Heatreflex

Green and Flexible District
Heating/Cooling in Turkey

Contents:
1. Introduction
2. Presented solutions in HeatReFlex
2.1. Geothermal-driven DHCN
2.2. Waste heat-driven DHCN
2.3. Hybrid systems
2.4. Municipal waste-fired DHCN
2.5. Biomass based solar boosted DHCN

Introduction
 Utilizing renewable and sustainable energy sources is one of the
future smart energy systems main features.
Sustainable energy:
Think to the next generation
Sustainable energy is the practice of using energy in a way that "meets
the needs of the present without compromising the ability of future
generations to meet their own needs.
Renewable energy:
That’s clear

 Local energy systems with high flexibility are
becoming more and more important due to reducing
transportation losses and associated cost while
significant benefits are connected with an increase in
the flexibility of the available energy systems.
 Among the all, centralized local energy systems,
district heating/cooling (DH/C) are under an special
attention.
DH/C: is a system for distributing heat/cool generated in a
centralized location through a system of insulated pipes
for residential and commercial heating/cooling
requirements.
Introduction

 HEATREFLEX:
GREEN AND FLEXIBLE DISTRICT HEATING/COOLING
https://heatreflex.et.aau.dk/
This project will lay the foundation for a future bottom-up energy system based on renewables, communities
(from building-level up to cities and beyond), and flexibility providing better user motivation/engagement,
stability, and transition to sustainability in Turkey to meet the climate commitments and improve economic
 Some of the main frameworks and constructions:
• Utilizing locally available renewable energy sources like geothermal, solar, biomass, …
• Utilizing locally available waste heat from the industries
• Proposing energy systems with high flexibility
• Considering sustainability in the proposed solutions
• Considering cost analysis
• Benchmarking possibility of coupling different sustainable energy sources
• Managing both demand- and supply side
Introduction

Solutions
 Geothermal-driven DHCN:
• A combination of an small-scale ORC, a single effect absorption chiller and some auxiliary heat exchangers
• A medium temperature geothermal well in Izmir-Balcova region is selected as the candidate source
• System operated under the steady state condition to supply electricity, cooling and heating (both hot water and
district heating) of neighborhood
• Exergy and sustainability analysis are
carried out and system performance is
investigated under different chiller
supply
• a sensitivity analysis to obtain the best points of
operating condition from the thermodynamic and
sustainability points of view is provided

Thermodynamic and sustainability principles:
 Mass balance:
 Energy conservation:
 Exergy balance:
 Sustainability index:
  ei mm 
  eeii hmWhmQ 
   desteeWiiQ EemEemE 
pD
SI
1

in
D
p
E
E
D



Solutions

Chiller performance is optimized and several working fluids is considered in the ORC:
Finally, R123 is selected as the most appropriate candidate:
Compound Molecular weight
(kg/kmol)
Critical
temperature (˚C)
Critical pressure
(bar)
Boiling temperature at 1
atm (°C)
Eccentric
Factor
R123 152.9 183.7 36.7 27.8 0.2821
Solutions

Share of each component in the total exergy destruction is obtained as:
HE1
9%
HE2
19%
HE3
6%
ORCT
3%
ORCE
21%
Cond
5%
Eva
2%
Abs
10%
Gen
24%
SHE
1%
As it was expected, the highest exergy destruction refers to the generator implemented in the absorption chiller
mainly due to the water content evaporation within this unit which causes 24% of total exergy destruction.
Solutions

Since the components with the lower second law efficiency are always matters of concern, the second law
efficiency of each component is determined as:
Temperature mismatching between the hot and cold streams resulted in the irreversibility within the heat
exchangers and more difference between hot and cold streams temperature glide and more exergy destruction.
0
10
20
30
40
50
60
70
80
90
100
HE1 HE2 HE3 ORCT ORCE Eva Gen SHE Total
Exergyefficiency(%)
System main components
Solutions

A sensitivity analysis regarding chiller supply and source condition is carried out:
• Both exergy efficiency and sustainability index of the proposed system increase with increasing chiller supply
rate.
• Energy efficiency of the geothermal-driven
CCHP system decrease with an increase in
chiller supply rate.
Solutions

• change in the geothermal flow rate has no considerable effect on the system performance.
Solutions

 Waste heat-driven DHCN:
• A specific waste heat source of a cement plant is considered with real data to run a domestic-scale CCHP
system.
• CCHPs are operating with steam and organic Rankine cycles under steady state conditions equipped with
absorption chiller.
• Thermodynamic, sustainability and economic performance of the proposed systems are investigated and
compared.
 Sanliurfa cement plant waste heat source condition:
Temperature (K) Mass flow rate (kg/s) Compositions
523 18.43 68.9% N2, 22.5% CO2, 5.8% H2O, 1.1% O2, 1% Ar, 0.7% SO2
Solutions

