Thermal-Hydraulic Performance of Printed Circuit …...Thermal-Hydraulic Performance of Printed...

ThermalThermal--Hydraulic Performance of Hydraulic Performance of

Printed Circuit Heat Exchanger Printed Circuit Heat Exchanger

in Supercritical COin Supercritical CO22 CycleCycle

K. Nikitin, Y. Kato, L. NgoK. Nikitin, Y. Kato, L. Ngo

Research Laboratory for Nuclear ReactorsResearch Laboratory for Nuclear ReactorsTokyo Institute of TechnologyTokyo Institute of Technology

2005/1/52005/1/5 Tokyo Institute of TechnologyTokyo Institute of Technology 22

Study IncentivesStudy Incentivesoo Supercritical COSupercritical CO22 cycle demonstrates some advantages cycle demonstrates some advantages

in comparison to He cyclein comparison to He cycle-- higher cycle efficiency (Y. Kato, 2003),higher cycle efficiency (Y. Kato, 2003),

-- better better turbomachineryturbomachinery (Y. Muto, 2003),(Y. Muto, 2003),-- power generation cost is expected to be smaller.power generation cost is expected to be smaller.

oo High efficiency recuperator is a crucial component of High efficiency recuperator is a crucial component of supercritical COsupercritical CO22 cycle. The targeted recuperator cycle. The targeted recuperator effectiveness is as high as 95%.effectiveness is as high as 95%.

oo PCHEPCHE is a promising heat exchanger because itis a promising heat exchanger because it-- is able to withstand the pressure up to 50 MPa and the temperatis able to withstand the pressure up to 50 MPa and the temperature up ure up to 700to 700ooC (reliability ),C (reliability ),-- has a high compactness and high efficiency (cost reduction).has a high compactness and high efficiency (cost reduction).

PCHE = PCHE = PPrinted rinted CCircuit ircuit HHeat eat EExchangerxchanger


What is the PCHE?What is the PCHE?

Fluid flow channels are Fluid flow channels are etched chemicallyetched chemically on metal on metal plates.plates.

-- Typical plate: thickness = 1.6mm, Typical plate: thickness = 1.6mm, width = 600mm, length = 1200mm,width = 600mm, length = 1200mm,

-- Channels have semiChannels have semi--circular profile withcircular profile with11--2 mm diameter.2 mm diameter.

Etched plates are stacked and Etched plates are stacked and diffusion bondeddiffusion bondedtogether to fabricate a blocktogether to fabricate a blockThe blocks are then welded together to form the The blocks are then welded together to form the complete heat exchanger corecomplete heat exchanger core


Construction of Construction of PCHEsPCHEs

Plate stacking Diffusion bondingthe bond strength is achieved by the bond strength is achieved by

pressure, temperature, time of contact, pressure, temperature, time of contact, and cleanliness of the surfacesand cleanliness of the surfaces


Advantages of PCHEAdvantages of PCHEPhotoPhoto--etching technologyetching technology::

Micro channels with smaller hydraulic diameter Micro channels with smaller hydraulic diameter DDhh::Pressure capability Pressure capability

in excess of 50 MPa.in excess of 50 MPa.

Compact size (Compact size (LL) or Higher efficiency (98%).) or Higher efficiency (98%).

No plateNo plate--fin brazing:fin brazing:Manufacturing cost reduction.Manufacturing cost reduction.

Diffusion bonding technologyDiffusion bonding technology::Maintain parent material strength:Maintain parent material strength:

Extreme temperature from cryogenic up to 700Extreme temperature from cryogenic up to 700ooC.C.

.2 t

PD h=σ

( ). wherePr4

3/2

LMTD

ioh

TTTNN

jDL

∆−

==


From HEATRIC homepage


Experimental FacilityExperimental FacilityOil Separator

Heater

Compressor

Cooler

PCHE (3kW)


Experimental LoopExperimental Loop

OilSeparator

CO2 tank

Compressor

Cooler 1

Cooler 2

PCHE

Heater 1 Heater 2

PressureReducer

FR

FR T,PT

T,P∆P

∆P

T

T :thermocouple, :pressure meter, :differential pressure meter, : flow rate meterP ∆P FR


PCHE Test SectionPCHE Test SectionDimension of 896 x 76 x 71 mm and a dry mass of 40 kgDimension of 896 x 76 x 71 mm and a dry mass of 40 kg

Channel geometry (mm) Channel geometry (mm) Area, (mArea, (m22))

Channels Channels number, number, nn

Diameter, Diameter, DD

Active Active length, length, LL

Hydraulic Hydraulic diameter, diameter, DDhh

Heat Heat transfer, transfer, AA

Free flow, Free flow, AAcc

Hot sideHot side 144144 1.69 1.69 10106262 1.1.0303 0.60.66464 0.0000.0001616

Cold Cold sideside

6666 1.69 1.69 11117070 1.1.0303 0.30.33636 0.00000.00007474


Experimental ConditionsExperimental Conditions

No.No. 11 22 33 44 55Cold Cold sideside

6.56.5 7.47.4 8.58.5 9.59.5 10.210.2

Hot sideHot side 2.22.2 2.52.5 2.82.8 3.03.0 3.33.3

Cold Cold sideside

9090--108108

Hot sideHot side 280280--300300

Flow rate, kg/hFlow rate, kg/h -- From From 40 to 8040 to 80 with 5 kg/h incrementwith 5 kg/h increment

Temperature, Temperature, ooCC

Pressure, MPaPressure, MPa


Overall Heat Transfer Coefficient, Overall Heat Transfer Coefficient, UU

LMTD method: where

[ ])/()(ln)()(

)(21

,,,,

,,,,

icohocih

icohocihGh

hc

TTTTTTTT

FA

QQU

−−

−−−

+= )( ,, icoccc hhWQ −=

)( ,, ihohhh hhWQ −=

120 160 200 240 280

1000

1100

1200

1300

1400

1500

3.32.2

6.510.2

H ot s ide

Cp, J

/(kg*

K)

