efficient cooling in engines with nucleate boilingbarriers to utilization of boiling heat transfer...
TRANSCRIPT
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Efficient Cooling in Engines with Nucleate Boiling
Principal Investigator: Wenhua YuCoworkers: D. France and R. Smith
Energy Systems DivisionArgonne National Laboratory
OVT Merit ReviewFebruary 28, 2008
This presentation does not contain
any proprietary or confidential information.
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Purpose of Work
Utilize the high heat transfer rates of boiling engine coolants under high heat load conditions to:• Reduce cooling system size and weight
Potential to reduce aerodynamic dragReduce fuel consumption
• Reduce parasitic pumping power• Enable precision cooling of engine areas
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Barriers to Utilization of Boiling Heat Transfer in Engines at High Heat Load Conditions
Change coolant system design approach• From: attempt to suppress coolant boiling under all conditions• To: utilization of high boiling heat transfer rates at high heat
loads
Preprogram results almost non-existent for• The combination of binary mixture boiling and small channels• Ethylene glycol/water boiling
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Approach to Boiling Coolant Technology DevelopmentDevelop boiling coolant technology for engine applications• Design, fabricate, and utilize a unique experimental facility
Horizontal flowVertical flow
• Experimentally determine boiling heat transfer rates andpressure drops
Emphasis on small coolant passages of head region Emphasis on boiling of binary coolant mixtures of water &
ethylene glycol• Determine boiling heat transfer limits
Critical heat fluxTwo-phase flow instability
Develop models for• Vehicle coolant system design• Heat transfer design New vertical test section
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Performance Measures
Successful boiling experiments with water and ethylene glycol mixtures
Interpretation and correlation of data for use in engine cooling-system design
Design and implementation of vertical test section
Development of vertical versus horizontal boiling technology
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AccomplishmentsDeveloped a new procedure, based on equilibrium ideal-mixtures and Raoult’slaw, to calculate boiling temperatures along the test section and, subsequently, local heat transfer coefficientsCompleted experiments & data analysis for boiling heat transfer and pressure drop in horizontal flows to water and ethylene glycol/water mixtures
1
10
100
1000
0.01 0.1 1 10 100
G = 50 kg/m2sG = 76 kg/m2sG = 103 kg/m2sG = 129 kg/m2sG = 151 kg/m2s
Hea
t flu
x (k
W/m
2 )
Wall superheat (oC)
convection dominant
nucleationdominant
3
transition boiling
p = 200 kPa, d = 2.98 mm
(a) water boiling1
10
100
1000
0.01 0.1 1 10 100
G = 45-60 kg/m2sG = 65-85 kg/m2sG = 85-105 kg/m2sG = 115-130 kg/m2sG = 135-170 kg/m2s
Hea
t flu
x (k
W/m
2 )
Wall superheat (oC)4.50
p = 160 kPa, d = 2.98 mm
(b) 50/50 EG/W boiling
convection dominant
nucleationdominant
transition boiling
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Accomplishments
Developed a pressure drop correlation, modified from Chisholm’s correlation, with a concentration factor to better predict pressure drops for ethylene glycol/water mixturesDeveloped a general correlation for boiling heat transfer, modified from ANL earlier work, for flow boiling in small channels, including: refrigerants, water, and ethylene glycol/water mixtures• Predicts data for ethylene glycol & water concentrations
50/5060/4040/60
• Water• Refrigerants 12 & 134a
[ ] [ ] 5.17.05.05.05.0* )()()()5.0(61 −−−+= vlvllBoWevvhh μμρρ
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Horizontal Boiling Heat Transfer Coefficients
0
1 104
2 104
3 104
4 104
5 104
0 1 104 2 104 3 104 4 104 5 104
Pred
icte
d he
at tr
ansf
er c
oeffi
cien
t (W
/m2 K
)
Experimental heat transfer coefficient (W/m2K)
distilled water +30%
-30%
0
2 103
4 103
6 103
8 103
1 104
0 2 103 4 103 6 103 8 103 1 104Pr
edic
ted
heat
tran
sfer
coe
ffici
ent (
W/m
2 K)
Experimental heat transfer coefficient (W/m2K)
EG/W mixtures +30%
-30%
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AccomplishmentsDesigned & fabricated a new vertical experimental test sectionPerformed preliminary experimental tests and data analysis for two-phase, vertical, flow-boiling of pure water
0
1 104
2 104
3 104
4 104
5 104
0 1 104 2 104 3 104 4 104 5 104
Boiling Heat Transfer Coefficient
Pred
icte
d he
at tr
ansf
er c
oeffi
cien
t (W
/m2 K
)
Experimental heat transfer coefficient (W/m 2K)
Argonne
-30%
+30%
0
50
100
150
200
250
300
0 2 4 6 8 10
Horizontal flowVertical flow
Hea
t flu
x (k
W/m
2 )
Wall superheat (oC)
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Future Activities
Systematic two-phase heat transfer experiments of water and ethylene glycol/water mixtures with vertical flows to provide essential information for design of nucleate-boiling cooling systems
Study the effect of vertical versus horizontal flows on two-phase heat transfer
Experimentally determine heat transfer characteristics for subcooled flow boiling of water and ethylene glycol/water mixtures
Perform systematic experiments with alternative fluids
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SummaryPotential for petroleum displacement similar to nanofluid coolant of ≈ 300 x 106
gallons fuel/yr through reduced cooling system weight, reduced parasitic pumping power, and reduced aerodynamic drag Approach to research uses unique experimental facility for the study of horizontal and vertical flow-boiling water and ethylene glycol mixtures Technical Accomplishments• Horizontal flow boiling heat transfer and pressure drop
Extensive data base developedCorrelated data for engine cooling-system designCritical heat flux and flow instability limits established
• Vertical flow boiling heat transfer and pressure dropTest section completedPreliminary results obtained and compared with horizontal flow
Technology Transfer by publications & citations
Plans for Next Fiscal Year• Vertical boiling heat transfer experiments of water and ethylene
glycol/water• Comparisons of vertical and horizontal boiling heat transfer results• Correlation of data for engine cooling-system design purposes
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Publications & Technology Transfer (for reviewers only)
The first general journal paper from the program•
W. Yu, D.M. France, M.W. Wambsganss and J.R. Hull, “Two-phase pressure drop, boiling heat transfer, and critical heat flux to water in a small-diameter horizontal tube,” International Journal of Multiphase Flow, Vol. 28, 2002, pp. 927-941.
Received 21 citations July 2002 through December 2005Unusually high citation number representative of
Peer recognitionpioneering worktransfer of information
Citations included prominent researchersG. Hetsroni, I. Mudawar, & S. G. Kandlikar
W. Yu, D.M. France, V. Vellore-Ramamoorty, and J. Hull, “Small-Channel Flow Boiling of One-Component Fluids and an Ethylene Glycol/Water Mixture,” Experimental Heat Transfer Journal, Vol. 18, 2005, pp. 243-257.