Resonance Tube Length Research Articles

Structural optimization of resonance tubes for a looped thermoacoustic engine with multiple heat sources

The advantage of coupling different heat sources with each thermoacoustic core unit in a three-stage looped traveling-wave thermoacoustic system is used to solve the application problem of multiple waste heat sources. The effects of the heat-side heat exchanger temperature, the resonance tube radius and length, and their interaction terms on the thermoacoustic thermodynamic properties are analyzed using response surface methodology on the premise that thermoacoustic core structures remain unchanged. The results indicate that prediction deviations for acoustic power, thermoacoustic conversion efficiency, and relative Carnot efficiency are within ±9%, ±3%, and ±3%, respectively. The acoustic power can be improved by increasing the hot-side heat exchanger temperature and the resonance tube radius. Under the same heat source conditions, the acoustic power, thermoacoustic conversion efficiency, and relative Carnot efficiency of the optimized thermoacoustic system show the highest increases of 49.63%, 4.82%, and 3.20%, respectively, compared to the non-optimized thermoacoustic system. The optimized variable-temperature system not only has higher thermodynamic efficiency compared with the optimized constant-temperature system but also can realize the complementary regulation among the thermoacoustic engine units by matching decreasing-gradient variable temperature and increasing-gradient variable radii and effectively broaden the working temperature range of the looped thermoacoustic system.

Effect of coupling position on a looped three-stage thermoacoustically-driven pulse tube cryocooler

A looped three-stage thermoacoustically-driven cryocooler system is introduced. Based on classic thermoacoustic theory, simulations are performed to investigate the effects of three representative coupling positions (inlet, middle, and outlet) of the resonance tube. The total exergy efficiency is found to depend on the dimensions of the resonance tube, demonstrating the importance of this parameter. For the same resonance tube length, the highest exergy efficiency of 16.3% is achieved for the outlet coupling position, whereas the middle and inlet coupling positions only achieved highest exergy efficiencies of 9% and 14.93%, respectively. The distribution of the phase difference, acoustic power, and exergy loss ratios of the main components are then presented to clarify the coupling mechanism. The results show that better phase distribution in the regenerator and less exergy loss in the resonance tube contribute significantly to the superior performance of the outlet coupling position.

Experimental investigation of the effects of driver housing and resonance tube on the temperature difference across a thermoacoustic stack

This paper studies the effects of the driver housing and the resonance tube length on the temperature difference generated across the stack ends. The experiment uses air as the working fluid. The results indicate that the size of the back volume and the length of the resonance tube have affected both the optimal frequency and the temperature difference across the stack. The relationship of these parameters is necessary to the design and measurement performance of the thermoacoustic system.

G061016 水スターリング熱機関の逆サイクル運転時の液柱振動([G061-01]熱工学部門,一般セッション(1) : エネルギー利用等)

Operating characteristics of a liquid-piston Stirling engine in the inverse cycle movement were investigated experimentally. As the result, the possibility of a liquid-piston Stirling heat pump was shown. It is a distinguishing feature that a liquid-piston Stirling engine has no mechanical part in itself. Many people have been thought that a liquid-piston Stirling engine can work as a heat pump when it operates in the inverse cycle. But, there are only a few researches for the characteristic of an inverse cycle movement of a liquid-piston Stirling engine. In this report, forced vibration was given by a piston which was placed on the surface of the liquid column at the open-end of the resonance tube. The vibrations of the liquid columns were observed. It was confirmed that the optimum resonance tube length exists and both amplitude and phase difference reach at the length. In addition, though it was slight, it was confirmed that the low temperature was obtained by the inverse cycle movement of the liquid-piston Stirling engine.

