Performance Investigation Of The Adjustable Area Ratio Ejector On Variable Cooling Loads For Refrigerator

With the development of the economic,the demand of refrigerators increases continuously.And the total power consumption of the refrigerator system is huge.Energy saving of refrigerators has become a hot topic.In a hybrid compression-ejector refrigerator refrigeration system,an ejector is used to reduce the energy loss caused by the throttling loss.The ejector can also increase the suction pressure of the compressor which the compressor power consumption can be reduced and it will certainly lower the system energy consumption.The system is very beneficial to energy-saving refrigerators.However,when the cooling load of the refrigerator changes due to factors such as the variation of external environment and stored food,a fixed area ratio ejector may cause the system working less efficiently.In this paper,the variable area ratio ejector is introduced into the compression-ejector hybrid refrigeration system for dual-temperature refrigerators.The ability of the variable area ratio ejector to adapt to the variable load of the refrigerator is investigated.This research has important theoretical significance and application value for refrigerator energy-saving.The main work of this paper are described as follows:1.The geometry parameters of the fixed area ratio ejector were designed under fixed conditions.For a given refrigerator parameter,the cooling load of two storage compartments in the compression-ejector refrigerator refrigeration system is calculated.And the mass flow requirements and working conditions of the ejector are also determined.The initial ejector geometry parameters was designed by the relevant design experience and ejector design manual.2.The ejector performance is improved with the optimization of ejector geometry parameters.The computational fluid dynamics software was used to optimize the key geometric parameters of the ejector:nozzle outlet diameter,area ratio,and the length of the constant pressure mixing chamber,so that the ejector designed can satisfy the demand of the refrigerator which it can also have a high entrainment ratio.3.The performance of the adjustable area ratio ejector was studied.It can be indicated that the adjustable area ratio ejector can meet the changing load requirements of the refrigerating chamber and the freezing chamber.The movement of the needle is emulated with the simulation,which the actual flow cross-sectional area of the fluid at the nozzle is changed,so as to investigate the changes of the primary and secondary flow mass flow and the entrainment ratio.The results show that by changing the needle,the primary flow mass flow can be adjusted,and the secondary flow mass flow can be adjusted accordingly.Therefore,the adjustable area ratio ejector has the ability to adapt to the variable load of the refrigerator.4.The performance of the adjustable area ratio ejector was investigated when the back pressure changed.By simulating several groups of different nozzle blocking rates,the back pressure was changed to investigate the ejector performance.When the back pressure increased,the secondary flow mass flow rate and the ejection ratio are decreased.However,the ejector can maintain a relatively high entrainment ratio within a certain range.