Design and development of novel absorber coating for solar collector applications

Global average power consumption is 17 terawatts (10[to the power of]12W) and the rate of solar energy received at the Earth's surface is more than 120 petawatts (10[to the power of]15W). Therefore, the earth receives as much solar energy in one day as is used by the entire world in 20 years. Solar thermal collectors use absorber coatings and layers to convert incident radiation, via photothermal conversion, into useful energy i.e. heat. Re-radiation of this heat is minimised using a solar selective surface. Patterning non-thermal curing epoxy resins, in the micron scale, using electrohydrodynamic instability (EHD) patterning, could mitigate some of the challenges presented by other materials and methods used to produce these surfaces such as cost. Therefore, this was the objective of this study. As a contribution to the field of electrohydrodynamic instability patterning, the method of using this process to shape a thin, non-thermal curing epoxy resin film, was developed and the materials and equipment used are presented. Epoxy pillared surfaces, with pillar spcings from 3-200 [micrometres], were manufactured on silicon substrates using 30, 61 or 162 V and electrode gaps ranging from 3- 40 [micrometres]. A way of replicating the fabricated surfaces using moulding was also developed and is also described here. The patterned surfaces were replicated onto various substrates and were tested for their interaction with infrared (IR) radiation. In order to explore the range of versatility of theis technique for fabricating functional surfaces the structures surfaces were also tested as sustrates for tissue culture. To gain a better understanding and hence control over the use of electrohydrodynamic instability patterning with an epoxy resin, theories and numerical models of the process of electrohydrodynamic instability patterning were examined. Comparisons between predictions of results given by theory and our practical results are discussed since it was found that there was more disagreement between our results and theory when lower electric fields were being used. The studies of the interaction of the surfaces with IR radiation, and for use as tissue culture substrates, is also assessed and commented on. Lastly improvements that could be made and future work that could be undertaken is suggested.