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다중 마이크로 채널 PCHE의 열전달 성능 다중 마이크로 채널 PCHE의 열전달 성능 (Thermal performance of multi micro channel PCHE) 정상권 김진혁 백승환 정상권 , 김진혁, 백승환 Cryogenic engineering laboratory, KAIST
다중 마이크로 채널 PCHE의 열전달 성능다중 마이크로 채널 PCHE의 열전달 성능
(Thermal performance of multi micro channel PCHE)
정상권 김진혁 백승환정상권, 김진혁, 백승환
Cryogenic engineering laboratory, KAIST
Contents
I t d tiIntroduction
Proposed PCHE
Experimental apparatus
Experimental results
M lti h l PCHEMulti channel PCHE
Design modification
Conclusion
Page 2
Introduction
PCHE : Printed Circuit Heat ExchangerChemical etching& Diffusion bonding(typically)
Type Channel Size Area Density
Shell & Tube 10-50 mm 100 m2/m3
Plate 5 mm 200 m2/m3
Plate fin 2 mm 1000 m2/m3Plate-fin 2 mm 1000 m2/m3
PCHE 1 mm 2000 m2/m3
Page 3
PCHE fabrication
Easy fabrication process of PCHEEasy fabrication process of PCHE
Page 4
Potential applications of PCHE
• Offshore LNG industryOffshore LNG industry
(LNG-FPSO)
C i li f ti l t• Cryogenic liquefaction plant
• Cryogenic refrigerator
• Space equipments
• Nuclear reactorCourtesy of Linde
Courtesy of Linde
• Chemical reactorsCourtesy of Linde
Page 5
Conventional PCHE
Page 6
Newly proposed PCHE interlayer mixing possible !
Bypass hole215
(b) Stacked plates
21516
00 5060
(a) Drawing (c) Flow channel configuration
Inclination angle
Page 7
(a) Drawing (c) Flow channel configuration
Proposed PCHE : Dimensional parameters
DepthDepth
Etching depth
Etching width
Etching angle
Number of plates
Width
depth width angle plates
PCHE 1 26 μm 55 μm 45o 250
PCHE 2 26 μm 55 μm 45o 500μ μ
PCHE 3 200 μm 400 μm 30o 10
PCHE 4 200 μm 400 μm 45o 10
PCHE 5 200 μm 400 μm 60o 10
Page 8
Proposed PCHE : Plates
Page 9
Proposed PCHE : Transverse Bypass (CR)
Transverse bypass installation inside heat exchanger to alleviate flow mal distribution problemflow mal-distribution problemCross type (CR) transverse bypass– Fluid must go upper channel or lower channel at transverse bypass– Fluid must go upper channel or lower channel at transverse bypass.– Fluid ‘cannot’ go straight.
TransverseBypass
TransverseBypass
TOP
Bypass Bypass
Hot fluid in
BOTTOM
Cold fluid in
Page 10
BOTTOM
Vertical cross-section of stacked plates of the PCHE
Proposed PCHE : Transverse Bypass (UC)
Uncross type (UC) transverse bypassUncross type (UC) transverse bypass– Fluid can go two upper layers or two lower layers at transverse bypass.– Most fluid can go straight.
TOP
TransverseBypass
TransverseBypass
TOP
Hot fluid in
Cold fluid in
BOTTOM
Page 11Vertical cross-section of stacked plates of the PCHE
Experimental Apparatus
(a) For 80~300 K (b) For 30~80 K
Page 12
(a) For 80 300 K (b) For 30 80 K
Experimental results : Pressure drop (1)
PCHE 1&2 (Dh=40x10-6m)
6
7 PCHE 1(250 layer)PCHE 2(500 layer)
40 PCHE 1(250 layer)PCHE 2(500 layer)
4
5
6 ( y )
(bar
)
810
20PCHE 2(500 layer)
or
2
3
4
ress
ure
loss
4
68
Fric
tion
fact
o0
1
2Pr
1
2
0.0 0.5 1.0 1.5 2.0 2.5 3.00
Mass flow rate (kg/s)1 2 4 6 8 10 20 40 60 80100
1
Re
Page 13
Experimental results : Pressure drop (2)
PCHE 3-5 (Dh=250x10-6m)
6
7 PCHE 3(30o)PCHE 4(45o) 4
6
4
5
6 PCHE 4(45 ) PCHE 5(60o)
(bar
)
1
2
tor
2
3
4
ress
ure
loss
0.4
0.60.8
1
Fric
tion
fact
0
1
2Pr
0 1
0.2 PCHE 3(30o) PCHE 4(45o) PCHE 5(60o)
0.0 0.5 1.0 1.5 2.0 2.5 3.00
Mass flow rate (g/s)60 80 100 200 400 600 800
0.1
Re
Page 14
CFD Simulation : Modeling
Simulation result comparison with experimental data
b ANSYS CFD V 12 (F UENT)
Page 15
by ANSYS CFD V.12 (FLUENT)
CFD Simulation : Results
PCHE 1&2 (D =40x10-6m) PCHE 3 5 (D =250x10-6m)40
Exp.(PCHE 1)Exp.(PCHE 2)
2
PCHE 1&2 (Dh=40x10 6m) PCHE 3-5 (Dh=250x10 6m)
810
20p ( )
Cal.