Numerical Prediction of Performance of Water Type Stirling Engine Considering Heat Exchange with Heat Sources

Two different analytical models were developed on water type Stirling engine. One is the resonance model which qualitatively clarifies the relationship between performance and resonance tube length, and the other is the heat transfer model considering heat transfer between working gas and the tube walls of heating and cooling units. These analyses and experiments were carried out changing the resonance tube length variously, then it was confirmed that the resonance tube length which maximizes the water column amplitude of the power piston agrees well and the oscillations of water columns at that resonance tube length also agrees. In addition, a series of analysis using the heat transfer model was carried out with changing cross sectional area of the resonance tube, loss factors of the elbows, heat transfer area of heating and cooling unit, and pressure of working gas. By this numerical investigation, the effect on the resonance tube length and the work at the length in which these parameters maximize the amplitude of power piston water column was clarified.

Influence of resonator diameter on a miniature thermoacoustic Stirling heat engine

A small scale thermoacoustic Stirling engine (TASHE) is simulated according to the linear thermoacoustic theory. The computed results show that in a small scale thermoacoustic Stirling heat engine, the diameter of the resonance tube might have important influences on the working frequency and the performance of the engine, which are always neglected in a large scale system. Likewise, the analysis and experimental results show that in order to obtain better engine performance, the diameter of the resonance tube must be chosen appropriately according to the looped tube dimension and the input heating power. This provides an effective way to miniaturize the thermoacoustic Stirling heat engine. According to the computation and analysis, a small scale engine was built, the resonance tube length and diameter of which were about 350 mm and 20 mm, respectively, and the working frequency was about 282 Hz. When the input heating power was about 637 W, the maximal peak to peak pressure amplitude and pressure ratio reached 0.22 MPa and 1.116, respectively, which were able to drive a thermoacoustic refrigerator or an electrical generator.

1844 水スターリングエンジンの液柱運動に関する研究(G06-5 伝熱(3),G06 熱工学)

The water-type stirling engine is the heat engine which used liquid vibration. It has the simple structure with no mechanical system, and it can use a source of low heat. But, so that this engine uses the vibration of the water, it is difficult to do control. Furthermore, the length of resonance tube influences the performance of the engine. So, the performance characteristics of the water-type stirling engine was studied. In this paper, the engine model was made and effects of the resonance tube length on its performance characteristics were examined experimentally. Furthermore, a numerical analysis by the analytic model was done, and experimental results were compared with numerical results.

Influence of resonance tube length on performance of thermoacoustically driven pulse tube refrigerator

A resonance tube is an important component of a thermoacoustic engine, which has great influence on the performance of the thermoacoustically driven pulse tube refrigerator. A standing wave thermoacoustic engine is simulated with linear thermoacoustics. Computed results show that an appropriate accretion of the resonance tube length may lead to a decrease of the working frequency and an increase of the pressure amplitude, which will improve the match between the thermoacoustic engine and the pulse tube refrigerator. The theoretical prediction is verified by experiments. A refrigeration temperature as low as 88.6 K has been achieved with an optimized length of the resonance tube, helium as working gas, and 2200 W of heating power.

C01 突合せ形熱音響音波発生機の特性 : 圧力波形の変化

Change in pressure signals in single, open ends and closed ends connected types of thermoacousitc sound wave generators are discussed. Simultaneous measurements of pressure, velocity and temperature are performed. As a result, pressure signals in the open-ends connected one are different from the other's. They oscillate at fundamental frequency of f, which is based on resonance tube length and sound speed in the working fluid, near the closed ends, and oscillate at 2f near the connected region. And its amplitude is larger than those of the others. Simulation of pressure signals are also performed.

Aerothermodynamics of a Simple Resonance Tube

An experimental investigation of a simple resonance ignition tube has been conducted. The leading edge of the resonance tube was blunt in order to simulate the geometry of proposed rocket ignition systems. The jetstagnation pressure, the nozzle/resonance-tube separation distance, and the resonance-tube length were varied systematically. Strong resonance was found to occur when the leading edge of the resonance tube was located within the third compression cell of the underexpanded jet. High-speed motion pictures showed a significant upstream propagation of disturbances from the resonance tube to the nozzle. These results will be useful in determining the feasibility of using resonance-tube ignition systems for both liquidand solid-propellant rocket engines.