eurammon Natural Refrigeration Award 2020

eurammon Natural Refrigeration Award 2020

Lecture event, October 9, 2020

2

Programme and Presentations

8:30 – 8:40 Welcome and Introduction of the Award WinnersMonika Witt - TH. WITT Kältemaschinenfabrik GmbH, eurammon Vice Chair

8:40 – 9:10 Winner 1st place - Benjamin Zühlsdorf DTU Technical University of Denmark“High-performance heat pump systems - Enhancing performance and rangeof heat pump systems for industry and district heating”

9:10 – 9:40 Winner 2nd place - Maaike Leichsenring Delft University of Technology, Netherlands“Flow visualization of downward condensing ammonia in a gasketed plate heat exchanger”

9:40 –10:10 Winner 3rd place - Fabio Giunta KTH – Royal Institute of Technology, Sweden“Techno-economic assessment of CO2 refrigeration systems with geothermal integration,a field measurements and modelling analysis”

10:10 – 10:30 Q&A session and closing remarksAndrew Stockman, Managing Director for Europe and the Middle East at EVAPCO EuropeGroup and eurammon executive board

The future is Natural!

3

The smartest decision is to leapfrog other refrigerant options and turn to the natural choices…

eurammon Natural Refrigeration Award 2020High-performance heat pump systems

Enhancing performance and range of heat pump systems for

industry and district heating

Webinar, October 9, 2020 – Benjamin Zühlsdorf, Technical University of Denmark

Agenda

High-performance heat pump systems 2

• Zeotropic working fluids in heat pumps

− Motivation and potential

− Screening procedure

− Optimization of cycle and working fluid

− Summary and outlook

• [High-temperature heat pumps]

ThermCyc

Efficient use of low-temperature heat sources


March 2014 – February 2019

Hypothesis:

Low-temperature heat sources represent a favorable energy source.

There is a great potential to enhance their utilization by:

- Novel cycle layouts

- Utilization of working fluid mixtures

- Improved component design

Tem

pera

ture

Heat

PumpORCPower Power

http://www.thermcyc.mek.dtu.dk/

Project Partners

http://www.thermcyc.mek.dtu.dk/

HP

Heat Sink

(District heating)75 °C50 °C

50 °C 25 °CHeat Source

(Data Center)

Motivation and potential

Use of zeotropic working fluid mixtures


75 °C50 °C 50 °C 25 °C




Super-

Heater

Heat Sink

Source InSource Out

Sink OutSink In

Condenser Desuper-

Heater

Sub-

Cooler

Evaporator

Throttling

Valve Compressor

Heat Source

75 °C50 °C 50 °C 25 °C




Super-

Heater

Heat Sink

Source InSource Out

Sink OutSink In

Condenser Desuper-

Heater

Sub-

Cooler

Evaporator

Throttling

Valve Compressor

Heat Source

75 °C50 °C 50 °C 25 °C




Exergy

Product48%

Compressor

21%

TV 5%

Evaporator

14%

Condenser

12%

Exergy

Destruction52%

Exergetic Efficiency = 48 %

75 °C50 °C 50 °C 25 °C




ሶ𝐸D,fluid

ሶ𝐸D,pinch

ሶ𝐸D,fluid

Exergy

Product48%

Compressor

21%

TV 5%

HX (Pinch) 5%

HX (Fluid)

21%

Exergy

Destruction52%

Exergetic Efficiency = 48 %

75 °C50 °C 50 °C 25 °C




ሶ𝐸D,fluid

ሶ𝐸D,pinch

ሶ𝐸D,fluid

ሶ𝐸D,fluid

ሶ𝐸D,pinch

ሶ𝐸D,fluid


Relating exergy destruction and COP


6.1

6.1

5.8

6.3

10.8

10.7

43.4

29.2

24.8

2.1

19.3

1.7

0 20 40 60 80 100 120

Butane

30 % DME /

70 % Isopentane

ĖD / ĖP, %

Pinch (Sink)

Pinch (Source)

Valve

Compressor

Fluid (Source)

Fluid (Sink)

2

4

6

8

10

12

14

CO

P

COP75 °C50 °C 50 °C 25 °C

Screening procedure

Case study: Data Center to District heating


75 °C50 °C 50 °C 25 °C

Screening procedure



75 °C50 °C 50 °C 25 °C

Screening procedure

How to find promising mixtures?


