Determination of Heat of Reaction in Supercritical Water

The heat of reactions in supercritical water is difficult to measure. Our group fabricated a new reactor to enable the measurement of this heat with extremely high accuracy. The system consisted of a single, insulated tube reactor. The reaction heat was determined by the temperature change of the flow caused by the heat. We found, however, that the heat loss of the reactor compromised the measurements accuracy. Though small, this factor was impossible to completely remove, especially when the reaction was fast or the flow was slow. To compensate, we measured the heat loss and used the measured value to correct our calculation of the reaction heat. The direct measurements of the reaction heat agreed well with the calculated values, with relative error of only around 5% up to reaction heats as large as 100 kJ/kg-water.