SLIDE 1
KTH ROYAL INSTITUTE OF TECHNOLOGY
ON HIGH LEVEL EVALUATION AND COMPARISON OF ORC POWER GENERATORS - - PowerPoint PPT Presentation
ON HIGH LEVEL EVALUATION AND COMPARISON OF ORC POWER GENERATORS - - PowerPoint PPT Presentation
KTH ROYAL INSTITUTE OF TECHNOLOGY ON HIGH LEVEL EVALUATION AND COMPARISON OF ORC POWER GENERATORS ASME ORC 2015, Brussels Paper ID: 25 Henrik hman, Per Lundqvist Content 1. Lack of proper terms of merit 2. Utilization: A scale for
SLIDE 2
SLIDE 3
Inadequate terms of merit?
- Room for ”over-optimistic” or ”under-ethical” market
players
- Unrealistic customer expectations
- Investors find ”plenty of reasons to wait”
- Customers ”do not understand”
Entry barriers to the market No matter if technology is mature if communication is immature!
SLIDE 4
Criteria for useful terms of merit
- Cannot violate theory
- Explainable and acceptable to practitioners
- Free of bias from relevant boundary variations
- Show ”primary good” in a dimensionless manner
SLIDE 5
Conventional terms of merit for ORC power generators
Carnot efficiency Irrelevant Thermal efficiency Biased Exergy efficiency Ambiguous Exergy efficiency Iteration Non-intuitive
1 2
1 T T
c
1
Q W
th
exit entry ex
e e m W
, 1 , 1 1
exit entry exit entry ex
e e m e e m W
, 2 , 2 2 , 1 , 1 1
SLIDE 6
Dimensionless scale, Utilization
Chosen limit for use of first law potential where Common exit temperature of source and sink assuming a reversible power process => Curzon-Ahlborn temperature
CA U
Q Q
1
1 , 1 , 1 1 1
CA entry CA entry CA
T T T T Cp m Q
SLIDE 7
Integrated Local Carnot Efficiency => reversibly available thermal efficiency
Max Power Cycle:
Reformulated from (Ibrahim & Klein 1996)
Numerical solution using local Carnot cycles Öhman & Lundqvist 2013
1 , 1 , 2
1
1 Q d T T W
Q l l
n i l l Il c
T T n
1 , 1 , 2 ,
1 1
SLIDE 8
Reversible sensitivity to ”finiteness”
Öhman & Lundqvist 2013
SLIDE 9
Schematic relationships, reversible
W
exit
T ,
1 exit
T ,
2
Il c,
1
Q
1
U
[K, kW, %]
SLIDE 10
Fraction Of Carnot
Compilation of all irreversibilities of a power generator thus net output power is Application First law Second law Irreversibilities
U Il c U th U
FoC
,
FoC Q W
Il c U CA
,
Öhman & Lundqvist 2014
SLIDE 11
Normative Reference, empirical non-biased
Real unit performance + marketing data Nominal power range: 0.2kW to 5MW Source temperature range: 300˚C to 61.5˚C Different cycles and fluids
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0.2 0.4 0.6 0.8 1
FoC
U
SLIDE 12
Conclusions
ORC industry and academy needs improved terms of merit Semi-empirical data can provide such terms of merit We propose based on as term of merit for efficiency of ORC power generators We propose development of non-biased Normative References for more effective regulation and technological advancement
FoC
Il c,
SLIDE 13
Future work
Increase reference database with measured data Introduce Non-biased Normative References to regulatory bodies Sub-divide Normative References to application niches for improved accuracy
SLIDE 14