Renewable Energy Resources and Technologies
Daryoosh Borzuei; Seyed Farhan Moosavian; Abolfazl Ahmadi; Rouhollah Ahmadi; Kourosh Bagherzadeh
Abstract
Energy plays a vital role in all human life activities. Due to the problems caused by fossil fuels in recent decades such as global warming, greenhouse gas emissions, ozone depletion, etc., the use of renewable and clean energy has been considered. An experimental facility for the acquisition of reliable ...
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Energy plays a vital role in all human life activities. Due to the problems caused by fossil fuels in recent decades such as global warming, greenhouse gas emissions, ozone depletion, etc., the use of renewable and clean energy has been considered. An experimental facility for the acquisition of reliable data from Parabolic Trough Solar Collectors (PTCs) was established to develop a robust analytical model. A wide range of Heat Transfer Fluid (HTF) flow rates (0.0372-0.1072 kg/s) and solar radiation (400-900 W/m2) were used to determine PTC parameters such as the outlet temperature of HTF loss and temperature distribution. Vacuum conditions in the receiver were considered effective in terms of thermal efficiency. Also, three types of HTF including two oil fluids (Syltherm 800 and S2) and water were examined. The temperature distribution showed that when Syltherm 800 or S2 passed through the absorber tube, the outlet temperature was higher than water: 2.84 % for Syltherm 800 and 3.72 % for S2. Since the absorber tube temperature was much higher than water, the heat loss in this condition was considered for oil HTF. Of note, the results demonstrated that use of the vacuum tube could diminish heat loss for the oil HTF. The effect of solar intensity increases from 600 W/m2 to 900 W/m2 on the maximum temperature of the receiver tube indicated that when Syltherm 800 was used as an HTF, this temperature increased by 35.1 % (from 167 °C to 219 °C), while this percentage was 32.7 % and 6.8 % for S2 and water, respectively.
Renewable Energy Resources and Technologies
Seyed Amir Hossein Zamzamian; Mohsen Mansouri
Abstract
The enhancement of the thermal performance of Vacuum Tube Solar Collectors (VTSC) was studied by using alumina nanofluid as working fluid. VTSC is a simple and commonly utilized type of collector. This study established the heat transfer experimental model of all glass VTSCs used in a forced-circulation ...
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The enhancement of the thermal performance of Vacuum Tube Solar Collectors (VTSC) was studied by using alumina nanofluid as working fluid. VTSC is a simple and commonly utilized type of collector. This study established the heat transfer experimental model of all glass VTSCs used in a forced-circulation solar water heating system using alumina nanofluid as base fluid. Al2O3 (with an average particle size of 15 nm) nanoparticles were provided and utilized to prepare nanofluids at a low mass concentration (0.5–1 wt.%). The thermal performances of VTSC were 15.3%, 25.7%, and 27.2% for the deionized water and Al2O3/water nanofluids with 0.5 and 1.0 wt. % as the working fluid, respectively. Generally, for Al2O3/water nanofluids with mass concentrations of 0.5 and 1.0 wt. %, the thermal performance increased by 67.9% and 77.7%, respectively, superior to that of vacuum tube using deionized water as the working fluid. Experimental results also showed that, for all three experimental tests, the thermal efficiency of the VTSC would increase by enhancing the average solar radiation.
