www.orcnext. be ORCNext – WP4 Development of supercritical technologies Catternan Tom 1
Jan 03, 2016
www.orcnext.be
ORCNext – WP4Development of supercritical technologies
Catternan Tom
1
www.orcnext.be
ORCNext – WP4Development of supercritical technologies
Transcritical ORCs – Literature review
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Transcritical ORCs
• Best efficiency and highest power output when temperature profile of HS and WF match lower exergy destruction (Larjola et al.).
• Better thermal matching driving force LMTD↓ UA↑
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Screening criteria Cycle criteriaSafety (ASHRAE 34) Thermodynamic PIEnvironmental (GWP, ODP, ATL) Heat exchanger PIStability working fluid Cost PICompatibility with materialsThermophysical propertiesAvailability and cost
Selection of working fluids
• Wide range of applications and ranges no consensus for best working fluid.
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Selection of working fluidsPhysical data Safety data Environmental data
Name Type Tcrit (°C) pcrit (bar)Molecular
weight (g/mol)ASHRAE 34
safety group ATL (yr) ODPGWP
(100 yr)HFC-23 Wet 26,14 48,30 70,01 A1 270 0 14800R-747 (CO2) Wet 31,10 73,80 44,01 A1 >50 0 1HFC-125 Wet 66,02 36,20 120,02 A1 29 0 3500HFC-410A - 70,20 47,90 72,58 A1 16,95 0 2088PFC-218 Isentropic 71,89 26,80 188,02 A1 2600 0 8830HFC-143a Wet 72,73 37,64 84,04 A2 52 0 4470HFC-32 Wet 78,11 57,83 52,02 A2 4,9 0 550HFC-407C - 86,79 45,97 86,20 A1 15657 0 1800HFC-134a Isentropic 101,03 40,56 102,03 A1 14 0 1430HFC-227ea Dry 101,74 29,29 170,03 A1 34,2 0 3220PFC-3-1-10 Dry 113,18 23,20 238,03 - 2600 0 8600HFC-152a Wet 113,50 44,95 66,05 A2 1,4 0 124PFC-C318 Dry 115,20 27,78 200,03 A1 3200 0 10250HFC-236ea Dry 139,22 34,12 152,04 - 10,7 0 1370PFC-4-1-12 Dry 147,41 20,50 288,03 - 4100 0 9160HFC-245fa Isentropic 154,05 36,40 134,05 B1 7,6 0 900HFC-245ca Dry 174,42 39,25 134,05 A1 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 – WP4Development of supercritical technologies
Forced convective heat transfer at supercritical pressuresLiterature review
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Supercritical state
• Critical point ‘c’• For T>Tcrit Continuous transition from liquid-like fluid to gas-
like fluid (no phase change)
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Thermophysical properties
• h=f(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
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General characteristicsHeat transfer enhancement
Maximum HTC
• ↓• ↑• Due to variation of
thermophysical properties
(1) Theory (∆) Experimental: = 140±4.4 kg/h; q = 1.44 W/cm²
(2) Theory(x) Experimental: = 140±3.1 kg/h; q = 2.73 W/cm²
(3) Theory (○) Experimental: = 280±5.6 kg/h; q = 3.32 W/cm²
(4 Theory (●) Experimental: = 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 characteristicsHeat transfer deterioration
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).
• Comparison upward and downward flow– Downward no unusual behaviour– Upward Deterioration
Flow direction1 382 27 Vertical upward2 382 37 Vertical upward3 400 45 Vertical upward4 375 52 Vertical upward5 400 27 Vertical downward6 400 36 Vertical downward7 393 43 Vertical downward8 381 50 Vertical downward
Upward flow Downward flow
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General characteristicsHeat transfer deterioration
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): and
• 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
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Influence of parameters
• Heat flux • Mass flow • Flow direction• Pipe diameter
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Correlations• 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 – WP4Development 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.