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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?
