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Experimental Validation of Exergy Optimization of a Flat-Plate Solar Collector in a Thermosyphon Solar Water Heater

  • Koholé Yemeli Wenceslas
  • Tchuen Ghislain
Research Article - Systems Engineering
  • 12 Downloads

Abstract

In this paper, a flat-plate solar collector used in thermosyphon solar water heater has been optimized; and the optimization results used to fabricate a flat-plate solar collector with locally available materials. The constructed heater has then been tested under the climatic conditions of the city of Santa in Cameroon and the measured data used to validate the proposed theoretical model. The computational code that helps to obtain the right combination of the design parameters that maximizes the exergy efficiency was written employing the genetic algorithm. The optimization results show the ability of the heater to achieve high performances with lower surface area of the collector. The experimental and numerical simulation results of a chosen day have been confronted, and the concordance proves to be acceptable. It has also been observed that the absorber plate made of aluminum would have the same performance with that made of copper if it thickness is increased up to 0.005 m and that increasing the insulator thickness to approximately 0.05 m leads to a considerable decrease of the heat loss coefficients and consequently to an increase in the efficiencies of the system.

Keywords

Experimentation Simulation Exergy Flat-plate collector Optimization Water heater 

List of symbols

\(A_\mathrm{c}\)

Collector surface area (\(\hbox {m}^{2}\))

\(C_\mathrm{b} \)

Bond conductance (\(\hbox {W/m }{^{\circ }}\hbox {C}\))

\(C_\mathrm{c} \)

Specific heat capacity of the glass cover (\(\hbox {J}/\hbox {kg } {^{\circ }}\hbox {C}\))

\(C_\mathrm{f} \)

Specific heat capacity of the working fluid (\(\hbox {J}/\hbox {kg } {^{\circ }}\hbox {C}\))

\(C_\mathrm{p} \)

Specific heat capacity of the absorber plate (\(\hbox {J}/\hbox {kg } {^{\circ }}\hbox {C}\))

\(d_\mathrm{i} \)

Absorber tube inner diameter (\(\hbox {m}\))

\(d_\mathrm{o} \)

Absorber tube outer diameter (\(\hbox {m}\))

\(\dot{E}_{\mathrm{xdest}} \)

Destructed exergy rate (\(\hbox {W}\))

\(\dot{E}_{\mathrm{xin}} \)

Inlet exergy rate (\(\hbox {W}\))

\(\dot{E}_{\mathrm{xin,f}} \)

Inlet exergy carried by the working fluid (\(\hbox {W}\))

\(\dot{E}_{\mathrm{xout}} \)

Outlet exergy rate (\(\hbox {W}\))

\(\dot{E}_{\mathrm{xout,f}} \)

Outlet exergy rate carried by the working fluid (\(\hbox {W}\))

\(\dot{E}_{\mathrm{xu}} \)

Useful exergy rate (\(\hbox {W}\))

F

Fin efficiency factor

\({F}'\)

Collector efficiency factor

\(F_{\mathrm{R}} \)

Heat removal factor

g

Gravitational constant (\(\hbox {m}/\hbox {s }^{2}\))

G

Solar intensity (\(\hbox {W}/\hbox {m}^{2}\))

\(h_{\mathrm{c,p-c}} \)

Convective heat transfer coefficient between the absorber and the cover (\(\hbox {W/m}^{2}{^{\circ }}\hbox {C}\))

\(h_{\mathrm{r,c-s}} \)

Radiative coefficient between the glass cover and the sky (\(\hbox {W/m}^{2}{^{\circ }}\hbox {C}\))

\(h_{\mathrm{r,p-c}} \)

Radiative heat transfer coefficient between the absorber and the cover (\(\hbox {W/m}^{2}{^{\circ }}\hbox {C}\))

\(h_{\mathrm{c,c-a}} \)

Wind convection coefficient (\(\hbox {W/m}^{2}{^{\circ }}\hbox {C}\))

\(h_{\mathrm{c,p-f}} \)

Convective heat transfer coefficient in the tube (\(\hbox {W/m}^{2}{^{\circ }}\hbox {C}\))

\(k_\mathrm{a} \)

