Climate Chamber With Fast Humidity And Temperature ... · PDF filefor Small-angle Neutron...

WIR SCHAFFEN WISSEN – HEUTE FÜR MORGEN

Climate Chamber with Fast Humidity and Temperature Response

for Small-angle Neutron Scattering

Lothar Holitzner :: Designing Engineer :: Paul Scherrer Institut

.

Climate inside the chamber

.

Technical specification: Climate elements

climate

temperature T

rel. humidity φ

gas pressure p

(20 % ... 95 %)

(≈ 1 bar)

in all combinations

(50°C ... 100°C)

requiredprecision:

∆T = ± 1°C∆φ = ± 2 %

Small-angle Neutron Scattering (SANS)

The instrument :

Neutron guide hall

Sample example

SINQ

Our Application

Small-angle Neutron Scattering (SANS)

The principle :

Our Application

neutron beam(λ = 5...20 Å)

sample

2ϑ

possible dimensions: d = 1 ... 500 nm

d

d

1arcsin~

Experimental setup with device sketch

The principle :

Experimental setup

moist gas

neutron beam

System overview

Climate chamber system

Operation overview

max. water content XCEM.max = 6.000

min. water content XCEM.min = 0.014

relative humidity [%]

tem

per

atu

re [°C

]

428min.

max. CEM

CEM

X

X

Operating area and limits , Curves with constant water content

pprocess = 1070 mbar

Water content (= moisture content xvap)

.

Operation overview

water content

(mixing ratio)

)(

)(,,

..

..

. Tpp

Tp

M

MTpX

satvapw

satvapw

gasdry

water

Ideal gas law

TM

RmVp

water

univapwvapw ..

TM

RmVp

gasdry

unigasdrygasdry

.

..

Partial pressure sum

gasdryvapwi pppp ..

Vapor pressure of water

C

Tbar

p satvapw

426.233

630.173019625.5log

..

(Antoine equation for 1 -100°C)

Relative humidity

satvapw

vapw

p

p

..

.

gasdry

water

m

mX

.

(main equation)

p – pressure [bar]

T – temperature [°C]

φ – rel. humidity (RH)

M – molar mass

Internal chamber

.

Device details

cartridge heater

moist gas

material: aluminium alloy surface: chem. nickel-plated, 40 μm (corrosion protection)

temperature sensor Pt100

sample space

Fast heating & cooling the internal chamber

.

Device details

sample

neutrons

vacuum

thermal conductive bridge

cartridge heater0...100 W

external housing (water cooled)20°C

sapphire windows

20...110°C

Device details

moist gas

neutron beam

Longitudinal section

.

insulating flange (Ti6Al4V , t = 0.5 mm)

insulating vacuum

humidity sensor

sample space

insulating flange

Sample holder

.

Device details

frame (stainless steel, ø20 x 15 mm)

sample (ø16 x 0.03...5 mm)

Our goals:

❶ Gas flow distribution

near the sample surface: as uniform as possible

❷ Climate precision: temperature ∆T = ± 1°C

rel. humidity ∆φ = ± 2 %

❸ Change of temperature: time constants Theating ≈ Tcooling

→ improved temperature controllability

❹ Change of climate: as fast as possible

Design criteria

Stationary velocity distribution

Example with moisty gas flow for φ = 95% at 100°C

❶.

sampleholder

moist gas

Example with moisty gas flow for φ = 95% at 100°C

❷.

Stationary temperature distribution

Temperature scan in gas flow direction (x-axis) , climate: φ = 95% at 100°C

❷.

Stationary temperature distribution

T=100°C0.2°C

sample centre

tem

per

atu

re [°C

]

x-coordinate [mm]

Humidity distribution

Example with moist gas flow for φ = 95% at 100°C

❷.

Humidity scan in gas flow direction (x-axis) , climate: φ = 95% at 100°C

❷.

Humidity distribution

rela

tive

hu

mid

ity

[%]

φ=95 %

sample centre

2 %

x-coordinate [mm]

Chamber with insulating vacuum, under process pressure, at 100°C

.

Total displacement

insulating vacuum

max. 18 μm


.

Mechanical stress

insulating vacuum

max. 42 N/mm2

Temperature change

Tcooling = 80 s

Step function response when heating-up or cooling-down

❸.Theating ≈ Tcooling

tem

per

atu

re [°C

]

time [s] time [s]


.

Temperature distribution and displacement

insulating vacuum

Starting sequence (insulating vacuum → process pressure → temperature change)

.

Animation

1. switch on vacuum pump

2. applyprocess pressure

3. set sample temperature

Wir schaffen Wissen – heute für morgen

At PSI we used

COMSOL Multiphysics

to design a

climate chamber as

research environment.

Design goals were, to

understand und

optimise

… temperature effects.

… humidity

distribution.

… fluid flow.

… structural

mechanics effects.

Wir schaffen Wissen – heute für morgen

My thanks go to

• Dr. Lorenz Gubler 1)

• Dr. Urs Gasser 2)

• Raphael Müller 3)

• Jan Krebs 3)

• Gioacchio Cristallo 4)

• Roger Stefani 4)

• Juerg Thut 1)

• Manuel Lehmann 3)

• Philipp Looser 3)

1) Electrochemistry Lab.

(LEC)2) Neutron Scattering Lab.

(LNS)3) Scientific Develop. Lab.

(LDM)4) PSI Mech. Prod. (AMI)

Climate Chamber With Fast Humidity And Temperature ... · PDF filefor Small-angle Neutron...

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