Application of Heat Pipe in Energy Storage System
Date Issued
2007
Date
2007
Author(s)
Chen, Bo-Ren
DOI
zh-TW
Abstract
This dissertation experimentally and theoretically investigates the thermal performances of three innovative energy storage system designs which are subcooled ice storage air-conditioning system, two-phase thermosyphon solar water heater and phase change material (PCM) cooling module. Theoretical models are developed to simulate the thermal characteristics of the systems with various design modifications by employing thermal resistance-capacitor model (RC model) in this research.
The subcooled ice storage air-conditioning system adopts an ice storage tank as a subcooler which utilizes the superior heat transfer characteristics of two-phase closed thermosyphon (with R-22 as working fluid) and eliminates the drawbacks found in conventional systems. The subcooler is effective to enhance 28 % more cooling capacity and 8% higher coefficient of performance (COP) by the subcooling process. The theoretical analysis result shows that the ice storage tank reduces 25 % of charging time by both increasing film condensation area in the fin tubes and heat transfer area between the fin tubes and energy storage material (water).
The proposed two-phase thermosyphon solar water heater absorbs and transfers thermal energy by conducting boiling and condensation mechanisms with working fluid of ethyl alcohol inside. The system thermal efficiencies are experimentally verified from the hourly, daily, and long-term test. The two-phase thermosyphon can effectively reduce heat loss and provide 18 % higher system characteristic efficiency than that of the conventional systems. The simulation results show that the system achieves 3 % and 4 % greater charge efficiency as fin tubes number becomes twice and thermal conductivity of working fluid is 50 % higher, respectively. Six percent enhancement is obtained when wick structure are installed in the thermosyphon within lower working fluid fill ratio.
The PCM cooling module applies energy storage concept in the system design. The device can shift peak heating power of the electronic component by storing or releasing the thermal energy. The performance testing results demonstrates that the cooling module lessens 46 % of the fan power consumption with PCM (tricosane) rather than water as energy storage material in the storage tank. The RC model analysis is performed to simulate the heater temperature variation for the case of oscillating heating power. The thermal performance can be enhanced with a larger fin area, higher PCM thermal conductivity, or increase of the area between the PCM and heat pipe. The maximum heater temperature decreases from 67.7 oC to 52.7 oC as the PCM thermal conductivity is treble.
Subjects
熱管
兩相熱紅吸管
儲冰空調
太陽能集熱器
相變材料
電子散熱
Heat Pipe
Two-Phase Thermosyphon
Ice Storgae Air-Conditioning System
Solar Water Heater
Phase Change Material
Electronic Cooling
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-96-F91522303-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):72488be31d03cc407c03bf9694da95ea