Study of the integration of a supersonic impulse turbine in a NH₃/H₂O absorption heat pump for combined cooling and power production from a low temperature heat source

Abstract

The present work is focused on the investigation of an absorption cycle integrated with an impulse axial turbine for the combined production of cooling and electric power. This technology holds great promise for its ability to harness low-temperature heat sources, more effciently in comparison to separate production with simple cycles. By developing a 1D model of the expander, and integrating it into a 0D model of the complete cycle, it is possible to evaluate the performance of the cycle and its variation with respect to the operating parameters, namely the temperature of the external resources. Pending an experimental validation of the results, this study showed the importance of correctly defining the temperature of the sources - namely the generator temperature - in order to satisfy the technological needs while also maximising the effciency of the cycle. Finally it was highlighted how the integration of a supersonic impulse turbine strongly limits the flexibility during operation given the constant mass flow rate treated by the expander.

Energy, exergy and exergoeconomic analysis and optimisation of the scale-up of a combined ammonia-water absorption pilot plant producing electricity and refrigeration

“…The prototype (shown in Fig. 2) is a thermally driven single-effect ammonia-water absorption chiller of 7 kW cooling capacity designed for solar cooling applications with the goal of testing innovative architectures [52].…”

“…A compressible 1D model of the turbo-expander [61] was also developed in EES and integrated in the cycle. The model takes into account the behaviour as a real-gas mixture of the working fluid and includes a description of the expansion occurring in the supersonic injector.…”