• Energy Research

Abstract Nanofluids are potential new generation heat transfer fluids, which have been investigated meticulously, in recent years. Thermophysical properties of these fluids have significant influence on their heat transfer characteristics. Viscosity is one of the most important thermophysical properties that depends on various parameters. Size of the particles used in nanofluids is one of these effecting parameters. In this work, experimental studies considering the particle size effect on the viscosity of the nanofluid have been reviewed. Firstly, comparison of nanofluid and surfactant type, production and measurement methods were considered. Viscosity results of selected studies were evaluated in view of the parameters such as particle size, temperature and concentration. Furthermore, effective viscosity models of nanofluids, which include particle size as a parameter were discussed. The results indicate that there is a discrepancy about the effect of particle size on the viscosity of nanofluids. Moreover, it is observed from the evaluated data that the relative viscosity variation can be almost 40% either upwards or downwards by only altering the particle size.

Abstract Nanofluids are potential new generation heat transfer fluids, which have been investigated meticulously, in recent years. Thermophysical properties of these fluids have significant influence on their heat transfer characteristics. Viscosity is one of the most important thermophysical properties that depends on various parameters. Size of the particles used in nanofluids is one of these effecting parameters. In this work, experimental studies considering the particle size effect on the viscosity of the nanofluid have been reviewed. Firstly, comparison of nanofluid and surfactant type, production and measurement methods were considered. Viscosity results of selected studies were evaluated in view of the parameters such as particle size, temperature and concentration. Furthermore, effective viscosity models of nanofluids, which include particle size as a parameter were discussed. The results indicate that there is a discrepancy about the effect of particle size on the viscosity of nanofluids. Moreover, it is observed from the evaluated data that the relative viscosity variation can be almost 40% either upwards or downwards by only altering the particle size.

In this study, a novel prototype of a hybrid concentrator photovoltaic/thermal and solar thermoelectric generator system has been designed and constructed for combined heat and power production. In the developed hybrid system, both the solar cells and thermoelectric modules that share a common heat transfer medium are exposed to concentrated irradiance via a compound parabolic concentrator and a parabolic trough concentrator, respectively. To assess the performance of the hybrid system, a prototype of the hybrid system was built and tested under outdoor operating conditions, and the findings were compared with those of a transient numerical simulation conducted using ANSYS Fluent. The average PV temperature obtained during the test period at a flow rate of 3.8 L/min is 318.19 K which is ∼5.6% lesser compared with a conventional hybrid CPVT-TEG system. The outdoor trials show maximum electrical efficiency of 4.86% and thermal efficiency of 40% when the solar irradiance is greater than or equal to 1000 W/m2. The overall efficiency of the developed prototype is 3 times higher compared to a standalone PV system. The hybrid system helps to reduce carbon emission by 0.5 kg/h, with an associated environmental cost of 0.025 €/h.

In this study, a novel prototype of a hybrid concentrator photovoltaic/thermal and solar thermoelectric generator system has been designed and constructed for combined heat and power production. In the developed hybrid system, both the solar cells and thermoelectric modules that share a common heat transfer medium are exposed to concentrated irradiance via a compound parabolic concentrator and a parabolic trough concentrator, respectively. To assess the performance of the hybrid system, a prototype of the hybrid system was built and tested under outdoor operating conditions, and the findings were compared with those of a transient numerical simulation conducted using ANSYS Fluent. The average PV temperature obtained during the test period at a flow rate of 3.8 L/min is 318.19 K which is ∼5.6% lesser compared with a conventional hybrid CPVT-TEG system. The outdoor trials show maximum electrical efficiency of 4.86% and thermal efficiency of 40% when the solar irradiance is greater than or equal to 1000 W/m2. The overall efficiency of the developed prototype is 3 times higher compared to a standalone PV system. The hybrid system helps to reduce carbon emission by 0.5 kg/h, with an associated environmental cost of 0.025 €/h.

