Thermoacoustic heat driven cooling

Kees de Blok

Aster Thermoacoustics, Smeestraat 11, 8194LG Veessen, The Netherlands

c.m.deblok@aster-thermoacoustics.com

Douglas Wilcox

Chart-Qdrive, 302 10th Street, Troy, NY 12180, USA

douglas.wilcox@chartindustries.com

Developments since the 1e workshop on thermoacoustics

Features of multi-stage TA engines

Multi-stage TA engine application examples

Thermoacoustic liquefaction of natural gas

Conclusions

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Developments since 1e workshop on thermoacoustics

• Pulse tube cryocoolers or cold heads Since 1980 Driven by (E-A) pressure wave generator Commercially available today

• Thermoacoustic engines with standing wave resonator

Since 1997 High efficiency High onset and operating temperatures Large internal (resonator) volume Most studied / copied configuration

• Multistage thermoacoustic engines with traveling wave resonance and feedback circuits

Since 2008 Low onset and operating temperatures Small internal (feedback) volume Prototypes build up to 100kWT at 160C

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Image: www.qdrive.com

Image: www.aster-thermoacoustics.com

Image: www.lanl.gov

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Features of multi-stage TA engines

Properties of multi-stage traveling wave thermoacoustic engines

Acoustic power gain proportional with number of stages

Less acoustic loop power relative to the net acoustic output power (more compact design)

Onset temperature difference < 30 C "Economic" operating temperature

difference > 100 C

Enables low and medium temperature heat sources as useful input heat

Waste heat (industry) Flue gas (e.g. CHP, …) Solar heat (vacuum tube collectors) ……..

4-stage thermoacoustic traveling wave engine/cooler (THATEA project, 2010)

Typical TA engine operating temperatures

Features of multi-stage TA engines

1) Default acoustic impedance matching

•In case of 4 stage TA engines, acoustic in- and output impedances are matched by default, because of the ¼ mutual distance between stages.

2) Traveling wave feedback multi-stage systems build so far hardly showed any streaming, Why?

Streaming is proportional with pressure amplitude and transported heat is proportional with temperature

•For the same acoustic power, pressure amplitude in traveling wave feedback systems is nearly half the amplitude in standing wave systems

•Multi-stage systems typcally operate at low and medium temperatures

•Asymmetry in minor losses at the in- and output junctions to the feedback tubes due to difference in local gas density (temperature) .

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Multi-stage TA engine application examples

ThermoAcoustic Power (TAP)

Conversion of industrial waste heat into electricity

•Dutch SBIR project, phase2

Design and built of a TAP converting 100 kW waste heat at 160ºC into 10 kW electricity

Location: Smurfit Kappa Solid Board, Nieuweschans(Gr), The Netherlands

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100 kWT Thermo Acoustic Power generator

3m

Multi-stage TA engine application examples

Solar powered cooling (SOTAC)

Add-on for vacuumtube collector systems

Latitude <35: Cooling only

Latitude >35: Combined heating and

cooling

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SOTAC demonstration setup (2012)

Thermoacoustic liquefaction of natural gas

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Thermoacoustic liquefaction of natural gas (LNG) •Basic idea since 1998 by LANL (Swift), Cryenco (later Praxair)

•Thermoacoustic Stirling engine (TASE) drives multiple pulse tubes sharing the same standing wave resonator

•Minimum engine input temperature: TH_engine = TC_engine . TH_cooler /TC_cooler

In theory: TH_engine = 330*300/110 = 900K (627C)

•In practice: TH_engine > 900C

High temperature (red) hot hex and pressure vesselLimited heat reduction burned gas (1300 C 900 C)Recuperation required, but limited by high exhaust temperature High temperature contruction materials required

Construction cost too high to become economic viable

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Image: www.lanl.gov

Thermoacoustic liquefaction of natural gas

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Thermoacoustic liquefaction of natural gas (LNG) or bio gas for transport and storage

The idea behind:

•Combine high performance pulse tube(s) with low input temperature multi-stage traveling wave thermoacoustic engine to lower input temperature

Reduce minimum engine input temperature by # stages Typical engine input temperature less than 300C Improved heat reduction burned gas (1300 C 300 C) Recuperation not required (optional) Allows for use of ordinairy construction materials

Cost reduction brings back the concept on stage Simple construction Scalable No moving parts Little or no maintenance Stand-alone operation

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Thermoacoustic liquefaction of natural gas

The experiment measurement layout

Gas mean pressure: 2.4 Mpa

Heat source: thermal oil heater

Heat sink: water cooling

•4-stage traveling wave engineAvailable at Aster-thermoacousticsGas: helium-argonFrequency: 50-77Hz

(set by ratio helium-argon)Pressure amplitude cold hex #4: 65 kPa ( dr: 2.7%)Theat source : 224C

Theat sink : 25C

•Cold head Type 102 supplied by QdriveGas: heliumOperating frequency: 60HzPressure amplitude cold head: 226 kPa ( dr: 9.4%)Electric heater: 5.2

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Thermoacoustic liquefaction of natural gas

Results

•First experiment Reached a cold head temperature of -110C Proved the concept

•Recent experiment Reduction of engine losses Heat load added to cold head Modified gas filling system

•Cold head temperature: -160C Heat sink cold head 25C

•TA engine Heat input temperature: 224C Heat sink: 25C

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First experiment january 2014

Cold head cooling power at engine input temperature of 224C

Conclusions

• Brief overview of features and projects making use of multi-stage traveling wave thermoacoustic engines

• Alternative concept for liquefaction of natural gas or bio-gas for transport and storage

• Combines a high performance pulse tube and a multi-stage traveling wave thermoacoustic engine

• Reduced engine input temperature down to 300C

• High temperature reduction (extracting more heat) of combustion gas prior to exhausting

• More than one order of cost reduction by using ordinary construction materials

• Brings back on stage, the concept of (combustion) heat driven liquefiers, not only for liquefaction of natural gas (LNG) but also for storage and transport of bio-gas or other gasses

Thermoacoustics is on its way to full scale techno-economic viable applications

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