Non-equilibrium Thermodynamics Model And Dynamic Characteristics Simulation Of Steam Accumulator

The steam accumulator is a kind of pressure vessel stored with a certain state mixture of water and steam.It is widely used in metallurgy,textiles,tobacco,wine and other traditional industries and solar thermal power generation system due to its fine performance in balancing steam heat load,easing the contradiction between steam output and usage.Applied to the steam catapult system on the aircraft carrier,steam accumulator provides a lot of steam in a very short period of time,which can help carrier-based aircraft take-off smoothly.The process of steam charge and discharge may be involved with flash evaporation,vapor-liquid two-phase flow,and a series of complex heat transfer changes.It is still challenging to forecast and analyze its dynamic characteristics accurately.The establishment of the steam accumulator precise simulation model is the key factor of system simulation and performance studies.Based on the quality conservation law and the energy conservation law of the vapor-liquid two-phase,considering working fluid evaporation(condensation)phase transition relaxation time and the heat exchange between fluid and metal wall,the paper established a non-equilibrium thermodynamic model of steam accumulator system.The supercharged boiler steam power test system was used to study the characteristics of the steam accumulator during the separate charge,discharge and continuous charge and discharge tests.Test results verified the accuracy of the non-equilibrium thermodynamics model of the steam accumulator and corrected the mathematical model characterization of non-equilibrium phenomena characteristic coefficient.According to the steam accumulator actual working process,the paper studied the variation of various steam accumulator characteristics parameters under changing the steam accumulator charge coefficient of water volume,initial pressure,steam source parameters,the steam output valve flow capacity and other factors in different charge conditions.The research results showed that the establishment of the steam accumulator non-equilibrium model can accurately reflect dynamic trends of each parameter during the transition from non-equilibrium to equilibrium in the charge and discharge process.In the charge process,steam accumulator pressure exhibited a character of first rise and then drop until a stable non-equilibrium process.Charging steam flow,the enthalpy of the steam source,accumulator volume and other factors had a significant effect on that.And in the discharge process,steam accumulator pressure presented rapid drop first until a stable trend rise lastly,and the amplitude of the pressure rise closely related to the discharge through-flow capacity of the valve.In the continuous charge and discharge process,the accumulator water level continuously decreased and the charge and discharge pressure affect the thermal storage efficiency significantly.Therefore,the actual application(such as steam catapult device)must take into account the impact of the non-equilibrium thermodynamic process of the steam accumulator characteristics.The study of steam accumulator non-equilibrium thermodynamic characteristics will provide strong technical support for steam accumulator design and system control strategies making.