Transcript Folie 1

IEA HPP Annex 28
Calculation method
Workshop IEA HPP Annex 28
8th International Heat Pump Conference, Las Vegas, 30 May 2005
Carsten Wemhöner, Operating Agent IEA HPP Annex 28
Institute of Energy, University of Applied Sciences Basel
Outline of the presentation
 Objectives
 Principle of the calculation
 Extension to combined systems
 Simplifications, calculations steps and input data
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Objectives of the calculation method
 Transparent
 no correction factors as far as possible
 Easy-to-use
 “hand calculation”, no extensive computer application or simulation
 suited for standards
 Based on publicly available data
 standard testing results
 component characteristics from technical data sheets
 Applicable to the majority of systems on the market
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Calculation method – basic situation
 Output capacity and efficiency (COP) strongly dependent on source and
sink temperature and changes over the operation range
 Output capacity and efficiency (COP) are known at defined testing points
(from standard component testing)
 Meteorological data available for evaluation of the source temperature
 Controller settings available for the characterisation of the sink
temperature
 Annual energy requirement for space heating and domestic hot water are
known from standard calculations (building regulations)
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Principle of the calculation method
Meteo data processing
 Cumulative
Annual frequency
annualof the
frequency
ambient
dry
ofbulb
the air
temperature
ambient
dry bulb air
temperature
ambient dry bulb temperature [°C]
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Principle of the calculation method
Upper ambient
temperature for heating
Design indoor
temperature
Bin distribution
3, upper
3
3, lower
OP2
OP3
 Operating
Bin limits between
point in the
Conclusion:
 Bins of
should
have
centre
operating
the
points
bin
connection to available
information on the heat
pump characteristic
 Operation conditions at
design outdoor
temperature
the operating points
valid for the entire bin
OP1
ambient dry bulb temperature [°C]
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Performance factor at operating point
 Efficiency values from standard testing valid for the whole bin
 COP interpolated for the conditions at the operating point
 Further system losses
 Storage losses
PFi =
Qnet,i
Qnet,i
Qnet,i
Qnet,i + Qloss,i
COPCOP
i
i
+ Eaux,i
 Additional electrical auxiliary expense
 heat pump auxiliaries not considered in the COP boundary (e.g. brine source
pump)
 Circulation pumps
 Control only in times when heat pumps is not running
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Principle of the calculation method
Upper ambient
temperature for heating
Design indoor
temperature
Energy requirement
3, upper
3
OP3
3, lower
HP3
 Relative
Measure
Energy
Area
Heating
of requirement
the
degree
energy
forbin
the(area
hours
energy
in
OP2
HP2
a
design outdoor
temperature
OP1
HP1
ID
dt
requirement
requirement:
the
between
bin corresponds
cumulative
= in the bin
to
Heating
difference
frequency
corresponds
degree
of
and
toaindoor
hours
( ID
 cumulative
)ratio
dt of

(HDH)
heating
design
bin
areas
temperature)
degree hours at
bin limit factor)
corresponds
(weighting
to energy
 requirement
Operation conditions at
operating point valid for
the entire bin
ambient dry bulb temperature [°C]
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Seasonal performance factor of heat pump
 Seasonal performance by summation over all bins
 Electricity input can be expressed with
performance factor
 Ratio between bin heat requirement
SPFhp =
i
1 net
iQ
net,i
winet,i
Q
iE
i
PFi ·Qnet
and total heat requirement can be
expressed by weighting factor
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Principle of the calculation method
Upper ambient
temperature for heating
Design indoor
temperature
Back-up energy
OP3
HP3
modepump
heat
runs
is switchedthrough
heating
defined
by
heat
pump
is mode
switchedoff
low temperature
 at
Operation
off
balance
point
cut-out
 at
Balance
point
Balance point
temperature
OP2
low temperature
cut-out
design outdoor
temperature
Alternate
operation
Mixed operation
operation
mode
 Parallel
Operation
of the mode
back-up
HP2
HP1
OP1
temperature
 Low temperature cutout
BU
BU
BU
HP1
ambient dry bulb temperature [°C]
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Seasonal performance factor of heating mode
 Overall performance of heat pump and back-up heating by weighting with
