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Reporting period: 2016-04-01 to 2018-03-31

Increased energy costs, the uncertainty of fossil fuel availability, and climate change concerns, have necessitated the quest
for renewable energy resources. Solar adsorption systems are quiet, simple to operate, and can last for a long time.
However, they have low cooling power density, and subsequently have to be bulky compared to similar solar thermal
systems offering the same performance. This can increase their initial costs, especially for small and medium sized systems,
thus reducing their uptake. Currently researchers have successfully tackled this issue by, for instance, using more than one
adsorbent bed to adopt a continuous cycle, and using forced cooling for the adsorber bed and condenser. These have not
resolved the bulk/cost issues, however. The main objectives of the project were to enhance the thermal energy collection of the solar collectors,
the adsorbent and refrigerant heat and mass properties, using nano-technology based techniques.
In order to achieve the objectives of the Fellowship, numerical, design, and analytical methods were used.
Two numerical models for the optimization of the solar refrigerator were applied, both transient simulation programs. This was to enable the implementation of the numerical optimization algorithm for determining the optimum cycle time for an adsorption solar thermal refrigeration system. Validation cases of known solar adsorption systems were carried out for one of the codes, and this will be useful for the numerical optimization of the solar thermal adsorption systems using nano-techniques.

The use of a thermally controlled high-speed diffusion bonding process for the collector/tube bonds allows disparate materials to be bonded. A diffusion bonding rig was built. Tests indicated that a redesign of the rig is required to accommodate the solar collector tube bond assembly more effectively, however a diffusion bonded sample was made.

A detailed design of the collector/tube bond assembly and the methodology for determining the thermal conductivity were carried out. This involved the use of different metal fillings in the bond.
The effect of the surface coating of the solar collector and the methodology for determining the effectiveness of different coatings were ascertained.
A method for determining the thermal conductivity of the adsorbents with or without metallic fillings were determined for packing densities ranging from 400 to 500 kg/m3.
Finally a method for determining the thermal conductivity of nano-refrigerants was chosen. From the details ascertained from the component parts, the design of the complete refrigeration unit was completed. The results from the calculations from the design indicated that using selective surface coatings for the solar collector, enhancing the adsorbent heat and mass transfer properties and using nano-refrigerants in a solar thermal adsorbent system will improve the thermal performance of the unit.

The project also revealed some of the costs and difficulties in preparing nano-refrigerants (agglomeration), and the potential environmental and health effects and the regulations required to minimize these effects. A journal paper was published highlighting these and is available as an Open Access paper. The EC H2020 Marie Curie action was acknowledged at the end of the paper.
The potential for solar adsorption solar thermal refrigerants with improved thermal performance; this will potentially increase the likely of adopting such units for small and medium sized uses as the energy density is increased.

The project led to a Coventry University funded project that is determined the optimum de-agglomeration parameters for nanorefrigerants.

The project led to 13 student projects, and 2 potential PhD student projects.

A paper 'Regulation of Nanorefrigerant Use: A Proactive Measure Against Possible Undesirable Health and Environmental Implications' was published in the European Journal of Sustainable Development Research.