Extending ammonia high temperature heat pump using butane in a cascade system.

Ammonia is widely used for industrial cooling, but also capable to deliver heat for hot water production up to 90 °C. Butane has favourable thermodynamic properties for high temperature applications above 90 °C. Recent improvement in both ammonia and hydrocarbon compressor technology shows potential for higher condensation temperature thereby expanding their application for heating. Both working fluids can independently convert waste heat to higher temperatures. When integrated into one system, the possibilities are further improved with more flexibility for industrial applications. This paper explores the potential of different cycle configurations of ammonia and butane cascade heat pump for high temperature industrial heating. The systems are designed to take advantage of the favourable properties of each working fluid, while optimized for different operating conditions. Several theoretical models using simulation tools are developed to implement the component and system designs. The model uses both technology that is commercially available and improved components to demonstrate the opportunities.