DME/

Isopentane

Propylene/

R-1234ze(Z)

DEE/

R-1234ze(E)

Hexane/

R-1234ze(Z)

DME/

DEE

Propylene/

Butane

Boundary

conditions

List of fluids

Pre-Screening

Energy

Analysis

Further Analysis

and Optimization

Post-Screening

Technical

Analysis

Economic

Analysis

Screening

Screening procedure



75 °C50 °C 50 °C 25 °C

Screening procedure



75 °C50 °C 50 °C 25 °C

• Pure fluids:

− COP around 4.5

− Lower ch mainly due to lower TCIspec

• Mixtures:

− Higher TCIspec allows for higher COP

− Increase in COP compensates higher

TCIspec

Screening procedure

Underlying assumptions for comparisons


75 °C50 °C 50 °C 25 °C

a) Fixed Pinch

− Simple design approach for each fluid

− Requires design experience

− Yields economically fair results

b) Fixed HX Investment

− Total investment in HX area fixed to result from ammonia in

a)

− Distribution to source/sink of area optimized

− Results were biased by choice of area/investment

c) Optimized area w.r.t. NPV

− Investment in HX area optimized w.r.t. NPV

− Numerically more demanding

Optimization of cycle and working fluid

Standard cycle


HP

Heat Sink



(e.g., process cooling)


Standard cycle


HP

Heat Sink




70 °C40 °C 20 °C 10 °C

Super-

Heater

Heat Sink

Source InSource Out

Sink OutSink In

CondenserDesuper-

Heater

Sub-

Cooler

Evaporator

Throttling

ValveCompressor

Heat Source


Standard cycle


HP

Heat Sink




70 °C40 °C 20 °C 10 °C

Super-

Heater

Heat Sink

Source InSource Out

Sink OutSink In

CondenserDesuper-

Heater

Sub-

Cooler

Evaporator

Throttling

ValveCompressor

Heat Source


Standard cycle


HP

Heat Sink




70 °C40 °C 20 °C 10 °C

No superheating in

evaporatorSuper-

Heater

Heat Sink

Source InSource Out

Sink OutSink In

CondenserDesuper-

Heater

Sub-

Cooler

Evaporator

Throttling

ValveCompressor

Heat Source


Internal Heat Exchanger cycle


HP

Heat Sink




70 °C40 °C 20 °C 10 °C

Heat Sink

Source InSource Out

Sink OutSink In

CondenserDesuper-

Heater

Sub-

Cooler

EvaporatorInternal

HX

Throttling

Valve

Compressor

Heat Source




HP

Heat Sink




70 °C40 °C 20 °C 10 °C

No Superheating in

IHX

Heat Sink

Source InSource Out

Sink OutSink In

CondenserDesuper-

Heater

Sub-

Cooler

EvaporatorInternal

HX

Throttling

Valve

Compressor

Heat Source




HP

Heat Sink




70 °C40 °C 20 °C 10 °C

Partial

Evaporation &

Superheating in

Internal HX

Heat Sink

Source InSource Out

Sink OutSink In

CondenserDesuper-

Heater

Sub-

Cooler

EvaporatorInternal

HX

Throttling

Valve

Compressor

Heat Source


Overview results


70 °C40 °C 20 °C 10 °C

a)

b)

c)d)

e)f)

