Small cooling capicity hybrid refrigeration system using R723

In the past two decades, concern about the impact of CFCs, HCFCs or CO2 emissions on the environment and in particular on the ozone layer and global warming phenomena has reactivated interest in Sorption Technology applied to heat pumps and refrigerating systems. This is for two main reasons: the refrigerants used (ammonia, water or alcohols) are less harmful to the environment (zero Global Warming Potential - GWP and zero Ozone Depletion Potential - ODP) and the systems are heat driven therefore could use 'free' or low cost heat sources such as solar energy, biomass or waste heat (domestic or industrial). With EU regulations aimed at enforcing the Kyoto Protocol and the rising cost of the primary sources of energy (Oil and Gas) worldwide, the need for environmentally friendly and highly efficient heat pumps and refrigerating systems is required. The current project proposes a Hybrid Refrigeration System using the environmentally friendly refrigerant R723 (azeotropic mixture: 40% DME and 60% Ammonia) that is compatible with conventional refrigeration copper alloy (CuNi10) It is a Combined Sorption-Vapour Compression Refrigeration System driven by a dual source (heat and/or electricity). Both the use of this refrigerant in an adsorption cycle and the hybrid energy source are key novelties.
Numerous Hybrid Refrigeration System layouts are to be modeled in association with the development of system control strategy. A proof of concept prototype of 10 kW cooling capacity will be designed, built and its performance (COP and cooling power) evaluated.

For two decades, there have been national and international efforts through various Protocols (Kyoto, 1997), Acts (UK Climate Change Act 2008) and Memorandums of Understanding (Copenhagen 2009 Accord) to reduce the emission of greenhouse gases (Methane, Nitrous Oxide N2O, CFCs, HCFCs and CO2) that are responsible for global warming. The proposed project fits this context not only by using refrigerant of very low GWP and ODP (R723) but also by blending the driving energy source (conventional and renewable) of the refrigeration system for improved flexibility and cost-effectiveness. In addition to this, industry (component and system manufacturers), end users and the scientific and engineering communities will gain benefits.
New market could open up to the manufacturers of activated carbon, heat exchangers and refrigeration systems without substantial additional capital investment. For instant, a manufacturer of activated carbon
could gain a potentially additional annual sell of £16.5M with only 2% of annual market penetration of the new technology. It is also estimated that if such hybrid systems are introduced in UK, there will a potential reduction of CO2 emission of 11% over ten years period through fuel saving.
The direct social benefits attached to this proposed system could be a better quality of air in addition to economic benefits and reduction of other cost linked to the consequences of CO2 emissions.
The dissemination of the results of this work through publications or communications in international journals (example: International Journal of Refrigeration), conferences (example: IIR-International Congress of Refrigeration) and various networks (example: SIRAC or IoR) will contribute and make an impact to future research and system design of heating and cooling equipment.