Air layer between absorber plate and glass thermal conductivity (\(\hbox {W/m}{^{\circ }}\hbox {C}\))

\(k_\mathrm{i} \)

Thermal conductivity of the insulation (\(\hbox {W/m}{^{\circ }}\hbox {C}\))

\(l_\mathrm{a} \)

Distance between absorber plate and glass cover (\(\hbox {m}\))

\(\dot{m}_\mathrm{f} \)

Mass flow rate in the collector (\(\hbox {kg/s}\))

N

Number of glass cover

\(N_{u} \)

Nusselt number

\(n_\mathrm{t} \)

Number of absorber tube

\(P_\mathrm{r} \)

Prandtl number

\(Q_\mathrm{u} \)

Collector useful energy (W)

\(R_\mathrm{a} \)

Rayleigh number

\(T_\mathrm{a} \)

Ambient temperature (\({^{\circ }}\hbox {C}\))

\(T_\mathrm{c} \)

Glass cover temperature (\({^{\circ }}\hbox {C}\))

\(T_\mathrm{f} \)

Working fluid temperature (\({^{\circ }}\hbox {C}\))

\(T_{\mathrm{fi}} \)

Inlet water temperature (\({^{\circ }}\hbox {C}\))

\(T_{\mathrm{fo}} \)

Outlet water temperature (\({^{\circ }}\hbox {C}\))

\(T_\mathrm{p} \)

Absorber plate temperature (\({^{\circ }}\hbox {C}\))

\(T_\mathrm{s} \)

Apparent sun temperature (\({^{\circ }}\hbox {C}\))

t

time (h)

\(U_\mathrm{L} \)

Overall heat loss coefficient (\(\hbox {W/m}^{2}{^{\circ }}\hbox {C}\))

V

Wind speed (m/s)

y

Space coordinate

W

Center to center distance between absorber tubes (m)

Greek symbols

\(\alpha _\mathrm{c} \)

Absorptivity of the glass cover

\(\alpha _\mathrm{p} \)

Absorptivity of the absorber plate

\(\beta \)

Collector inclination angle (\({^{\circ }}\))

\({\beta }'\)

Volumetric coefficient of expansion

\(\delta _\mathrm{c} \)

Glass cover thickness (m)

\(\delta _\mathrm{i} \)

Insulator thickness (m)

\(\delta _\mathrm{p} \)

Absorber plate thickness (m)

\(\varepsilon _\mathrm{c} \)

Glass cover emissivity

\(\varepsilon _\mathrm{p} \)

Absorber plate emissivity

\(\eta _{\mathrm{en}} \)

Energy efficiency

\(\eta _{\mathrm{ex}} \)

Exergy efficiency

\(\rho _\mathrm{c} \)

Glass cover density (\(\hbox {kg/m}^{3}\))

\(\rho _\mathrm{f} \)

Working fluid density (\(\hbox {kg/m}^{3}\))

\(\rho _\mathrm{p} \)

Absorber plate density (\(\hbox {kg/m}^{3}\))

\(\sigma \)

Stefan–Boltzmann constant (\(\hbox {W/m}^{2}{^{\circ }}\hbox {C}^{4}\))

\(\upsilon \)

Kinematic viscosity (\(\hbox {m}^{2}/\hbox {s}\))

\(\tau _{\mathrm{c}}\)

