Absolute thermal conductivity measurement: Simpler than ever

Absolute thermal conductivity measurement: Simpler than ever

In general, the guarded-hot-plate (GHP) as design for an absolute thermal conductivity measurement based on steady-state heat-flow is very well understood. The method is established in QA and certification on insulating materials and it is the basis for thermal conductivity check of every available thermal conductivity reference material for steady state methods. The standards ASTM C177 and ISO 8302 describe how to build a guarded-hot-plate.

In principle, you can GHP’s consider to be very complex devices! Users need to understand deeply, how the technology works and how to set up a proper measurement. The fact that these devices perform temperature measurements at countless locations sometimes makes it difficult – especially in self-built systems – to maintain the homogeneity of the measured temperatures required by the standard.

NETZSCH has created a groundbreaking solution for this with the newest SMART MODE Software for GHP. It raises the applicability of the method and the overview of the measurement signals to a completely new level – besides that it helps you to increase your efficiency in your lab .

For details on the instrument itself – see our Website!

To request more information or a quote – click here!

 

Pre-Defined Methods for absolute thermal conductivity measurement

Pre-Defined Methods make sure, that you check the instrument, like NETZSCH checked the instrument

Every delivered NETZSCH GHP comes with a set of “Pre-defined Methods”. It is forseen to check the functionality of a GHP in it’s temperature range with a set of reference materials, because you need to ensure the reliability and international comparability. Those checks are pre-definded as a measurement method and can easily be started by one mouseclick.

"<yoastmark

 

Wizards

The Wizards allow to easily define a absolute thermal conductivity measurement. You can enter the header-data easily, choose the type of cooling and change the cooling settings. The atmosphere and corresponding flow-rate makes sure, that the measurments are carried out under defined conditions and without the influence of condensation. We define every setpoint by:

  • Mean Temperature
  • Temperature-Gradient
  • Heating Rate
  • Type of Cooling
  • Time Limit (time, when the setpoint will be skipped if steady-state is not reached)

Every defined measurement of recurring tasks you should stored as a “USER METHOD” because you can recall them very easily at the click of a mouse.

"<yoastmark

 

Measurement

The tab “Measurement” gives you a total overview over the defined absolute thermal conductivity measurement. During the measurment, you can check the actual stability, all signals, plate temperatures and Lambda, the sensors, the heating and cooling power and the final results.

This Screenshot shows a measurment on Calcium Silicate
This Screenshot shows a measurement on Calcium Silicate from -160°C to 600°C in one single run. On mean-temperature 100°C we switch the cooling-system from liquid nitrogen to air without interrupting the measurement run. On 400°C the cooling is totally switched off.

 

Monitoring and Diagnosis – another big benefit

In the tab “Sensors” you see the total overview on all temperature sensors on the plates. The requirements of the standards are very strict in terms of homogenity of the temperature distribution. All installed sensors are from one lot and every single sensor has it’s own calibration. For every customer we stock spare-sensors from the same lot, because we want to provide you the best possible sustainability.

This screenshot shows every sensor in the plates and it's actual temperature
This screenshot shows every sensor in the plates and it’s actual temperature. For every plate and the guard furnace you see the mean-temperature, standard-deviation and the maximum difference of temperatures. In this case we see, that we are not in equilibrium, yet.

 

This screenshot shows you the sensors in perfect thermal equilibrium.
This screenshot shows you the sensors in perfect thermal equilibrium.

 

Results

In the “Results” tab you get every information that you need:

  • mean-temperature
  • delta temperature
  • thermal conductivity (Lambda)
  • standard devition of thermal condictivity
  • combined uncertainty of thermal conductivity (see publication from Schindler et al.)
  • thermal resistance
  • standard deviation of thermal resistance
  • uncertainty of thermal resistance
  • duration of measurement

"<yoastmark

 

Report Generator – in the end you need documentation

Due to requirements in the standards ASTM C177 and ISO 8301, you need to document the results. No one wants to write report after reaching the final result, manually. Therefore NETZSCH included a report generator in the software. By clicking of “Report” you can create a simple report as a word-document. Above all you can choose also an extended report as an excel-file. In contrast to the simple word file, it provides you every single detail of the measurement.

 

Excel-Report

 

Furthermore the details in plate-temperatue distribution are also part of the excel report.

Excel-Report: Plate-Temperature Distribution
Excel-Report: plate-temperature distribution

 

Summary

The NETZSCH Guarded Hot Plate for absolute thermal conductivity measurement in conjunction with the newest SMART MODE Software is a powerful tool to gain simplicity in this complex method. The software makes you more efficient and makes the instrument easy to use.

The NETZSCH Guarded Hot Plate fulfills the tough requirements from ASTM C177 and ISO 8302 over the whole temperature range from -160°C up to 600°C. The vacuum-tight design is pre-condition for defined and dry atmospheres during the measurement. This ends up with the highest possible measurment accuracy. The robustness of the design combined with our software and the NETZSCH-Services ensures security of investment, highest efficiency and best sustainability.

 

 

Alexander Frenzl has been employed in the Development Department at
NETZSCH Analyzing & Testing since 2005. In 2008, he became Head of the
Mechanical Development Department and, as such, has been involved
in the development of all NETZSCH instruments. Since 2014, Alexander
Frenzl has been the Business Segment Manager for Glass, Ceramics and
Building Materials and serves as an interface between our Development,
Sales and Marketing Departments. One of his focal points is industrial
quality assurance for insulating materials as well as the process optimization
during processing ceramics, especially with respect to new and more
efficient technologies.

Leave a Comment