Network Heat-dynamic Modeling And Characteristics Analysis Of Regenerative Oscillating Heat Engines

Regenerative oscillating heat engine refers to a type of heat engine that operates based on a regenerator under oscillating flow conditions.They have many advantages such as efficiency,environmental protection,simple and reliable structure,and the ability to utilize low-grade energy.With the development and application of various new regenerative oscillating devices,their efficient and practical analysis and design theories urgently need to be developed.This dissertation focuses on the development of a general heat-dynamic network model,characteristic analysis,and engineering design method for regenerative oscillating heat engines and the following research are conducted:(1)A general heat-dynamic network model for oscillating heat enginesBased on the common features of the regenerative oscillating heat engine in structure and working mechanism,a general heat-dynamic network analysis model for components together with a network topology method are established,and an efficient network model solution method based on particle swarm optimization(PSO)technology is provided.Considering the effects of distributed parameters,the active characteristics of regenerators,and the inherent nonlinear effects of oscillating heat engines,a method for processing nonlinear network parameters is proposed and explored,by which the network model is extended to analyze nonlinear problems.Complete heat-dynamic network models are established for three typical oscillating heat engines,and acoustic field as well as performance analysis are conducted,through which the effectiveness of the established general network model is verified.(2)A general stability analysis method for oscillating heat engines based on network model and electronic oscillator theoryBased on the established general network model,utilizing the Nyquist stability criterion in electronic oscillator theory,a general stability evaluation method suitable for oscillating heat engines of different structures is proposed.Based on the basic idea of the describing function method,the existing Nyquist criterion is improved to solve the nonlinear problems in oscillating heat engines.By combining PSO technology and Nyquist criterion,efficient solution of stability information is achieved.(3)Resonance characteristics analysis and design method for oscillating heat engine based on network model and electronic oscillator theoryBased on the established network model,the frequency characteristics of two typical resonant systems,namely gas and liquid-piston resonators,are analyzed,and the phase as well as impedance distribution characteristics of the oscillating heat engines at different frequencies are obtained.Based on frequency characteristic analysis and oscillator theory,a general and efficient engineering design method for oscillating heat engines is provided,according to which,a three-stage looped traveling-wave thermoacoustic heat engine is designed.(4)Enhanced performance prediction technology for oscillating heat engines coupled with artificial neural networkBy fully utilizing experimental and theoretical analysis data,a set of enhanced performance prediction technology for oscillating heat engines is developed based on artificial neural network(ANN),which further improves the prediction accuracy of theoretical models and provides two new ANN models with high accuracy and robustness in algorithm.Researches show that the two new ANN models can not only predict the performance of heat engines with high accuracy,but also maintain high predictive ability compared to conventional ANN models driven only by experimental data when the quality of experimental data is poor.A research tool is formed that integrates functions of performance simulation,characteristic analysis,and engineering design through the innovative application of heatdynamics,electronic oscillator theory,and artificial intelligence technology in this dissertation.It is suitable for the mechanism analysis and design rules research of multiphysical-field-coupling power generation/refrigeration systems.