Research progress on cryogenic
mixed-gases Joule-Thomson refrigeration
in TIPC of CAS
Maoqiong GONG
Technical Institute of Physics and Chemistry (TIPC)
Chinese Academy of Sciences (CAS)
Email: [email protected]
Tel/Fax: 86-10-82543728
Contents
1. Introduction
2. Thermophysical properties and components
selection of mixed-refrigerants
3. Thermodynamic features of the recuperative heat
exchangers
4. Thermodynamic optimization of various cycle
configurations
5. Composition shift
6. Performance and application of cryogenic MJTR
1. Introduction
230
80
Refrigeration requirements in different temperature ranges
biomaterials Medicine Energy
Aerospace
Domestic refrigerators Air conditioners Heat pumps etc.
The mixed-gases Joule-Thomson refrigerator (MJTR) can satisfy such requirements
The MJTR play the dominant role in this deep cooling temperatures ranging from 80 to 230 K
Near ambient temperature range
Deep cooling temperature range
370
Advantages of MJTR
Off-the-shelf components
High reliability.
Low cost.
Easy to be built in large scale.
The mixed-gases Joule–Thomson refrigerator
230
80
Near ambient temperature range
Deep cooling temperature range
370
Technical challenges & Scientific problems
Mixture Components selection and optimal composition.
Cycle configurations with high efficiency and reliability.
Mixtures properties in large temperature span.
Working mechanism of low-temperature mixed-gases Joule-Thomson refrigeration.
Accurate component design and manufacture
The mixed-gases Joule–Thomson refrigeration
230
80
Near ambient temperature range
Deep cooling temperature range
370
2. Thermophysical properties and components selection of
mixed-refrigerants
2.1 Phase equilibria
Fluid equilibrium is the fundamental for other thermal physical properties.
Basic parameters for other properties prediction
Determining the lowest evaporation temperature of the MJTR ……
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0140
150
160
170
180
190
T/K
x1, y
1
liquid-correlated
vapor-correlated
liquid-predicted
vapor-predicted
0.1 MPaInfluence of the presence of experimental data on the prediction results R14+R170 system
Experiments is most important and final method for phase equilibria study
Several facilities were built to study the mixtures VL(L)E behaviors used MJTRs
cryogenic apparatus T: 80~300 K
p: 0.1~10 MPa
Temperature uncertainty : ±10mK
Pressure uncertainty: ±2kPa
Composition uncertainty : ±0.003
2.1 Phase equilibria First apparatus for low-temperature
CH4+CF4 system C2H6+CF4 system
0.0 0.2 0.4 0.6 0.8 1.0
0.0
0.2
0.4
0.6
0.8
1.0 0.0
0.2
0.4
0.6
0.8
1.0
CH4
CF4
C2H
6
L+V
0.1 MPa
VLE of ternary system
(CH4+CF4+C2H6 system) 2.1 Phase equilibria
0.0 0.2 0.4 0.6 0.8 1.00.0
0.2
0.4
0.6
0.8
1.00.0
0.2
0.4
0.6
0.8
1.0
L+V
Bubble point
Dew point
R170 R23
R116
0.0 0.2 0.4 0.6 0.8 1.00.0
0.2
0.4
0.6
0.8
1.00.0
0.2
0.4
0.6
0.8
1.0
L+V
Bubble point
Dew point
R170 R23
R116
L+V
R170+R23 system（212.84 K） R170+R116 system（252.80 K）
(R170+R23+R116 system)
R170+R23+R116 Ternary system
2.1 Phase equilibria
