Experimental Investigation on Performance Comparison of Solar Water Heating-Phase Change Material System and Solar Water Heating System
Abstract
:1. Introduction
2. Experiments
2.1. Materials
2.2. Experimental Rig
2.3. Experimental Conditions
3. Calculation of Heat Storage and Thermal Efficiency
3.1. Heat Storage
3.2. Thermal Efficiency
4. Results and Discussion
4.1. Comparison of Heat Storage between Water and Composite Paraffin Emulsion
4.1.1. Effect of Solar Radiation on Heat Storage
4.1.2. Effect of Solar Radiation on Heat Storage
4.2. Comparison of Thermal Efficiency between Water and Composite Paraffin Emulsion
4.2.1. Effect of Solar Radiation on Thermal Efficiency
4.2.2. Effect of Flow Rate on Thermal Efficiency
5. Conclusions
- (1)
- The SWH-PCM system has a higher temperature rising rate than that of the SWH before all paraffin particles melt into liquid. When the melting process has finished, the SWH-PCM system shows a similar temperature change trend as the SWH system. The SWH-PCM system obtains more heat storage than the SWH system
- (2)
- The heat storage of SWH-PCM system and SWH system all increase with the increase of solar irradiance, while the thermal efficiency has the opposite trend. The thermal efficiency of SWH-PCM system can achieve the maximum value of 90.40% as the solar irradiance of 500 W/m2.
- (3)
- As flow rates increase, the thermal efficiency of the SWH-PCM system decreases slightly, while the thermal efficiency of the SWH system basically is unchanged. The thermal efficiency of the SWH-PCM system can reach up to 89.67% with the flow rate of 200L/h, which is 14.76% higher than that of the SWH system.
Author Contributions
Funding
Conflicts of Interest
References
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Performance Parameters | Process | Phase Change Temperature/°C | Phase Change Enthalpy/kJ·kg−1 | Thermal Conductivity/W·m−1·K−1 | Super Cooling/°C | Viscosity/Pa·s | |
---|---|---|---|---|---|---|---|
Graphene composite paraffin emulsion (0.6%wt graphene, 20%wt paraffin emulsion) | Melting | 1 | 36.0 | 6.23 | 0.472(30 °C) | 2.13 | 0.438– 0.00615 (30 °C–60 °C) |
2 | 50.4 | 20.58 | |||||
Solidification | 56.48 | 25.51 |
Parameter | Measurement Equipment |
---|---|
Temperature | K-type thermocouples range: −200–1300 °C, accuracy: ±0.2 °C |
Flow rate | LYDF-DN10 electromagnetic flowmeter range: 30–600 L/h, accuracy: 0.5% |
Solar radiation (Ambient temperature) | Delta-T SPN1 pyranometer range: 0–2000 W/m2, accuracy: ±5 W/m2 (range: −40–80 °C, accuracy: ±0.4 °C) |
Layer | Parameter | Value |
---|---|---|
Covering glass | Thickness | 5 mm |
Material | Tempered glass | |
Air layer | Thickness | 20 mm |
Vacuum coating | length × width × thickness | 1050 × 514 × 2 mm |
Thermal conductive silica gel | Thickness | 2 mm |
Thermal conductivity coefficient | 1.2 W/(m·K) | |
Absorber plate | Material | Copper |
Thickness | 2 mm | |
Absorbent film | material | Blue titanium |
thickness | 0.2 mm | |
absorptance | 95% | |
Tube | Material Diameter | Copper 12 mm |
Distance of adjacent tubes | 70 mm | |
Insulation material | Material | Rock wool |
Thickness | 40 mm | |
Thermal conductivity coefficient | 0.039 W/(m·K) |
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Sun, L.; Xiang, N.; Yuan, Y.; Cao, X. Experimental Investigation on Performance Comparison of Solar Water Heating-Phase Change Material System and Solar Water Heating System. Energies 2019, 12, 2347. https://doi.org/10.3390/en12122347
Sun L, Xiang N, Yuan Y, Cao X. Experimental Investigation on Performance Comparison of Solar Water Heating-Phase Change Material System and Solar Water Heating System. Energies. 2019; 12(12):2347. https://doi.org/10.3390/en12122347
Chicago/Turabian StyleSun, Liangliang, Nan Xiang, Yanping Yuan, and Xiaoling Cao. 2019. "Experimental Investigation on Performance Comparison of Solar Water Heating-Phase Change Material System and Solar Water Heating System" Energies 12, no. 12: 2347. https://doi.org/10.3390/en12122347