23456789

CO

P

COP

22.4

21.2

20.2

18.7

18.0

17.9

9.3

11.6

12.6

3.8

4.7

3.2

11.7

8.0

4.7

7.0

4.8

4.9

20.9

16.6

14.1

17.9

14.8

14.8

1.0

1.1

1.6

0 10 20 30 40 50 60 70 80

a) Std-Cycle, 5 K SH

Butane

b) Std-Cycle, 5 K SH

20 % Propane / 80 % Butane

c) Std-Cycle, 0 K SH


d) IHX-Cycle, 5 K SH


e) IHX-Cycle, 0 K SH


f) IHX-Cycle, qevap= opt


ĖD / ĖP, %

Compressor Valve Evaporator Condenser Internal HX

qevap,out = opt

Zeotropic working fluids in heat pumps

Summary and outlook


• Heat pump applications often show temperature glides (contrary to refrigeration systems)

• Conclusions:

− Large potential for zeotropic working fluid mixtures

⬧ COP increases >30 %

⬧ Higher COP can compensate additional investment

− Temperature glide matching possible

⬧ Glide match on source side has dominating impact

⬧ Further influence from e.g., compression & expansion

− Screening required for identifying promising fluids

− Cycle layout

⬧ Considerable increases possible using standard cycle

⬧ Further improvements obtainable by cycle optimization (e.g., IHX, reduction of superheating, …)

• Challenges

− Design procedure following the screening procedure

− Experimental validation of these procedures

Benjamin Zühlsdorf

Consultant

Energy and Climate

+45 72201258

[email protected]

Thank you for your attention!

1/32

eurammon Natural Refrigeration Award 2020

Flow visualization of downward condensing

ammonia inside a gasketed plate heat exchanger

Webinar, October 9, 2020

Maaike Leichsenring

2/35

Content

Introduction

Experimental setup

Flow visualization experiments

Data analysis and evaluation

Conclusions & Recommendations

University

of

Technology

1/22‘Flow visualization of downward condensing ammonia in a Gasketed Plate Heat Exchanger’

3/35

IntroductionOTEC – by means of Ammonia

4/35

Introduction

Setup

Experiments

Analysis

Conclusions

2/22

Ocean Thermal Energy Conversion• Renewable• Natural Refrigerant

OTEC

Ammonia• Zero GWP & ODP• High availability

PHEPlate Heat Exchanger• Condensing ammonia

1

2 4

3

‘Flow visualization of downward condensing ammonia in a Gasketed Plate Heat Exchanger’

Introduction

OTEC – by means of Ammonia

5/35

Introduction

Setup

Experiments

Analysis

Conclusions

Expected

Flow patterns influence the performance

Better predictions of flow patterns enhance the accuracy

of performance calculations

Benefits

• Favourable heat transfer

coefficients

• Compactness

• Design flexibility

• Thermal effectiveness

Challenge

• Two-phase behaviour

not yet fully understood

• Over- and underestimating

heat transfer and pressure

drop correlations

IntroductionPlate heat exchangers (PHEs)


6/35

IntroductionFlow patterns

FilmSlug ChurnBubbly

4 main flow patternsGeometric configuration

of vapor and liquid

Occurring flow pattern in the

PHE generally unknown

Liquid

Vapor

4/22

Introduction

Setup

Experiments

Analysis

Conclusions


7/35

IntroductionResearch question

Scientific knowledge gapNo information is available on flow patterns of

condensing ammonia in corrugated PHE’s

Main research question’Which flow patterns are dominant inside the PHE condenser

and how do they relate to its performance?’

ApproachPerforming flow visualization experiments

and data analysis

5/22

Introduction

Setup

Experiments

Analysis

Conclusions


8/35

Experimental setupTest section

9/35

Water(cold)

