Innovative High Temperature Heat Pump - PFI...

2nd User Group Meeting, MIROM Roeselare PFI Workshop Heat Pumps in CHP Bruno Vanslambrouck 03/09/2013 1

Innovative High Temperature Heat Pump

Ing. Bruno Vanslambrouck

HOWEST/Ghent University,

Research Group on Thermal

Energy in Industry (TEI)


Presentation overview

1. High Temperature Industrial Heat Pumps (HT IHP)

2. How to power a HT IHP ?

3. Case study from food industry

4. HT IHP R&D projects

5. HOWEST – ESSET/E2S project


Example:

Waste heat temperature: 30°C

Desired process heat temp: 80°C

COP = 353 / (353 – 303) = 7 (Theoretical optimum according to Carnot)

In fact: about 50-60% of Carnot eff., in this case 3,5 à 4,2

Profit of an electrical driven heat pump:

- Primary energy savings when COP > 1/eff E-production, being about 2,5

- Gain on energy costs if COP > E-price/Heat cost (2,5 à 4 within industry)

IHP: bigger as for residential use

HT IHP: heat flow temp

output from ca 65-70°C !

Limit (current market supply):

ca 90°C !!

High Temp Industrial HP


How to realize HPs for higher temperature regimes ?

Some (low temperature) ORC’s are in fact reversed cooling devices: - evaporator and condenser are switched

- compressor becomes expander, motor becomes generator

- expansion valve replaced by a pump

- system pressure increased to evaporate/condense on higher t° level

Example: ORC (right) to

produce electricity from

(geothermal) hot water of

75-85°C, if ambient t° <

5°C (Alaska), derived from

a Carrier chiller (left)



To further increase evaporator/condenser temperatures when max

pressure level is reached, working fluid can be changed.

Example: previous ORC can convert waste heat on 140°C (or more) into electricity

on “normal” ambient temperatures after replacing R134a by R245fa.

This is the well known Pure Cycle 280

(250 kWe) ORC of Pratt&Whitney



High temperature heat pump:

- Keep configuration as a cooling device

- Increase pressure (to max allowable )

and switch working fluid

- Reverse temperature differences

over evaporator and condensor

Example:

The Pure Cycle 280 could be

“reversed” to produce 110-115°C

process heat from 40-50°C waste heat



Important: which COP could be reached ?

Realistic goal on HT IHP: COP = 2,5 or higher, depending on t°-diff

between low and high t° stream (the smaller the better).

On current industrial energy prices (ca EUR 30/MWh gas and EUR

90/MWh E), energy costs savings by using an E-powered HT IHP

only to realize if the COP exceeds 3 !

Solution when COP < 3 à 4 (often on HT IHP):

Power the HT IHP directly with a thermal machine (internal

combustion engine or gas turbine).

Waste heat from this machine is to integrate into the entity (jacket

cooling water on the input or output side, surheating output using

exhaust gas heat to realize smaller delta t all over the heat pump)

How to power a HT IHP ?


Heat

Exchanger

Combustion

Engine

Waste Heat

Boiler Condenser

Evaporator

Exhaust Gases, 480°C Expansion

Device

Compressor

4 MW

3 MW

500 kW 650 kW

1 MW η=42% Fuel in: 2,38 MW

95 l/s, 60°C

90°C

70°C 71,3°C

75°C

20°C 20°C

COP = 4

Heat Source (Water) 48 l/s, 40°C

25°C

85°C

Heat Sink

72,9°C

Cooled Exhaust Gases, 90°C

η =P + Q

Fuel=

1 + 1,15

2,38= 90,3%

η =Q

Fuel =

4 + 1,15

2,38= 216%

CHP:

CHP + HP:

Example 1:



Combustion

Engine

Waste Heat

Boiler Condenser

Evaporator

Exhaust Gases, 480°C Expansion

Device

Compressor

3 MW

2 MW:

1,5 recuperation +

0,5 Jacket cooling

600 kW

1 MW, η=42% Fuel in: 2,38 MW

100°C Saturated Steam 5 bar, 159°C

170°C

80°C 80°C

COP = 3

Heat Source (Vapors), 95°C

85°C

Cooled Exhaust

Gases, 120°C

85°C 90°C

Example 2:



Source: MAN Dezentrale

Energiesysteme, 1995



Case from food industry

Boundary conditions:

- Waste heat available as vapors from a frying process (about 3 MW recoverable,

mainly latent heat @ 95°C)

- Process heat needed to reheat frying oil

from ca 150 tot 180°C (about 4,8 MW)

First approach(*): - 1-stage compressor

- Evaporator temp about 80°C

- Condensor temp about 180°C

(further heating by use of engine exhaust)

