5 August 2010

HEAT LOSS ANALYSIS AND OPTIMIZATION OF A FLEXIBLE PIPING NETWORK

‘Engineering for plastic networks’

Hans Korsman

Liandon B.V.

5 August 2010

Liandon

• Subsidiary of Alliander, largest network operator (former Nuon)

• Engineering firm for Energy Distribution Networks– High voltage– Natural Gas– District Heating & Cooling

• Activities– Research & Development– Engineering– Projects– Operation

Leeuwarden

Alkmaar

Duiven

5 August 2010

Contents

• Optimisation of a flexible pipe system, with a rigid reference– Plastic medium pipes vs Steel pipes– Flexible PE foam vs rigid PUR foam

• Product optimisation– Pipe heat loss performance

• System optimisation– Network heat loss performance– Improved network engineering strategy– Using the specific advantages of plastics

5 August 2010

Theory of heat loss calculations

• Heat loss dependant on:

– Insulation thickness (d3-d2)

– Insulation quality (λinsulation)

insulation 2 Tprobe Tcasing

1

mediumln

d2

d1

1

insulationln

d3

d2

1

casingln

d4

d3

5 August 2010

2 70ºC 15ºC( )1

0.19W

m K

ln25mm

20.4mm

1

0.03W

m K

ln44.8mm

25mm

1

0.4W

m K

ln45.9mm

44.8mm

16.796

W

m

What can we do to reduce heat loss?

• Example:– Plastic 50A25

1.1 19.4 0.06

5 August 2010

Reducing heatloss

• By increasing insulation thickness• Example Plastic 50A25

0

2

4

6

8

10

12

14

16

0 25 50 75 100 125 150 175

Insulation thickness [mm]

Hea

t L

oss

[W

/m]

5 August 2010

Compensation for poor λ_insulation

0.025 0.03 0.035 0.040.8

0.9

1

1.1

1.2

d3 _insulation( )

44.8 mm

_insulation W/m.K

5 August 2010

Improvements in PE insulation quality

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

50A25

63A32

75A40

90A50

90A40

90A32

125A

63

125A

50

160A

90

160A

75

200A

110

Nominal Diameter

La

mb

da

[W

/mK

]

Lambda Assumed Lambda Realised

5 August 2010

Product improvement

• An increase in foam thickness and quality

5 August 2010

Engineering strategy

• Example district heating network, Arnhem, The Netherlands

5 August 2010

Hydraulic engineering steel

• Conventional engineering:– Linear target pressure drop over distance, ΔP/L, e.g. 300 Pa/m

• Optimised engineering:– Nonlinear target pressure drop– Maximum speed is constraint

5 August 2010

Using the advantage of plastic pipes

• Less friction• Higher speeds allowed • Less noise propagation• Nonlinear target pressure drop

5 August 2010

Diameter distribution

ST/PUR/PE ref.

PB impr. fresh

5 August 2010

Overall system heat loss calculation

Overall

distribution system heat loss

Per pipe heat loss performance

Pipe diameter distribution

ST/PUR/PE ref.

PB impr. fresh

5 August 2010

Life cycle heat loss

• Ageing of insulation foam

PUR reference contains 95% blowing agent

5 August 2010

Conclusion

1. It is quite feasible to reach comparable heat loss for flexible systems

2. It is easier (cheaper) to do so for smaller diameters

3. High rate of product improvement, lots of potential

4. Insulation properties of PE foam possibly as good as PUR

5. Specific properties of plastic pipes can be utilised to reduce system heat loss

6. Interesting engineering optimisation problem between 2 and 5

5 August 2010

The End

• Thanks for your attention!

• Any questions?