Research On Thermoacoustic Engine With Dissipative Structure Theory

Thermoacoustic engine is a new kind of dynamic device which can convert heatenergy into acoustic energy. The unique advantages of thermoacoustic engine such assimple structure, low-loss and low-pollution have made it potential for variousapplications, because of which it has appealed a lot of research interest.The research on thermoacoustic engines lies in the cross field of thermal physicsand acoustics, which makes theoretical analysis complicated. Until now, the theoreticalworks about the thermoacoustic engine are generally based on traditional acoustics andthermal physics. Generally, complicated partial differential equations in fluid mechanicsneed to be dealt with and analytic solutions can not be obtained. Thermoacousticphenomena also involve nonlinear problems, because of which there would bedifficulties in math for studying in depth thermoacoustic engines.The concept of Dissipative Structure was presented by Ilya Prigogine in1960s.Driven by external forces, an open system can go away from equilibrium, if the distancefrom equilibrium becomes so far that the system lies in a critical nonequilibrium state,perturbations in the system now can make it lose stability and further develop into anordered structure which is called by Prigogine “Dissipative Structure”. The dissipativestructure theory emphasizes the concept of excess entropy of the system, through whicha general stability criterion about the system is given. This criterion has been applied tofields such as chemistry and bioscience.In thermoacoustic engines, the fluid medium is driven by temperature differenceaway from equilibrium and finally an ordered oscillation is formed. This is essentiallythe process that a dissipative structure is formed in nonequilibrium field.A.Rivera-Alvarez and F.Chejne noticed this in2001. However, they did not treat thisphenomenon from the nonequilibrium viewpoint. In this paper we treat thermoacousticproblems with dissipative structure theory. We set up a simplified model ofstanding-wave thermoacoustic engine and deduce the stability criterion for it. Byanalyzing the sign of this criterion, we figure out the onset temperature and thesepredicted temperature values are confirmed by our experiments. Therefore, on a certainextent, we confirmed the validity of applying dissipative structure theory tothermoacoustic problems.The innovation points are:1. We have attempted to study in thermoacoustic problems with dissipative structuretheory. Our work has proved that this way is simple and efficient because complicatedcalculations and numerical simulations are avoided. This way may be useful in futurethermoacoustic research.2. The relation of the onset temperature with position and length of the stack isobtained, which is meaningful for designing thermoacoustic engines with low onsettemperature.