The second VLLE apparatus T: 200~310 K
p: 0.1~5 MPa
Temperature uncertainty : ±4mK
Pressure uncertainty : ±0.2~0.5kPa
Composition uncertainty : ±0.002
2.1 Phase equilibria Second apparatus for VLLE
Journal Cover Journal of Chemical & Engineering Data,
2012, 57:541-544
Experimental data of the vapour-liquid-liquid
equilibria of {R134+R600a} system
(VLLE)
Clear single
liquid phase
Clear two
liquid phases
Vapor-liquid-liquid equilibria of R134+R600a system
Phase
separation
Critical
opalescence
0.20.3
0.40.5
0.60.7
0.80.9
0.070
0.075
0.080
0.085
0.090
235236
237238
239240
241242
p/M
Pa
T/Kx1
2.1 Phase equilibria
Institutes Experiment
method
Temperture
uncertainty
/mK
Pressure
uncertainty
/kPa
Mole
Composition
uncertainty
Seoul National University Vapor cycle 20 1 0.003
Ecole Nationale Supérieure des
Mines de Paris CENERG/TEP, France
Static method 10 0.3 0.02
Korea Institute of Science and
Technology (KIST), South Korea
Vapor and liquid
double cycle
10 1 0.002
Institute of Building Technologies, Italy Vapor cycle 20 1 0.003
Ajou University, Korea Vapor cycle 20 2 0.003
Instituto Politecnico Nacional, Mexico Static method 30 0.04% 0.01
National Metrology Institute of Japan,
National Institute of Advanced
Industrial Science and Technology,
Japan
Vapor and liquid
double cycle
3 0.62 0.001
TIPC,CAS
Three facilities，
temperature: 80~400 K
pressure: 0.1-10 MPa
Vapor cycle
quasi-static
Vapor cycle
4
4
10
0.3
0.26
2
0.003
0.002
0.002
Comparison of vapor liquid equilibria experimental facilities
Negative azeotropic
1 1 1 2
V L
1 1
( ) (d d )d0
d ( ) d
y xp
x v v x
2
2
1
d0
d
p
x
2
2
1
d0
d
p
x
Azeotropy prediction model of the
equilibria pressure extremum.
Positive azeotropic
(Theoretical prediction model)
Combined with experimental data, mixing principles for PR
thermodynamic model equations was improved, binary
interaction coefficients were also obtained.
Predictions of the binary azeotropic characteristics of several
systems were conducted.
0.0 0.2 0.4 0.6 0.8 1.0
0.2
0.3
0.4
0.5
0.6
p/M
Pa
x1,y
1
2.1 Phase equilibria
Summary on vapor-liquid equilibria work
Some VLE data of mixtures was were first measured:
HCs + R14/R23/R116 and other systems;
Some of the theoretical predictions and correlation models were
established and improved;
There are still many problems:
1) Gas-liquid, liquid-solid equilibria of oil with refrigerants
2) Vapor-liquid-liquid equilibria;
3) High-precision theoretical prediction model.
2.2 Throttling effect
0 10 20 30 40 50 600
100
200
300
400
500
600
700
T /
K
p /MPa
K
L
N
JT
>0
JT
<0
PN
Basic conceptions of throttling effects
Throttling device
High pressure, high
temperature gas Low pressure, low
temperature gas
Ts Tr
Some conceptions
50 100 150 200 250 300 350
Temperature (K)
-5
0
5
10
15
20
25
Isoth
erm
al th
rottle
effect (k
J/m
ol)
N2
CH4
C2H6
C3H8
iC4H10iC5H12
1 2 3 4 5
Pl=0.1MPa
1. PH=1.0MPa, 2. PH=2.0MPa, 3. PH=3.0MPa, 4. PH=4.0MPa, 5. PH=5.0MPa
The higher pressure
before throttling, the
wider temperature
range would be
covered with effective
throttling effect.