Developing stable, economic, safer and carbon-based nanoparticles from agro solid waste facilitates a new dimension of advancement for eco-friendly nanomaterials in competition to existing nanoparticles. Herewith, a three dimensional highly porous honeycomb structured carbon-based coconut shell (CS) nanoparticle is prepared through green synthesis technique using tube furnace to energies organic phase change material (PCM). CS nanoparticle synthesis using a green approach is incorporated with polyethylene glycol (PEG) using a two-step technique to develop PEG/CS nanocomposite PCM. Thermophysical features of the nanocomposites are characterized using transient hot bridge (ThB), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA), whereas optical property and chemical stability is evaluated using UV–Vis and FTIR spectrometers. Resulting nanocomposite demonstrates higher thermal conductivity by 114.5 % (improved from 0.24 W/m⋅K to 0.515 W/m⋅K). Energy storage enthalpy increased from 141.2 J/g to 150.1 J/g with 1.0 % weight fraction of CS nanoparticles. Optical absorbance of the nanocomposite is improved by 2.14 times compared to base PCM. The developed nanocomposite samples exhibit extreme thermal stability up to 215 °C. The 3D porous structure of CS nanoparticles shows better contact area with PEG, causing low interfacial thermal resistance for improved thermal network channels and pathways for extra heat transfer and phonon propagation.

Developing stable, economic, safer and carbon-based nanoparticles from agro solid waste facilitates a new dimension of advancement for eco-friendly nanomaterials in competition to existing nanoparticles. Herewith, a three dimensional highly porous honeycomb structured carbon-based coconut shell (CS) nanoparticle is prepared through green synthesis technique using tube furnace to energies organic phase change material (PCM). CS nanoparticle synthesis using a green approach is incorporated with polyethylene glycol (PEG) using a two-step technique to develop PEG/CS nanocomposite PCM. Thermophysical features of the nanocomposites are characterized using transient hot bridge (ThB), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA), whereas optical property and chemical stability is evaluated using UV–Vis and FTIR spectrometers. Resulting nanocomposite demonstrates higher thermal conductivity by 114.5 % (improved from 0.24 W/m⋅K to 0.515 W/m⋅K). Energy storage enthalpy increased from 141.2 J/g to 150.1 J/g with 1.0 % weight fraction of CS nanoparticles. Optical absorbance of the nanocomposite is improved by 2.14 times compared to base PCM. The developed nanocomposite samples exhibit extreme thermal stability up to 215 °C. The 3D porous structure of CS nanoparticles shows better contact area with PEG, causing low interfacial thermal resistance for improved thermal network channels and pathways for extra heat transfer and phonon propagation.

Solar thermal technology to supply process heat in different industrial sectors has become very promising in recent years. Industries can reduce their consumption of fossil fuels by replacing them with solar process heat with non-conventional system integration and using clean energy. In this paper, a systematic review of 10 countries is presented which demonstrated extensive use of solar industrial process heating systems in their manufacturing sectors. This country-wise analysis is then used to compare with current Australian scenario and identify future prospects of integrating solar process heating in Australian industrial sectors. The choice of countries is based on a database where promising industrial sectors and solar process heating applications are currently using incident solar energy. These are analyzed for their potential of integration to developing solar heat in industrial processes (SHIP) and a number of potential industrial sectors that have the highest potential like Motor vehicles, Textiles, Printing, Wood, Paper, Fabricated metal, Rubber and plastics, chemicals, Food, beverages, electrical equipment, machinery, and equipment are being identified. An overview of available studies is discussed in this paper focused on specific countries and the industrial heat demand of existing operational plants. Future trends due to solar energy potential are also outlined.

Solar thermal technology to supply process heat in different industrial sectors has become very promising in recent years. Industries can reduce their consumption of fossil fuels by replacing them with solar process heat with non-conventional system integration and using clean energy. In this paper, a systematic review of 10 countries is presented which demonstrated extensive use of solar industrial process heating systems in their manufacturing sectors. This country-wise analysis is then used to compare with current Australian scenario and identify future prospects of integrating solar process heating in Australian industrial sectors. The choice of countries is based on a database where promising industrial sectors and solar process heating applications are currently using incident solar energy. These are analyzed for their potential of integration to developing solar heat in industrial processes (SHIP) and a number of potential industrial sectors that have the highest potential like Motor vehicles, Textiles, Printing, Wood, Paper, Fabricated metal, Rubber and plastics, chemicals, Food, beverages, electrical equipment, machinery, and equipment are being identified. An overview of available studies is discussed in this paper focused on specific countries and the industrial heat demand of existing operational plants. Future trends due to solar energy potential are also outlined.