ORCNext – WP4
Development of supercritical technologies
Catternan Tom
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ORCNext – WP4
Development of supercritical technologies
Transcritical ORCs – Literature review
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Transcritical ORCs
Best efficiency
highest
when temperature
• Better
thermal and
matching
power
drivingoutput
force LMTD↓
 UA↑
profile of HS and WF match  lower exergy destruction
(Larjola et al.).
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Selection of working fluids
• Wide range of applications and ranges  no consensus for
best working fluid.
Screening criteria
Cycle criteria
Safety (ASHRAE 34)
Thermodynamic PI
Environmental (GWP, ODP, ATL)
Heat exchanger PI
Stability working fluid
Cost PI
Compatibility with materials
Thermophysical properties
Availability and cost
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Selection of working fluids
Physical data
Name
Type
Tcrit (°C)
HFC-23
Wet
26,14
R-747 (CO2)
Wet
31,10
HFC-125
Wet
66,02
HFC-410A
70,20
PFC-218
Isentropic 71,89
HFC-143a
Wet
72,73
HFC-32
Wet
78,11
HFC-407C
86,79
HFC-134a
Isentropic 101,03
HFC-227ea
Dry
101,74
PFC-3-1-10
Dry
113,18
HFC-152a
Wet
113,50
PFC-C318
Dry
115,20
HFC-236ea
Dry
139,22
PFC-4-1-12
Dry
147,41
HFC-245fa Isentropic 154,05
HFC-245ca
Dry
174,42
Molecular
pcrit (bar) weight (g/mol)
48,30
70,01
73,80
44,01
36,20
120,02
47,90
72,58
26,80
188,02
37,64
84,04
57,83
52,02
45,97
86,20
40,56
102,03
29,29
170,03
23,20
238,03
44,95
66,05
27,78
200,03
34,12
152,04
20,50
288,03
36,40
134,05
39,25
134,05
Safety data
ASHRAE 34
safety group
A1
A1
A1
A1
A1
A2
A2
A1
A1
A1
A2
A1
B1
A1
Environmental data
GWP
ATL (yr) ODP (100 yr)
270
0
14800
>50
0
1
29
0
3500
16,95
0
2088
2600
0
8830
52
0
4470
4,9
0
550
15657
0
1800
14
0
1430
34,2
0
3220
2600
0
8600
1,4
0
124
3200
0
10250
10,7
0
1370
4100
0
9160
7,6
0
900
6,2
0
693
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Heat exchanger design
Influence ORC parameters on HX design
(Schuster and Karellas, 2012)
• R134a, R227ea and R245fa
• Jackson correlation (1979): Water and CO2
• HTC decreases with increasing supercritical pressure and
temperature HX area increases
• Relatively unknown heat transfer mechanisms around C.P.
 need further investigation
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ORCNext – WP4
Development of supercritical technologies
Forced convective heat transfer at supercritical pressures
Literature review
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Supercritical state
• Critical point ‘c’
• Supercritical state
• For T>Tcrit  Continuous transition from liquid-like fluid to
gas-like fluid (no phase change)
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Thermophysical properties
• (cp, m, r, l, Pr…)=f(T)
• Pseudo-critical temperature
 Tpc= f(p)
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Thermophysical properties
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Literature overview
• Experimental
– H2O, CO2, nitrogen, hydrogen, helium, ethane, R22
– Uniform cross section
• Circular
• Recently: triangular and square
– Uniform heat flux  electrically  forced Tw
– Different experimental results
• Numerical
– Only recent
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General characteristics
Heat transfer enhancement
Maximum HTC
(1) Theory
(∆) Experimental:
𝑚 = 140±4.4 kg/h;
q = 1.44 W/cm²
• 𝑇𝐵𝑢𝑙𝑘 ≤ 𝑇𝑝𝑐 ≤ 𝑇𝑤𝑎𝑙𝑙
• 𝑞↓
• 𝑚↑
• Due to variation of
thermophysical properties
(2) Theory
(x) Experimental:
𝑚 = 140±3.1 kg/h;
q = 2.73 W/cm²
(3) Theory
(○) Experimental:
𝑚 = 280±5.6 kg/h;
q = 3.32 W/cm²
(4 Theory
(●) Experimental:
𝑚 = 280±7.8 kg/h;
q = 5.20 W/cm²
Variation of the heat transfer coefficient with bulk temperature for forced convection in a
heated pipe for carbon dioxide of 78.5bar flowing upwards in a 1.0 diameter vertical pipe.
