Mathematical modelling of nanofluid-based direct absorption solar collectors

Solar-thermal collectors capture solar energy and convert it into heat energy. Several types of solar-thermal collectors have been used to harness solar radiation in both residential, electricity generation, and industrial settings; one class of solar-thermal collector design is the direct-absorption solar collector (DASC). An ongoing technological challenge in this area of science is to develop a truly widespread, coste ective system which e ciently converts solar energy and can compete with fossil fuel power generation. Nano uids are a relatively new class of uid that o er great promise as an alternative to conventional uids in a DASC due to their unique optical properties. This thesis develops and analyses novel mathematical models to describe and better understand the complicated interactions between solar radiation absorption, uid ow and heat transfer within nano uidbased DASCs (NDASCs) in a multiphysics continuum mechanics approach involving the use of coupled partial di erential equations. Overall, we discuss and model six di erent NDASCs: Collector 1 is an NDASC consisting of a nano uid owing through parallel-plates on an inclined plane, Collector 2 is similar to Collector 1, but with a re- ective base-panel, Collector 3 is an NDASC consisting of a nano uid owing through cylindrical pipes on an inclined plane, Collector 4 is a nano uid-based direct absorbing parabolic trough solar collector (NDAPSC) under laminar ow, Collector 5 is an NDAPSC under turbulent ow, and Collector 6 is an NDAPSC under turbulent ow with a time-dependent source term.