The benefit of droplet injection on the performance of an ejector refrigeration cycle working with R245fa

This work presents a combined experimental and thermodynamic approach used to investigate the influence of droplet injection on the performance of an ejector-based refrigeration cycle developed for Heating, Ventilation and Air-Conditioning (HVAC) applications. Thermodynamic models have been developed within MATLAB for each component of the cycle. They are validated against experimental data of an R245fa test rig installed at Hydro-Québec's Energy Technologies Laboratory (LTE). The numerical models agree fairly well with the experiments. The results show that injecting R245fa droplets at the end of the ejector diffuser with different glycol temperatures ranging from 20 to 26 °C has a significant impact on the performance of the ejector itself and more interestingly on the performance of the whole cycle. It reduces especially and significantly the temperature and the pressure of the overheated vapors at the outlet of the ejector leading to a significant improvement of the thermodynamic coefficient of performance (COP) by up to 20%.