Potential of residential buildings as thermal energy storage in district heating systems - Results from a pilot test
https://doi.org/10.1016/j.apenergy.2014.07.026
short-term energy storage
also beneficial for HP and RES
variation of electricity prices
special benefits for CHP [2,3]
el. power generation decoupled from heat load
decreases daily variation
conditions for heat generation more favorable
up to few days possible
usually few hours
can increase overall efficiency
periodically overheating and underheating
small indoor T variations
security of energy supply raises
building inertia utilized for thermal storage
intent: generate more heat when favorable
less peak load demand
more base load
better fuel economy
less enviromental impact
heat demand
significant variation within 1 day
problematic conditions for efficient heat generation
variation in DH w/ magnitude of 100 MW during a few hours [1]
on/off boilers
pilot test study
fixed time constant not enough to desribe vriation in indoor T caused by short-term building storage [11]
instead degreehours
storing 0,1 kWh/m^2 will cause rarely dT>|5°C| in heavy building
scope
evaluate magnitude of th. energy storagy capacity while remaining comfort
variation in indoor T only main limiting factor
here: desribed as fcn of limitations for control system expressed in deghrs
can be translated into energy quantity for any building of DH
when energy signature known
independent of building size and location
new method for analyzing how indoor T is affected by utilization of building inertia
signals from outdoor T adjusted in different cycles
supply T radiators set based on outdoor T and control curve
periods of charging and discharging @ diferent times of the day
to seperate variations by test from normal variations
find clear relation between how building TES is controlled and variation of indoor T
building degree hours vs. time constant w/ max. allowed variation of T
closer look at magnitude of heat power per floor area btw. DP, CP, NOP [15]
feedback controller, [11] similar
earlier pilot tests [5-12]
Potential utilization of each building
might be beneficial to have shorter CPs or store heat for a whole day
dT>|0,5°C|
restrictions by cyle II
CP/DP 9h w/ du=+-7°C
not jeopardizing service by heating system
larger du might lead to
residents feeling warm or cold radiators
noise in radiators
small increase in potential
most heating systems shut off when Tout>15°C
3 relations found
Tvar21h~du
Q~du
after step response
rate of change in indoor T decreases w/ time
until more tests available
heavy buildings w/ concrete core tolerate relatively large variations in heat delivery
energy consumption 150 kWh/m^2/a
du = +-7°C
NOP to CP/DP
dQ=10W/m^2
strategies
hot water tanks
quite common
PCMs
require investment
variation of T in DH network
used to compensate time delay
limited
efficiency losses due to higher T in distr.
material fatigue
utilizing building inertia
low cost
great potential