6/22

Introduction

Setup

Experiments

Analysis

Conclusions



10/35

100W small scale setup

• Organic Rankine Cycle

• Pure ammonia

• OTEC purposes

High speed camera

LED

Visualization plate

ammonia

PHEVisualization section

• Plate heat exchanger

• LED illumination

• 3000 fps camera

• Visualization plate

Water(cold)• Visualization plate

Similar components to

Refrigeration cycle

7/22

Introduction

Setup

Experiments

Analysis

Conclusions



11/35

Experimental setupMaterial selection

Requirements visualization plate

Chemically resistant to ammonia

High mechanical performance

Transparent

Easy to machine

• Chemical resistance charts

• Actual chemical resistance

Contradicting Chemically resistant to ammonia

Chemical resistance tests

• Transparent materials

• Liquid ammonia

• Four days

Glass PS PMMAPS / PMMA

Introduction

Setup

Experiments

Analysis

Conclusions


12/35

Experimental setupFinal setup

PS

PMMA

Top layer

• Corrugated PS layer (4.75 mm)

• Chemically resistant

Base plate

• PMMA (20 mm)

• High mechanical performance

9/22

Introduction

Setup

Experiments

Analysis

Conclusions


13/35

Experimental setupFinal setup

PS

10/22

Introduction

Setup

Experiments

Analysis

Conclusions


14/35

Visualization experimentsTest conditions

15/35

Vapor quality

𝑥 =𝑚𝑉

𝑚𝑉+𝑚𝐿[-]

Mass flux

𝐺 =ሶ𝑚𝑎

𝐴𝑐ℎ𝑎𝑛𝑛𝑒𝑙[kgm−2s−1]

Varying parameters 𝐺, 𝑥

Introduction

Setup

Experiments

Analysis

Conclusions



16/35

Vapor quality

𝑥 =𝑚𝑉

𝑚𝑉+𝑚𝐿[-]

𝑥 [-]

𝐺[kgm

−2s−

1]

Varying parameters 𝐺, 𝑥

𝑃Condenser 7 [bar]

𝑇cold water 10 [°𝐶]

Constant parameters

Conditions chosen for

OTEC applications

Introduction

Setup

Experiments

Analysis

Conclusions



17/35

Visualization experimentsFlow path & flow pattern

1

Film flow

Separated flow

‘Dry’ zone

13/22

Introduction

Setup

Experiments

Analysis

Conclusions


18/35

Visualization experimentsFlow path & flow pattern

Film flow

Separated flow

‘Dry’ zone

14/22

Introduction

Setup

Experiments

Analysis

Conclusions


43≤ 𝐺 ≤ 64 [kgm−2s−1] 64 > 𝐺 ≥ 91 [kgm−2s−1]

19/35

Visualization experimentsInfluence of 𝐺

𝐺 = 43 [kgm−2s−1] 𝐺 = 64 [kgm−2s−1] 𝐺 = 81 [kgm−2s−1]

15/22

𝐺 = 43[kgm−2s−1]

𝑥= 0.22 𝑥 = 0.48 𝑥 = 0.62

Partial film flow

‘Dry zone’

Introduction

Setup

Experiments

Analysis

Conclusions


20/35

Visualization experimentsInfluence of 𝑥

Partial film flow Partial film flow Film flow

𝑥 = 0.3 [−]

𝐺 = 43 [kgm−2s−1] 𝐺 = 64 [kgm−2s−1] 𝐺 = 81 [kgm−2s−1]

16/22

‘Dry zone’

Introduction

Setup

Experiments

Analysis

Conclusions


21/35

Data analysisDry zone fraction

22/35

Introduction

Setup

Experiments

Analysis

Conclusions



23/35

Dry-zone fraction

𝜖𝐴 =𝐴𝑑𝑟𝑦

Aplate%

Matlab image processing

Assumptions

• Dynamic Fluid = 𝑓 𝑡• Static dry area ≠ 𝑓(𝑡)

𝐺 = 64 [kgm−2s−1]

𝑥 = 0.2 [-]

𝐺 = 43 [kgm−2s−1]

𝑥 = 0.3 [-]

𝜖𝐴 = …% ?