C O 2 tem perature, oC

C o ld s ideP, M Pa:

A - Heat transfer area, 0.664 m2

FG - Geometric factor, 0.9624

h, c - hot, cold side

o, i - outlet, inlet


Heat Loss Estimation (1)Heat Loss Estimation (1)

1) From outer surface temperature of PCHE insulator[ ] ][120~110)()(

10,1,,

44, WTThTTAQ

isurrisiconvsurris

insiloss ≈−+−= ∑

=

εσ

2) From heat balance

ch QQQloss

−=

40 50 60 70 80 9090

100

110

120

130

140

150

Pressure range, [MPa] 6.5-2.2 7.4-2.5 8.5-2.8 9.5-3.0 10.2-3.3

Hea

t los

s, [W

]

Flow rate, [kg/h]

From outer surface temperature

From heat balance

Total value:


Heat Loss Estimation (2)Heat Loss Estimation (2)Effect on the outlet temperatures:3) From 2D FLUENT CFD calculations (with(2)/without(1) heat loss)

4) From the heat loss compensation experiments(1) (2)

PCHE

Insulator 0 ≈

= −−−

loss

ksurfheaternear

ksurfPCHE

QTT

Heaters

',

', 65.0)),(( : ;35.0)),(( :

,,

,

,,

,

loss

TT

Tcoldoutcoldloss

TT

Thotouthot QdTTTPCpWTQdTTTPCpWT

outcoldoutcold

outcold

outhotouthot

outhot

−=×∆−=×∆ ∫∫∆+∆+


Overall heat transfer coefficient, U Overall heat transfer coefficient, U

2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

300

350

400

450

500

550

600

650

U, [

W/m

2 K]

Reynolds number × 10-3

Pressure, [MPa] 6.5-2.2 7.4-2.5 8.5-2.8 9.5-3.0

10.2-3.3

33 106Re102 Re,)002.0105.0()8.66.18( ×<<××±+±=U


Pressure factor, Pressure factor, ffPP

2 4 6 8 10 120.02

0.03

0.04

0.05

0.06

0.07

cold side


Pres

sure

fact

or, f

P


hot side

3386, 106Re102 ,Re)1061001.1()002.0032.0( ×≤≤×××±×−±= −−hotPf

3386, 1012Re106 Re,)1071011.1()001.0066.0( ×≤≤×××±×−±= −−coldPf


PCHE crossPCHE cross--sectionsection


Head loss in PCHEHead loss in PCHE

115o 100o

∑∑ −+=∆=∆m

mam

m

mbm

UmdLUKHgp

2Re316.0

2

225.0

2

ρρρloss in elbows + loss in a straight pipeloss in elbows + loss in a straight pipe

I. Kb=K1*K2*K3from Hydraulic Engineering, A. from Hydraulic Engineering, A. LencastreLencastre, 1987, 1987

II.

from JSME Textbook, 2003from JSME Textbook, 2003

III. CFD FLUENT

%3714 :exp

exp −=∆

∆−∆p

ppcalc

⎟⎠⎞

⎜⎝⎛+⎟

⎠⎞

⎜⎝⎛=

2sin047.2

2sin946.0 42 θθ

bK %326 :exp

exp −=∆

∆−∆p

ppcalc

: N/A yet


PCHEPCHE’’ss EffectivenessEffectiveness( )( )icih

icocc

TTCTTC

QQ

,,min

,,

max −−

== &

&ηEffectiveness:

2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.00.965

0.970

0.975

0.980

0.985

0.990

0.995

1.000


Effe

ctiv

enes

s, η


PCHEPCHE’’ss effectiveness reaches value up to 98.7%. effectiveness reaches value up to 98.7%. 1%1% of recuperator effectiveness of recuperator effectiveness the gas turbine cycle efficiency the gas turbine cycle efficiency 0.6%0.6%


MUSE Code SimulationMUSE Code Simulation

Developed for plate-fin heat exchanger,

Use Wavy fin plate heat exchanger model,

This model is the most similar model to our tested PCHE.

Various plate-fin models


Experimental data & MUSE CalculationsExperimental data & MUSE Calculations

40 50 60 70 80 90200

300

400

500

600

700U

, [W

/m2 K

]

Flow rate, [kg/h]

MUSE Calcualtions

Experimental Data

The different slopes may be due to:- Difference of PCHE from wavy fin model, - Neglect of cross flow in the distributor sections.


ConclusionsConclusions

The overall heat transfer coefficient and pressure loss factor oThe overall heat transfer coefficient and pressure loss factor of f PCHE were investigated both experimentally and numerically; the PCHE were investigated both experimentally and numerically; the empirical correlations are proposed.empirical correlations are proposed.

The method to take into account the heat loss for overall heat The method to take into account the heat loss for overall heat transfer coefficienttransfer coefficient estimations has been established.estimations has been established.

The overall heat transfer coefficient varies from 300 to 650 The overall heat transfer coefficient varies from 300 to 650 W/mW/m22K while the heat transfer effectiveness reaches up to 98.7 %.K while the heat transfer effectiveness reaches up to 98.7 %.

PCHE might be judged as a promising compact heat exchanger PCHE might be judged as a promising compact heat exchanger for the high efficiency recuperator.for the high efficiency recuperator.

The experimental data are currently used for CFD FLUENT The experimental data are currently used for CFD FLUENT code verification and developing the new heat exchanger type.code verification and developing the new heat exchanger type.

Date post:	21-Jun-2020
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