Ammonia as natural refrigerant in electrically and thermally driven engines for heat pumps.

Ammonia is an excellent refrigerant for use in absorption or in vapor compression heat pumps because of its favorable thermodynamic and heat transfer properties. We examine the choice of driving a heat pump with a thermally-driven (TD) engine as in the case of an absorption device, or with an electrically-driven (ED) engine, as in the case of a Rankine cycle heat pump. Which engine has a lower carbon footprint and has the least environmental impact is the quintessential issue discussed in this presentation. The question is examined through a comprehensive methodology of energy and exergy analysis which explains why the output of these two engines is so different, and what impact it makes for source energy consumption, and environmental stewardship. This work is a fundamental analysis which discusses the choices and consequences of ED versus TD heat pumps and its direct impact on the environment. Thermodynamic consistency is guaranteed by invoking the First and the Second Laws applied to various components and subsystems of the TD and ED heat pumps.