Conclusion

𝜖𝐴 increases with 𝑥𝜖𝐴 decreases with 𝐺

Introduction

Setup

Experiments

Analysis

Conclusions



24/35

Data analysisHeat transfer vs. flow pattern

𝜖 𝐴[−]

Conclusion

Partial film flow and film flow show

different heat transfer characteristics

Partial film flow is preferred flow

pattern w.r.t. heat transfer

𝜖𝐴 trendline𝜖𝐴 Matlab data pointsHTCs partial film flowHTCs film flow*

𝛼𝑎Wm

−2K−1

∙103

𝑅𝑒𝐿[−]

19/22

Introduction

Setup

Experiments

Analysis

Conclusions


25/35

Data analysis Flow pattern maps (FPMs)

FPMs:

• Prediction tools

• Describe which flow pattern is expected

Experimental results do not agree with

FPM

Experimental results

20/22

General FPM by Tao et al. (2018):

• vertical downward PHEs

• Mainly air-water

• Expected applicable for ammonia

Introduction

Setup

Experiments

Analysis

Conclusions


26/35

Data analysis Flow pattern maps (FPMs)

FPMs:

• Prediction tools

• Describe which flow pattern is expected

Proposed new FPM

• Downward condensing ammonia

• PHEs, current geometry

21/22

General FPM by Tao et al. (2018):

• vertical downward PHEs

• Mainly air-water

• Expected applicable for ammonia

Can be used to optimize accuracy of FPM

by Tao et al. (2018)

Introduction

Setup

Experiments

Analysis

Conclusions



Conclusions & recommendations

28/35

RecommendationsConclusions

Flow patterns

• Partial film flow

• Film flow

Partial film flow

• 𝐺 ≤ 64 kgm−2s−1

• 𝜖𝐴 increases with 𝑥

Film flow

• 𝐺 ≥ 81 [kgm−2s−1]

Flow pattern maps (FPMs)

• Results contradict FPMs

• New FPM is proposed

Performance calculations

• Flow patterns show different

Heat transfer characteristics

• Use results to improveperformance calculations

Perform more flow visualization

experiments with ammonia

In order to:

• Improve performance calculations

• Prevent faulty heat exchanger design

• Reduce unnecessary costs

In Natural Refrigeration applications.

Introduction

Setup

Experiments

Analysis

Conclusions





29/35

RecommendationsConclusions

Flow patterns

• Partial film flow

• Film flow

Partial film flow

• 𝐺 ≤ 64 kgm−2s−1

• 𝜖𝐴 increases with 𝑥

Film flow

• 𝐺 ≥ 81 [kgm−2s−1]

Flow pattern maps (FPMs)

• Results contradict FPMs

• New FPM is proposed

Performance calculations

• Flow patterns show different

Heat transfer characteristics

• Use results to improveperformance calculations

Perform more flow visualization

experiments with ammonia

In order to:

• Improve performance calculations

• Prevent faulty heat exchanger design

• Reduce unnecessary costs

In Natural Refrigeration applications.

Introduction

Setup

Experiments

Analysis

Conclusions





Questions?

Name Maaike Leichsenring

Country Netherlands

Phone +316-41913087

Mail [email protected]

eurammon Natural Refrigeration Award 2020Techno-economic assessment of CO2 refrigeration systems with

geothermal integration

Fabio Giunta - KTH – Royal Institute of Technology, Sweden

Webinar, October 9, 2020

Agenda

Techno-economic assessment of CO2 refrigeration systems with geothermal integration 2

• Objectives

• Introduction

• Field measurements analysis

• Techno-economic analysis of the geothermal integration

• Conclusion & future work

Objectives


In relation to supermarkets’ CO2 refrigeration systems integrated with geothermal storage

• Assess the heat recovery control strategy

• Evaluate the efficiency of the heat recovery system

• Assess the economic savings related to the geothermal storage

• Identify the most important parameters affecting the cost-effectiveness

• Suggest relevant future work

Introduction Field Measurements Techno-economic Assessment Conclusions

Introduction - Supermarkets’ CO2 Transcritical Booster System


Cabinets

Freezers

MT

LT

Outdoor

Heat Recovery


The most common CO2 refrigeration system installed in supermarkets is a transcritical booster system. In

these systems the heat recovered can cover both tap water and space heating demand. The heat is

recovered in the so-called “heat pump mode”. This consists of increasing the discharge pressure of the MT

compressors to recover heat at higher temperatures. When the system performs a transcritical cycle the

COP heat recovery is particularly high, thanks to the properties of the refrigerant.