2.2 Throttling effect
Influence of pressures and temperatures on pure substance throttling effects
Isothermal J-T effect
50
100
150
200
250
T(K)
0
0.5
1
1.5
2
P(MPa)
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
50
100
150
200
250
T(K)
0
0.5
1
1.5
2
P(MPa)
0
10
20
30
40
50
60
70
0
10
20
30
40
50
60
70
50 100 150 200 250 300
T(K)
-10
0
10
20
30
40
50
60
70
80
inte
gra
ted
JT
eff
ec
t (K
)
mix.1
mix.2
mix.3
50 100 150 200 250 300
T(K)
-2,000
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
iso
the
rma
l J
T e
ffe
ct(
J/m
ol)
mix.1
mix.2
mix.3
A method for optimizing mixture composition
Throttling effect of mixed refrigerants under
various pressures and temperatures
2.2 Throttling effect
The minimum isothermal throttling effect of the
optimized mixture in the whole temperature range is
larger than that of any pure component, which is the
reason that mixed refrigerants could increase the
thermal efficiency of the MJTR cycle.
2.2 Throttling effect
90 120 150 180 210 240 270 3000
5
10
15
20
25 iC5H
12
iC4H
10
C3H
8
C2H
6
CF4
CH4
N2
pH=2.0 MPa
pL=0.1 MPa
h
T (
kJ/m
ol)
T (K)
mixture
A)
90 120 150 180 210 240 270 300 330 3600
10
20
30
40
50
60
70
80
90
100
N2
CH4
CF4
C2H
6
C3H
8
iC4H
10
iC5H
12
pH=2.0 MPa
pL=0.1 MPa
T
h （
K）
T (K)
mixture
B)
2.3 Components selection
Selecting component to make their effective throttle effect
temperature range cover each other (relaying) in
temperatures ranging from ambient to the target.
Physical and chemical stability, impact on the environment
(ODP, GWP), as well as economic factor, etc.
No. Components Boiling points（K） Temperature zone
1 He, Ne 4.2, 27.0 Low temperature zone
2 N2, Ar 77.4, 87.3 Normal temperature zone
3 CH4 111.7 Low-medium temperature zone
4 CF4 145.2 Low-medium temperature zone
5 C2H4, C2H6 169.4, 184.6 Medium temperature zone
6 C3H8, C3H6, iC4H10 231.04, 225.53, 261.4 Medium-high temperature zone
7 iC5H12 300.98 High temperature zone
Components selection for liquid nitrogen temperature refrigeration
3. Behaviors of the recuperative heat exchangers and two-phase
heat transfer study
Vapor Compression
Recuperator
Evaporator
After
cooler
Recuperative heat exchanger is a critical component of mixed-refrigerant J-T refrigerator.
Recuperative heat exchanger is the biggest difference between mixed-gases J-T refrigeration cycle and the vapor compression cycle in terms of hardware.
3.1 Experimental research on the operation features of tube-in-tube recuperative heat exchanger
3.1 Experimental research on the operation features of tube-in-tube recuperative heat exchanger
0 1 2 3 4 5150
175
200
225
250
275
300
A)
B)
TL
_A
TH
_A
TL
_B
TH
_B
T (
K)
lx (m)
1 2 3 4 5 6 7 8 9 100
300
600
900
1200
n
HT
C (
W/m
2K
) /
HE
AT
(W
)
HTC
HEAT
0
2
4
6
8
10
12
14
A)
AL
MT
D (
K)
ALMTD
1 2 3 4 5 6 7 8 9 100
300
600
900
1200
1500
B)
n
HT
C (
W/m
2K
) / H
EA
T(W
) HTC
HEAT
0
5
10
15
20
ALM
TD
(K
)
ALMTD
Built a special HX with 10
sections to measure:
temperature and
pressure distribution
Overall heat transfer
coefficients
The locations of pinch points. The distribution of heat load versus the temperature.
0 1 2 3 4 550
100
150
200
250
300
A3
pH
pL
T (
K)
lx (m)
0 1 2 3 4 5100
150
200
250
300
A4
pH
pL
T (
K)
lx (m)
1 2 3 4 5 6 7 8 9 100
60
120
180
240
300
A3
n
HT
C (
W/m
2K
) /
Q (
W) HTC
Q
0.0
3.2
6.4
9.6
12.8
16.0
AL
MT
D (
K)
ALMTD
1 2 3 4 5 6 7 8 9 100
140
280
420
560
700
A4
nH
TC
(W
/m2K
) /
Q (
W)
HTC
Q0
3
6
9
12
15
18
AL
MT
D (
K)
ALMTD
The mixture composition determines:
3.1 Experimental research on the operation features of tube-in-tube recuperative heat exchanger
Complicated heat and mass transfer process in the recuperator.
