DSD-INT 2015 - bridging the gab in future sanitation - adithaya thoa radhakrishnan

1Challenge the future
D-SHIT
Adithya Thota Radhakrishnan
Domestic Slurry Hydraulics
In Transport systems
a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!

Introduction
1 Objective
2 Rheology
3 Modelling
4
Sanitation systems
Planned
5
• Simple to Complex
• Industrialised countries
• High water consumption
• Expensive treatment
• Loss of resource

Objective
2 Rheology
3 Modelling
4
New sanitation concept
Introduction
1 Planned
5
Source
separation
Resource
recovery
Low water
consumption

Introduction
1 Objective
2 Rheology
3 Modelling
4
New sanitation: elements
Treatment
Transport
Collection
Source
Separation
Vastly
overlooked
Planned
5
D-SHIT project??
Transport design for domestic slurry of
Grinded Kitchen Waste + Feces + Urine?
Collection tank
WWTPD-SHIT

Introduction
1 Objective
2 Rheology
3 Modelling
4
What does this mean for us?
Planned
5
Increase in
total solid
concentration
Vacuum toilets
+
Kitchen grinder
Example: Ketchup vs. Water

Introduction
1 Objective
2 Rheology
3 Modelling
4
D-SHIT Objective?
Planned
5
• To study the flow of domestic slurry at various solid
concentration and temperature
• To determine the optimum design conditions for
the slurry transport
• To determine the optimum dilution for the slurry

Rheology
Rheology of Concentrated Domestic Slurry
A mixture of Brown water (Faeces + Urine)
and Grinded Kitchen Waste

Introduction
1 Modelling
4
Complexity of CDS
Planned
5
0
0,2
0,4
0,6
0,8
1
1,2
0 50 100 150 200 250 300 350
Shearstress(Pa)
Shear rate (1/s)
Water Low mix Medium mix High mix
Non-Newtonian
Objective
2 Rheology
3

Introduction
1 Objective
2 Rheology
3 Modelling
4
Rotating viscometer
Rotating viscometer to measure Torque vs Rotation speed
Shear stress vs Shear rate
Yield stress
Temperature
Solid concentration
Slurry lifetime
Influence of
Output
Rheological model
Sisko model
Herschel-Bulkley
Combined Herschel-Bulkley
Planned
5

Introduction
1 Objective
2 Modelling
4
0
1
2
3
4
5
6
0 100 200 300 400 500
Shearstress(Pa)
Shear rate (1/s)
GKW 6% GKW 11% Fit 6% Fit 11%
0
5
10
15
20
25
30
35
40
45
0 50 100 150 200 250 300
Shearstress(Pa)
Shear rate (1/s)
GKW 18% Fit 18%
At temperature 10º C At temperature 10º C
Combined Herschel-Bulkley model
Bingham model
Viscosity increases with concentration
Rheology
3 Planned
5

Introduction
1 Objective
2 Modelling
4
0
0,5
1
1,5
2
2,5
0 100 200 300
Shearstress(Pa)
Shear rate (1/s)
BrW 1.8% BrW 3% BrW 4%
Sisko 1.8% Sisko 3% Sisko 4%
0
10
20
30
40
0 50 100 150 200 250 300
Shearstress(Pa)
Shear rate (1/s)
GKW 18% Combined Herschel-Bulkley 18%
Sisko model
Combined Herschel-Bulkley model
At temperature 10º CAt temperature 10º C
Viscosity increases with concentration
Rheology
3 Planned
5

Introduction
1 Objective
2 Modelling
4
0
2
4
6
8
10
12
14
16
18
20
0,1 1 10
Deformation(rad)
Stress (Pa)
GKW 6% GKW 11% GKW 18%
0
2
4
6
8
10
12
14
16
18
20
0,1 1 10
Deformation(rad)
Stress (Pa)
Mix 3.4% Mix 7% Mix 11%
Yield stress increases with concentration
Rheology
3 Planned
5

Introduction
1 Objective
2 Modelling
4
0
5
10
15
20
25
30
35
40
45
0 100 200 300
Shearstress(Pa)
Shear rate (1/s)
18% 10C 18% 20C 18% 30C 18% 40C 18% 60C
0
2
4
6
8
10
12
14
0 2 4 6 8 10 12 14
Deformation(rad)
Stress (Pa)
18% 10C 18% 20C 18% 30C 18% 40C 18% 60C
Viscosity and yield stress decreases with temperature
Rheology
3 Planned
5

Modelling
Why? To aid the design process.
How to model Concentrated Domestic Slurry?

