Resonator Influence Simulation of Designed Close-Open Standing Wave Thermoacoustic Engine (original) (raw)
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Experimental investigation of an adjustable standing wave thermoacoustic engine
This work is primarily concerned with the experimental investigation of the performance of a standing wave thermoacoustic engine (TAE). The TAE technology converts thermal power into acoustic power which may be used to generate electricity or, to drive thermoacoustic cooling devices. Although there is a number of existing researches that suggest the link between the geometrical configuration of the device and its performance, there are no existing work that point out how to incorporate this aspect in the designing. Therefore, this study proposes the use of an adjustable TAE in order to alter the performance of the device while in operation. This new TAE model has an adjustable resonator length, which consisted of a 103 mm (4-in.) honeycomb ceramic stack sample, buffer volume and a cooling shell-tube heat exchanger was developed. Six different stacks were used to evaluate the performance of the TAE. Three different stack lengths (50, 100, and 150 mm), positioned at three different locations, were investigated. These locations were measured from the hot ends of the stack to the pressure antinode. In addition, the influence of the mean pressure and the working gas was investigated. Measurement of temperature difference across the stack and sound pressure levels at the steady state were used to determine the efficiency of the device. Through the adjustment of the resonator length, this study point out the benefit of choosing the best frequency so that TAE can work optimally and produce higher acoustic power.
Procedia Manufacturing, 2019
The production of sound-wave in thermo-acoustic device is necessary to induce cooling or generate electricity. The magnitude of the sound-wave is normally proportional to the amount of heat provided to the device. The possibility to use waste heat in any locations can be enough to justify the use of thermo-acoustic technology for sustainable electricity generation or refrigeration. In this work, an adjustable thermoacoustically-driven engine has been developed using the Design Environment for Low-amplitude ThermoAcoustic Energy Conversion (DELTAEC). Many studies have highlighted the relationship between the geometry of the stack and the performance of the device. Unlike previous studies, the resonator of this thermoacoustically-driven device, made of two portions, was adjusted. The performance of the device has been analysed in order to evaluate the influence of the alteration of the resonator on the heat-to-sound conversion. Performance indicators like the acoustic power, the temperature difference across the stack and the frequency of the sound-wave have been studied. This work points out the possibility to regulate the performance of thermo-acoustic engine by adjusting the geometry of the resonator.
Resonator Shape Effect on the Performance of a Standing-Wave Thermoacoustic Heat Engine
9th Annual International Energy Conversion Engineering Conference, 2011
This thesis demonstrates an attempt to make a design of an about 1-meter-long thermoacoustic heat engine that has an optimum efficiency. This will be done using DeltaEC, software which was developed especially for low amplitude thermoacoustic devices modeling. The optimization process includes geometrical parameters of the resonator tube and the stack, the working fluid, and the heat input to the engine. The present optimization process has shown that slab stacks made of Celcor (a Ceramic material) demonstrated much better performance than other stack shapes and materials. For a 1.1239-meter-long and 0.011 m2 square-shaped resonator tube, a 7.75 cm long slab stack made of Celcor having 0.304 mm-thickplates, spaced by 0.648 mm, giving a porosity ratio of 0.68067, will theoretically convert heat to acoustic power at an efficiency of 30.611% which is equivalent to 47.97% of Carnot's efficiency. The thesis ends with a brief summary of conclusions.
Development and performance evaluation of a standing-wave thermo-acoustic engine
2019 Open Innovations (OI), 2019
The current work describes the development, construction and experimental investigation of a simple Standing-Wave Thermo-Acoustic Engine (SWTAE). This work aims at providing additional clarity on the construction and the performance of simple SWTAEs. The proposed SWTAE will be used to drive a traveling wave thermo-acoustic refrigerator, through the generated sound wave and ultimately induce cooling. For experimental purposes, the heat supply used in this experimental study are electric cartridge heaters. This study provides clarity as far as the temperature supplied to the system is concerned. To characterize the acoustic power of the SWTAE, the onset temperature differences across the stack for the engine to start producing sound has been measured. Three different configurations have been investigated and general trends showing the relationship between the supply heat, the generated sound wave and the minimum temperature required to produce a sound wave have been obtained.
Influence of stack geometry and resonator length on the performance of thermoacoustic engine
Applied Acoustics, 2012
Thermoacoustic engines convert heat energy into high amplitude sound waves, which is used to drive thermoacoustic refrigerator or pulse tube cryocoolers by replacing the mechanical pistons such as compressors. The increasing interest in thermoacoustic technology is of its potentiality of no exotic materials, low cost and high reliability compared to vapor compression refrigeration systems. The experimental setup has been built based on the linear thermoacoustic model and some simple design parameters. The engines produce acoustic energy at the temperature difference of 325-450 K imposed along the stack of the system. This work illustrates the influence of stack parameters such as plate thickness (PT) and plate spacing (PS) with resonator length on the performance of thermoacoustic engine, which are measured in terms of onset temperature difference, resonance frequency and pressure amplitude using air as a working fluid. The results obtained from the experiments are in good agreement with the theoretical results from DeltaEc.