Flow-boiling
Flow-condensation
3.2 Researches on two-phase heat transfer of mixed-refrigerants
0 2 4 6 8 100
2
4
6
8
10
Palen&Small [22]
Jungnickel et. al [23]
Thomes&Shakir [24]
Fujita&Tsutsui [25]
Inoue et. al [26]
Calc
ula
ted r
esults (
kW
m-2
K-1)
Measured data(kW m-2K-1)
-25%
+25%
3.2 Researches on two-phase heat transfer Pool-boiling
Refrigerant tank
Keithley
2700
GC
1
2
5
4
3
Vacuum
pump
Cold lightHigh speed
camera
DC regulator
Compressor
DC regulator
scale
Computer
Pool-boiling experiments.
Covering 80~300 K.
Components of natural gas,
pure substances and mixtures.
Cooling
loop
Δp
DC Regulator 1
ΔppT
T
DC Regulator 2
Preheater
Vacume pump
T T T
pCharging port
Heat
exchanger
Liquid
reservoir
Throttling
valve
C
Maganetic
gear pump
Sight glass
Heat transfer test section
Adiabatic pressure drop test section
Vacume chamber
Sight glass
SENSORS
C:coriolis mass flow meter
T: resistances thermometer
p: absolute pressure sensor
Δp: differential pressure sensor
Throttling
valve
Researches on two-phase flow boiling heat transfer and flow characteristics.
Covering 100~300 K.
Components of natural gas,
pure substances and mixtures.
3.2 Researches on two-phase heat transfer Flow-boiling
0.875 0.714 0.230Re ( ) 0.92 0.45Ltp
kh BoK Co
D
New correlation of flow boiling
heat transfer coefficients:
0 3 6 9 120
3
6
9
12
R290
R152a
R170
Pre
dic
ted h (
kW
.m-2
.K-1)
Experimental h (kW.m-2.K
-1)
+20%
-20%
In the literature (Cryogenics
57,2013,18-25) on LNG heat
transfer, our correlation was proven
the best one with the smallest
deviation.
…the best correlation…
3.2 Researches on two-phase heat transfer Flow-boiling
Δp
ΔppT
T T T T
p
C
T T
p
TT
Vacume pump
Vacume chamber
Cooling
loop 2
Cooling
loop 1Heat
exchanger
Magnetic-
driven pump
Throttling
valve
Reservoir
DC Regulator
Preheater Sight glass Sight glass
Heat transfer test section
Adiabatic pressure drop section
SENSORS
C:Coriolis mass flow meter T: resistances thermometer
p: absolute pressure sensor Δp: differential pressure sensor
3.2 Researches on two-phase heat transfer Flow-condensation
Flow condensation heat transfer and flow characteristics.
Covering 100~300 K.
Components of natural gas,
pure substances and mixtures.
0.0 0.2 0.4 0.6 0.8 1.00
1000
2000
3000
4000
5000
6000
7000
8000
p=1.01 MPa G=202 kg (m2s)
-1 q
avg=64.4 kW m
-2
p=1.56 MPa G=201 kg (m2s)
-1 q
avg=76.4 kW m
-2
p=2.06 MPa G=201 kg (m2s)
-1 q
avg=81.9 kW m
-2
p=2.56 MPa G=201 kg (m2s)
-1 q
avg=85.1 kW m
-2
h (
W (
m2K
)-1)
x
0.0 0.2 0.4 0.6 0.8 1.050
100
150
200
250
300
350
Plug Transition
Slug Annular
G kg m
-2 s
-1
x
R170
4. Thermodynamic optimization of various cycle configurations
Optimization objective
function:
Maximize
thermodynamic
efficiency
Optimization parameters:
Mixture
components
Mixture
composition
High and low
pressures of cycle
The single-stage mixed-gases Joule-Thomson cycle
4.1 Thermodynamic optimization: single-stage cycle
0 5 10 15 20100
150
200
250
300
PL
PH
T (
K)
QHX
(kJ/mol)
4.1 Thermodynamic optimization: single-stage cycle
（1） Compression, throttling and evaporation processes Higher high-boiling component fraction leads to a smaller compressibility factor and a lower compressor inlet temperature, reducing the compression power consumption. Lower temperature before throttling results in smaller exergy loss
（2）Recuperative process
When the fraction of one component gets larger, the intrinsic temperature difference in the relevant temperature zone would increase, as well as the exergy loss.
