KD2 Manual

KD2 Manual
KD2
Thermal Properties
Analyzer
User’s Manual
version 1.0
Decagon Devices, Inc.
UMS GmbH
Gmunderstr. 37
D-81379 München
Tel. +49 (0) 89-12 66 52-0
Fax: +49 (0) 89-12 66 52-20
[email protected]
www.ums-muc.de
©2001 Decagon Devices, Inc.
All rights reserved.
Decagon Devices, Inc.
950 NE Nelson Court
P.O. Box 835
Pullman WA 99163
KD2 User’s Guide
Table of Contents
Contents
1. Introduction . . . . . . . . . . . . . . . . . .1
About the KD2 . . . . . . . . . . . . . . . . 1
KD2 Specifications . . . . . . . . . . . . 2
Contact Information . . . . . . . . . . . 2
Warranty Information . . . . . . . . . 3
Seller’s Liability . . . . . . . . . . . . . . . 3
2. Operation . . . . . . . . . . . . . . . . . .5
Turning it on . . . . . . . . . . . . . . . . . . 5
Taking Measurements . . . . . . . . . 6
How the KD2 takes measurements 11
3. Care and Maintenance . . . . . . .13
Cleaning . . . . . . . . . . . . . . . . . . . . . 13
Battery Replacement . . . . . . . . . . 13
Caring for the Probe . . . . . . . . . . 15
4. Theory . . . . . . . . . . . . . . . . . . . . .16
Declaration of Conformity . . . . . .22
i
KD2 User’s Guide
Table of Contents
ii
KD2 User’s Guide
Introduction
1. Introduction
Welcome to your new KD2 Thermal Properties Analyzer. This guide is designed to help
you understand and use your instrument to
the best of its capability.
About the KD2
The KD2 is a compact, portable meter used to
measure thermal properties. It consists of a
hand-held readout and a single-needle sensor
that can be inserted into the medium you
wish to measure. A reading is initiated by
pressing the left button on the readout. The
controller waits for 90 seconds to ensure temperature stability, then heats the probe for 30
seconds. At the end of the reading, the controller computes the thermal properties based
on the measurements made during the heating period of the probe. This data is used to
calculate thermal conductivity, thermal resistivity, and thermal diffusivity. Further details
about the measurements and how they’re
1
KD2 User’s Guide
Introduction
made are given in chapters 2 and 3 of this
guide.
KD2 Specifications
Measurement Speed: 2 minutes
Accuracy:
• 5% Thermal Conductivity/Resistivity
• 10% Thermal Diffusivity
Power: 3.0V CR2-type lithium-ion battery
Weight: 148g (5 oz.)
Operating Environment: 5 to 40°C
Range of Measurement:
• K (thermal conductivity): 0.1—2 Wm-1C-1
• D (thermal diffusivity): 0.1—1.0 mm2s-1
• R (thermal resistivity): 0.5—10mC W-1
Sensor:
• Needle length: 60mm
• Needle diameter: 0.9mm
• Cable length: 72cm
Contact Information
If you need to contact Decagon for customer
support or any other questions, you can reach
us by any of the following:
• Email us at [email protected]
2
KD2 User’s Guide
Introduction
•
•
Send us a fax at: (509) 332-5158
Call us at: 1-800-755-2751 (US and Canada only) or 509-332-2756.
Warranty Information
The KD2 has a 30-day satisfaction guarantee
and a one-year warranty.
Seller’s Liability
Seller warrants new equipment of its own
manufacture against defective workmanship
and materials for a period of one year from
date of receipt of equipment (the results of
ordinary wear and tear, neglect, misuse, accident and excessive deterioration due to corrosion from any cause are not to be considered
a defect); but Seller’s liability for defective
parts shall in no event exceed the furnishing
of replacement parts F.O.B. the factory where
originally manufactured. Material and equipment covered hereby which is not manufactured by Seller shall be covered only by the
warranty of its manufacturer. Seller shall not
be liable to Buyer for loss, damage or injuries
to persons (including death), or to property
