Optimal slope angle selection of an evacuated tube collector for domestic solar water heating

Rigardt Alfred Coetzee, Aggrey Mwesigye, Zhongjie Huan

Abstract


A pressurized system utilizing evacuated tube collectors with internal heat pipes was investigated for the production of hot service-water for domestic use during all seasons in Pretoria, South Africa. The investigation focused on the prediction of seasonal hourly performance trends and the maximum thermal performance at the static optimal slope angle. This study was accomplished by developing the system’s theoretical performance model which was solved numerically using Engineering Equation Solver (EES). Results show the thermal performance trend changes during the seasons depending on the slope angle. Optimal performance parameters that influence the collector overall performance, depending on the water consumption of the occupants, were obtained and presented. The maximum performance in the summer was achieved at a slope angle of 25° and in winter the maximum performance was shown to exist at an angle of 40°. In a 20 receiver tube collector system, maximum performance was in September, reaching an outlet temperature of 103.98 °C and useful heat rate of 1 919.85 W.


Keywords


Solar thermal; evacuated tube collector; solar water heating; heat pipes; slope angle.

Full Text:

PDF

References


ALLOUHI, A., JAMIL, A., KOUSKSOU, T., MOURAD, Y. & ZERALOUI, Y. 2015. Solar domestic water heating system in Morocco: An energy analysis. Energy Conversion and Management 92, 105-113.

ASOWATA, O., SWART, J. & PIENAAR, C. 2012. Optimum Tilt angles for photovoltaic panels during winter months in the Vaal triangle, South Africa. Smart Grid and Renewable Energy, 3, 119 - 125.

AZAD, E. 2008. Theoretical and experimental investigation of heat pipe solar collector. Experimental Thermal and Fluid Science, 32, 1666-1672.

BRIEL, A. Z. A. & BUNT, E. A. 1994. Optimization of flat plate solar collector angles at a latitude just outside the tropics. N&O Joernaal, 10, 58-60.

CENGEL, Y. A. & GHAJAR, A. J. 2011. Heat and Mass Transfer : Fundamentals and Applications, New York, Mc Graw Hill.

DUFFIE, J. A. & BECKMAN, W. A. 2013. Solar Engineering of Thermal Processes, Canada, John Wiley & Sons, Inc.

ESKOM. 2015. COP17 Fact sheet: Solar Water Heating Rebate Program [Online]. Available: http://www.eskom.co.za/AboutElectricity/FactsFigures/Documents/The_Solar_Water_Heating_SWH_Programme.pdf [Accessed 2015/03/09 2015].

HAYEK, M., ASSAF, J. & LTEIF, W. 2011. Experimental Investigation of the Performance of Evacuated Tube Solar Collectors under Eastern Mediterranean Climatic Conditions. Energy Procedia, 6, 618-626.

HAZAMI, M., KOOLI, S., NAILI, N. & FARHAT, A. 2013. Long-term performances prediction of an evacuated tube solar water heating system used for single-family households under typical North-African climate (Tunisia) Solar Energy, 94, 283-298.

HLAING, S. & SOE, M. M. 2012. Design Calculation and Heat Transfer Analysis of Heat Pipe Evacuated Tube Solar Collector for Water Heating. International Journal of Science, Engineering and Technology Research (IJSETR), 1, 1-5.

ITS SOLAR 2015. Evacuated Tube Specifications. ITS Solar.

ITS SOLAR. 2015. How does an evacuated tube heat pipes collector work [Online]. Available: http://www.itssolar.co.za/download.php?file=evac/ITS%20-%20How%20does%20Evacuated%20%20Tubes%20work.pdf [Accessed 11/08 2015].

JAFARKAZEMI, F. & ABDI, H. 2012. Evacuated tube solar heat pipe collector model and associated tests. Journal of Renewable and Sustainable Energy, 4, 1-13.

JAFARKAZEMI, F., AHMADIFARD, K. & ABDI, H. 2016. Energy and exergy of heat pipe evacuated tube solar collectors Thermal Science, 20, 327-335.

KALOGIROU, S. A. 2014. Solar Energy Engineering Processes and Systems Oxford, United Kingdom, ELSEVIER.

MAZARRON, F. R., PORRAS-PRIETO, C. J., GARCIA, J. L. & BENAVENTE, R. M. 2016. Feasibility of active solar water heating systems with evacuated tube collector at different operational temperatures. Energy Conversion and Management, 113, 16-26.

MEYER, J. P. & TSHIMANKINDA, M. 1996. Domestic Hot Water Consumption in South African Townhouses. Energy Convers., 39, 679-684.

NG, K. C., YAP, C. & KHOR, T. H. 1999. Outdoor testing of evacuated tube heat-pipe solar collectors. IMechE, 214 Part E, 23-30.

REN21 2014. Renewable Energy 2014 Global Status Report. Paris: REN21 Secretariat.

SA STRM 2014. The South African Solar Thermal Technology Road Map Direction for South Africa's solar thermal energy future .

SOLARRAY 2015. High pressure solar water heater catalog. Solarray.

SOUTH AFRICAN WEATHER SERVICE 2015. Global, Beam and Diffuse Irradiance of Pretoria, South Africa (January 1957- December 1987)

SOUTH AFRICAN WEATHER SERVICE 2015. Meteorological Data of Pretoria UNISA, South Africa (January 2009 -December 2014).




DOI: http://dx.doi.org/10.17159/2413-3051/2017/v28i1a1621

Refbacks



Copyright (c) 2017 Rigardt Alfred Coetzee, Aggrey Mwesigye, Zhongjie Huan

Creative Commons License
This work is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.