Cabinets

Freezers

MT

LT

Outdoor

Heat Recovery







Cabinets

Freezers

MT

LT

Outdoor

Heat Recovery



50 bar









65 bar

Cabinets

Freezers

MT

LT

Outdoor

Heat Recovery









75 bar

Cabinets

Freezers

MT

LT

Outdoor

Heat Recovery














Cabinets

Freezers

MT

LT

Outdoor

Heat Recovery


90 bar








Cabinets

Freezers

MT

LT

Heat Recovery


Gas Cooler

by-pass

Introduction - CO2 Transcritical Booster System with geothermal integration


In the coldest period of the year, when the heat recovered from cabinets and freezers

cannot cover the heating demand, heat is extracted from the geothermal storage. Since in

summer, the ground is colder than the outdoor air, the geothermal storage is “re-charged”

sub-cooling the refrigerant. Parallel compressors are used to extract heat from the ground.









Electricity is the only energy vector, no gas, no district heating








Methodology



Field Measurements Analysis

Inputs as a function of the outdoor temperature

Modelling with BIN Hours Method

Model validation with Power Meters Readings

Geothermal Field Optimization and Techno-economic analysis

Sensitivity Analysis

Field Measurements – Cooling Demands


Cabinets

Freezers

MT

LT

0

20

40

60

80

100

120

-20 -10 0 10 20 30 40

Co

oli

ng

De

ma

nd

[k

W]

Outdoor Temperature [°C]

Cooling load averaged on the outdoor temperature

Cabinets Freezers

The typical cooling demand of the cabinets in a supermarket increases when the heating period

ends. This is due to a rise in indoor absolute humidity which is translated into a more frequent

defrosting in the cabinets. The cooling demand of the freezers is more stable since there is less

air exchange with the supermarket’s indoor environment


0

10

20

30

40

50

60

70

-20 -10 0 10 20 30 40

Po

wer

[kW

]


Tap-water Heating averaged on the outdoor temperature

Field Measurements – Heat Recovery


0

20

40

60

80

100

-15 -10 -5 0 5 10 15 20 25

Po

we

r [k

W]


Space Heating provided averaged on the outdoor temperature

The heat recovery system is driven by the space heating demand. The tap-water demand is

considered a secondary product. Therefore, the pressure is increased only when the space

heating demand requires it. This is the reason for a decrease in high-temperature heat (tap-

water) supply between 10 and 20°C. Electric resistances are used to provide the (small) extra

heating capacity for tap-water demand.


Field Measurements – COP Heat Recovery


𝐶𝑂𝑃𝐻𝑅 =𝑄𝐻𝑅𝑇𝑂𝑇

𝐸𝑇𝑂𝑇 − 𝐸𝑐𝑜𝑜𝑙 𝑜𝑛𝑙𝑦

-2

0

2

4

6

8

10

-20 -15 -10 -5 0 5 10 15

CO

P H

eat

Rec

ove

ry


COP Heat Recovery as a function of outdoor temperature

The electricity spent only for recovering the heat (𝐸𝑇𝑂𝑇 − 𝐸𝑐𝑜𝑜𝑙 𝑜𝑛𝑙𝑦)

is calculated as the total electricity spent (𝐸𝑇𝑂𝑇) and the electricity

that would have been spent if the system had satisfied only

the cooling load (𝑬𝒄𝒐𝒐𝒍 𝒐𝒏𝒍𝒚).