or things of whatsoever kind (including, but
3
KD2 User’s Guide
Introduction
not without limitation, loss of anticipated
profits), occasioned by or arising out of the
installation, operation, use, misuse, nonuse,
repair, or replacement of said material and
equipment, or out of the use of any method
or process for which the same may be
employed. The use of this equipment constitutes Buyer’s acceptance of the terms set forth
in this warranty. There are no understandings,
representations, or warranties of any kind,
express, implied, statutory or otherwise
(including, but without limitation, the implied
warranties of merchantability and fitness for a
particular purpose), not expressly set forth
herein.
4
KD2 User’s Guide
Operation
2. Operation
The KD2 is designed to be a simple, easy to
use instrument that will allow you to make
quick and accurate thermal properties measurements. Following are some instructions
on how the instrument functions.
Turning it on
To turn on the KD2, press the left button (I)
once. The LCD display will appear, showing
the previous measurement taken.
Wm
m-1 C-1
2 3.0
5
C
|
KD2 User’s Guide
Operation
Taking Measurements
The KD2 measures thermal conductivity,
resistivity, and diffusivity at the same time
from one measurement, but can only display
one reading at a time after the measurement
is made. The right (II) button is used to toggle through the calculated readings after the
measurement has been made. To begin a
measurement, press the left (I) button to turn
on the instrument. The instrument will be in
the same measurement mode as it was when
it was last used (thermal conductivity, thermal
diffusivity, or thermal resistivity mode) and
will display the last reading taken.
NOTE!: It is important to wait for about 5
minutes between readings if the probe is
left in the same location! If multiple measurements of a sample are made too rapidly
in succession, the sample’s temperature will
not have had enough time to equilibrate from
the previous reading, and the resulting measurement will be inaccurate. For best results,
the sample should be as close to equilibrium
as possible. An ideal environment for equilibration can be accomplished by placing the
6
KD2 User’s Guide
Operation
KD2 probe and sample in an isothermal
chamber or styrofoam box.
How to Start the Measurement
Once the instrument is on, do the following:
1.
Carefully insert the probe into your
medium.
2.
Press the left button to begin the measurement process. The instrument will
first equilibrate for 90 seconds. During
this time you will be able to see that it is
equilibrating by the blinking “hourglass”
icon below the value. The temperature
measured by the probe will be displayed
in the lower right corner of the screen:
Wm
m-1 C-1
2 0.0 C
hourglass icon
7
temperature
KD2 User’s Guide
Operation
Note!: Make sure to watch the temperature during the equilibration stage to
make sure it doesn’t drastically fluctuate
or rapidly change. If the temperature is
still rapidly changing, pull the probe out
of the sample and wait until the sample
temperature is stable before measuring
again.
3.
After equilibrating, it begins its 30-second
heating and measurement cycle. During
this stage of measurement you will see a
blinking thermometer icon appear, and
the temperature reading will increase:
Wm
m-1 C-1
2 7.0
C
|
thermometer icon
4.
When the reading is finished, the checkered “finish line” flag will blink on the
screen, and a final reading will be dis8
KD2 User’s Guide
Operation
played along with the sample temperature:
Wm
m-1 C-1
2 3.0
C
|
“finished” icon
Thermal Conductivity
To display the measurement in terms of thermal conductivity, press the right (II) button