• Waste heat-driven CCHP based on the
regenerative ORC is proposed
• Waste heat-driven CCHP based on the
steam cycle is proposed
Solutions

Exergoeconomic principles:
 Cost balance equation:
 Unit cost of exergy:
 Levelized cost of equipment:
 Capital recovery factor:
  kokwkkikq CCZCC ,,,,

i
i
i
E
C
c



3600

N
CRFZZ

1)1(
)1(


 n
n
i
ii
CRF
Solutions

Compound Molecular weight
(kg/kmol)
Critical
temperature (˚C)
Critical
pressure (bar)
Boiling temperature
at 1 atm (°C)
Eccentric
factor
R123 152.9 183.7 36.7 27.8 0.2821
MM 162.4 245.5 19.39 100.3 0.4192
MDM 236.5 290.9 14.15 152.6 0.5301
• Considering temperature range of the waste heat source, siloxanes are involved in the ORC working fluid list and
MM is selected as the most appropriate one.
56
57
58
59
60
61
62
63
64
65
MM MDM R123
550
560
570
580
590
600
610
620
Exergyefficiency[%]
Working fluids
Netproducedpower[kW]
Net produced power [kW]
Exergy efficiency [%]
Solutions

• Steam turbine inlet pressure and different superheating degree are taken into account to obtain the best
operating point for the steam based CCHP system.
• Both system exergy efficiency and net produced power by the steam cycle are optimized in a specific value of
turbine inlet pressure.
Solutions

Destruction
within ORC
25%
Destruction
within HE
3%
Destruction
within Chiller
5%
Effluent
4%Power
54%
SPH
3%
SPC
1%
DHW
5%
ORCE
33%
ORCT
18%
IHE
17%
ORCC
32%
ORCP
0%
Exergy balance within the ORC based CCHP system:
• 54% of the input exergy is altered to mechanical power,
5% is transferred as DHW, 3% as SPH and 1% as SPC
• Then the exergy efficiency of 63% is calculated.
• Details of the exergy destruction within the ORC, as the
most exergy destructive unit, is calculated.
Solutions

Exergy balance within the steam based CCHP system:
• 40% of the input exergy is altered to mechanical power,
8% is transferred as DHW, 3% as SPH and 2% as SPC
• Then the exergy efficiency of 53% is calculated, 10 points
(compared with 63%) lower than ORC based CCHP
system
• Details of the exergy destruction within the steam cycle, as
the most exergy destructive unit, is calculated.
Destruction
within Steam
cycle
28%
Destruction
within HE…
Destruction
within Chiller
9%Effluent
4%
Power
40%
SPH
3%
SPC
2% DHW
8%
HRSG
57%ST
15%
SC
28%
SP
0%
Solutions

Both suggested systems are compared economically in detail:
Parameter Steam-based CCHP ORC-based CCHP
Estimated purchased equipment cost [million $] 0.7 0.78
Estimated total capital investment [million $] 2.9 3.259
Unit cost of produced electricity [$/GJ] 3.268 3.089
Unit cost of produced SPH [$/GJ] 7.858 3.609
Unit cost of produced SPC [$/GJ] 13.29 17.38
Unit cost of produced hot water [$/GJ] 0.6481 1.033
Payback period [year] 4.738 5.074
 Although the ORC based CCHP performs better, exergetically, has higher payback
period compared with steam based CCHP
Solutions

Effect of chiller supply on the economic performance and sustainability of the systems is analyzed:
When cooling demand varies from 100 to 500 kW in the ORC-based system sustainability index decreases from
2.964 to 2.551 and payback period increases from 4.677 to 5.469 year. For the case of steam-based CCHP when
cooling demand increases from 100 to 900 kW sustainability index decreases from 2.24 to 1.906 and payback
period increases from 4.112 to 5.293 year
Solutions

Energy
Exergy
Economic
Sustainability
CCHP to
waste heat
recovery from
Sanliurfa
cement plant
with domestic
applications
Case 1:
Rankine Cycle-
based CCHP
Case 2:
ORC-based
CCHP
Case 2
Case 2
Case 1
Case 2
Solutions

 Hybrid systems:
Utilizing waste heat and low-medium temperature geothermal heat sources in a centralized domestic heating,
cooling and electricity network in line with sustainable development is suggested.
Solutions

