Transfer line method drawbacks

Several approaches have been proposed in the literature to estimate the overall heat transfer coefficient [7-12]. The most common approach implemented in commercial lab scale calorimeters (like the RCl calorimeter from Mettler-Toledo), uses a two point calibration (nsing a calibration heater of a known power) [13]. The calibration is carried out at the beginning and at the end of the polymerization (in absence of reaction) and then the value of U is interpolated. There are two main drawbacks with this approach The first is that the heat of reaction cannot be obtained online because the expected change of U during the polymerization reaction (typically a decrease) cannot be calculated until the end of the reaction, and the second drawback is that the off-line calculated depends on the interpolation of the U values calculated at the beginning and at the end of the experiment. Although commercial equipment allows for different interpolations methods (linear, proportional to conversion, etc.), significant errors can be made in the computation of the... 

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