Droplet injection at the diffuser outlet in an ejector-based 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 applications. A thermodynamic model has been developed within Matlab for each component of the cycle with a particular emphasis on the ejector modeling, which is based on the constant pressure mixing assumption. It is validated against the experimental data obtained on the Hydro-Quebec’s test rig working with R245fa. The numerical model agrees fairly well with the experiments. The results show that injecting R245fa droplets at the end of the ejector diffuser at the condensing temperature has a significant impact on the performance of the ejector itself and of the whole cycle. It reduces especially and significantly the temperature of the overheated vapors at the outlet of the ejector leading to a significant improvement of the Coefficient of Performance (COP).