MUON Collaboration meeting at Mission Inn, Riverside, California

1
MUON Collaboration meeting at Mission Inn,
Riverside, California January 27 - 30, 2004
Study on the cooling performance of the current
Absorber design
Stephanie Yang Wing Lau Oxford Christine
Darve Ed Black -- Fermilab
2
This discussion paper touches on the cooling
development of both absorber designs, i.e. the
forced flow and the convective designThe study
on the forced flow absorber design looks at how
to improve the cooling performance without
increasing the pressure drop across the absorber,
which is the limited operating criteria for the
liquid hydrogen pump.
The study on the convective absorber design looks
at whether the cooling performance can be
improved by re-directing the current flow path
with a pair of baffles Two configurations on
the LH2 absorber have been studied
Absorber without baffledAbsorber with
baffled All with beam power of 60W, 150W and 200W
3
Summary of the Forced Flow absorber cooling
performance analysis
4
Forced-flow Heat Transfer Numerical Calculations
5
Forced-flow Heat Transfer Numerical Calculations
Main inlet outlet nozzle diameter is
25.8mm Branch nozzle diameter is 14.28mm (0.56)
6
Forced-flow Heat Transfer Numerical Calculations
Velocity distribution
7
Forced-flow Heat Transfer Numerical Calculations
Additional plots on flow patterns
8
Forced-flow Heat Transfer Numerical Calculations
Temperature distribution
Inlet velocity is at 4.4m/s
9
Forced-flow Heat Transfer Numerical Calculations
Pressure distribution
10
Forced-flow Heat Transfer Numerical Calculations
11
Summary of the Convective Absorber cooling
improvement analysis
12
The idea of a baffle and how it might improve
convective cooling
Expected flow pattern of the current
Baffle
The baffle is expected to assist the convective
cooling by directing the warm current to flow
down the side of the absorber which receives
direct cooling from the gas helium, and come up
as a cooler liquid through the centre.
13
The CFD model with baffles
14
Boundary conditions and material properties used
Boundary condition for all the cases around the
outer absorber body surfaces fixed temperature _at_
14K and set outer window surfaces as Adiabatic
wall.
Material properties used for the CFD
studies LH2 (fluid domain) Density 71
Kg/m2 Cp 9680 J / kgK Thermal conductivity
0.119 W/mK Dynamic viscosity 1.33e-5 kg /
ms Thermal expansivity 0.02 K-1 Reference
temperature 17 K
Aluminium window (solid domain) Density 2702
kg/m3 Cp 903 J / kg K Thermal conductivity
237 W / m K Glass Plate (represent baffle)
sub-solid domain Density 2500 kg / m3 Cp 750 J
/kg K Thermal conductivity 1.4 W / m K
NOTE The Al window centre thickness is 0.9mm in
this study and the absorber body wall thickness
is 5mm. Glass plate thickness is 3mm, the
distance to the inner wall of absorber body is
20mm, 135 degree coverage area at each side of
the absorber body. Beam is 5mm diameter and
340mm length tube.
15
Heat Source at 60W LH2 Absorber without baffled
16
LH2 absorber without baffled and heat source at
60W
17
Y 0m
Y 0.25m
LH2 absorber without baffled and heat source at
60W
Flow At Window
Y 0.75m
Y 0.5m
18
Global delta T 2.98K Delta T at fluid domain
1.864K (15.117K) Delta T at solid domain 1.845K
(1415.8K) Rayleigh number 2.216E11
19
(No Transcript)
20
LH2 absorber without baffled and heat source at
60W
21
Heat Source at 60W LH2 Absorber with baffled
22
LH2 absorber with baffled and heat source at 60W
Y0.01m
23
LH2 absorber with baffled and heat source at 60W
Y0.01m
24
LH2 absorber with baffled and heat source at 60W
25
Heat Source at 150W LH2 Absorber without baffled
26
Velocity pattern
LH2 absorber without baffled and heat source at
150W
27
LH2 absorber without baffled and heat source at
150W
28
Delta T at LH2 absorber (solid domain) 2.2K
(1416.2K) Delta T at fluid domain 4K
(15.919.9K) Rayleigh number 4.78E11 Max
pressure 1.39Pa Max velocity 0.1156m/s
LH2 absorber without baffled and heat source at
150W
29
Heat Source at 150W LH2 Absorber with baffled
30
Velocity pattern
Y 0.025
LH2 absorber with baffled and heat source at 150W
Y0.025
31
Max velocity 0.1m/s
Y 0
LH2 absorber with baffled and heat source at 150W
32
LH2 absorber with baffled and heat source at 150W
33
Delta T at fluid domain 3.3K (15.919.2K) Delta
T at Al solid domain 2.5K (1416.5K) Global
delta T at all domain 5.2K Rayleigh number
3.92E11
LH2 absorber with baffled and heat source at 150W
34
Max Pressure 1.35Pa
LH2 absorber with baffled and heat source at 150W
35
Heat Source at 200W LH2 Absorber without baffled
36
Max velocity 0.165m/s
LH2 absorber without baffled and heat source at
200W
37
Delta T at fluid domain 6.6K (16 22.6K) Delta
T at Al absorber (solid domain) 2.5K
(1416.5K) Global delta T at all domains 8.6K
Rayleigh number 7.83E11
LH2 absorber without baffled and heat source at
200W
38
Max pressure 0.825 Pa
LH2 absorber without baffled and heat source at
200W
39
Heat Source at 200W LH2 Absorber with baffled
40
Max velocity 0.1189 m/s
LH2 absorber with baffled and heat source at 200W
41
Delta T at fluid domain 5.28K (1621.3K) Delta T
at Al absorber (solid domain) 2.8K
(1416.8K) Global delta T at all domains
7.3K Rayleigh number 6.17E11
LH2 absorber with baffled and heat source at 200W
42
Max pressure 1.47Pa
LH2 absorber with baffled and heat source at 200W
43
Comparison of the LH2 absorber with and without
baffled
With baffled
Without baffled
44
Observations The baffled LH2 absorber do not
have much effect when the heat source is less
than or equal to 60W. However, when the heat
source increased to 150W and 200W, the delta T
for the liquid hydrogen is lower compared with
the that without baffled. However, the delta T
at the Aluminium window is higher than that
without baffled. It would seem the presence of
the baffle did not help with the cooling on the
windows. Further investigation is needed to see
if this trend persists when the baffle position
is moved nearer to or further from the centre of
the absorber. The results so far indicate that
the presence of the baffle may only help to
decrease the overall temperature of the coolant,
thereby reducing the chance of it reaching the
gasifying temperature. Further design work will
be needed to see how the drop in the coolant
temperature could also benefit the windows The
pressure drop in the case of absorber with baffle
is lower than that without