An experimental study on designs of new geysers with heat recirculations.

• Main Authors: Shih-Chieh Lo, 羅士傑
• Other Authors: Sheng-Yang Shih
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/39165379213100749209

碩士 === 國立中央大學 === 機械工程研究所 === 93 === 英文摘要 The purpose of this research is to design an energy-saving geyser using heat-recirculating lean premixed combustion technique in the Swiss-roll burner (SRB). The burner uses lean premixed C3H8/air mixtures as a fuel. The effects of Reynolds number (Re) and equivalence ratio (ψ) on the hot water temperature and the heat efficiency of the geyser are investigated in order to judge and improve design. Emissions, such as CO and NOx are measured by the flow gas analyzer. Three different designs of the heat exchangers inside and outside the SRB are proposed, (1) a fin-tube heat exchanger similar to that used by the personal computer, (2) a self-designed copper water plate with fins which is used as the upper plate of the SRB, and (3) similar to (2) but plugging the extended copper tubes along the flow channel of the products to increase heat transfer for water heating. Experiment results show that the water condense problem on the fin-tube surface, as the first design, can degrade the heat transfer efficiency especially at high Re. The second and third designs are free from the water condensed problem. The second design with 1.5 turns of the SRB is not good enough, because the exit temperature of the products is still high, over 500oC. In order to fully utilize the hot temperature of the products, we use the third design, and the exit temperature of the SRB can be reduced to about 100oC. Furthermore, a bigger SRB with 2.5 turns is also built for increasing higher hot water flow rates in the geyser. Probably, the most important point in this thesis is to develop a simple mathematic model based on several heat loss parameters in the heat-recirculating system to predict the performance of the geyser and thus improve its design. Finally, this simple mathematical model is proposed.