How to Improve The Accuracy of Specific Heat Capacity?
Specific heat, also known as "specific heat capacity". It is an important physical quantity in thermodynamics. The larger the specific heat, the stronger heat absorption and dispassion ability is behaved on a specific material. The international unit of specific heat capacity is presented as J / (kg · K), which means the energy required for a one kilogram sample to raise up the temperature by 1K degree. Calculation of specific heat capacity is typically using a calorimeter, such as a Differential Scanning Calorimetry (DSC) and measure the absorption (release) heat by a material, as well as the increasing/decreasing temperature in the chamber.
However, the use of general DSC for specific heat capacity is typically not accurate. The error may be more than 10%. This is because the general DSC has the heat flow sensor only on the bottom side of crucible/sample. And this way, only the heat exchange on the bottom of the sample is measured.
A traditional DSC has 3 major problems in measuring the specific heat capacity:
- Low sensitivity: DSC measures weaker thermal signal, the reproducibility of baseline is relative worse, because of the larger error on the Cp testing. The error can be 5% to 10% or even higher;
- Poor accuracy of calibration: Typically, DSC uses standard of molten metal for calibration. So, it is influenced in a certain level by the forms of sample, reaction types, and the atmosphere, and effects the results of testing. Therefore, it needs to choose corresponding Cp standard for calibration. With the wrong standards, it will influence the accuracy of the test result.
- Poor adaptability of samples: Generally, the sample need to have good contact to the crucible, in order to have good heat conductivity. So, to those samples of powder, or larger size, will have much more limitation in Cp test. Besides, DSC usually accepts smaller crucible (tens of uL), so, it is not easy to seal, and it’s not capable for liquid samples.
SETARAM C80 3D CALVET Calorimeter, three-dimensional full-covered type calorimeter is designed by 9 x 38 thermocouples, and fully coats the sample (from top to bottom, there are totally nine rings, each rings contains 38 thermocouples), and accurately measure the heat absorbing (releasing) of the sample. To those samples with irregular shape, or uneven thermal conductivity, C80 can maximize its effectiveness, and provide very accurate and reliable measurement results for the specific heat calculation.
For more technical information of C80 microcalorimeter, please refer to the article "Evolution of DSC - C80 3D Calvet Calorimeter", as well as [Product Page] of C80.