0 5 10 15 20100
150
200
250
300
PL
PH
T (
K)
QHX
(kJ/mol)
0 5 10 15 20100
150
200
250
300
PL
PH
T (
K)
QHX
(kJ/mol)
More high-boiling components Optimized Composition More low-boiling and middle-
boiling components
0 3 6 9 12 15 18100
150
200
250
300
PL
PH
T (
K)
QHX
(kJ/mol)
Optimization results: The single-stage mixed-gases J-T cycle could achieve a theoretical cycle efficiency of 63% (relative Carnot efficient).
4.1 Thermodynamic optimization: single-stage cycle
0 5 10 15 20100
150
200
250
300
PL
PH
T (
K)
QHX
(kJ/mol)
iC4 iC5
Various configurations of mixed refrigerant J-T cycle
4.2 The influence of cycle configuration
DEACDEHX2DEJT1DBLEND
DEHX3DEJT2DEEVCEF
One phase separator Relative Carnot efficiency of 62.5%
DEAC
DEJT1
DEJT2
DEHX1
DEHX2
DEHX3
DBLEND1
DBLEND
DEJT3
DEEV
CEF
Two phase separators Relative Carnot efficiency of 61.5%
4.2 The influence of cycle configuration
DEAC
DEHX
DEJT
DEEV
CEF
63%
10%
9.5%
8.5%
9%
No phase separator Relative Carnot efficiency of 63%
Conclusions of thermodynamic analysis
Different cycle configurations could reach close performances under each optimal conditions, while the single-stage cycle with the most simple structure could achieve the best performance in the thermodynamic point of view .
Cycle configuration is the external factor while mixture is internal factor. Effective refrigeration could be achieved by matching the external and internal factors.
5. Composition shift
5.1 Composition shift characteristics of mixed refrigerants
0 10 20 30 40 50 60 70 80 90 100-100
-50
0
50
100
150
200
250
R
N2
CH4
C2H
6
C3H
8
iC4H
10
iC5H
12
T=300 K
p=101.3 kPa
Roil
, %
Rj,
%
0
25
50
75
100
R,
%
Composition shift characteristics of mixtures.
Circulation concentration changes from the original charged data in MJTRs
Two factors: liquid holdup and solution with oil
5.2 Composition shift caused by liquid holdup
1 2 3 4 5 6 7 8-100
-50
0
50
100
150
200
250
300
N2
CH4
C2H6
C3H8
iC4H10
Sampling Point
R /
%
120
150
180
210
240
270
300
T /
K
140 160 180 200 220-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
R /
%T /K
N2
CH4
C2H6
C3H8
iC4H10
Oil-free compressor liquid holdup
5.3 Composition shift caused by solubility in lubricants
21
11
nn
nx
PTv
v
PTv
VV
PTv
V
PTv
V
PTv
V
n
v
gasabs
v
cellcell
pump
v
pump
endend
v
begbeg
v
,1
,,,,
1
,
1
,2
11
bottle
1
bottle
1
Solubility:
Gas-liquid phase equilibria
Composition shift caused by the solubility in lubricants.
5.4 Composition shift characteristics
Problems caused by composition shift
Decreasing the concentration of high-boiling components
Reduce cycle performance.
