profwei dai

7/31/2019 Profwei Dai

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Electricity Generator and Other Research in Key

Laboratory of Cryogenics of CAS

Wei Dai

Technical Institute of Physics and Chemistry,

Chinese Academy of Sciences Beijing China


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Our groupThe group members:

Prof. Ercang Luo and Wei Dai

5 other staff members>10 graduate students

Research Activity:

Coolers based on thermoacoustic cycles, down to 20 K

Thermoacoustics engines and generators, from

100We-3kWe, target bigger


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Typical Research

300 Hz thermoacoustically-driven pulse tube cooler

Stirling-type pulse tube coolers

Thermoacoustic generators including free piston Stirling generators


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Tc


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High frequency thermoacoustically-driven

pulse tube coolers 300Hz

The standing-wave engine The pulse tube cooler


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500W heating power 1W@80K


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Traveling wave thermoacoustic engine driving

traveling wave thermoacoustic cooler

Heating


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Heatingpower 2.1kW, Cooling power 340W@-20 410W@0 , on-going research include high frequency

operation, impedance match, etc


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10&20W@80K, relative Carnot efficiency around

20%, >100 Watt under development

High efficiency Stirling-type pulse tube cooler


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Thermoacoustic generators

Free piston Stirling generators

Thermoacoustic Stirling heat engine-based generators

Double effect thermoacoustic generators


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1.Hot heat exchanger 2.Regenerator 3.Ambient heat exchanger

4.Linear motor 5. Mechanical spring 6. Backside volume

7.Expansion space 8.Displacer 9.Compression space 10.Power

piston


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100 We class 1kWe class, ~20%

thermal to electric efficienc


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Double effects thermoacoustic generators

Engine set with heat

exchangers, regenerator and

thermal buffer tube

Linear motorwith double effect

pistons


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Double effects thermoacoustic generators

Best results so far: nearly 2 kWe

with 18% thermal to electric

efficiency


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TASHE loop

Resonance tube

Linear

alternator

Thermoacoustic Stirling heat engine-based generators


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Numerical Model

18

2

dpR U

dx=

1 3

dUR p R U

dx

= +

1 2

xdTH c cdx

= +

( )

0e eU R jX I A

+ =

( )2

m mR jXU I p

A A

+

+ =

Engine Model Generator Model


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Comparison of the model with RC load to measure

output

Computational and experimental data of the TASHE

(4MPa helium,75Hz working frequency, 650 heating temperature )

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When it comes to a linear alternator, frequency

coupling between the system working frequency

(dominated by the engine) and the naturalfrequency of the linear alternator (dominated by its

spring stiffness, moving mass, piston area) is

crucial to the system performance.

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Changing the natural frequency of the linear alternator

makes big difference ( adjusting the moving mass)

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Computational results of power and pressure

ratio as a function of the natural frequency of

linear alternator (6cm piston diameter, 4.0

MPa helium, 650 oC heating temperature and

15 oC cooling water temperature).

The system stops working in this

natural frequency range.

6cm piston


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Changing Piston diameter makes big difference

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Changing the engine frequency makes big difference

(mixing Argon with Helium)

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Experimental setup

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TASHE loop

Linear alternator

Resonance tube


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Experimental results

Best results 1 kWe output with 19%

thermal to electric efficiency


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Solar-powered version, set up in Shen Zhen, China

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Thanks for your attention

profwei dai

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