 Hybrid systems:
• Both geothermal- and waste heat-driven CCHPs are equipped with the ORC and single effect LiBr-H2O
absorption chiller, which are shown in previous slides.
• Energy demand profiles are calculated for the hypothesized case study over an entire year in terms of space
heating/cooling, domestic hot water and electricity. In order to make a domestic hot water consumption pattern,
the draw-off profile of a typical single-family dwelling without bathtub is utilized.
• In the considered case study in the Gaziantep, Turkey it is supposed that a total of 100 single-family detached
houses exist, which will be covered by DHCN.
• Presented system was a combination of the 3rd and the 4th generations of district heating systems with the
regular operation temperature of around 40 °C for space heating and 80 °C for domestic hot water.
• Both CCHPs covering DHCN are modeled thermodynamically.
Solutions

 Hybrid systems:
Contributions of this study compared to the previous studies in this subject area are as follows:
• Assessment of both supply- and demand-sides performance of DHCNs in terms of different types of energy
demand (space heating/cooling, domestic hot water and electricity).
• Calculating economic benefits of using designed local energy system instead of the main grid to supply
domestic energy demand.
• Utilizing low quality energy sources like geothermal and cement industry waste heat to run a CCHP supplying
district energy demand.
• Using heat rejection from the CCHPs during condensation process for domestic space heating (SPH)
application.
Solutions

 Hybrid systems:
Ambient condition for the Gaziantep:
 Solar radiation in the considered
residential area in Gaziantep,
Turkey over Jun 29 and Dec 24
(the highest and the lowest)
 Average ambient high and low
temperature and average daily incident
solar energy of the considered
residential area in Gaziantep, Turkey
over an entire year
Solutions

 Hybrid systems:
Since the ambient temperature profile is available, the CCHPs performances are investigated during the entire
year:
For the case of geothermal-driven CCHP:
During summertime exergy efficiency and sustainability index of the system decrease and this is mainly refers to
a reduction in the exergy rate associated with the supplied DH
Solutions

 Hybrid systems:
For the case of waste heat-driven CCHP:
During the entire year, exergy efficiency of the waste heat-driven CCHP varied between 62.28-64.1% and
sustainability index of 2.651-2.785 are obtained for this system.
Solutions

 Hybrid systems:
Domestic hot water consumption profile and overproduced by the designed local energy system for one day
(daily pattern is repeated over the entire year.):
Domestic hot water consumption by the case study varies between 0 and 188 kW and this amount of demand
can be completely fed by the proposed local energy system. In this way extra 2830-3018 kW hot water can be
supplied to the main grid of domestic hot water supply.
Solutions

 Hybrid systems:
Electricity consumption profile:
No air conditioning is needed for the considered buildings and seasonal changes do not affect electricity
consumption pattern considerably (daily pattern is repeated over the entire year.):
The maximum electricity that is needed to be fed by the main grid is almost 387 kW. During the off-peak period,
however, the local energy system is able to charge the main grid with a maximum electric power of 677.6 kW
Solutions

 Hybrid systems:
Space heating:
A range of indoor comfort temperature is considered for the winter days (20-24 °C).
The maximum heat demand changes between 717 and 861 kW within the first months of the year for the
comfort temperature of 20 and 24 °C, respectively.
The designed local CCHPs not only supplies the required heat, but also provides more than 5100 kW extra
heating to the main grid
Solutions

 Hybrid systems:
Space cooling:
A range of indoor comfort temperature is considered for the winter days (24-27 °C).
The space cooling demand touches the maximum value of 526.8 and 631 kW for the indoor comfort
temperature of 27 and 24 °C, respectively.
The proposed local CCHPs have a overproduce of 193.8 – 824.8 kW cooling, which can be delivered to the
main grid.
Solutions

 Hybrid systems:
Economic benefit of the householders:
It is assumed that cost of the electricity supplied by the main grid is 20 €/MWh, while cost of heating and cooling
is almost 15 €/MWh.
Different forms of energy SPH SPC DHW Electricity Total
Cost of energy supplied via
the main grid (€/year)
18168 7315 5206 6569 37258
Cost of energy supplied via
designed local CCHPs
(€/year)
14304 2774 1173 3320 21571
Economic benefits of
households (€/year)
3864 4541 4033 3249 15687
Almost 15687 € will be saved for the households with employing the proposed local energy system.
Solutions

 Municipal waste-fired DHCN:
A waste-fired CCHP is presented to cover the heating, cooling and electricity demand of the neighborhood and
results are compared with those of a conventional CHP.
Solutions

