Design And Performance Analysis Of Ejector Based On 1-D Model

Ejector has been extensively studied as the core components of solar-powered ejector refrigeration system.However,owing to the complexity of the internal flow field,and the ideal gas model was taken considered to ejector's design and performance,the calculated results didn't good agree with the experiment result.Recently,Chen[14]classified the refrigeration as dry vapor and wet vapor based on whether refrigeration will phase transition or not in an ejector.For the reason,the R134a and R141 are chosen to be the representive of wet and dry refrigeration reprehensively to analysis the effect of refrigeration on ejector's design and performance in the paper.The Sokolov's ejector design model is chosen to study the effect of design conditions to deigned entrainment ratio and design the ejector.To analysis of ejector's performance,the real gas models of R134a and R141b are introduced,and a 1-D methodology is built to predict the performance of ejector based on conservation of energy,momentum,and Continuity equation.And then it is used to analysis the ejector's performance after verified by the experimental data.In ejector's design,the designed entrainment ratio increases with the temperature of primary and secondary flow increasing,and decreases with the condense temperature increasing for the R141b.For R134a,the designed entrainment ratio has the same trend with R141b,when the temperature of secondary and condense flow changed,but the influence of primary flow temperature to the designed entrainment ratio is increasing to the peak then decreasing.For R134a,the best temperature of designed primary flow is 85?when the secondary flow temperature lower than 8 Celsius and the condense temperature higher than 30 Celsius.Also,it is found that the superheat of primary flow have no advantage to the designed entrainment ratio,but the most increasing extent is 10 percentage when the refrigeration is R134a.In addition,the compression ratio and expansion ratio can be used to analysis the designed entraiment ratio.For the performance analysis of ejector,it is found that the entrainment ratio increasing with secondary flow temperature and deceasing with the condense temperature,and increasing the peak then decreasing when the primary flow temperature increasing.However,when the refrigeration is different,the trend of entrainment ratio is changed.For R134a,with the increasing of primary flow temperature,the bigger area ratio,the better entrainment ratio,and it appear a cascading mountain with the primary flow temperature increasing.But for R141b,the bigger area ratio and primary flow temperature,the better performance of ejector and it appears staggered mountain with the primary flow temperature increasing.For the R134a when the condense temperature is changed,the bigger area ratio,the higher condense temperature;but for the R141b,the trend is opposite.In addition,the superheat of primary flow can increase the entrainment ratio to 20%-40%for the R134a;But for the R141b,the entrainment ratio has no apparent changed when the superheat of primary flow changed.When the area ratio is higher than 5.5,the shock wave with the refrigeration is R134a is stronger than with the refrigeration is R141b.Based on the calculated and analysis of entrainment ratio,the component equations of solar ejector refrigeration system is integrated to calculate the performance of system.It is found that the trend performance of ejector refrigeration system with the generate temperature,evaporating temperature,condensing temperature,and superheat are corresponding to the entrainment ratio with the primary flow temperature,secondary flow temperature and condensing temperature,superheat.