1. Nano-Materials Solar Selective Paint for Flat Plate Collectors
Nidal Y Abdalla
National Energy Research Center

2. Contents Solar Radiation Spectrum. Absorber Coating techniques
Selective Coating Versus Selective Paints.
Project Procedures
Preparing The Specimens and Emittance Test
Preparing The Flat Plate Solar Collectors
Efficiency Test of The Collectors at RSS Solar Lab
Results and Discussion
Conclusions

3. Solar Radiation

4. Solar Spectrum X &  Rays Solar radiation Radio Rays تزداد طول الموجة
الأشعة تحت الحمراء
Infrared radiation
الأشعة المرئية
0.4 – 0.8 m
8 km
10-8 m
الأشعة الحرارية Thermal radiation
0.3 –2.5 m
Solar radiation

5. Absorber Coating techniques
Solar collector coating technique can be divided into two types :
Non-selective coatings technique: Absorber with high absorptance , , as well as high Emittance, , which is found in all local solar collector manufactured in Jordan using ordinary black paints (with λ1 ≈ 0.95 and  λ2 ≈ 0.94).

6. Absorber Coating techniques
Selective coatings deposited by chemical or electrical processes have a high  λ1 and low  λ2 (e.g., in black chrome surface,  λ1 ≈ 0.95 and  λ2 < 0.3) so they are more attractive for use in solar collectors.
Efficient absorber has high absorption of irradiation and low emission of heat radiation

9. Absorber selective coating:
Black Nickel
Black chrome
Physical vapor deposition (PVD), TINOX

10. Selective Coating Versus Selective Paints
Absorber selective coating has lower Emittance than selective paint.
For absorber with selective coating  λ is less than 0. 3 (Ti sputtered on Cu, λ =0.02 ).
For absorber with selective painting  λ is between 0. 7 and 0.3

11. Selective Coating Versus Selective Paints
In flat plate collector and for absorber temperature lower than 100° C, the collector heat loss is reduced dramatically if  is reduced from 0.95 to 0.3, but a further reduction in  from 0.3 to 0.1 brings only a small benefit.

12. Selective Coating Versus Selective Paints
Therefore the selective paints are cheaper and easier to apply look more attractive for flat plates. It doesn’t need complicated chemical or electrical processes.

13. Project Objective
The aim of this study is to investigating the thermal impact of the modified paints on the collector performance by adding certain nano-materials to the dull carbon black paint

14. Project Procedures
Dull black carbon paint was first prepared by grinding the carbon material into non particles and was well mixed with especial solvent called turpentine. Preparing of the nano-particles was carried out by ICC at RSS.
Certain nano particles were prepared and grinded to smaller size and mixed with the carbon black paint formulas.

15. Project Procedures
Different specimens surfaces were painted by the following processes:
The specimens surface were cleaned with chemical cleaner to ensure a good paint-surface adhesion.
A panel were pained with dull black carbon and considered as a base reference specimen.

16. Several specimens with different nano-materials (modified paints) were painted.
All specimens were dried by using oven at 200 C.

17. Preparing The Specimens For Emittance Test

18. Emittance Test of the Specimens Using Emissometer

19. Measurement Results

20. Preparing The Flat Plate Solar Collectors
Two solar collectors were manufactured at NUR company . One collector was painted with dull black paint. The second one was painted with the new modified (selective) paint. Dimensions, thermal insulation and all other design parameters are kept the same for all collectors.

21. Design parameters for the collectors

22. Efficiency Test of The Collectors at RSS Solar Lab

23. Results and Discussion
67%
64%

24. Results and Discussion
It was found that the optical collector efficiency was increased by about 4.5%.
Moreover, the efficiency slope was improved by about 15%

25. Results and Discussion
The actual improvement can be found by estimating the annual useful heat that can be gained using each of the collectors as applied for domestic hot water system.
Shortcut method program available, F-Chart software was used.

26. Results and Discussion
The results shows that annual difference heating delivered about 277 kWh per square meter of collector.
The annual thermal performance for the modified collector was improved around 11% over the existing local manufactured collector.

27. Results and Discussion
This modification on solar flat plate collector will increase the market penetration of the local manufactured so that it will competes the exported solar collector.

28. Results and Discussion
 Referring to survey which was made by NERC in 2009, the annual solar collector installed by the local manufacturing industries is about 20,000 m².
Therefore, annual reduction of CO2 emission from the modified-painted collectors (20,000 m²) will be more than the conventional painted solar collectors by an amount of 3,123 ton per year

29. Conclusions
 Adding nano-chromium particles to the carbon black paint modify the collector as follows:
The optical collector efficiency was increased by about 4.5%.
The efficiency slope was also improved by about 15%.
The annual thermal performance for the modified collector was improved around 11% over the existing local manufactured collector.

30. Thank You