 524-526 (1985)

Shiina,Kohji：“直接接触式蒸发器传热性能的评估方法（第二次，流动状态和传热相关性）”第 22 届日本全国传热研讨会论文集。

藤田恭伸: 日本機械学会論文集. 51. 2647-2655 (1985)

Yasunobu Fujita：日本机械工程师学会会议记录 51. 2647-2655 (1985)。