Start-up and damping of a standing wave thermoacoustic engine: model development and experimental evaluation

This paper puts forward a transient numerical model for thermoacoustic energy convertors using Rott’s equations combined with electrical circuit analogy. To enhance the accuracy of model outcomes, the lumped element values are updated at each time step as a function of temperature. Accordingly, a nonlinear temperature distribution is obtained along the hot core. The developed numerical approach is in line with the experimental results of a standing wave thermoacoustic engine. Based on this method, the temperature variations along the stack and the impact of stack material on start-up time and onset temperature are numerically investigated. Additionally, the onset temperature profiles are calculated and presented comparatively for the numerical and experimental results. The start-up time of spontaneous oscillations is calculated for the standing wave system. Consequently, the best geometry that quickly reaches sustained oscillations can be selected using this model. Examining the temperature profile during the start-up and damping process highlights a temperature difference between these two processes. This is calculated as 35 K in the numerical solution and measured as 38 K in the experiment for a standing wave engine. Observations show that using a material with lower thermal conductivity in the stack section can reduce the onset-damping temperature difference. The novel approach described here shows potential in capturing the onset-damping behavior of thermoacoustic systems efficiently.