until the thermal conductivity is displayed in
Wm-1C-1 (watts per meter-degree Celsius):
Wm
m-1 C-1
2 3.0
9
C
|
KD2 User’s Guide
Operation
Thermal Resistivity
To display the measurement in terms of thermal resistivity, press the right (II) button until
the thermal resistivity is displayed in mC W-1
(meter-degrees C per watt):
m CW
2 0.0 C
-1
|
If the value shown for thermal resistivity is
9.99, this indicates that your sample is out of
range for the KD2 to measure.
Thermal Diffusivity
To display the measurement in terms of thermal diffusivity, press the right (II) button until
10
KD2 User’s Guide
Operation
2 -1
the thermal diffusivity is displayed in mm s
(square millimeters per second):
2
-1
mm s
2 0.0 C
|
Turning it off
The KD2 will shut off automatically after 5
minutes of inactivity. To turn it back on, press
the left (I) button once.
How the KD2 takes measurements
The KD2’s sensor needle contains both a
heating element and a thermistor. The controller module contains a battery, a 16-bit
microcontroller/AD converter, and power
control circuitry.
When you begin a measurement, the microcontroller waits for 90 seconds for temperature stability, then applies a known amount of
current for 30 seconds to a heater in the
11
KD2 User’s Guide
Operation
probe that has an accurately known resistance. The microprocessor calculates the
amount of power supplied to the heater. The
probe’s thermistor measures the changing
temperature for 30 seconds while the microprocessor stores the data. At the end of the
reading, the controller computes the thermal
conductivity and diffusivity using the change
in temperature (∆T) vs. time data. Thermal
resistivity is computed as the reciprocal of
thermal conductivity.
12
KD2 User’s Guide
Care and Maintenance
3. Care and Maintenance
Your KD2 should require a minimum amount
of maintenance. Following are instructions for
cleaning and battery replacement, as well as
considerations for the KD2 probe.
Cleaning
The KD2’s controller is stainless steel. If it
needs cleaning, do so with a damp cloth. Do
not immerse it in water. Clean the LCD
readout with a soft, damp cloth moistened
with water or a glass cleanser. Do not use tissue or other wood-based fibers, as they can
scratch the plastic LCD screen.
Battery Replacement
The KD2 uses a 3.0V CR-2 type Lithium-ion
battery. It typically should last for about 1000
measurements. If the battery charge is getting
low, a low-battery indicator icon will appear
in the lower right corner of the LCD screen
when the heater comes on (an occasional low
13
KD2 User’s Guide
Care and Maintenance
battery indication does not necessarily mean
the battery needs replacing):
Wm
m-1 C-1
+
2 0.0 C
|
If this screen appears continually, do the following to replace the battery:
1.
Unscrew the small screw on the back of
the KD2 case.
2.
Lift the back shell off to reveal the battery:
battery
location
14
KD2 User’s Guide
Care and Maintenance
3.
Remove the battery and replace it with
the new one, making sure to orient the
battery the same way you removed it.
Caring for the Probe
The KD2 sensor contains a heater and thermistor that are essential for the function of the
instrument. Care should be taken to prevent
bending the probe. The probe itself is stainless steel, so it may be cleaned with a wet
cloth or sponge if it becomes dirty.
15
KD2 User’s Guide
Theory
4. Theory
KD2 calculates its values for thermal conductivity (K), resistivity (R), and diffusivity (D) by
monitoring the dissipation of heat from a line
heat source given a known voltage.
The equation for radial heat conduction in a
homogeneous, isotropic medium is given by
 ∂ 2T
∂T
∂T 

