Virtual representation of a Differential Scanning Calorimetry test

Sammanfattning

This thesis presents the development of a virtual representation of a Differential Scanning Calorimeter (DSC) in COMSOL Multiphysics, specifically the DSC3+ from Mettler Toledo. The objective of the model is to accurately determine the specific heat capacity of any material. The model is then used to investigate parameters influencing the response from a physical test, with particular focus on explaining dispersions observed in the previously conducted physical paperboard experiments. The principal idea of a DSC is to measure the heat flow to a sample during heating and cooling. The heat flow can then be used to determine the specific heat capacity of the sample. The setup involves a sensor and two crucibles – one serving as a reference while the other contains the sample. In order to develop a model that closely resembles the physical DSC, both in its geometric configuration and measurement methodology, a stepwise approach is employed. Three models of increasing physics complexity are set up successively, ultimately resulting in a simulation of a DSC test on paperboard. The model incorporates several physics interfaces in COMSOL, including heat transfer in solids and fluids, laminar flow and mass transport. To implement the paperboard material in the COMSOL model, a mixture theory framework is adopted. Sensitivity analyses of the final model primarily focus on sample mass and positioning of the sample crucible. Results indicate that a smaller sample mass is more sensitive to measurement errors in the heat flow than a larger mass, and that sample crucible placement has a significant impact on the DSC signal and specifically the specific heat capacity. To obtain reliable measurements, the crucible placement needs to be consistent and precise.