Introduction
1 Objective
2 Rheology
3 Modelling
4
How to model domestic slurry?
Multiphase
models
Eulerian-
Eulerian
Eulerian-
Lagrangian
Inhomogeneous Homogeneous
Torque derieved from the shear stress
being a bulk property; comparing the
measured shear stress to the one
simulated provides a valid measure for
the verification of the model.
0
10
20
30
40
50
60
70
80
0 100 200 300 400 500 600
Shearstress(Pa)
Shear rate (/s)
Secondary flow
Planned
5

Introduction
1 Objective
2 Rheology
3 Planned
5
Single-phase Homogeneous fluid!
25
30
35
40
45
50
55
60
65
70
75
100 200 300 400 500
Shearstress(Pa)
Shear rate (1/s)
Results from CFD, comparing the shear rate and stresses,
derived from Torque and Rotational rate
Modelling
4

Planned
Preparation of Artificial Slurry.
Pressure drop experiments.
Turbulence pressure drop model for slurries.

Introduction
1 Objective
2 Rheology
3 Modelling
4 Planned
5
Rheological models
Bingham
Sisko
Herschel-Bulkley
Combined Herschel-Bulkley
Different models
for same slurry

Introduction
1 Objective
2 Rheology
3 Modelling
4 Planned
5
Experimental setup
Appropriate pipe lengths are provided
to reach a completely developed flow

Introduction
1 Objective
2 Rheology
3 Modelling
4 Planned
5
Experimental setup
• Tank capacity of 4m3 to provide require
NPSHA and fill the system
• Di of 0.20m
• 6 to 8 pipe lengths for the development of
flow
• Components
• Horizontal pipe
• Vertical pipe
• Inclined pipe 60°
• Inclined pipe 45°
• Butterfly valve
• Gate valve
• Bend 90°
• Bend 180°

Introduction
1 Objective
2 Rheology
3 Modelling
4 Planned
5
Artificial slurry
Preparation of artificial slurry to mimic the rheological behaviour of the CDS
• To mimic the yield stress
• To mimic the power law behaviour
Criteria for artificial slurry
• Environmentally friendly
• Easily disposable
• Easily preparable
• Preferably transparent
Possible mixtures of
• Bentonite, Xanthum gum, glucose

Introduction
1 Objective
2 Rheology
3 Modelling
4 Planned
5
Pipeline experiment
Single phase experiments
•Pressure drop for non-Newtonian fluids
•Velocity range of 1 – 2 m/s
•For different slurry concentrations
Multiphase experiments
•Pressure drop for non-Newtonian fluids + gas (air)
•Studying the flow regimes at different superficial velocities
•For different slurry concentrations

Introduction
1 Objective
2 Rheology
3 Modelling
4 Planned
5
Turbulence pressure drop model for slurries
Pressure loss using
hydraulic friction factor
Using mixing length theory to
derive the velocity gradient in
the boundary layer
Assumption
At high velocity, due to near wall lift force,
only water is predominantly present.
Kinetic energy
Friction coefficient

Introduction
1 Objective
2 Rheology
3 Modelling
4 Planned
5
Turbulence pressure drop model for slurries
Comparing this with the standard friction loss
for water flow using Darcy-Weisbach friction,
we can find a relative measure for pressure loss
Integrating we get an expression for
velocity difference
But, one problem! Verification of the assumption is required.

Introduction
1 Objective
2 Rheology
3 Modelling
4 Planned
5
Model approach!
Equation of continuity
Equation of motion
Integrating using
non-Newtonian
viscosity relation
Adopting the energy loss equations.
Equation for pressure drop
in the turbulence regime.

Summary
For CDS
•Viscosity and yield stress increase with concentration
•Viscosity and yield stress decrease with temperature
(higher thermal motion)
•CDS can be modelled as a single-phase homogeneous fluid
represented by its bulk viscosity and density
Planned
•Preparation of artificial slurry
•Performing the single phase experiments
•Building the turbulence model
Thank you!

DSD-INT 2015 - bridging the gab in future sanitation - adithaya thoa radhakrishnan

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DSD-INT 2015 - bridging the gab in future sanitation - adithaya thoa radhakrishnan