Experimental study for improving unglazed solar system

Figures & data

Figure 1. Assembly schematic of the unglazed solar collector (all dimensions in cm)

Table 1. The description of the equipment used during the work

Equipment	Description
Unglazed Transpired Collector	Baghdad- Iraq, (33 °N and 44 °E)
Orientation & Slope Solid Cover Plate Cover Thickness	South, 42° degree. Galvanized steel (1.5 m^2), accuracy of ±0.002 m^2. 3 mm, accuracy of ±0.5 mm.
Collector Area Collector High	(1.5 × 1.0) m^2, accuracy of ±0.002 m^2. 0.07 m, accuracy of ±0.5 mm.
Wire Mesh Layers Wire Mesh Layers No.	Absorptivity 0.96, Porosity Φ = 0.87. 15
Pyranometer	RK200-03, SN:R18021068, resolution of ±0.5%, Range: 0–2000 W/m^2.
Centrifugal Fan	0.75 kW, Model 135C16A,
Hot Wire Anemometer	HT-9829, 60–90 mA, accuracy of ±0.02 m/s.
Temp. Data-logger (EXTECH) T-type Thermocouples Inverter model of 0.01–400 Hz, 5A, SV008iC5-1.	Accuracy of ± (0.4 % + 0.5 °C), model SDL200. Accuracy of ±(0.75%, ±0.5 °C). Control the Centrifugal Fan speed, (velocity air of 2 to 7 m/s).

Figure 2. Solar intensity versus time of the day for UTC, during testing having, opening cover plate area of 0.2 m²

Figure 3. Inlet temperature versus time of the day for opening cover plate area of 0.2 m²

Table 2. Shows the uncertainty (ω), the average values of the inlet temperature, ambient temperature, and solar intensity values

Parameters	Average value	Uncertainty (ω)
Ti (^oC)	38.04	±0.5
Ta (^oC)	37.26	±0.5
To (^oC)	55	±0.5
I (W/m^2)	638.12	±7
V (m/s)	4.4	±0.085
η %	39.9366	±0.633

Figure 4. Temperature difference versus time of the day at different for the collector opening perforated plate area of 0.2 m²

Figure 5. Variation of UTC instantaneous efficiencies with a temperature parameter $\left(T_i-T_a\right)/I$

short-legendFigure 5.

Figure 6. Experimented measured outlet temperature and predicted outlet air temperature

Figure 7. A variation of the collector efficiency of different air velocity for opening cover plate area of 0.2 m²

Table 3. The comparison between present work and previous works

Researcher	Type of UTC	UTC Dimensions	Porosity %	Solar intensity W/m^2	∆T ^oC	Velocity m/s	η%
W. Zheng et al., (2017)	Perforating corrugated packing	2.2 m x 0.8 m x 0.16 m	10	830	17	0.6	59.5
R. Nowzari et al., (2014)	Quarter perforated cover plexiglas cover	1 m x 1.5 m x 0.05 m	83	724	24.6	6.5	56
M. Badache (2012)	Perforations were chosen to be slits	0.36 m x 0.0048 m x 0.003 m	5	600	18.8	0.016	48
Present work	Wire mesh with galvanized cover	1.5 m x 1 m x 0.07 m	88	880	34	7	63

Figure 8. The relation of average outlet temperature, T_o with the average thermal efficiencies for the air velocity from 2 m/s to 7 m/s

Zheng, W., Zhang, H., You, S., & Fu, Y. (2017). Experimental investigation of the transpired solar air collectors and metal corrugated packing solar air collectors. Energies, 10(3), 1–12. https://doi.org/10.3390/en10030302

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Nowzari, R., Aldabbagh, L. B. Y., & Egelioglu, F. (2014). Single and double pass solar air heaters with partially perforated cover and packed mesh. Energy, 73(10), 694–702. https://doi.org/10.1016/j.energy.2014.06.069

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Badache, M., Rousse, D. R., Hallé, S., Quesada, G., & Dutil, Y. (2012). Experimental and two-dimensional numerical simulation of an unglazed transpired solar air collector. Energy Procedia, 30(20), 19–28. https://doi.org/10.1016/j.egypro.2012.11.004

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