Investigation of Loop Heat Pipe Energy Storage System
Date Issued
2007
Date
2007
Author(s)
Yu, Cheng-Jung
DOI
zh-TW
Abstract
The energy storage system has been widely researched and used in recent years due to the energy crisis and environment protection. The development of energy storage system can help to collect the natural energy such as solar energy, or recycle the excess heat generated from the industrial processes. The loop heat pipe employs the phase-change mechanism, and hence has better efficiency. Loop heat pipes are not only cheap and easy to get, its passive design also makes it more reliable. Thus a loop heat pipe is used in our energy storage system. The liquid inside the evaporation tube will absorb the energy transferred from the heat source and becomes vapor, then moves toward the condenser and releases the latent heat into the water inside the energy storage tank. In our experiments, smooth, sintered and meshed copper tubes were used as different evaporation tubes. Other parameters were the fill-ratio of the system, power input, and different working fluids, inclusive of pure water and Al2O3 nanofluid (0.5wt%). Boiling characteristics and efficiencies are discussed.
For the experiments with pure water as working fluids at low fill-ratio, results showed that the sintered tube had the best average energy storage efficiency, about 3%~7% better than meshed tube; and the meshed tube was 3%~10% better than smooth tube. At higher fill-ratio, the performances of sintered and meshed tubes were similar, but both were better than smooth tube about 3%~10%. When the nucleate boiling occurred in the smooth tube, its average efficiency became comparable to the meshed tube. The best average efficiencies of sintered, meshed and smooth tubes were 37.80%, 35.38%, and 33.30%, respectively. For the smooth and meshed tubes experiments with nanofluid as working fluids, results showed that the nanofluid did not aggressively enhance the average efficiency due to its higher superheat and late occasion of nucleate boiling characteristics. But it is able to enhance the efficiency for sintered tubes at low input power (5W) experiments about 5.86%~8.47%.
Subjects
迴路式熱管
毛細結構
儲能系統
核沸騰
奈米流體
Loop Heat Pipe
Wick Structure
Energy Storage System
Nucleate Boiling
Nanofluids
Type
thesis
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