= κ  2 + r −1
∂t
∂r 
 ∂r
(1)
where T is temperature (°C), t is time (s), κ is
thermal diffusivity (m2 s-1), and r is radial distance (m). When a long, electrically heated
probe is introduced into a medium, the rise in
temperature from an initial temperature, T0, at
some distance, r, from the probe is
16
KD2 User’s Guide
Theory
 q
T − T0 = 
 4πλ h
  − r2
 Ei
  4κt



(2)
where q is the heat produced per unit length
per unit time (W m-1), λh is the thermal conductivity of the medium (W m-1c-1), and Ei is
the exponential integral function
2
∞
 r2  r2  r2 
1
 +
 + ...
− 
− Ei (− a ) = ∫   exp(− u )du = −γ − ln
u

 4κt  4κt  8κt 
a
(3)
with a = r /4κt and γ is Euler's constant
(0.5772…). When t is large, the higher order
terms can be ignored, so combining Eqs. (2)
and (3) yields
2
T − T0 ≅
q
4πλ h

 r2
 ln(t ) − γ − ln
 4κ




 


(4)
It is apparent from the relationship between
thermal conductivity and ∆T = T-T0, shown in
17
KD2 User’s Guide
Theory
Eq. (4), that ∆T and ln(t) are linearly related
with a slope m = (q/4πλh). Linearly regressing ∆T on ln(t) yields a slope that, after rearranging, gives the thermal conductivity as
λh ≅
q
4πm
(5)
where q is known from the power supplied
to the heater. The diffusivity can also be
obtained from Eq. (4). The intersection of the
regression line with the t axis (∆T = 0) gives

 r 2 
 
ln(t 0 ) =  γ + ln

κ
4



(6).
From the calculated t0 (from the intercept of
∆T vs. ln(t)) and finite r, Eq. (6) gives the diffusivity.
Because the higher order terms of Eq. (3)
have been neglected, Eq. (4) is not exact.
However, if the slope and intercept are computed only for ∆T and ln(t) values, where t is
18
KD2 User’s Guide
Theory
large enough to ignore the higher order
terms, Eq. (5) and (6) give correct values for
λh and κ. To verify these relationships, realistic values of λh and κ were supplied to Eq.
(2), varying both λh and volumetric heat
capacity (ρcp), and the resulting slope and
intercept tabulated for t ranging from 1 to 30
s. Plots of slope vs. theoretical λh and
ln(intercept) vs. ln(theoretical κ) show an
exact linear relationship (Fig. 1 and 2, respectively) with low cross-covariance.
Figure 1: calculated λh vs. theoretical λh
19
KD2 User’s Guide
Theory
Figure 2: calculated κ vs. theoretical κ
The experimental analysis differs from the
theoretical shown in Eq. (2) in that the heater
and sensor have their own conductivity and
diffusivity, which, in general, differ from
those of the medium being measured. We
have shown experimentally that the relationships in Eq. (5) and (6) still allow calculations
of λh and κ, but empirical factors must be
introduced to correct for heater thermal properties.
20
KD2 User’s Guide
Theory
Assumptions: The thermal conductivity
measurement assumes several things: the
long heat source can be treated as a infinitely
long heat source, the medium is both homogeneous and isotropic, and a uniform initial
temperature, T0. Although these assumptions
are not true in the strict sense, they are adequate for accurate thermal properties measurements.
21
KD2 User’s Guide
Declaration of Conformity
Declaration of Conformity
Application of Council
Directive:
Standards to which
conformity is declared:
89/336/EEC
EN55022:1987
EN500082-1:1992
Manufacturer’s Name: Decagon Devices, Inc.
950 NE Nelson Court
Pullman WA 99163 USA
Type of Equipment: Thermal Properties Meter
Model Number:
KD2
Year of First Manufacture:
2001
This is to certify that the KD2 Thermal Properties Meter, manufactured by Decagon
Devices, Inc., a corporation based in Pullman,
WA, USA meets or exceeds the standards for
CE compliance as per the Council Directives
noted above. All instruments are built at the
factory at Decagon and pertinent testing documentation is freely available for verification.
22
KD2 User’s Guide
Index
Index
A
accuracy 2
B
battery
replacing 13
type 13
C
CE
compliance 22
cleaning 13
contact information 2
D
D (diffusivity) 16
E
email 2
23
KD2 User’s Guide
Index
F
fax number 2
K
K (thermal conductivity) 16
KD2
overview 1
specifications 2
L
low battery indicator 13
M
maintenance 13
measurement
method 11
measurement range 2
O
off(turning off) 11
on(turning on) 5
operation
24
KD2 User’s Guide
Index
on 5
P
probe
maintenance 15
specifications 2
R
R (thermal resistivity) 16
range 2
S
seller’s liability 3
specifications 2
T
telephone number 2
temperature equilibrium 6
theory 16
assumptions 21
thermal conductivity
calculation 18
25
KD2 User’s Guide
Index
thermal diffusivity
calculation 18
units 11
thermal resistivity
computed 12
units 10
U
units
thermal diffusivity 11
thermal resistivity 10
W
warranty 3
26
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