Introduction Field Measurements Techno-economic Analysis Conclusions



𝐻𝑅𝑅 =𝑄𝐻𝑅𝑇𝑂𝑇

𝑄𝑐𝑜𝑜𝑙𝑖𝑛𝑔𝑀𝑇+ 𝑄𝑐𝑜𝑜𝑙𝑖𝑛𝑔𝐿𝑇

+ 𝐸𝐿𝑇𝑆ℎ𝑎𝑓𝑡

𝑄𝐻𝑅𝑇𝑂𝑇

𝑄𝑐𝑜𝑜𝑙𝑖𝑛𝑔𝑀𝑇

𝑄𝑐𝑜𝑜𝑙𝑖𝑛𝑔𝐿𝑇

𝐸𝐿𝑇𝑠ℎ𝑎𝑓𝑡

MT

LT

0

2

4

6

8

10

12

20% 40% 60% 80% 100% 120% 140% 160% 180% 200% 220%

CO

P H

eat

Rec

ove

ry

Heat Recovery Ratio HRR

COP Heat Recovery as a function of HRR

COP Heat Recovery (system as a whole)




𝐶𝑂𝑃𝑔𝑒𝑜𝑒𝑥𝑡𝑟𝑎𝑐𝑡𝑖𝑜𝑛=

Qgeosupplied

𝐸𝑝𝑎𝑟𝑎𝑙𝑙𝑒𝑙 𝑐𝑜𝑚𝑝𝑟𝑒𝑠𝑠𝑜𝑟𝑠 + 𝐸𝑠𝑒𝑐𝑜𝑛𝑑𝑎𝑟𝑦 𝑝𝑢𝑚𝑝𝑠

0

2

4

6

8

10

12

20% 40% 60% 80% 100% 120% 140% 160% 180% 200% 220%

Hea

t R

eco

very

CO

P

Heat Recovery Ratio HRR

COP Heat Recovery as a function of HRR

COP Heat Recovery (system as a whole) COP Geothermal Heat Extraction

When the COP geothermal extraction and total COP heat recovery overlaps

it means that geothermal heat pump function is working in steady

conditions. This happens only during the peaks of heating demand. In

other words, the parallel compressors are forced to work in start-and-stop for

low values of HRR.


Field Measurements – Sub-cooling


0

5

10

15

20

25

30

35

40

-20 -10 0 10 20 30 40

CO

2Te

mp

erat

ure

[˚C

]

Outdoor Temperature [˚C]

Great Sub-cooling effect

Gas Cooler Outlet Temperature Expansion valve inlet Temperature

Heat recovery mode Floating Condensing

8% yearly electricity savings on the power consumed by the machine room

16 x 200m


(Over-dimensioned)

High-pressure expansion valve inlet temperature

Model validation - through power meters readings


11%

64%

18%

3% 4%

Annual electricity consumption for the refrigeration room

PC

MT

LT

Pumping

Gas Cooler Fans

0

20

40

60

80

100

-20 -10 0 10 20 30 40

Elec

tric

Po

wer

Co

nsu

mp

tio

n [

kW]


Model Results vs Field Measurements – Error ±7.5%

Average Power Consumption from power meters Average Power Consumption Calculated

Floating Condensing mode + ACHeat Recovery mode

A model representing the system was built to simulate the effect of

potential improvements and different sizes of the geothermal storage.

The model was validated comparing the expected power consumption

and the readings from the power meter installed in the machine room.



The amount of heat exchanged with the ground influences the

temperature of the secondary refrigerant which in turns influences the

amount of heat extracted (efficiency of the heat pump function) or

injected (capability to sub-cool the CO2). This means that the techno-

economic assessment needs to be solved through an iterative process!


How to size a geothermal storage for this application?

Techno-economic assessment


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Modelling Output - Ground Load

Heat Injection

Heat Extraction


The ground load represents the amount of heat extracted from or injected

into the ground in one year.

The ground is extremely unbalanced. This means the amount of heat

injected in summer is much more than the heat injected in winter. This

increases the necessary size of the storage reducing its cost-effectiveness.