Glass cover transmissivity

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References

  1. 1.
    Atmaca, M.: Efficiency analysis of combined cogeneration systems with steam and gas turbines. Energy Sour. Part A Recovery Util. Environ. Eff. 33, 360–369 (2010)CrossRefGoogle Scholar
  2. 2.
    Ellabban, O.; Abu-Rub, H.; Blaabjerg, F.: Renewable energy resources: current status, future prospects and their enabling technology. Renew. Sustain. Energy Rev. 39, 748–764 (2014)CrossRefGoogle Scholar
  3. 3.
    Atmaca, M.; Gümüş, M.; Yilmaz, T.; İnan, A.T.: Optimization of irreversible cogeneration systems under alternative performance criteria. Int. J. Thermophys. 30, 1724–1732 (2009)CrossRefGoogle Scholar
  4. 4.
    Mohsen, M.S.; Al-Ghandoor, A.; Al-Hinti, I.: Thermal analysis of compact solar water heater under local climatic conditions. Int. Commun. Heat Mass Transf. 36, 962–968 (2009)CrossRefGoogle Scholar
  5. 5.
    Andoh, H.Y.; Gbaha, P.; Koua, B.K.; Koffi, P.M.E.; Touré, S.; Andoh, H.Y.; Gbaha, P.; Koua, B.K.; Koffi, P.M.E.; Touré, S.: Thermal performance study of a solar collector using a natural vegetable fiber, coconut coir, as heat insulation. Energy. Sustain. Dev. 14, 297–301 (2010)CrossRefGoogle Scholar
  6. 6.
    Taherian, H.; Rezania, A.; Sadeghi, S.; Ganji, D.D.: Experimental validation of dynamic simulation of the flat plate collector in a closed thermosyphon solar water heater. Energy Convers. Manag. 52, 301–307 (2011)CrossRefGoogle Scholar
  7. 7.
    Kumar, S.; Mullick, S.C.: Glass cover temperature and top heat loss coefficient of a single glazed flat plate collector with nearly vertical configuration. Ain Shams Eng. J. 3, 299–304 (2012)CrossRefGoogle Scholar
  8. 8.
    Jafarkazemi, F.; Ahmadifard, E.: Energetic and exergetic evaluation of flat plate solar collectors. Renew. Energy 56, 55–63 (2013)CrossRefGoogle Scholar
  9. 9.
    Subiantoro, A.; Tiow, O.K.: Analytical models for the computation and optimization of single and double glazing flat plate solar collectors with normal and small air gap spacing. Appl. Energy 104, 392–399 (2013)CrossRefGoogle Scholar
  10. 10.
    Koffi, P.M.E.; Koua, B.K.; Gbaha, P.; Touré, S.: Thermal performance of a solar water heater with internal exchanger using thermosiphon system in Côte d’Ivoire. Energy 64, 187–199 (2014)CrossRefGoogle Scholar
  11. 11.
    Said, Z.; Saidur, R.; Rahim, N.A.; Alim, M.A.: Analyses of exergy efficiency and pumping power for a conventional flat plate solar collector using SWCNTs based nanofluid. Energy Build. 78, 1–9 (2014)CrossRefGoogle Scholar
  12. 12.
    Said, Z.; Sabiha, M.A.; Saidur, R.; Hepbasli, A.; Rahim, N.A.; Mekhilef, S.; Ward, T.A.: Performance enhancement of a flat plate solar collector using titanium dioxide nanofluid and polyethylene glycol dispersant. J. Clean. Prod. 92, 343–353 (2015)CrossRefGoogle Scholar
  13. 13.
    Das, R.; Akay, B.; Singla, R.K.; Singh, K.: Application of artificial bee colony algorithm for inverse modelling of a solar collector. Inverse Probl. Sci. Eng. 25, 887–908 (2017)MathSciNetCrossRefGoogle Scholar
  14. 14.
    Das, R.: Inverse study of double-glazed solar collector using hybrid evolutionary algorithm. In: International Conference on Contemporary Computing (IC3), pp. 571–576 (2014)Google Scholar
  15. 15.
    Das, R.: Application of simulated annealing for inverse analysis of a single-glazed solar collector. Adv. Intell. Inf. 320, 267–275 (2015)Google Scholar
  16. 16.
    Panda, S.; Singla, R.K.; Das, R.; Martha, S.C.: Identification of design parameters in a solar collector using inverse heat transfer analysis. Energy Convers. Manag. 88, 27–39 (2014)CrossRefGoogle Scholar
  17. 17.