- Max system pressure about 25 bar

- Max pressure ratio about 10

* Mechanical Vapor Recompression rejected because of oil content vapor


Working fluid selection:

Focus on commonly used ORC fluids: cooling fluids, silicone-oils, organic fluids

such as pentane, toluene,…

Selection criteria are:

• Tcrit > 180°C

• psat 180°C < 25 bar

• psat 80°C > 1 bar (if possible, to avoid vacuum)

• Boiling point < 90°C

• Pratio 80-180° < 10 (common screw compressor)



Fluidname Formula Tcr [°C] pcr [bar] 180 80

pentane C5H12 196,6 33,68 26,33 3,69 7

R113 R113 214,2 34,10 20,46 2,64 8

toluene C7H8 318,7 41,06 5,20 0,39 13

Hexamethyldisiloxane HMDS 245,5 19,51 6,58 0,53 12

Octamethyltrisiloxane OMTS 291,0 14,15 1,96 0,09 21

R11 (*) R11 198,0 44,03 33,84 5,20 7

R365mfc R365mfc 186,9 32,66 29,01 3,52 8

Cyclopentane C5H10 238,6 45,10 19,58 2,52 8

water H2O 374,1 220,90 10,02 0,47 21

cyclohexane C6H12 280,49 40,75 9,75 0,99 10

hexane C6H14 234,15 30,1236 13,17 1,42 9

Psat [bar] on Tsat [°C]Pressure

ratio

(180/80)

Some results (candidate fluids):



HP simulation with Cycle Tempo (simple configuration)

Medium : cyclopentane

COP = 2648 kW / 1053 kW = 2,5 ( 55% of Carnot-limit)



HP – simple configuration



HP – cycle with recuperator

COP = 3017 kW / 1053 kW

= 2,9

(64% of Carnot-limit)



Calculation Pmech and Pth

Pmech 1452 kW Fryer vapor heat recuperation

Pth out,HP (= Pmech x COP) 4211 kWth Pfryer vapour 2759 kWth

Pth,recup (ex gases ) 589 kWth

Pth out,HP + Pth,recup 4800 kWth (thermal energy to fryer)

Gas consumption

PNG 3377 kWth (Pmech/eff. gas engine)

Gas savings 36,7% (Assume boiler eff. = 90%)

HP–cycle with recuperator:

energy savings by using a gas engine for driving an (expensive)

process gas compressor with discharge t° over 230°C



HT IHP R&D projects

EDF R&D France


HT IHP R&D projects


HT IHP R&D projects

Coordinator: EDF-R&D

Partners:

JOHNSON CONTROLS, FRANCE EVAPORATION,

AGROPARISTECH, CETHIL,IPB-ENSEIRB-

MATMECA

Duration of project:

4 years (December 2009 - December 2013)

Total budget of the project: 3.2 million €

Goal: to develop an industrial water based heat

pump, to recycle high-temperature waste heat


HT IHP R&D projects

Why water ?


Results:

- HP with screw compressor: 92°/137°C evaporator/condensor t°

realized but mechanical efficiency evaluated as too low

- with magnetic driven centrifugal compressor: mechanical/thermal

validation in progress.

Expected results:

COP = 5,5 on 85°/125°C

regime

HT IHP R&D projects


HT IHP R&D projects


Thermoacoustic heat

transformer

Waste heat temperature: 140°C

Process heat temperature: 190°C

HT IHP R&D projects


Test facility @ HOWEST

Originally designed for ORC test and demonstration but also adapted

for:

- Heat pump test and demonstration

- Heat exchanger tests

- Heat storage tests (e.g. PCM)


High temperature heat pump – Lab setup (ESSET)

HOWEST-ESSET/E2S


Industrial project: ESSET/E2S

Development of a HT IHP, derived from a

Modified towards a completely open heat pump

Heat source:

Thermal oil

Heat sink:

water/glycol

120°C

80°C

HOWEST-ESSET/E2S


Superheating after compressor to avoid by fluid injection:

HOWEST-ESSET/E2S


HOWEST-ESSET/E2S


Pressure ratio

HOWEST-ESSET/E2S


Graaf Karel de Goedelaan 5, B-8500 Kortijk

Mail: [email protected]

Tel: +32 56 241211 of +32 56 241227 (dir)

www.ugent.be ww.wasteheat.eu

www.cornet-w2pheat.eu

Contact

Thanks to all of you for your attention

Time for questions…discussion ?

Ing. Bruno Vanslambrouck

HOWEST/Ghent University,

Research Group on Thermal Energy in Industry (TEI)

mailto:[email protected]

mailto:[email protected]

http://www.ugent.be/

http://www.wasteheat.eu/

http://www.cornet-w2pheat.eu/



Innovative High Temperature Heat Pump - PFI...

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