1 Kobe Steel Supplies High Heat Transfer Titanium Sheet for Use in OTEC Demonstration Project in Okinawa October 7, 2013 AKIO OKAMOTO Titanium Marketing & Technical Service Section KOBE STEEL, LTD.
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1
Kobe Steel Supplies High Heat Transfer Titanium Sheet
for Use in OTEC Demonstration Project in Okinawa
October 7, 2013
AKIO OKAMOTO
Titanium Marketing & Technical Service Section KOBE STEEL, LTD.
2
What has been improved? Heat transfer coefficient ( h )
for Ocean Thermal Energy Conversion
Q = U A ∆t h t1
t2
Heat
∆t
heat transfer sheet
Q : heat exchange [J/s] h : heat transfer coefficient [W/m2 K] A : heat transfer area [m2] ∆t : temperature difference [K]
3
Image of OTEC Plant
onshore type
floating type
by courtesy of Tokyo Univ.
by courtesy of Xenesys
4
High heat transfer titanium sheet used in heat exchangers for OTEC
PHE using titanium plates for evaporator and condenser
Warm Seawater at Surface
Cold Seawater in Depth
5
Improved heat transfer reduces OTEC power generation costs
Image of OTEC plant (floating type)
heat exchanger
Q = U A ∆t h h A
by courtesy of Japan Marine United
6
plate heat exchangerfloating structureturbine & pumptank etcplant constructionintake pipetransmit electricitydesign
Initial cost for 10MW floating type OTEC plant Renewable energy symposium 2012 (NEDO)
Improved heat transfer reduces OTEC power generation costs
7
But mass productivity is indispensable
System of Power Generation
Quantity of Titanium / Power Generation Output
(MT / MW)
Coal, Petroleum, LNG 0.08
Nuclear 0.18
OTEC 12.4 – 18
Quantity of Titanium for OTEC
8
We chose transfer-printing technology in the rolling process
Hot rolling Annealing and pickling Cold rolling
Annealing and pickling Shear cutting Cold pressing Thermal spraying
Mass production Batch
production
9
for tubular
bended fin “Y” fin
One feature in common was hidden
for sheet
minute dimple
that was “cavity” :
Heat transfer enhancement (result of former studies)
10
“Cavity” made in rolling process increases heat transfer
Normal surface
Special surface treated sheet Grade : 1
Thickness : 0.4~0.6mm
Special surface
11
Special surface
“Cavity” made in rolling process increases heat transfer
“cavity”
12
The effects are apparent
Normal surface Special surface (HEET TM)
13
Proving the effectiveness of the heat exchanger in the OTEC demonstration plant
Renewable energy symposium 2012 (NEDO)
1,000
10,000
1.0 10.0
熱流束 [kW/m2]
熱通過係数 [W
/m2K
]
平滑8
平滑11
平滑14
凹凸8
凹凸11
凹凸14
heat flux [ kW/m2 ]
ove
rall
heat
tran
sfer
c
oeff
icie
nt [W
/m2 K
]
normal
high heat transfer
HEET
normal
Overall heat transfer coefficient for heat flux
14
OTEC pilot plant on Kume Island
HEET TM @ the heat exchanger in the OTEC demonstration plant
by courtesy of Okinawa prefectural office
15
Heat transfer improves at demonstration plant
0.60
0.80
1.00
1.20
1.40Ex
perim
enta
l Dat
a/ A
ppro
xim
ateF
orm
ula
[-]
Evaporator U-Value (Experimental Data /Approximate Formula) Time-Series Data Aug,2013): 10 Minutes Average
by courtesy of Xenesys
normal
HEET
16
titanium - normal HEET
Deep sea water depth m 700
Deep sea water temperature oC 4.4
Surface sea water temperature oC 25.5
Generating-end output kW 15036 14,809
Sending-end output kW 10,000 10,000
Deep sea water mass flow rate t/h 165,979 152,354
Surface sea water mass flow rate t/h 173,131 158,776
Evaporator U-Value W/m2K 3265 4594
Electricity cost yen/kWh 19.9 18.5
Electricity cost cut ratio % - 6.9
Economical effect ( 10MW floating type off Okinawa main island )
Renewable energy symposium 2012 (NEDO)
Power generation efficiency improves
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Okinawa main island
Kume Island
Miyako Island
Ishigaki Island
Temperature difference between surface and 1,000m depth Energy resource
by OTEC [MW] 2,797
Present power capacity [MW] 1,905
(NEDO, 2011)
Okinawa District
Practical use aimed at 2015 - 2020
Potential site for OTEC in Okinawa
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Power Generation Output
C.Y. 2015 2020 2030 2050
TWh / year 2.5 12.5 40
MW 510 2,550 8,150
*New Energy and Industrial Technology Development Organization
Practical use aimed at 2015 – 2020
Road map for the practical use of OTEC (NEDO*)
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Further development of HEET TM to make effective use of energy
High heat transfer -with higher strength -for condenser
National project by NEDO R&D of core technology for 10MW OTEC (Kobe Steel , Saga Univ.)
by courtesy of Okinawa prefectural office
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by courtesy of Okinawa prefectural office
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