Technical Institude of Physics and
Chemistry, CAS
25th International Cryogenic Engineering Conference
and the International Cryogenic Materials Conference
in 2014, ICEC 25–ICMC 2014
Experimental Study of an Acoustically Resonant
Cooling System
Tong Huan, Hu Jianying, Zhang Limin, Luo Ercang
Presented by: Hu Jianying
2014-7
Contents
1 Introduction
2 Experimental
System
3 Experimental
Results
4 Conclusion
1 Introduction
Reliability, no moving component,
high efficiency
a) In 1979 Ceperley first proposed the
concept of travelling wave TE.
b) In 1998, Yazaki et al setup a looped travelling
wave TE
a.
b.
c) Backhaus and Swift came up with a kind of
thermoacoustic stirling engine
c.
d) In 2010, Kees de Blok brought a
4-stage travelling TE
e) In 2012, Luo Ercang put forward a
double-acting thermoacoustic system.
d.
e.
1 Introduction
A travelling wave acoustically resonant system
Advantages：
1、Utilizing a TE to drive a PTC will
achieve the object of completely no
moving parts;
2、Using external heat source such as
the waste heat, solar energy;
3、When enlarging the diameter and
cascading more units, the system can
have larger cooling capacity.
The structure contains three units
forming a loop.
A TE, a resonant tube and a PTC
constitute a single unit.
2 Experimental system
Components
Thermoacoustic engine
Ф50mm×L75mm，300 mesh
stainless screen
Thermal buffer tube Ф50mm×L75mm
Ф13mm×L3m
Resonant tube
Regenerator
Pulse tube cryocooler
Ф50mm×L65mm，300 mesh
stainless screen
Ф32mm×L105mm
--
Inertance tube
--
Ф3.5mm×L2.3m
Air reservoir
--
1L
2 Experimental system
1、 Water of 293 K is used to circulate in the
primary and secondary water coolers；
2、The temperature of the cold head is
measured by a calibrated platinum resistance
thermometer; The heating temperature is
measured by a calibrated thermocouple
thermometer；
3、Constantan wire heated by direct current
is twined around the cold head to simulate
thermal load；
4、The PCB pressure sensors are equipped at
the entrance of each PTC; one of the TEs is
fitted with a Kunlun pressure sensor.
Component Tests before experiment
1200
1100
1# Engine
2# Engine
3# Engine
1000
900
800
700
600
500
10
20
30
40
Resistance/ 
50
Cooling capacity/W
Net acoustic power output/W
2 Experimental system
100
90
80
70
60
50
40
30
20
10
1# Cryocooler
2# Cryocooler
3# Cryocooler
1.15
1.2
1.25
Pressure ratio
1.3
The inconformity of the three engines and PTCs is small, less than 10%.
3 Experimental results
The influence of DC flow
Pressure ratio
The DC flow is unavoidable when there is a closed loop, and it will seriously influence the
performance.
1.28
1.26
1.24
1.22
1.20
1.18
1.16
1.14
1.12
1.10
550
With a membrane
Without a membrane
With a membrane
Without a membrane
500
450
400
T
em
peratureofheatingblock/℃
350
300
250
200
1000
1500 2000 2500
Heating power/W
3000
1000
1500 2000 2500
Heating power/W
The performance increases when a membrane is added.
3000
3 Experimental results
Driving a single PTC, 3MPa
Onset temperature: 105℃, Working frequency: 64.4Hz.
3
600
T
em
perature/℃
500
400
300
300
1# engine
2# engine
3# engine
cryocooler
200
200
100
100
0
0
20
40
60
time/min
80
0
100
Pressure amplitude/Bar
700
1#
2#
3#
2
T
em
perature/℃
1
0
-1
-2
-3
0.00
0.01
0.02
0.03
time/s
The temperature of the TE loaded with a PTC increases much slower, and the
fluctuation range is the smallest, but the phase difference between each unit could
generally match 120°.
The PTC can achieve the lowest temperature of 64.3K and gain the cooling capacity of
3 Experimental results
Driving three PTCs, 3MPa
Onset temperature: 140℃, Working frequency: 60Hz.
700
600
T
em
perature/℃
1# Engine
2# Engine
3# Engine
1# Cryocooler
2# Cryocooler
3# Cryocooler
500
400
300
250
200
150
200
100
100
0
0
20
40
60
Time/min
80
50
100
2.0
Temperature/K
Pressure Amplitude/Bar
300
1#
2#
3#
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
0.00
0.01
Point
0.02
0.03
T

The temperatures, pressures show good consistency.
Q   1
The lowest temperatures the three PTCs : 81K、84K and 83K .    T 
 T 
Q 1  
The heating capacity: 1620W、1630W and 1650W.
 T 
The total cooling capacity: 82W @130K. The relative Carnot efficiency : 3.32%.
0
c
c
0
h
h
3 Experimental results
180
160
140
120
100
80
60
40
20
0
-20
60
Relative Carnot Efficiency
Cooling Capacity/W
Different charging pressure with constant
heating temperature of 650℃
2MPa
3MPa
3.5MPa
80
0.06
2MPa
3MPa
3.5MPa
0.04
0.02
em
perature/℃
ColingT
em
perature/℃ ColingT
100
120
140
160
180
0.00
60
80
100
120
140
160
180
The obtainable lowest temperature would decrease as charging pressure
increases and the total cooling capacity would also increase, but the efficiency
at 3MPa is not obvious higher than 3.5MPa.
3 Experimental results
4
5
0
℃
650℃
ColingT
em
perature/℃
4
5
0
℃
650℃
ColingT
em
perature/℃
160
140
120
100
80
60
40
20
0
-20
Relative Carnot Efficiency
Cooling Capacity/W
Different heating temperature and charging
pressure of 3MPa
80
100
120
140
160
180
0.06
0.04
0.02
0.00
80
100
120
140
160
180
The cooling capacity and efficiency increases with the heating and cooling temperature
Further increasing the average pressure to 3.5MPa and heating temperature to 650 ℃,
the lowest temperatures the three PTCs : 76K.
The total cooling capacity: 100W @130K. The relative Carnot efficiency : 3.5%.
4 Conclusion
1、The three units can present good consistency even when each
component is not very consistent. The loop structure can fix the
phase difference of the pressure fluctuations at 120°even when the
system drives only one PTC.
2、As the charging pressure and heating temperature increase, the
acoustic resonant heat-driven cooling system can obtain larger
2000 capacity and higher relative Carnot efficiency.
cooling
3、With charging pressure of 3.5MPa and heating temperature of
650℃, the PTCs can acquire the minimum temperature of 76K and
obtain 100W cooling capacity at 130K with relative Carnot efficiency
of 3.5%.