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The global energy system faces a dual challenge; the need for more energy and less carbon emission. Out of the 50 billion tonnes of greenhouse gases emitted each year, 24.2 % comes from energy use in industries such as processing and manufacturing that require constant heating and cooling. Heat transfer improvements in heating and cooling industries cause energy saving thus reducing operational costs, increase the operational life of heat transfer systems and reducing greenhouse gas emissions. While nanofluids usage in heat exchangers presents a critical step for emission reduction, several factors including instability of suspended nanoparticles, the effect of a surfactant on physical property measurements and combining nanofluids with inserts have not been adequately assessed. This thesis investigates the use of highly conductive nanofluids as a potential alternative to conventional working fluids with low thermal conductivity, such as water, currently used in heat exchangers for heating and cooling systems. A distinguishing feature of this study is the consideration of the effect of surfactants on the stability of nanofluids, the physical properties of the nanofluids and the thermal performance of the nanofluids. The use of nanofluids in combination with hiTRAN® heat transfer inserts was also investigated. Activated carbon (C), copper oxide (CuO) and alumina (Al₂O₃) nanoparticles were suspended in distilled water (H₂O) and Ethylene glycol (EG). Surfactants were added including sodium dodecyl benzene sulfonate (SDBS), cetyltrimethyl ammonium bromide (CTAB), sodium lauryl sulphate (SDS) and Arabinogalactan (ARB) to create 20 combinations of nanofluids. ARB as a surfactant kept C/H₂O and CuO/EG nanofluid stable for 29 days. Whereas CTAB and SDBS surfactants kept C/H₂O and Al₂O₃/H₂O nanofluids stable for 17 and 11 days respectively. Viscosity results showed that in some cases the surfactant caused a slight increase in viscosity and in some cases viscosity decreased.

Industrial refrigeration equipment companies are continuously looking for ways to optimise the design of chilling and freezing tunnels in order to minimise food quality loss and increase the energy efficiency of the equipment. However, possibilities for dedicated experimental tests of the industrial operations are limited due to a large amount of food product involved while the number of design variables to be considered is high. A cost-effective alternative to experiments is numerical modelling. The main goal of this research was to simulate heat transfer of packaged food products in a chilling and freezing tunnel. Computational fluid dynamics (CFD) models were developed to improve prediction in industrial cheese chilling and chicken freezing. The industrial cheese chilling model was developed based on six blocks of agar that mimic the product arrangement and airflow pattern of a cheese chiller; while the chicken freezing model represents the first case of a CFD freezing model where the geometry was derived empirically via computed tomography scan data. The model predictions were validated by experimental temperature histories generated as part of the study. Once validated, the model was used to investigate the cooling heterogeneity and the effect of different operating conditions on the processing time. In addition to the CFD model, a simple heat transfer simulation based on the one-dimensional finite difference method was developed for industrial users. Thermal property models in the literature were also reviewed to propose the most suitable choice for thermal processing calculations.

The conversion of solar energy into usable forms of energy such as electricity and heat is attractive given the abundance of solar energy and the numerous issues recently raised in the consumption of fossil fuels. Solar conversion technologies may generally be categorised as either photovoltaic or solar thermal types capable of converting incidental sunlight into electricity and heat respectively. The photovoltaic cell is able to transform incidental sunlight into electricity via the Becquerel effect, however, the single junction crystalline silicon solar cell, the predominant cell type in today’s photovoltaic market is only able to utilise a small portion (less than 20%) of incidental sunlight for this purpose. A majority of the remaining portion is absorbed much like a traditional solar thermal collector and sunk as heat by the cell, elevating its operating temperature. Given the negative effect of temperature on photovoltaic cell operation, where a linearly proportional drop in conversion efficiency with elevated temperature can be expected, photovoltaic conversion can be reduced significantly particularly in areas of high irradiance and ambient temperatures. Based on the intrinsic absorption characteristics of the photovoltaic cell, a third type of solar panel referred to as the hybrid photovoltaic thermal collector (PVT) collector has been developed where fluid channels running along the underside of the photovoltaic panel transfer heat away from the cells to minimise this detrimental effect. Furthermore, heat captured from the cells may then be used for space heating or domestic hot water improving the overall collector efficiency. In this study a unique building integrated PVT (BIPVT) collector is investigated consisting of an aluminium extrusion with structural ribs, fluid channels, and solar conversion materials. In order to evaluate this design, a mathematical model of the collector was developed in order to determine both thermal and electrical yield of t