Gas bubbles in downward
sloping water pipes
MSc project description
Further information:
Contact Ivo Pothof
[email protected]
in co-operation with
Sanitary Engineering
Delft University of Technology
Background
Research goals
Gas pockets in pressurised waste water mains cause
significant capacity reductions, resulting in unnecessary
CSO’s and excessive power input. The current state of
knowledge on the rate at which a gas pocket is transported
through a downward slope, is limited.
The CAPWAT joint industry project is co-funded by most
Dutch water boards, several consultants and research
foundations. The objectives of the CAPWAT project include:
• development of a detection method for gas pockets
• development of measures to minimise air inflow
• determination of the required velocity to remove
capacity reducing gas pockets
• rate of gas pocket breakdown and transport
• guidelines for design, operation and maintenance of
wastewater mains
High speed camera observations have been made to
determine the gas transport rates at various combinations
of water and gas flow rates. At a critical water flow rate,
the gas is transported downward as regular plugs (see
photo). The objective of the MSc project is to develop a
predictive model for the gas transport rate around the
critical water flow rate.
Social impact
The CAPWAT project focuses on more reliable pressurised
wastewater transport and consequently contributes to
fewer Combined Sewer Overflows, smaller design
uncertainties and more efficient operation. This R&D
project is carried out by Deltares | Delft Hydraulics and
Delft University of Technology in close co-operation with
16 co-funding partners: 10 waterboards, 3 consultants, 1
pump manufacturer, Stowa and the Dutch Ministry of
Economic Affairs.
Contact: [email protected]
+31 15 278 4734 / +31 15 285 8448
www.deltares.nl/capwat
Section Sanitary Engineering
Department Water Management
Faculty of Civil Engineering and Geosciences