碩士 / 國立臺北科技大學 / 冷凍與低溫科技研究所 / 89 / This thesis is on a new air-conditioning technology that uses natural convection heat transfer of finned-tube type heat exchanger performance for cooling. Natural convection air-conditioning has some advantages as it uses no electric fan, no fan noise and no fan energy, and it is becoming very popular in Europe.
This research thesis has three parts. First, heat transfer performance of finned-tube heat exchanger was studied by changing the fin pitch, number of chilled water tubes, chilled water inlet temperature, and chilled water flow volume. The natural convection cooling performance of the fifteen different heat exchangers were tested using an experiment approach. Secondly, simulation of whole flow field of natural convection by computational fluid dynamic approach was performed. Corrections of the theoretical model were done after comparison of simulation results with those of experiment data. The computational simulation was then used in studies and analyses of the effects of different heat transfer parameters.
The third part of this thesis is on the use of experiment measurements and simulation results to predict the natural convection heat transfer coefficient of the finned-tube heat exchanger. The results are used to develop natural convection heat transfer model of the finned-tube heat exchanger. The results of this thesis help to buildup a reference in the future study of natural convection air-conditioning.
On the experimental side, the results the natural convection heat exchange performance is about 100 W/m2 of heat exchange area, and the convection heat transfer coefficient (h value) is about 10 W/m2℃. These results show that finned-tube heat exchanger can be applied to natural convection cooling practically.
On the computational simulation side, this study attempted to simulate the whole heat flow field that includes the water and the airside heat transfer. The same heat exchanger geometry and heat transfer parameters were used either in the experiments or in the simulations. Good agreements between simulations and experiment measurements were achieved for the temperature distribution of the fin and the heat transfer performance. This indicates the computational models of this thesis are viable. Finally, the results of the experiment measurements and simulations were used to build the finned-tube heat exchanger’s heat transfer model that considers the characteristic length of finned-tube heat exchangers under natural convection conditions.
| Identifer | oai:union.ndltd.org:TW/089TIT00703003 |
| Date | January 2001 |
| Creators | Jean Der Chen, 陳俊德 |
| Contributors | 蔡尤溪 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 92 |
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