Document Type : Research Paper


Electromechanical Eng. Dept., University of Technology - Iraq


In this study, the effect of vacuum with micro-channel technique
on solar air collector performance is investigated experimentally. Vacuum
space reduces the loss of heat for the absorption plate by conduction and
thus improves the solar collector performance. It has been demonstrated
that the solar collector is evacuated to 0.1 bar of pressure for absorber-tocover spacing of 4cm. An absorber plate was manufactured from Aluminum
metal with 30 rectangular micro-channels (length 0.9, width 0.004, height
0.0008 m) is constructed with measurements facilities of velocity,
temperature and differential pressure. The tests are carried out indoor using
solar simulator. Results showed that the performance of solar collector
increases with vacuum about 2-5% than gained with non-vacuum utilizing a
micro-channel absorber plate-black surface.


Main Subjects

[1] C.B. Eaton and H.A Blum, “The use of moderate
vacuum environments as a means of increasing the
collection efficiencies and operating temperatures of
flat-plate solar collectors,” Solar Energy 17.3, pp. 151-
158, 1975.
[2] Georgiev, “Simulation and experimental results of
a vacuum solar collector system with storage,” Energy
conversion and management, 46(9-10), pp. 1423-1442,
[3] P. Fang, C. Eames, B. Norton, and T.J. Hyde,
“Experimental validation of a numerical model for
heat transfer in vacuum glazing,” Solar Energy, 80(5),
pp. 564-577, 2006.
[4] B. Bhushan and R. Singh, “Thermal and
thermohydraulic performance of roughened solar air
heater having protruded absorber plate,” Solar energy,
86(11), pp. 3388-3396, 2012.
[5] M.K. Mansour, “Thermal analysis of novel
minichannel-based solar flat-plate collector,” Energy,
60, pp. 333-343, 2013.
[6] L. Chai, G. Xia, L. Wang, M. Zhou, and Z. Cui,
“Heat transfer enhancement in microchannel heat sinks
with periodic expansion–constriction cross-sections,”
International Journal of Heat and Mass Transfer, 62,
pp. 741-751, 2013.
[7] D. Desai, and D. Subhedar, “Hydraulic and
Thermal performance of microchannel.” International
Journal of Engineering Trends and Technology
(IJETT), Volume4Issue5, 2013.
[8] B. Li, S. You, T. Ye, H. Zhang, X. Li, and C. Li,
“Mathematical modeling and experimental verification
of vacuum glazed transpired solar collector with slitlike perforations,” Renewable Energy, 69, pp. 43-49,
[9] M.A. Oyinlola, G.S.F. Shire, and R.W. Moss,
“Thermal analysis of a solar collector absorber plate
with microchannels,” Experimental Thermal and Fluid
Science, 67, pp. 102-109, 2015.
[10] F. Arya, T. Hyde, P. Henshall, P.C. Eames, R.
Moss, and S. Shire, “Fabrication and characterisation
of slim flat vacuum panels suitable for solar
applications,” 2015.
[11] V. Yadav, K. Baghel, R. Kumar, and S.T. Kadam,
“Numerical investigation of heat transfer in extended
surface microchannels,” International Journal of Heat
and Mass Transfer, 93, pp. 612-622, 2016.
[12] O V. Shepovalova, D.A. Durnev, A.V. Chirkov,
and S. V. Chirkov, “High Vacuum Glass Units
Application for Solar Radiation Thermal Conversion,”
Energy Procedia, 119, pp. 995-1002, 2017.
[13] R.W. Moss, G.S.F. Shire, P. Henshall, P.C.
Eames, F. Arya, and T. Hyde, “Optimal passage size
for solar collector microchannel and tube-on-plate
absorbers,” Solar Energy, 153, pp. 718-731, 2017.
[14] R. Moss, S. Shire, P. Henshall, F. Arya, P. Eames,
and T. Hyde, “Performance of evacuated flat plate
solar thermal collectors,” Thermal Science and
Engineering Progress, 8, pp. 296-306, 2018.
[15] A. Ghahremannezhad, and K. Vafai, “Thermal
and hydraulic performance enhancement of
microchannel heat sinks utilizing porous substrates,”
International Journal of Heat and Mass Transfer, 122,
pp. 1313-1326, 2018.