FVB: Ulrika Ottosson, Heimo Zinko Lund University: Janusz ... konf...RHC 2012 / Next Generation...
Transcript of FVB: Ulrika Ottosson, Heimo Zinko Lund University: Janusz ... konf...RHC 2012 / Next Generation...
Next Generation District Heating
FVB: Ulrika Ottosson, Heimo Zinko
Lund University: Janusz Wollerstrand,
Patrick Lauenburg, Marek Brand (DTU)
a project
The Swedish District Heating Association’s R&D programme
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Network operation and design
Heat and power production
Substation/HVAC design
Economy and environment
Next Generation DH in Sweden
Today: Large market penetration, almost 60 %
Future: Changed heat load profiles to expect
Impact on:
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
New Developments
Residential Changes
Retrofitting Existing Areas
Densifying City Center
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Increased energy efficiency in area Rud, Karlstad (“million programme” building)
• Improved building envelope
• Exhaust air recovery
• Improved control
• Reduced annual heat load and peak load
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
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10
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50
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500
DH
Lo
ad (
W/m
2)
Duration (h)
DH load before retrofit (W/m2)
DH Load with 20% reduction in space heating load (W/m2)
DH Load with 20% reduction in space heating + Heat recovery ventilators (W/m2)
DH Load with 20% reduction in space heating + Exhaust air heat pumps for rad (W/m2)
DH Load with 20% reduction in space heating load + Exhaust air heat pumps for rad and DHW (W/m2)
How different measures changes the DH load
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Yearly consumption various scenarios
0 kWh/m2
20 kWh/m2
40 kWh/m2
60 kWh/m2
80 kWh/m2
100 kWh/m2
120 kWh/m2
140 kWh/m2
160 kWh/m2
Before retrofit 20% Space heating reduction
20% Space Heating Reduction + Heat
Recovery Ventilators
20% Space heating reduction + Exhaust Air Heat Pumps for
rad
20% Space heating reduction + Exhaust Air Heat Pumps for
rad&DHW
District Heating Electricity
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
New Development with Single Detached
Houses A low heat density area with 58
dwellings (50 connected to DH) low
energy houses and houses with solar
collectors
Connection to main DH
network
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Yearly Load for Area of Single Houses (50 low energy houses, of which half have solar heating)
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30
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50
60
70
80
90
100
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
En
erg
y (
MW
h)
Heating (MWh) DHW (MWh)
Appliances (MWh) Secondary Connection Heat Losses (MWh)
Primary Connection Heat Losses (MWh)
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Single detached house area – primary
connection to DH system
• Pressure – either increase pressure in whole system or
booster pump
• Same temperatures as the whole system, i.e. substantial
heat losses
• Pipes, components and substation must be designed for
high pressures and temperatures – higher installation costs
and limited freedom for system layout
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
• Pressure –1-1,5 bars at area substation enough
• For new-built houses – supply temperature of 60-65°C
enough
• Plastic pipes can be used – which can reduce installation
costs
• May result in multiple heat exchange
Single detached house area – secondary
connection to DH system
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Next Generation DH substation
• Forced air ventilation with heat
coil providing low return
temperature
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Next Generation DH substation
• Forced air ventilation with heat
coil providing low return
temperature
• Domestic hot water prioritization
with or without directly
connection of waterborne
heating
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Next Generation DH substation
• Forced air ventilation with heat
coil providing low return
temperature
• Domestic hot water prioritization
with or without directly
connection of waterborne
heating
• Flat substations in multi-
residential building
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Next Generation DH substation
• Forced air ventilation with heat
coil providing low return
temperature
• Domestic hot water prioritization
with or without directly
connection of waterborne
heating
• Flat substations in multi-
residential buildings
• In case of solar heating for
domestic use – domestic hot
water storage
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Consumer installations
• Not evident what HVAC system will dominate in the future
– Radiators, underfloor heating, airborne heating
• New control systems required
– Not only outdoor temperature important, but much
larger influence from human behaviour
• Heat supply via air in the first Swedish passive houses, but
indications for comeback of waterborne heating
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Literature review
• Experiences from e.g. Denmark, flat substations, low-
temperature DH
• Low energy buildings
– Evaluation of passive houses
– In general good, but bathrooms generally in need of heat
source
– Comfort heating often requested by users
– Heat supply when ventilation is turned off (during
vacations etc.)
– Concerns regarding heat distribution via air
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
– Indoor temperature in low energy buildings mainly
affected by variations in internal heat gains – not
outdoor temperature
– Fast variations, but long time constants due to good
insulation
– Different opinions regarding use of underfloor heating
(and comfort floor heating)
Literature review
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
– Passiv houses industry has not disqualified waterborne
heating, only a matter of economy
– A positive attitude towards DH as heat source in future
low-energy houses
– (Not an equally positive attitude towards DH industry)
Literature review
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Adaptive control of radiator systems
- a way to reduce supply temperatures?
• Continuation of a successful project were a new control
algorithm for radiator system control was developed
• By control of not only radiator supply temperature but also
radiator system flow rate, the return temperature could be
reduced by approx. 2 dgc in four tested buildnings
• The algorithm will adapt to external changes, e.g. an
improved building envelope or a reduced DH supply
temperature.
• Simulations show that can be a useful tool to handle
existing buildings in an area where you want to reduce the
network supply temperature
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Other studies within the project
• Field study of old secondary network
– Two equal secondary systems, both with 80 detached
house built during 70ies, one of these performs poorly
– Methods to optimize temperatures and flow rate
• Comparison of different heating systems – radiators,
underfloor heating and forced air heating – with regards to
return temperature, peak load and operating hours
RHC 2012 / Next Generation District Heating / Lund University / 2012-04-26
Thanks!
• Ulrika Ottosson, FVB
• Patrick Lauenburg, Lund University