Direct Absorption Solar Collector: An Experimental Investigation of Al2O3-H2O Nanofluid over the Flat Plate at Different Tilt Angles, and Mass-Flow Rates


Jyani, L., Sharma, S., Chaudhary, K., & Purohit, K. (2024). Direct Absorption Solar Collector: An Experimental Investigation of Al2O3-H2O Nanofluid over the Flat Plate at Different Tilt Angles, and Mass-Flow Rates. New Energy Exploitation and Application, 3(1), 24–40.


  • Lalit Jyani Department of Mechanical Engineering, MBM University, Jodhpur, Rajasthan 342001, India
  • Shivangi Sharma
    University of Birmingham
  • Kailash Chaudhary Department of Mechanical Engineering, MBM University, Jodhpur, Rajasthan 342001, India
  • Kamlesh Purohit Department of Mechanical Engineering, MBM University, Jodhpur, Rajasthan 342001, India

The escalating demand for solar thermal energy, coupled with the current inefficiencies in existing systems, underscores the critical need for innovative advancements in thermal storage solar collectors. The efficiency of solar collectors relies not solely on design effectiveness but also on the thermophysical properties, such as heat capacity and thermal conductivity, inherent in the working fluid. This study investigates a novel solar collector with a gross area of 0.36 m2, operating on the principle of direct absorption. Experimental investigations were done at various tilt angles (15°, 20°, and 30°) with respect to the horizontal, considering different flow rates and nanofluid settlement within the base fluids. The use of Al2O3 nanoparticles into the base fluid as water, exhibits significant positive effects on the thermophysical properties of the nanofluids, with a volume concentration of 0.003%. The efficiency of the solar collector was calculated across three mass flow rates (0.5, 1, and 1.33 L/min) at each tilt angle. Notably, the study reveals that the efficiency peaks at a 15° tilt due to an optimal flow configuration for maximum energy harvest across all three mass flow rates. Increasing the mass flow rate yields efficiency increments for all tilt angles (15°, 20°, and 30°), with 1 L/min emerging as the optimal mass-flow rate in most cases. This research not only addresses the immediate need for improved solar thermal technologies but also aligns with global sustainability goals, contributing to the IEA Net Zero Emissions initiative and supporting UN Sustainable Development Goals 7, 9, and 11. The paper also includes a critical literature review on the use of nanofluids in solar thermal collectors to improve thermo-physical properties and enhance solar efficiency. Additionally, the key findings regarding the influence and tilt angle on solar efficiency are discussed.


solar thermal collector (STC) direct absorption solar collector (DASC) Al2O3-H2O nanofluid impact of tilt angle effects of mass flow rate