 Waste-fired cogeneration system is proposed to not only make an integration between the cold, heat and
electricity sectors but also to improve the energy, exergy and sustainability indices of the conventional waste-
driven CHPs.
 A waste heat recovery system is also considered (flue condensation system) to improve the system efficiency.
 A wide spectrum of heat supply schemes, including the existing system (3rd generation), low-temperature and
ultralow-temperature technologies, is considered.
 Municipal solid waste is considered as the waste source:
Item Information/value
Type of waste Municipal solid waste
Waste compositions (weight percent)
5.91% Ash
47.18% Carbon
6.25% Hydrogen
39.57% Oxygen
0.91% Nitrogen
0.18% Sulphur
LHV of the waste (kJ/kg) 12,500
Turbine isentropic efficiency (%) 90
Electricity generator efficiency (%) 95
Effluent temperature (K) 438
Excess air in the incineration process 80%
Combustion product temperature (K) 1373
Solutions

Exergy balance within the proposed waste-fired CCHP
ST
2%
Incin
79%
HE2
1%
HE1
2%
Gen
3% Cond
1%
Effluent
10%
Others
2%
The highest exergy destruction is associated with the incinerator, which is inevitable due to the existence of all the
irreversibility sources such as chemical reaction, mixing, heat losses from the control volume, temperature difference
etc. in this control volume.
Solutions

Effect of chiller supply (α) on the system efficiency operating with different district heating technologies
Both of the energy and exergy efficiencies of the system decrease as α goes up. Lowering the operating
temperatures of district heating system (going from the 3rd generation design to low- and ultralow-temperatures)
increases the energy efficiency but decreases the exergetic efficiency of the system
Solutions

Effect of chiller supply (α) on the system technical performance
In the system operating with the 3rd generation standard temperatures, increasing α from 0.1 to 0.9 increases
the supplied cooling from almost 21 kW to 5,655 kW and reduces the supplied heat from 7,804 kW to 843 kW.
An increase in chiller supply results in a growth in the steam turbine outlet pressure and net output power
reduction.
Solutions

Effect of chiller supply (α) on the system sustainability
The sustainability index of the CCHP system operating with the 3rd generation district heating concept decreases
from 1.4 to 1.269 when α changes from 0.1 to 0.9.
Solutions

 Biomass based solar boosted DHCN:
Biomass is selected as a renewable energy source and a novel CCHP with capacity of delivering 1
MWe system is designed and modeled to meet the energy demand of an special neighborhood in terms
of electricity, heating, and cooling.
Solutions

Describing the designed system:
• Efficient use of solar energy and biomass resources has been considered.
• Biomass thermal energy is utilized as an incorporating energy source to run a domestic-scaled
CCHP.
• An externally fired gas turbine, a steam Rankine cycle, an absorption chiller and a concentrated
photovoltaic thermal (CPVT) were the main components of the presented system, which are
analyzed using the thermodynamic principles.
• Gas and steam turbines produce the main part of electrical power, while the chiller and the
employed heat exchangers recover the waste heat of the system to supply district cooling and
heating.
• A pressurized water circuit is also harvested the waste heat from the employed steam cycle and
concentrated photovoltaic to supply domestic space heating.
Solutions

Solutions
Comparison of constituents between present model and those obtained from experimental analysis for wood as biomass at a
gasification temperature of 800 ˚C and moisture content of 20%.
Constituents Present model Experiment
H2 20.16 15.23
CO 20.03 23.04
CH4 2.719 1.58
CO2 13.34 16.42
N2 43.75 42.31
O2 0 1.42
Wood is considered as the utilized biomass and the obtained results for the gasifier were compared with
experiments in order to validate the results.

Solutions
Breakdown of the exergy destruction within the
proposed DHCN
 the most important component from the exergy
destruction point of view is the CPVT, followed
by the gasifier
 A high value of exergy destruction within the
solar cells are mainly due to inappropriate
temperature glide between the cell surface and
pressurized water.
 For the case of gasifier it should be considered
that, the exergy destruction within this
component is mostly due to chemical reactions
and, which seems not much can be done in
improving its exeretic performance.

Solutions
A parametric study has been carried out

Solutions
Both summertime and wintertime operating conditions were taken into account in the system modeling
Thermodynamic performance of the proposed CCHP under the summertime and wintertime conditions
Parameter (unit) Summertime Wintertime
Net produced power (kW) 1000 1000
Delivered SPH (kW) 0 1241
Delivered SPC (kW) 0-110.7 0
Delivered DHW (kW) 202.9 - 0 202.9
Rankine cycle exergetic efficiency (%) 70.46 71.53
CPVT thermal efficiency (%) 8.688 68.13
CPVT exergetic efficiency (%) 12.16 14.2
Total thermal efficiency (%) 41.18 – 38.02 83.68
Total exergetic efficiency (%) 34.78 - 34.31 35.47
SI (-) 1.533 – 1.522 1.55

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