We ran our first experiments in the reaction calorimeter today. They were very elementary, involving only the metering one reactant into another at constant reaction temperature. The results suggested strongly that the reactants were consumed promptly and that good control of temperature is obtained by adjustment of the feed rate. Halt the feed and Qr falls off promptly. This is a very desirable attribute in semi-batch processing.
From the data workup we determined the adiabatic ΔT, or ΔTad, and were able to follow the heat evolution measured in several ways, but most interestingly in watts per liter. It is desirable to know how many watts of heat evolution your reactor is capable of removing. Engineers think in terms of heat evolution as watts per unit volume. Calibration of a reaction vessel can tell you how many watts of heat the reactor can remove at a defined level of fill and agitator speed. RC1 data can tell engineering how many watts per liter the reaction mass is capable of.
Next we ran the reactor in adiabatic mode where the jacket temperature is programmed to follow the reaction mass temperature. The idea is to exert dynamic temperature control via the jacket to make the vessel behave as a Dewar. We predicted the maximum reaction temperature by simply adding the ΔTad to the initial temperature. We allowed the reaction enthalpy to ramp the temperature.
The actual endpoint temperature was within two degrees of the predicted temperature and below the bp of THF. This is a measure of the potential for runaway. If the Maximum Temperature of the Synthetic Reaction (MTSR) is below the solvent bp, then you are in a lesser hazard zone. This temperature would be achieved in an adiabatic system.
A few observations- the heat capacity, Cp, is not constant over the course of a reaction. A little reflection should suggest this. But it does not automatically follow that the Cp increases in magnitude over the reaction progress, which would offer some thermal buffering capacity.