Performance Study On An Adjustable Ejector Used In CO₂ Heat Pump Water Heater

With people's increasing attention to the environmental crisis, the natural refrigerant CO2 springs up again because of its environmentally friendly characteristics, CO2 used in trans-critical heat pump system has become a hot research topic. To decrease the expansion loss and increase the cycle efficiency, it has been proposed to replace the throttle·valve with an ejector expansion device. In this way, it can not only recover most of the expansion work which is normally lost, but also improve the performance of the evaporator. In this paper, an adjustable ejector has been proposed. The main researches on CO2-heat pump water heater with an adjustable ejector are as follows:1. Analyze the thermodynamic process on ejector. Compile the procedure to complete the design.2. Make out the experimental research plan. Adjust the needle. Investigate experimentally the effects of the motive nozzle throat area of the ejector, entrained flow pressure, back pressure and primary flow pressure on the entrainment ratio.3. Based on the flow and heat transfer mechanism in the ejector, create two-dimensional ejector model, finish mesh generation, establish boundary conditions and choose turbulence model.4. Finish the simulation of the ejector and obtain the pressure, velocity vectors distributions of domains. Compare numerical results with experimental data to verify the accuracy of the model.