A silicon photovoltaic module (30x10cm) was used to charge 12Volts battery needed to drive the N-S tracking axis DC motor, control components, and a DC closed loop water pump (in case of forced convection). The PV module was fixed on the tracking frame to improve PV cell efficiency by minimizing solar incident angle. Having this type of power supply the system can operate independently and remotely. The selection of PV and battery sizes was based on the power required by the DC electric motor. The required motor torque was estimated experimentally and found equal to (100 N. m).

Testing platform

The testing platform of the parabolic collector is shown in Fig. 7. The platform allows the flexibility of different outdoor tests as well as different tracking axis inclinations. The system working fluid (water in this study) inside a closed loop pipe delivers heat to the storage tank via a tube coil heat exchanger. The storage tank height is adjustable to allow the study of natural circulation effect of the working fluid.

A DC fluid pump is also connected to have forced circulation of the fluid.

Conclusion

Parabolic-trough solar water heating is a well proven solar energy technology which is being used on a commercial scale to produce heat for industrial and residential applications. In this work, a single tracking axis parabolic trough collector was designed and constructed for moderate heat load processes. The solar tracking collector was designed to be a self powered system so it can operate remotely and independently under moderate radiation levels. Simplicity in manufacturing and operation was considered in the design of this collector such as using stainless steel as a reflecting surface and a closed loop control system for the single solar tracking axis.

References

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