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Heat Injection

Heat Extraction






increases the necessary size of the storage reducing its cost-effectiveness.The present value of the operational savings represents the amount that

the supermarket should be willing to pay per meter of storage, taking into

account only the operational savings. This does not take into account

a potential difference in the CAPEX.



43 kW

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Total Length of the storage [m]

Present Value of the Operational Savings

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Heat Injection

Heat Extraction







Moreover, also the power peaks of heat injected (in this application)

are one of the parameters driving the size of the storage.

7.4% Discount rate

15 Years lifetime

The present value of the operational savings represents the amount that






43 kW

40 kW

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15 Years lifetime







43 kW40 kW33 kW

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Heat Extraction









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15 Years lifetime







43 kW40 kW33 kW

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15 Years lifetime







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Optimizing the cost-effectiveness reducing design capacity -

Present Value of the Operational Savings Current Drilling Cost

7.4% Discount rate

15 Years lifetime








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Heat Extraction

43 kW40 kW33 kW

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Optimizing the cost-effectiveness reducing design capacity -

Present Value of the Operational Savings Current Drilling Cost

7.4% Discount rate

15 Years lifetime





a potential difference in the CAPEX.-10

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Design Sub-cooling Capacity

Net Ground Balance

Heat Extraction (heat pump mode) Heat Injection (Subcooling) Net Ground Balance

Sensitivity Analysis – Supermarket size

Techno-economic assessment of CO2 refrigeration systems with geothermal integration

Different cooling demand profiles were tested, varying the other

parameters proportionally (e.g. heating demand).

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Present Value of the Operational Saving – Size Variation

Reference Higher Cooling Demand Lower Cooling Demand Current Drilling Cost


32

Umeå

Stockholm

Kiruna

Sensitivity Analysis – Climate zone


Different climate zones were tested. This was

performed using BIN hours from other climate zones.

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Present Value of the Operational Saving - Climate Zone Variation

Reference (Stockholm) Umea Kiruna Current Drilling Cost


33

Sensitivity Analysis - Heat Recovery Ratio


Different values of heat recovery ratio were tested. A higher heat recovery ratio

means operating a system with a higher heating demand for the same cooling load.

Typical examples of systems operating with a high heat recovery ratio are

supermarkets embedded in shopping malls or ice rinks exporting heat to the

neighbouring facilities.

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Total Length [m]

Present Value of the Operational Saving - Variation of HRR

Reference (HRR 54%) HRR 70% HRR 76% Current Drilling Price


𝐻𝑅𝑅 =𝐻𝑒𝑎𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑

𝑇𝑜𝑡𝑎𝑙 𝐶𝑜𝑜𝑙𝑖𝑛𝑔 𝐿𝑜𝑎𝑑

Seasonal

HRR 54%

Seasonal

HRR 70%

Seasonal

HRR 76%

34

Conclusion



• The COP heat recovery can compete with the most modern heat pumps

• The operational savings only do not pay back the installation cost. There must be savings on the

CAPEX when comparing alternatives for satisfying the peaks of heating demand.

• The average HRR is the parameter affecting the cost-effectiveness the most

Conclusion


Future Work:

• Is it possible and profitable to use these systems for exporting heat to district heating networks in power-to-heat

applications?

• Is it cost-effective to use air-to-CO2 load evaporators instead of a geothermal integration?


• The COP heat recovery can compete with the most modern heat pumps

• The operational savings only do not pay back the installation cost. There must be savings on the

CAPEX when comparing alternatives for satisfying the peaks of heating demand.

• The average HRR is the parameter affecting the cost-effectiveness the most

Thank You!

Questions?

Fabio Giunta

[email protected]

Brinellvägen 68, 10044 Stockholm, Sweden

mailto:[email protected]

eurammon Contact Details

Dr. Karin JahnManaging Directoreurammon e.V.Lyoner Straße 1860528 [email protected] +49 69 6603 1277

mailto:[email protected]

Documents

eurammon Natural Refrigeration Award 2020