    Chen, G.; Doroshenko, A.; Koltun, P.; Shestopalov, K.: Comparative field experimental investigations of different flat plate solar collectors. Sol. Energy 115, 577–588 (2015)CrossRefGoogle Scholar
  18. 18.
    Wojcicki, D.J.: The application of the typical day concept in flat plate solar collector models. Renew. Sustain. Energy Rev. 49, 968–974 (2015)CrossRefGoogle Scholar
  19. 19.
    Wang, N.; Zeng, S.; Zhou, M.; Wang, S.: Numerical study of flat plate solar collector with novel heat collecting components. Int. Commun. Heat Mass Transf. 69, 18–22 (2015)CrossRefGoogle Scholar
  20. 20.
    Koholé, Y.W.; Tchuen, G.: Comparative study of three thermosyphon solar water heaters made of flat-plate collectors with different absorber configurations. Int. J. Sustain. Energy 36, 430–449 (2017)CrossRefGoogle Scholar
  21. 21.
    Tchuen, G.; Koholé, Y.W.: A numerical investigation of three different thermosyphon solar water heating systems. Int. J. Ambiant Energy (2017).  https://doi.org/10.1080/01430750.2017.1324815 Google Scholar
  22. 22.
    Xue, H.S.: Experimental investigation of a domestic solar water heater with solar collector coupled phase-change energy storage. Renew. Energy 86, 257–261 (2016)CrossRefGoogle Scholar
  23. 23.
    Singh, K.; Das, R.: Improved quantification of exergy destruction in mechanical cooling tower considering all tower inlet parameters. J. Heat Transf.  https://doi.org/10.1115/1.4038479
  24. 24.
    Singh, K.; Das, R.: Exergy optimization of cooling tower for HGSHP and HVAC applications. Energy Convers. Manag. 136, 418–430 (2017)CrossRefGoogle Scholar
  25. 25.
    Shojaeizadeh, E.; Veysi, F.: Development of a correlation for parameter controlling using exergy efficiency optimization of an \(\text{ Al }_{2}\text{ O }_{3}\)/water nanofluid based flat-plate solar collector. Appl. Therm. Eng. 98, 1116–1129 (2016)CrossRefGoogle Scholar
  26. 26.
    Koholé, Y.W.; Tchuen, G.: Optimization of flat-plate solar collectors used in thermosyphon solar water heater. Int. J. Renew. Energy Technol. Res. 6, 1–23 (2017)Google Scholar
  27. 27.
    Wirba, A.V.; Mas’ud, A.A.; Sukki, F.M.; Ahmad, S.; Tahar, R.M.; Rahim, R.A.; Munir, A.B.; Karim, M.E.: Renewable energy potentials in Cameroon: prospects and challenges. Renew. Energy 76, 560–565 (2015)CrossRefGoogle Scholar
  28. 28.
    Duffie, J.A.; Beckman, W.A.: Solar Engineering of Thermal Processes, 4r edn. Wiley, Hoboken (2013)CrossRefGoogle Scholar
  29. 29.
    Hollands, K.G.T.; Unny, T.E.; Raithby, G.D.; Konicek, L.: Free convection heat transfer across inclined air layers. Trans. ASME J. Heat Transf. 98, 189 (1976)CrossRefGoogle Scholar
  30. 30.
    Gümüş, M.; Atmaca, M.: Energy and exergy analyses applied to a CI engine fueled with diesel and natural gas. Energy Sour. Part A Recovery Util. Environ. Eff. 35, 1017–1027 (2013)CrossRefGoogle Scholar
  31. 31.
    Bejan, A.: Advanced Engineering Thermodynamics. Wiley Interscience, New York (1988)Google Scholar
  32. 32.
    Jeter, S.M.: Maximum conversion efficiency for the utilization of direct solar radiation. Sol. Energy 26, 231–236 (1981)CrossRefGoogle Scholar
  33. 33.
    Gupta, K.K.; Saha, S.K.: Energy analysis of solar thermal collectors. Renew. Energy Environ. 19, 283–287 (1990)Google Scholar
  34. 34.
    Singh, N.; Kaushik, S.C.; Misra, R.D.: Exergetic analysis of a solar thermal power system. Renew. Energy 19, 135–143 (2000)CrossRefGoogle Scholar

Copyright information

© King Fahd University of Petroleum & Minerals 2018

Authors and Affiliations

  1. 1.LISIE, Department of Energetic, Environment and Thermal Engineering, IUT-FV BandjounUniversity of DschangDschangCameroon
  2. 2.L2MSP, Department of Physics, Faculty of ScienceUniversity of DschangDschangCameroon

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