31 December 2008

Ammonia as refrigerant in small-capacity systems


Ammonia is widely used in large systems because of its excellent thermodynamic and transport properties, resulting in energy-efficient systems with little environmental impact. Nevertheless, despite its favourable properties, ammonia has not been used in small systems. The present paper reports on work on small ammonia systems being performed as part of the EU SHERHPA project, aimed at developing heat pumps with natural refrigerants.
First, the availability, and lack, of components for small ammonia systems is considered. Second, potentials and problems specific to small ammonia systems are discussed. Finally, the paper describes the design of a 9 kW water-to-water heat pump that contains as little as 100 g of ammonia, producing domestic hot water at close to 60 ° C while having a condensing temperature of below 50 °C.
The text is partly identical to that in previously published reports to the Commission.