Experimental evaluation of an ejector as liquid re-circulator in an overfeed NH3 system with a plate evaporator
Abstract This paper deals with the experimental performance evaluation of an ejector, linked to a manual expansion valve, working as a liquid re-circulator component in an overfeed NH 3 plate evaporator. The evaporator was tested in a single stage system belonging to a cascade refrigeration system prototype. The evaporator is an ALFANOVA HP76 plate heat exchanger with 50 plates. A Phillips ejector with a 1/2″ diameter throat and 1.4 mm diameter nozzle was used. The recirculation rate was experimentally determined for different operating conditions. Experimental data are reported for volumetric flow rate at the manual expansion valve inlet from 0.8 to 1.6 l min −1 , evaporating pressure from 0.14 to 0.22 MPa and condensing pressure from 0.85 to 1 MPa. The experimental result showed recirculation rates between 2 and 4. The evaporating capacity varied from 9.48 kW to 18.37 kW. In addition, another two nozzles were tested and the results are also presented and discussed.