delivered energy fractions
SPFh =
Qhp
Qnet
+ Qbu
Qbu
Ehp + Ebu
Q
+ 
SPFhp
bu
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Principle of the calculation method
Upper ambient
temperature for heating
Domestic hot water
Design indoor
temperature
OP4
W4
OP3
HP
W3
OP2
HP
Balance point
temperature
design outdoor
temperature
W2
 Evaluation
Approach:
Back-up
Combination
energy
Daily
of of
heat
different
of
tapping
pump
characterstic
profile
domestic
operation hot
modes
based
water
by on
DHW-testing
mode
weighting
determined
withenergy
the by
 Hotiswater
dependent
on bin time
temperature
respective
energy
level
(operation
fractions limit heat
pump)
OP1
BU
HP
ambient dry bulb temperature [°C]
W1
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Extension to combined systems
Alternate combined operating systems (heat pump switched):
 Result from testing:
characteristic does not change significantly
 Calculation of space heating and domestic hot water part
 Superposition of single operation modes with weighting of energy
fractions
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Extension to combined systems
Simultaneous combined operating systems (heat extraction):
 Characteristic in simultaneous operation changes significantly!
 Three operation modes have to be considered:
 Single space heating (e.g. winter operation, DHW storage entirely loaded)
 Single domestic hot water (e.g. summer operation)
 Simultaneous space heating and domestic hot water (SH and DHW demand)
 Fraction of operation in each operation mode by evaluating the running
time
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Extension to combined systems
 Running time t: produced heat/output capacity
 Maximum running time in combined operation
 If tSH > tDHW
=> tcombi = tDHW => DHW operation limiting factor for simultaneous operation
 If tDHW > tSH
=> tcombi = tSH => SH operation limiting factor for simultaneous operation
 Either space heating (intermediate season) or DHW (winter) could be the
limiting factor for combined operation
 Maximum value may not be reached due to control effects and not
necessarily simultaneous load requirement
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Overall seasonal performance factor
 As in the alternate case
the overall seasonal performance of simultaneous operation is calculated
 Weighting of the performance factors of the operation modes
 with the respective energy fraction
SPF =
Qh
Qh
SPFh
+
+ QDHW
QDHW
SPFDHW
+
Qcombi
SPFcombi
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Assumptions/Simplifications
 Main impact on space heating is outside temperature
 Effects of intermittent heating included in the calculation of energy
requirement (EN ISO 13790)
 defrosting considered in the heat pump characteristic (e.g. EN 14511)
 Domestic hot water requirement constant over the year
(daily consumption)
 Control effect cannot entirely be described but is reflected by standard
situations
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Calculation steps
 Determination of energy requirement per bin
 Determination of fraction by back-up energy (bivalent operation)
 Interpolation of output capacity and COP for source and sink temperature
 Correction for part load operation
 Evaluation of running time in different operation modes
 Calculation of auxiliary energy
 Calculation of generator losses (recoverable/recovered)
 Calculation of total energy input, system seasonal performance
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Input data
 Data of the site
 Meteorological data (i.e. hourly values of the outside temperature, irradiation)
 Source temperature (e.g. outside air, ground, ground water etc.)
 Energy Requirements
 Space heating energy requirement
 Domestic hot water energy requirement
 Heat pump
 Type of the heat pump (e.g. brine-to-water, outside-air-to-water etc.)
 Heat pump characteristic (standard testing, e.g. EN 14511, ASHRAE 116 etc.)
 Operation limits
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Input data
 System components characteristics
 Installed storages (heating buffer, domestic hot water)
 Back-up generators (electrical, fossil)
 Domestic hot water operation (independent/alternate/combined)
 Nominal power of auxiliaries (pumps, fans, control…)
 System design
 Controller settings (heating characteristic curve, upper temperature limit for
heating)
 Balance point (input or based on design heat load)
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Thank you for your attention!
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