Authors:G. De Domenico, D. Lister, G. Maschio, and A. Stassi
A simple method for the on-line calibration, in which both the heat transfer coefficient and the heat capacity of the reactor
contents are determined, is described for laboratory scale heat transfer calorimeters. The calorimeter is operated in the
isoperibolic mode for the calibration and a constant power is supplied to a resistor placed inside the reactor. The reactor
heat balance differential equation is used to produce a set of linear simultaneous equations with each data acquisition cycle
giving one equation. The heat transfer coefficient and the heat capacity are obtained from this set of equations by linear
least squares. The application of the calibration procedure is illustrated by experiments in which the heat of reaction is
determined on-line fora simulated reaction with first order kinetics and for the hydrolysis of acetic anhydride.
Authors:G. Maschio, J. Feliu, J. Ligthart, I. Ferrara, and C. Bassani
Adiabatic calorimetry is a technique that has been introduced as an important approach to hazard evaluation of exothermically reactive systems. In this paper the free radical polymerization of methyl methacrylate (MMA) has been studied. One of the most important aspects of MMA polymerization is its exothermicity and autoaccelerating behaviour, these characteristics can generate the occurrence of a runaway reaction.In a runaway situation the reacting system is close to adiabatic behaviour because it is unable to eliminate the heat that is being generated. An even worse situation can be reproduced in the laboratory with the Phi-Tec pseudo-adiabatic calorimeter. Process design parameters that are usually calculated from thermodynamic data or using semiempirical rules, such as adiabatic temperature rise or maximum attainable pressure, can be directly determined.The existence of the ceiling temperature has been experimentally demonstrated.
Authors:C. Ampelli, D. Di Bella, D. Lister, G. Maschio, and J. Parisi
A small ultraviolet-visible absorption spectrometer which uses fibre optic coupled immersion probes has been incorporated
into a laboratory scale reaction calorimeter. The combined instrument has been tried out using the hydrolysis of acetic anhydride
as a test reaction. With the calorimeter operating in the isoperibolic mode good agreement is found for the pseudo-first order
reaction rate constant as determined from spectroscopic and calorimetric measurements. Experiments have been made in order
to follow the reaction indirectly using optical pH measurements with acid-base indicators. The possibility of determining
the temperature dependence of the rate constant in a single experiment has also been investigated.