Transcript Folie 1 - Annex 28

IEA HPP Annex 28 N 140
IEA HPP Annex 28
Calculation of compact units
Workshop IEA HPP Annex 28
8th International Heat Pump Conference, Las Vegas, 30 May 2005
Thomas Afjei, Institute of Energy,
University of Applied Sciences Basel
Outline of the presentation
 Introduction compact units
 System layout of compact units
 Approach for the calculation
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Introduction compact units
 Background
 In low- and ultra-low energy dwellings, significantly reduced heating
energy requirement
 Share of domestic hot water energy requirement increasing up to 50%
(ultra-low energy houses)
 Air-tight buildings
=> usually equipped with mechanical ventilation system with heat
recovery
 High insulation and high passive solar gains
=> eventually comfort cooling demand in summertime
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Conclusion system layout
 Compact unit
 Highly integrated system layout with core elements
 Heat pump
 Domestic hot water storage
 Ventilation heat recovery system
 Optional solar collector
 Optional cooling function in summertime
 Air heating systems and/or systems with hydronic distribution
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Principle of system layout
Source:
Viessmann
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Consequences calculation
 Heat recovery
Energy requirement:
 Reduction of energy demand by recovery of ventilation losses
 Electrical expense for the operation of the ventilation system
Source temperature:
 heat recovery influences source temperature of the heat pump
 ground-to-air heat exchanger influences source temperature
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Assumptions calculation
 Operation
Heating energy requirement is covered in the order:
1. heat recovery (running through in the heating period)
2. heat pump
3. back-up heater
Domestic hot water energy requirement is covered in the order:
1. solar collector (optional)
2. heat pump
3. back-up heater
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Additional input data for compact units
 Heat recovery:
 key value: temperature change coefficient
Temperature change coefficient
OA
=
temperature difference outside-supply air
temperature difference return-outside air
 mass flow rates
 electricity input for ventilation
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Additional input data for compact units
 Solar energy system:
 solar collector characteristics, meteo data
 Ground-air heat exchanger:
 outlet temperature
(if not already considered in performance characteristics,
see testing method HTA Lucerne)
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calculation method compact units
Upper ambient
temperature for heating
Design indoor
temperature
S
OP4
HP
OP3
H
R
HP
Balance point
temperature
HP
OP2
HP
Balance point
temperature
design outdoor
temperature
S
HR
S
HP
 domestic
Heating
heat
Domestic
recovery
requirement
hot water
water
hot
covered
by heat
pump
energy
requirement
 Reduction
of heating
energy
requirement
and
back-up
partly
covered
by solar
contribution
 lower inlet temperature
to heat pump
(optional)
OP1
HP
BU BU
HR
HP
ambient dry bulb temperature [°C]
Space Heating
DHW
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Thank you for your attention!
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