Measures to reduce or eliminate the influences 1) The deep oil separation in compressor unit 2) Increasing volume ratio for warm to cold sections 3) Increasing charging quantity
6. Performance and application of cryogenic MJTR
6.1 Series cryo-freezers
Ambient
temperature
-40℃
-80℃
-150℃
-196℃ (LN2)
-120℃
Cryo-freezers for biomaterial long-term preservation Six temperature zone series:
-86℃ -105 ℃ -132 ℃ -154 ℃ -164 ℃ -186℃
Industrial production for almost 15 years!
6.1 Series cryo-freezers
Institutes Japan
SANYO
US FORMA、
REVCO This Project
Refrigeration cycle
two-stage cascade
two-stage cascade
Mixed-gases recuperative
cycle
Compressor lower back pressure
compressor
lower back pressure
compressor
Single-stage oil-lubricated
hermetic compressor
Refrigerant R407/
R508B+R290 R404a /
R508B+R290
Multivariate mixed
refrigerant Chamber volume/L
320 328 328
Compressor displacement/cc
47.1 (20.7+26.4)
51.2 (25.6+25.6)
34.8
Rated input power/kW
1.36 1.47 1.15
-80℃ energy consumption /kWh/Day/L
0.084 0.086 0.054
Ultimate temperature/℃
-85 -86 -92
Cooling time/hr > 5 > 5 ＜3.5
Performance comparison -86℃ cryogenic preservation chambers
Reducing energy consumption by ~36%.
Reducing cooling time by ~30%
Ultimate temperature lower more than 6K
25% smaller compressor displacement 16% smaller installed power (lower cost)
6.1 Series cryo-freezers
Requirements Recovery of remote and scatted natural gas resources, not suitable for pipeline and fixed LNG plant
Measures: 1) Efficient and compact cold box structure. 2) Compact air-cooled compressor unit. 3) Manufacture mini-liquefiers with high flexibility.
Results and effects: 5000 ~100,000Nm3/d moveable trailer-mounted liquefiers were developed.
The factory-assembled production mode of the liquefiers greatly reduced the construction period
6.2 Trailer-mounted natural gas / coalbed gas liquefier
No. Institutions Liquefaction technology
Capacity/Feed gas pressure
Efficiency
1
Gas Technology Institute (GTI), US
Mixed-refrigerant liquefaction process, skid-mounted, water-cooled
2000 Nm3/d 0.1~0.7MPa
25% consumed, 75% liquefied
2 Harbin Cryo, Jilin Songyuan
Mixed-refrigerant liquefaction process (centralized), water-cooled
70000 Nm3/d ≥0.3MPa
14.3% consumed, 85.7% liquefied, Calculated by the shaft power of all devices
3 Hamworthy, UK
Nitrogen expander process (peak load regulating)
100000 Nm3/d N/A
16% consumed, 84% liquefied
4 SINTEF, Norway
Mixed-refrigerant liquefaction process, seawater-cooled
30000 Nm3/d 1.82 MPa
16.7% consumed, 83.3% liquefied Estimated on literatures
5 TIPC, CAS
Mixed-refrigerant liquefaction process, trailer-mounted, full air-cooled
10000 Nm3/d 0.7~1.3MPa
15.3% consumed, 84.7% liquefied, Measured power consumption of all devices
The comparison of liquefaction performance with other devices
6.3 Trailer-mounted natural gas / coalbed gas liquefier
Summary of the researches on cryogenic mixed-gases Joule-Thomson refrigeration in TIPC
Root
Thermophysical properties
Heat transfer Two-phase flow
Trunk
Cycle configuration
Mixture Composition
Control and integrate technology
Tree crown and fruit
Natural gas liquefiers
Cryo-freezers High and low temperature experiment chamber
Technical Institute of Physics and Chemistry
Chinese Academy of Sciences
Email: [email protected]
Maoqiong Gong, Prof. Dr.
Thank you
