Calorimeters with cylindrical sample

A calorimeter C 80 (SETARAM) run in scanning mode with a heating rate of 0.2°C/min. The heat flux is recorded as a function of temperature and time. Samples around 6 g are placed into a cylindrical holder with an internal diameter of 1.7 cm. Two holders are placed into the heating block, one containing the reactive sample, the other alnmina. 

The shown calorimeter has an accuracy of +0.1% and a temperature range of 170 to 600 K. A sample of 100-300 g is placed in two sets of silver trays, one outside and one inside a cylindrical heater. In the middle of the sample, the tip of the platinum resistance thermometer can be seen. Sample trays, thermometer, and heater are enclosed in a rounded steel shell, which for ease of temperature equilibration is filled with helium of less than one pascal pressure. The shell is covered with a thin silver sheet on the outside, gold-plated to reduce radiation losses. The calorimeter is then hung in the middle of the adiabatic jacket, drawn in heavy black. This adiabatic jacket is heated by electrical heaters and cooled by a cold gas flow, as indicated by the dials of the instmments pictured on the left at the bottom. The whole assembly, calorimeter and adiabatic jacket, is placed in a sufficient vacuum to avoid convection. 

A sample of 0.008-in. Dexter paper was wrapped on a 60-liter cylindrical container having flat ends. The conductivity of this sample was about twice that measured on the calorimeter. The discrepancy is attributed to heat leak into the corners where the end insulation joins the cylindrical insulation and to the poor vacuum so far attainable with this apparatus. We are continuing our investigation of the better insulations, using this apparatus. 

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