Infrared-driven Pyrolysis for a Microscale Combustion Calorimeter with Dynamic Temperature Autotune

摘要

A version of the microscale combustion calorimeter has been developed that performs pyrolysis of milligram-sized polymer samples through direct infrared heating. Advantages gained by this approach over conventional electrical-resistance heating include temperature scanning stability, higher heating rates, furnace longevity and a lower furnace thermal mass. A method for furnace temperature control utilizing a rigorous Ziegler-Nichols PID autotune calibration at several points across the desired temperature spectrum and applying a temperature-dependent line fit across the subsequent proportional, integral and derivative values has been developed. Improvements to the sample heating-rate stability result in a more stable heat release rate baseline by reducing the degree and frequency of temperature-induced gas flow perturbations. The linearity of the sample temperature heating rate used in this method is comparable to that of a modern commercial thermogravimetric analyzer.