DESIGN OF A STANDING-WAVE THERMOACOUSTIC ENGINE
The project entitled 'Stove for Cooking, Refrigeration and Electricity' has the ambitious objective of making a 150 W electricity generator based on thermoacoustic principles that is driven by the heat of a wood-burning stove. With a linear alternator involving the only moving part, it is intended that the device should eventually be produced at very low cost for widespread deployment in under-developed countries. The first concept to be explored on the grounds of simplicity was the so-called 'standing-wave' design in which only a small fraction of the acoustic pressure is in-phase with the acoustic velocity. The engine consisted of a closed linear duct containing a high-temperature heat exchanger connected to the heat source and a low-temperature heat exchanger rejecting heat to the surroundings, with a 'stack' of narrow channels between them, and a linear alternator at the low-temperature end of the duct. The high-temperature heat exchanger concept was one of radiative transfer from a ceramic bulb in the fire to a number of metal plates spanning the duct, and thence into the self-excited acoustic waves. The conservation equations of thermoacoustics were solved together with equations describing the radiative heat exchange, in order to determine the overall performance of this concept in terms of the acoustic power that would be incident on a matched alternator at the chosen frequency. Sensitivity studies were undertaken to examine the influence of the mean pressure and of the composition of gas in the duct, and of the length and diameter of the passages in the stack. Ultimately it was decided that the alternator could not be matched to the high acoustic pressures involved (>100 mbar) and attention was switched to a 'travelling-wave' device.
Design and Fabrication of Two Stage Thermoacoustic Engine to Reduce the Onset Temperature
About 60% of primary energy is treated as waste heat but the temperature of this heat is low (200-300 0 C). Thermoacoustic engine convert heat energy into high amplitude sound waves, which is used to drive thermoacoustic refrigerator or pulse tube cryocoolers by replacing the mechanical piston such as compressors. The potential of thermoacoustic engine is high but because of heat loss the actual efficiency is not so high. The onset temperature difference, defined as the minimum temperature difference across the sides of the stack at which the dynamic pressure is generated. Lowering the critical onset temperature is a challenging task. The authors designed a multistage thermoacoustic engine which oscillates with relatively low critical onset temperature TH/TR. The influence of the position of honeycomb ceramics is also investigated in this study. Introduction There are energy crises around the world so there has been a demand to use more efficient energy. And making use of waste heat is one way to reduce the energy crises. Currently a heat of 100 0 C or less which is wasted each year in Japan is about 22.3 Peta Calorie ≒ 9.34×10 16 J. This amount is greater than the amount of geothermal energy produced in the year 2010 which was 2.3×1016 J [1]. It is possible to use this heat effectively which can be very important in the future. Devices in which heat-sound interactions play an important role are known as thermoacoustic systems [2]. Generally, as described by Swift [3] and Ceperley [4], etc., thermoacoustic engines are classified into the standing wave engine and travelling wave engine by leading phase φ. In the standing wave engine, gas parcels with φ = 90 0 convert heat to acoustic energy through irreversible thermal contacts between the working gas and the walls of the regenerator. Such engines have been constructed for coolers [5]. Standing wave type with the advantage to oscillate at smaller TH/TR, while travelling wave type has higher energy conversion efficiency [5]. Amplification ratio of the acoustic work as shown in the figure 1, can be expressed as
Experimental Study on Variation of Tilted Angles Toward Acoustic Power of Thermoacoustic Engine
Journal of Physics: Conference Series, 2019
Tilted angles have to be researched for determining the good position of thermoacoustic engine. The research aims to find the best acoustic power with a tilted angle of the position, therefore the performance of Standing-Wave Thermoacoustic Engine (SWTE) is going to be increased. The performance is affected by the tilted angles. The natural convection which occurs in the core of Themoacoustic Engine will be different every tilted angle. The heat transfer characteristics within it were investigated under three tilted angles including, -90°, 0°, and 90°, with the resonator length 780 mm. This study was for getting the acoustic power which used the two sensors method with Data Acquisition (DAQ) NI-DAQmx 15.5 and two pressure transducers. It was calculated by Matlab R2013a. In this research is found that the acoustic power which is the best value is resulted on 90° of tilted angle, while the smallest value is found on 0°. Thes matter can be occured because phase difference of acoustic w...