Professor Neil J Hewitt Director Centre for Sustainable Technologies Demand Side Management Heat Pumps amp Thermal Storage an enabling mechanism Heat Pumps Decarbonisation of space heating ID: 537800
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Heat Pumps and Thermal Storage – Household Implementation to Grid Challenge
Professor Neil J HewittDirector, Centre for Sustainable TechnologiesSlide2
Demand Side Management
Heat Pumps & Thermal Storage – an enabling mechanism
Heat Pumps
Decarbonisation of space heating
Markets
Technology Challenges
Novel Approaches
Policy Implications
Commercial Possibilities
Behavioural ChangeSlide3
Heat Pump Developments
Air-source for direct retrofit
CALEBRE
Economised Vapour Injection
Experimental Facilities
Compressor/Expander
Experimental Facilities
ASHP Test ChamberSlide4
Heat Pump Developments
Air-source for direct retrofit
CALEBRE
Economised Vapour Injection
Lab Results CompletedSlide5
Heat Pumps
i-STUTEWP3.3 has a number of roles for advanced air source heat pumps:
Demand
side management/response
Integration
with storage
Upgrading
Heat Pump
New
working fluids
Meeting householder thermal needs Understanding wider domestic heat demand patterns Integration into energy markets New business models for heat pumps & thermal storageSlide6
Heat Pumps
Heat Pump, Storage & ControlSlide7
Heat Pumps
Control Strategy
1. DIRECT
3. INDIRECT
2. STORINGSlide8
Heat Pumps
Control Strategy
System Operator Data Online for NI
Actual System Demand
Forecast System Demand
Digital Temperature Sensor on storage tank – Direct connection to
RPi
Programme gets data from web and tank temp sensor
Calculates demand data
Makes
system
mode decision based on forecast demand and tank temperature
Activates or deactivates control relaysRepeats loop every minuteSlide9
Heat Pumps
PerformanceSlide10
Heat Pumps and Thermal Storage
1. Insulation ImprovementsSimple Fourier Heat Loss calculation
75mm Spray Foam (0.035 W/
mK
) =>25% of the stored heat is lost every 24 hours.
VIP Insulation (0.007 W/
mK
) => 4%
of the stored heat is lost every 24 hours
.
HAVE A SQUARE TANK!Slide11
Heat Pumps and Thermal Storage
2. Tank Size ReductionIntegration of thermochemical store with
air-
source
heat pump
Low
energy buildings <50 kWh/
sq.m
/year?
Maximum size of store = 2.5 cu.m Energy density for 100 sq.m house = 50 x 100 kWh/year i.e. 18 GJ 2.5 cu.m store leads to an energy density of 7.2 GJ/cu.m being required – This is a major challenge!!!Slide12
Heat Pumps and Thermal Storage
2. Tank Size ReductionTrausel et al (2014) – salt hydrates –
3.17
GJ/
cu.m
–
Also
is temperature too high?
PCM or Sorption? Low temperature salts?Hardorn ,JC. Thermal energy storage for solar and low energy buildings – IEA Solar Heating and Cooling, Task 32, 2005. Slide13
Heat Pumps and Thermal Storage
2. Tank Size Reduction
Low temperature salts
N’Tsoukpoe
et al (2014) when
including
the efficiencies = 120 kWh/
cu.m
= 0.432 GJ/
cu.m
Assumption33% EFFICIENCY!UK Domestic Example40kWh for 3 hours+ DSM1/3 cu.m? (or insulate house?)Slide14
Heat Pumps and Thermal Storage
2. Tank Size Reduction
Challenges when using TCM or PCM
Fixed operation heating temperature for the heat pump
No weather compensation
No reduced running temperatures
Poor
COPh
?Slide15
Heat Pumps and Thermal Storage
3. Novel Heat Pump & Tank Design
Use new working fluids to “allow” store to “lead”
New working fluids for high temps.?
R245fa, R290
R1234yf, R1234ze
etc
R245fa Under very favourable conditions!Slide16
Heat Pumps and Thermal Storage
3. Novel Heat Pump & Tank Design
Microencapsulated PCM
(High Density Slurry Store)
Water + PCM
0-40%
Entrainment
Pump
Circulator
Pump
Sparger
Effect
Variation in PCM Slurry
= Entrainment Pump and Circulator Pump proportionalOperation = desired slurrySlide17
Heat Pumps and Thermal Storage
Controls & Control StrategiesWhat if? Economy 7
style..Slide18
Heat Pumps and Thermal Storage
Controls & Control StrategiesWhat if? Market Load Needs type..Slide19
Heat Pumps and Thermal Storage
Controls & Control StrategiesWhat if? Market Voltage/Frequency Needs..
Impact of electric vehicle
charging on residential
Distribution networks: an Irish
demonstration initiative
Richardson et al, 2013Slide20
Heat Pumps and Thermal Storage
Controls & Control StrategiesWhat if? Market Voltage/Frequency Needs..
On/Off V. Current VSD V. Current Best?
The two newly launched variable speed models
offer
a capacity range from 1 to 10 kW and coupled
with
Emerson qualified inverter drives allow for a
modulation
range with speed variation from 15 to 120 HzSlide21
Heat Pumps and Thermal Storage
Controls & Control StrategiesWhat if? Low Capacity Heating Needs
Heat Genius & Husky Heat PumpsSlide22
Heat Pumps and Thermal Storage
And the rest……….Need a smart grid?Need to aggregate their performance to avail of Balancing Agreements?
Need to address low voltage network stability and its knock-on effects?
Can we build in for £200/kW?
Can you spare a couple of square meters?
Would you like a more tightly controlled home?Slide23
Heat Pumps
Thermal StoresWhat type and size of thermal storage system in the future?
(when working with an advanced air-source heat pump in a tightly controlled home and responding to market signals???)Slide24
Thank you for your attention
Questions?