Investigation On Ejector Refrigeration System Based On Active Pressure Balance

The global temperature is rising,electricity consumption is soaring,and energy shortage has become a bottleneck restricting the continued growth of the economy and industry.Therefore,The refrigeration systems driven low-grade waste heat have attracted the attention of domestic and foreign scholars.The ejector refrigeration system is a low-grade thermal energy drive system that can use green natural working fluids.It can not only be driven by low-grade heat sources such as combustion waste heat,vehicle waste heat,solar energy,etc.,but also has simple structure,stable operation,convenient maintenance,and low investment cost.It is a refrigeration system choice that conforms to the development situation,and has broad development prospects.However,the entrainment ratio of the ejector limits the improvement of the energy efficiency of the system,and there are fewer applications.This article first focuses on improving the energy efficiency of the ejector refrigeration system,and proposes an active balanced ejector refrigeration system using R245 fa as the working fluid,which uses the waste heat of the generator to drive the liquid return,avoids the use of mechanical running parts,and further simplifies the system structure to improve the energy efficiency of the system.Pure thermal drive becomes possible,broadening the application range of ejector refrigeration systems.Then,the ejector is modeled in one dimension,and the entrainment ratio is calculated iteratively.And on this basis,the active balance system was modeled and analyzed.The system operating parameters such as generation pressure,condensing pressure,evaporating pressure,etc.changed over time,and the influence of the volume and operating frequency of the liquid storage tank on the operation and energy efficiency of the system was studied.Draw up system control strategy and provide guidance for system component selection.Secondly,for the ejector used in the active balance system with R245 fa as the working fluid,the nozzle adjustable ejector test bench was designed and the experimental research was carried out.Under the design conditions,the influence of the ejector geometric structure parameters on the ejector performance was studied.And get the selection strategy of ejector structure parameters including nozzle distance,nozzle diameter,mixing chamber length,diffuser chamber length,etc.under this working fluid and working conditions.Finally,a visual active balance experiment platform was built to study the operating characteristics and performance of the active balance system.The experimental results show that: the system operating parameters periodically change,the system can maintain stable operation;the volume of the condensing storage tank and its own heat capacity have a greater impact on the stability and energy efficiency of the system;the use of active balance can effectively reduce energy consumption and the COP value of the active balance system is higher than the traditional ejector refrigeration system.