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Thermoacoustic heat driven cooling
Kees de Blok
Aster Thermoacoustics, Smeestraat 11, 8194LG Veessen, The Netherlands
Douglas Wilcox
Chart-Qdrive, 302 10th Street, Troy, NY 12180, USA
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
19 april 2023 1
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
19 april 2023 2
Image: www.qdrive.com
Image: www.aster-thermoacoustics.com
Image: www.lanl.gov
19 april 2023 3
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) .
19 april 2023 4
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
19 april 2023 5
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
19 april 2023 6
SOTAC demonstration setup (2012)
Thermoacoustic liquefaction of natural gas
19 april 2023
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
7
Image: www.lanl.gov
Thermoacoustic liquefaction of natural gas
19 april 2023
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
8
+
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
19 april 2023 9
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
19 april 2023 10
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
19 april 2023 11