Energy Postgraduate Conference 2013

Stand-alone Solar Reflector DishStand-alone Solar Reflector DishUniversity of StellenboschUniversity of Stellenbosch

Rohan Meyer (Undergraduate BEng Mechanical)Supervisor: Mr Robert Dobson

How “enginerds” are characterized:

Contents1) Common designs2) Our Design Philosophy3) Our Design4) Wind loading5) Beam theory6) Software theory: MSC Nastran and SimXpert 20117) Results8) Experimental testing9) The way forward10) Conclusions and Recommendations11) Acknowledgements12) References

Common designs

McDonnell-Douglas Heliofocus design(linear Fresnel)- 12 kWe Stirling dish- Weight of reflector and receiver balance on pivot point

- Flat surface with tilted mirrors- Equivalent of Fresnel dish concept- Similar to Solar Tower Heliostat,

but single dish frame

Source: www.solarenergytopics.comSource: www.cliquesolar.com

Common designs(continued)

German Eurodish Spanish titan- 17m diameter, 50kWe - 3.2m diameter double dish

Source: www.titantracker.comSource: www.xaharts.org

Our Design Philosophy• Cheap! Because less is more.

• Assembly of structure: Think of a camping tent!

• Light weight, but durable and strong.

• The consequence: Rural Africans can assemble their own power source in their back yard, for next to nothing.

Our design (G. Prinsloo, R. Meyer)

Wind loading

Beam theory

Software theoryMSC Nastran and SimXpert 2011

CBEAM Element geometry in SimXpert PSHELL CQUAD4 Element in SimXpert

L-shaped beam cross section

Structure analysed using beam elements for spokes and bars and shell elements for middle-flange.

Results(Intuitive model)• Displacement

Results(continued)• Torsion due to asymmetric section

Results(continued)• Maximum combined beam stresses

Experimental testing• Aluminum strain gauges to measure strain and

displacement. Top and bottom of flat surface for bending, 2 x 45° for “torsion” of a asymmetric L-shaped section.

The way forward• Added aluminum plates with reflective material in

software simulation. Adds to stiffness and mass matrix of model.

• Dynamic analysis of structure with wind loading varying with time.

• Experimental testing

Conclusions and Recommendations• Knowledge on response of structure – future simulations• Easily assembled, stand-alone solar reflector• Possible SKA power source• Renewable energy, replacing sources like nuclear and coal• Solar power to rural African communities• Moral of the story: Always take the motorcycle, because

the clothes won’t fit.

Acknowledgements• A million thank you’s goes out to Mister Dobson for his

supervision, advice and funding of the research I am doing.

• My sincere appreciation goes out to Mister Gerro Prinsloo, MSc Mech student, for his astonishing work he is doing on the design, construction and testing of a self-tracking solar concentrating reflector and his helpful advice with my research.

• It is an honour working with people that has faith in Renewable Energy and that are doing fascinating research in this field.

ReferencesCengel, Y. A. & Cimbala, J. M., 2010. Fluid Mechanics Fundamentals

and Applications. Second Edition in SI Units ed. Asia: McGraw-Hill Education.

Cook, R. D., Malkus, D. S., Plesha, M. E. & Witt, R. J., 2002. Concepts and Applications of Finite Element Analysis. Fourth Edition ed. United States: John Wiley & Sons Inc..

MSC, 2012. MSC SimXpert. [Online] Available at: https://www.mscsoftware.com/product/simxpert[Accessed 12 March 2013].

Thank you very much!Rohan Meyer