  1. Gupta, H.K.; Agrawal, G.D.; Mathur, J. Investigations for effect of Al2O3–H2O nanofluid flow rate on the efficiency of direct absorption solar collector. Case Stud. Therm. Eng. 2015, 5, 70–78.
  2. Rai, G.D. Solar energy utilisation, 5th ed.; Khanna Publishers: New Delhi, India, 1995.
  3. Sukhatme, S. Solar energy fundamental and applications; Tata Mcgraw Hill Publication: New York, US, 1984.
  4. Taylor, R.A.; Phelan, P.E.; Otanicar, T.P.; Walker, C.A.; Nguyen, M.; Trimble, S.; Prasher, R. Applicability of nanofluids in high flux solar collectors. J. Renew. Sustain. Ener. 2011, 3, 023104.
  5. Solar Heat Worldwide: Global Market Development and Trends 2021. Available online:
  6. IEA. Solar thermal technologies deployed in around 400 million dwellings by 2030. In Technology and innovation pathways for zero-carbon-ready buildings by 2030; IEA: Paris, French, 2022.
  7. Mousavi Ajarostaghi, S.S.; Mousavi, S.S. Solar energy conversion technologies: principles and advancements. In Solar energy advancements in agriculture and food production systems; Gorjian, S.; Campana, P.E. Eds.; Academic Press: Cambridge, UK, 2022. pp. 29–76.
  8. Selvakumar, N.; Barshilia, H.C.; Rajam, K.S. Review of sputter deposited mid-to high-temperature solar selective coatings for flat plate/evacuated tube collectors and solar thermal power generation applications. NAL Project Document SE. 2010.
  9. Gupta, H.K.; Agarwal, G.D.; Mathur, J. Experimental evaluation on the effect of nanofluids concentration on the performance of Direct absorption solar collector. Int. J. Adv. Eng. Nanotechnol. 2014, 1(12), 16–20.
  10. Sainz-Mañas, M.; Bataille, F.; Caliot, C.; Vossier, A.; Flamant, G. Direct absorption nanofluid-based solar collectors for low and medium temperatures. A review. Energy. 2022, 260, 124916.
  11. Otanicar, T.P.; Phelan, P.E.; Golden, J.S. Optical properties of liquids for direct absorption solar thermal energy systems. Sol. Energy. 2009, 83, 969–977.
  12. Minardi, J.E.; Chuang, H.N. Performance of a “black” liquid flat-plate solar collector. Sol. Energy. 1975, 17, 179–183.
  13. Bahiraei, M. Particle migration in nanofluids: A critical review. Int. J. Therm. Sci. 2016, 109, 90–113.
  14. Peyghambarzadeh, S.M.; Hashemabadi, S.H.; Naraki, M.; Vermahmoudi, A. Experimental study of overall heat transfer coefficient in the application of dilute nanofluids in the car radiator. Appl. Therm. Eng. 2013, 52, 8–16.
  15. Wang, X.Q.; Mujumdar, A.S. Heat transfer characteristics of nanofluids: A review. Int. J. Therm. Sci. 2007, 46, 1–19.
  16. Pak, B.C.; Cho, Y.I. Hydrodynamic and heat transfer study of dispersed fluids with submicron metallic oxide particles. Exp. Heat Transf. 1998, 11, 151–170.
  17. Xuan, Y.; Li, Q. Heat transfer enhancement of nanofluids. Int. J. Heat Fluid Flow. 2000, 21, 58–64.
  18. Koo, J.; Kleinstreuer, C. Impact analysis of nanoparticle motion mechanisms on the thermal conductivity of nanofluids. Int. Commun. Heat Mass Transf. 2005, 32, 1111–1118.
  19. Mu, L.; Zhu, Q.; Si, L. Radiative properties of nanofluids and performance of a direct solar absorber using nanofluids. In Proceedings of the ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer, Shanghai, China, 18–21 December 2009.
  20. Tyagi, H.; Phelan, P.; Prasher, R. Predicted efficiency of a low-temperature nanofluid-based direct absorption solar collector. J. Sol. Energy Eng. 2009, 131, 041004.
  21. Trong Tam, N.; Viet Phuong, N.; Hong Khoi, P.; Ngoc Minh, P.; Afrand, M.; Van Trinh, P.; Thang, B.H.; Żyła, G.; Estellé, P. Carbon nanomaterial-based nanofluids for direct thermal solar absorption. Nanomater. 2020, 10, 1199.
  22. Khatri, R.; Kumar, M.; Jiyani, R. An experimental investigation on direct absorption solar collector using TiO2-water nanofluid. In Proceedings of the 2018 2nd International Conference on Green Energy and Applications (ICGEA), Singapore, 24–26 March 2018.
  23. Otanicar, T.P.; Phelan, P.E.; Prasher, R.S.; Rosengarten, G.; Taylor, R.A. Nanofluid-based direct absorption solar collector. J. Renew. Sustain. Ener. 2010, 2, 033102.
  24. Huang, B.J.; Hsieh, S.W. An automation of collector testing and modification of ANSI/ASHRAE 93-1986 standard. J. Sol. Energy Eng. 1990, 112, 257–267.
  25. Timofeeva, E.V.; Yu, W.; France, D.M.; Singh, D.; Routbort, J.L. Nanofluids for heat transfer: An engineering approach. Nanoscale. Res. Lett. 2011, 6, 182.
  26. Khanafer, K.; Vafai, K. A critical synthesis of thermophysical characteristics of nanofluids. In Nanotechnology and energy; Jenny Stanford Publishing: Dubai, U.A.E., 2017; pp. 279–332.
  27. Han, Z. Nanofluids with enhanced thermal transport properties. Ph.D. thesis, University of Maryland at College Park, College Park, Maryland, 2008.
  28. Best Practices Handbook for the Collection and Use of Solar Resource Data for Solar Energy Applications. Available online:
  29. Zonen, K., CMP11 Pyranomètre, in CMP11 Pyranomètre, O.H. B.V., Editor. 2021,
  30. /CMP11-Pyranometre. OTT HydroMet B.V.: The Netherlands.
  31. Ajeeb, W.; da Silva, R.R.T.; Murshed, S.S. Experimental investigation of heat transfer performance of Al2O3 nanofluids in a compact plate heat exchanger. Appl. Therm. Eng. 2023, 218, 119321.
  32. Rashmi, W.; Ismail, A.F.; Asrar, W.; Khalid, M.; Faridah, Y. Natural convection heat transfer in nanofluids: A numerical study. In Proceedings of the ASME 2008 Fluids Engineering Division Summer Meeting, Jacksonville, Florida, USA, 10–14 August 2008.
  33. Bahiraei, M.; Hosseinalipour, S.M. Particle migration in nanofluids considering thermophoresis and its effect on convective heat transfer. Thermochim. Acta. 2013, 574, 47–54.
  34. Mumma, S.A.; Yellott, J.I.; Wood, B. Application of ASHRAE standard 93-77 to the thermal performance testing of air solar collectors. ASHRAE J. 1978, 84.
  35. Trisaksri, V.; Wongwises, S. Critical review of heat transfer characteristics of nanofluids. Available online:
  36. Mahbubul, I.M.; Saidur, R.; Amalina, M.A.; Elcioglu, E.B.; Okutucu-Ozyurt, T. Effective ultrasonication process for better colloidal dispersion of nanofluid. Ultrason. Sonochem. 2015, 26, 361–369.
  37. Gupta, H.K.; Agrawal, G.D.; Mathur, J. An overview of Nanofluids: A new media towards green environment. Int. J. Environ. Sci. 2012, 3, 433–440.
  38. Choudhary, R.; Khurana, D.; Kumar, A.; Subudhi, S. Stability analysis of Al2O3/water nanofluids. J. Exp. Nanosci. 2017, 12, 140–151.
  39. Behura, A.K.; Gupta, H.K. Efficient direct absorption solar collector using Nanomaterial suspended heat transfer fluid. Mater. Today Proc. 2020, 22, 1664–1668.
  40. Lee, S.; Choi, S.S.; Li, S.A.; Eastman, J.A. Measuring thermal conductivity of fluids containing oxide nanoparticles. J. Heat Transfer 1999, 121, 280–289.