Performance Analysis Of Solar Water Heating System Using Taguchi Method To Develop Irradiance-based Nusselt Number Correlation With Single-Phase Fluids And Nanofluids / Nur Wadhyana Binti Haji Yahya.

Thesis submitted for the degree of Doctor In Philosophy Universiti Teknologi Brunei

ABSTRACT
High electricity consumption in homes can partially be due to the high daily usage of water heater. Solar water heating system is a good alternative as it consumes less energy
than conventional water heater. Its thermal performance, however, can be further improved by incorporating performance enhancement materials in its main components (i.e., heat transfer fluid, solar thermal collector and heat storage). Water, saline water and glycols are generally good heat transfer fluids for thermal systems but still has poor thermal conductivity. Suspending nanoparticles into these single-phase fluids to produce nanofluids can significantly enhance their thermophysical properties and consequently the thermal performance of solar water heating systems. Flat plate solar thermal collector incorporates the use of heat absorber that consisted of selective- and black-coated absorbers. However, there is still a notable lack of research on reflective component enclosed within the collector casing and glass cover, hence was investigated in this thesis.
The study also considered rocks being natural solids as performance enhancement material for the storage unit.

To experimentally investigate the performance enhancement of these materials, a laboratory model solar water heating system called the Gunt Hamburg E1202 system was used. The novelty of this work is the utilization of Taguchi-Buckingham T hybrid approach to simultaneously investigate the performance of numerous performance enhancement materials and conduct a dimensional analysis to produce a Nusselt number correlation upon identifying the significantly contributing factors.

The first experiment with the ET202 system investigated the effect of single-phase fluids (water, 50:50 ethylene glycol-water mixture and 0.6M sodium chloride solution), heat absorbers of different coatings (selective, black and reflective), irradiance, flow rate and coverage on the thermal performance of the ET202 system. The signal-to-noise ratio (S/N) and ANOVA have confirmed the significance of heat transfer fluids, the heat absorber, flow rate and solar radiation on the thermal performance.

Thesis (PHD) - Universiti Teknologi Brunei, 2021