or 0.6
0.8
1
or
4
68
Fric
tion
fact
o
0.4
Fric
tion
fact
o
Exp. (PCHE 3,30o)
20.2
p ( ) Exp. (PCHE 4,45o) Exp. (PCHE 5,60o) CFD (PCHE 3,30o) CFD (PCHE 4,45o
CFD (PCHE 5,60o)
1 2 4 6 8 10 20 40 60 801001
Re200 300 400 500 600 700 800 900 1000
0.1
Re
CFD (PCHE 5,60 )
Page 16
CFD Simulation : Case study
Various diameters Various inclination angle
4060
20
40
Various diameters Various inclination angle
468
10
20
ctor 4
68
10
20
ctor
0.60.8
1
2
4
Fric
tion
fac
Dh=20X10-6m
Dh=40X10-6m
D 80X10-60.60.8
1
2
Fric
tion
fac
β=15o
β=30o
1 2 4 6 8 10 20 40 60 80100 2000.1
0.2
0.4Dh=80X10 6m
Dh=120X10-6m
Dh=160X10-6m
1 2 4 6 8 10 20 40 60 80100 2000.1
0.2
0.4β
β=45o
β=60o
β=75o
1 2 4 6 8 10 20 40 60 80100 200
Reynolds number
1 2 4 6 8 10 20 40 60 80100 200
Reynolds number954.0964.0663.0 Re)()(129 −−=
hr
h
rcor D
Dfββ
Page 17
hrrβ)150Re,1040,101601020,45,7515( 555 ≤×=×≤≤×=≤≤ −−− mDmDm hrh
orββ
Thermal performance model
Simple counter flow heat exchanger
( )[ ] ⎫⎧ ++=−
λNTU1λNTU/λ11ε1
1/2
Th,in
T t ( )[ ]⎭⎬⎫
⎩⎨⎧
+++
+λNTU1
λNTU1λNTU/λ1NTU1
/ LkA U A
Tc,out
empe
ratu
re
( )minp
cond /λcm
LkA&
= 0NTU U AC
=
1 1 1R
Th,out
Te
,0 ,0
1 1 1cond
h HT c HT
RUA h A h A
= + +
Nu 1T T
HEX direction
Tc,in
HeNu
H
hA kD
= 1
SUS
Rk S
=, ,
, ,
c out c in
h in c in
T TT T
ε−
=−
Page 18
Axial conduction in PCHE
HOT Ch l flHeat Exchanger body
HOT Channel flow
Heat transfer through BODY(Axial Conduction)
Hot environment
ColdEnvironment
Heat transfer between Fluid
(NTU)
COLD Ch l FlCOLD Channel Flow
Page 19
Experimental results : Ineffectiveness (1)
at 80~300 K
0.100.10
PCHE 1 (250 layers) PCHE 2 (500 layers)
0.08
s
1-ε : 500 layered exp. 1-ε : 500 layered est. 1/(1+NTU) : 500 layered est. λ : 500 layered est.
0.08
ss
1-ε : 250 layered exp. 1-ε : 250 layered est. 1/(1+NTU) : 250 layered est. λ : 250 layered est.
0.04
0.06
effe
ctiv
enes
s
0.04
0.06
effe
ctiv
enes
0.02
Ine
0.02
In
0.0 0.5 1.0 1.5 2.0 2.5 3.00.00
Helium Mass flow rate (g/s)0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.00
Helium Mass flow rate (g/s)
Page 20
Experimental results : Ineffectiveness (2)
at 30~80 K
PCHE 1 (250 layers) PCHE 2 (500 layers)
0.10 0.10
0.08
ss
1-ε : 250 layered exp. 1-ε : 250 layered est. 1/(1+NTU) : 250 layered est. λ : 250 layered est.
0.08
ss
1-ε : 500 layered exp. 1-ε : 500 layered est. 1/(1+NTU) : 500 layered est. λ : 500 layered est.
0.04
0.06
neffe
ctiv
enes
0.04
0.06
neffe
ctiv
enes
0.02
In
0.02
In
0.0 0.5 1.0 1.5 2.0 2.5 3.00.00
Helium Mass flow rate (g/s)0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.00
Helium Mass flow rate (g/s)
Page 21
Multi channel PCHE : Proposed design
3stream with 2 types of plates
Page 22
Multi channel PCHE : Photo of fabricated PCHE
Etched plates PCHE
Page 23
Multi channel PCHE : Thermal performance
0.20
0.16
0.18Exp.
Cal. λ1/(1+NTU)
0.12
0.14( )
ss (1
-ε)
0 06
0.08
0.10
effe
ctiv
enes
0 02
0.04
0.06
Ine
0.0 0.5 1.0 1.5 2.0 2.50.00
0.02
Mass flow rate (g/s)
Page 24
Mass flow rate (g/s)
Design modification : Concept
5 mm -> 3 mm
To reduce axial conduction area
5 mm -> 3 mm
Page 25
Wire-cutting
Design modification : Concept
Axial conduction area can be remarkably reduced
Page 26
Design modification : Weak points
weak points
Unnecessary zone
Page 27
27
Design modification : Half etching
Half etching for week pointHalf etching for week pointflow area
half etching
Increase in pressure drop -> negligible !
Page 28
Design modification : Thermal performance
Axial conduction can be ignored!
0 09
0.10calculation
Axial conduction can be ignored!
0.07
0.08
0.09 1/(1+ntu) λ
0.05
0.06
ctiv
enes
s
0.02
0.03
0.04
Inef
fec
0 0 0 5 1 0 1 5 2 0 2 5 3 00.00
0.01
0.02
Page 29
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Mass flow rate (g/s)
Conclusion
Newly type (flow configuration) PCHEs are proposed.
Pressure drop characteristics are validated with CFD simulationPressure drop characteristics are validated with CFD simulation.
Heat transfer characteristics are highly affected by axial conduction at low Re.
PCHE design was modified for reducing axial conduction using wire-cutting.
Page 30