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General characteristics
Heat transfer deterioration
• Comparison upward and downward flow
– Downward  no unusual behaviour
– Upward  deterioration
Upward flow
1
2
3
4
5
6
7
8
𝒎 𝑨 (𝒈𝒎 𝒔 𝒄𝒎²)
382
382
400
375
400
400
393
381
𝒒 (𝑾/𝒄𝒎𝟐 )
27
37
45
52
27
36
43
50
Downward flow
Flow direction
Vertical upward
Vertical upward
Vertical upward
Vertical upward
Vertical downward
Vertical downward
Vertical downward
Vertical downward
Wall and bulk temperature as a function of the distance along a vertical
heated 1.6 cm diameter pipe for water at 245 bar (1.11 pcrit).
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General characteristics
Heat transfer deterioration
• Comparison upward, downward and horizontal flow
(1) Horizontal pipe – upper surface
(2) Horizontal pipe – lower surface
(3) Vertical pipe – upward flow
(4) Bulk fluid temperature
Temperature distribution as a function of local bulk enthalpy along heated vertical and horizontal pipes (1.6 cm diameter) for water at
245 bar (= 1.11 pcrit): 𝒎 𝑨 = 𝟔𝟎 𝒈𝒎 𝒔 𝒄𝒎² and 𝒒 = 𝟓𝟐 𝑾/𝒄𝒎𝟐
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Influence of parameters
• Heat flux 𝑞
Left: Ratio of the experimental heat transfer coefficient to the value calculated via the Dittus-Boelter equation;.
Right: Wall temperature behaviour for low and high heat fluxes.
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Influence of parameters
• Heat flux 𝑞
• Mass flow 𝑚
Generalized curves for water at 250bar (Lokshin et al.)
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Influence of parameters
• Heat flux 𝑞
• Mass flow 𝑚
• Flow direction
Comparison of heat transfer between an upward
and downward flow for CO2 by Jackson and EvansLutterodt
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Influence of parameters
•
•
•
•
Heat flux 𝑞
Mass flow 𝑚
Flow direction
Pipe diameter
Effect of tube diameter on heat transfer coefficient (Cheng X. et al.)
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Correlations
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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Bringer and Smith (1957)
Miropolsky and Shitsman (1959, 1963)
Petukhov, Krasnoshchekov and Protopopov (1959, 1961, 1979)
Domin (1963)
Bishop (1962, 1965)
Kutateladze and Leontiev (1964)
Swenson (1965)
Touba and McFadden (1966)
Kondrat’ev (1969)
Ornatsky et al. (1970)
Yamagata (1972)
Yaskin et al. (1977)
Jackson (1979)
Yeroshenko and Yaskin (1981)
Watts (1982)
Bogachev et al. (1983)
Griem (1995, 1999)
Heat transfer coefficient for supercritical water
according to different correlations (Cheng X. et al.)
…
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ORCNext – WP4
Development of supercritical technologies
Goals and planning for the next 6 months
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Transcritical ORCs
• Finish literature study (± 10 more papers to read)
• Model sub – and transcritical cycle (together with WP1)
– Choose parameter range
– Compare both cycles using the Performance Indicators for
several working fluids
– Check influence of the variable parameters on the
objective functions  sensitivity
– Make a list of 3 working fluids, which will be used in the
experimental setup
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Supercritical forced convection heat transfer
• Investigate thermophysical properties under supercritical
conditions of the selected working fluids (via REFPROP or EES)
• Finish literature study
– Deteriorated and improved heat transfer regimes
– Onset deterioration
– Correlations
• Fundamental understanding heat transfer and occurring flow  Test setup have to be built:
– Prepare setup
– Choose materials
– Order
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Thank you for your
attention.
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