Pilot 100 kW TAP

Converting 100 kW waste heat at 130-150°C into electricity

This project is funded by the Dutch Economic Affairs within the framework of the Small Business Research Programme (SBIR).

Based on the four stage traveling wave concept, a 100 kWT thermoacoustic power (TAP) generator is under construction now.

For the TAP project Aster collaborate with Huisman Innovations B.V. (www.huisman-elektro.nl) and Innoforte (www.innoforte.nl). Recently the first phase of this project which include also identification of component supplier and launching customers in industry is finished.

This project is carried out in the framework of phase two of the Dutch SBIR program. The 100 kW TAP will be installed at a paper manufacturing plant in the Netherlands for converting part of the flue gas at 130-150°C from the paper drying process into electricity. Emphasis in this project is on production and cost aspects lowering the investment per kWe to a level competitive to ORC’s. After successful completion of this pilot, commercialization and delivery of 100kWT to 1 MWT thermoacoustic power generators for industrial waste heat recovery and as add-on for CHP systems is planned to begin in 2012.

Effect of temperature on TAP output power

Performance of the TAP or any other low temperature heat driven thermo acoustic system like the thermo acoustic solar cooler depends heavily on the available input temperature and the temperature at which heat can be rejected. This is due to the second law of thermodynamics, which state that the theoretical amount of heat that can be converted is proportional with the temperature difference supplied.

To show this dependency an simulation is made for the TAP.

ta power

With the left side slider input temperature can be set between ambient and 160°C. Above about 60°C oscillation will start and at 85°C temperature the acoustic power level is high enough to switch on the counterbalanced alternators in the middle for converting acoustic output power of each engine stage into electricity. Full electric output power is reached at 160°C heat input temperature.

Asterdemo  (seperate window).

Acoustics08, Paris, France

Low operating temperature integral thermo acoustic devices for solar cooling and waste heat recovery


Utilizing low temperature differences from solar vacuum tube collectors or waste heat in the range 70-200 °C seems to be the most promising field of applications for thermo acoustic systems.At these reduced temperatures overall system performance is increasingly affected by the ratio between amplified (useful) power and acoustic power in the resonance circuitry.Well known is that this ratio can be improved by deploying multiple regenerator units (hex-reg-hex).However, in commonly used torus or coaxial bypass configurations the correct timing (real and high acoustic impedance) is hardly to realize inside more than two regenerator units (soft spot).Acoustic losses in the standing wave resonator together with a high regenerator impedance account for another fundamental limitation because of the relatively low transferred and loop power at a given pressure amplitude.Therefore a novel acoustic geometry will be presented in which a near real impedance can be maintained in even more than two regenerator units and in which acoustic feedback is performed by a near traveling wave.This approach improves the overall performance of low operating temperature thermo acoustic systems.

Read the full article

Low operating temperature integral thermoacoustic devices for solar cooling and waste heat recovery

or view the presentation


Patent list

C.M. de Blok. “Multistage traveling wave thermoacoustic engine with phase distributed power extraction”. PCT/NL2010/050057

C.M. de Blok. “Meertraps thermoakoestische warmtemotor met fase gedistribueerde vermogensuitkoppeling”, 2009, NL 1036630

C.M. de Blok. “Multi stage heat driven thermoacoustic engine” . PCT/NL2004/000405, WO2005/001269 A1

C.M. de Blok, N.A.H.J. van Rijt. Thermo acoustic system, 1997, WO 99/20957, US 6,314,740 B1.

C.M. de Blok, N.A.H.J. van Rijt. “Device for utilizing heat via via conversion into mechanical energy, in particular cooling device”. PCT/NL89/00012, WO1989NL0000012

Measuring technology

In the beginning we at Aster realized that representing and measuring acoustic components was essential to understand the physics and to be able to develop and optimize the  acoustic configuration and interaction of thermoacoustic engines and  heat pumps or other loads like linear alternators.

The first article describes the representation of acoustic components based on N-ports and scattering (S) parameters.  The second paper deals with the design and construction of direct reading 1-port acoustic network analyzer for measuring complex acoustic reflection in the range of 1-100 Hz.

Characterization of acoustic networks

Acoustic network analyzer