碩士 / 正修科技大學 / 機電工程研究所 / 95 / This study reports an experimental investigation of heat transfer and pressure drop behavior during evaporation of R-290 and R-600a mixed with the lubricating oil (150SUS) in the micro-fin tubes within four different inserts (twined coil, wire coil, twisted tape, and helical-coil). The test were conducted at the saturation temperature of 15 , inlet oil concentration from 0 to 5 mass% oil, mass flux of 200 – 500 and the heat flux of 10.24 .
The evaporation heat transfer coefficients for the present study display a common trend in that the heat transfer coefficient increases as the mass velocity increases and as the lubricant concentration decreases. In addition, the two-phase pressure drop increase with an increases of the mass flow rate and the lubricant concentrations. The overall enhancement ratio ranged from 3.12 to 3.60, which indicates that the twined coil in micro-fins tubes enhances heat transfer effectively. The micro-fins tubes within twined coil insert has the best heat transfer performance, the others are wire coil, helical-coil, and twisted tape inserts, respectively. More, empirical correlations to estimate the evaporation heat transfer coefficients for the present hydrocarbons mixed with the lubricating oil have been developed.
| Identifer | oai:union.ndltd.org:TW/095CSU00657010 |
| Date | January 2007 |
| Creators | Tsai, Wu-chuan, 蔡武全 |
| Contributors | 溫茂育 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 102 |
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