A REACTION CALORIMETER WITH COMPENSATION HEATER AND DIFFERENTIAL COOLING

An attempt has been made to combine and improve the advantages of diff erent types of reaction calorimeters pursuing the main objectives of s imple design and simple data treatment. The calorimeter is operated in the so-called heat-balance mode, i.e. the heal flow through the wall is determined from a heat balance over the jacket, and so is the heat transfer coefficient even if changing during a run. A main new feature is that the jacket can be operated as a once-through differential coo ler at high flow rates. The problem of accurately measuring differenti al temperatures of 0.1 K or below has been solved by applying modern m ethods of measurement, control and signal processing. A second new adv antage to be mentioned is the strictly isothermal operation of both th e reactor, by means of a compensation heater, and the jacket, through separate control loops. 'Strictly isothermal' means that the accumulat ion terms in the heat balances with their ill-defined heat capacities can safely be neglected and error-amplifying differentiation of sample d temperature data be avoided. Some experimental runs to test the perf ormance of this calorimeter are described. (C) 1998 Elsevier Science S .A.