Calorimetric Assessment of Rates of Desorption

This paper concerns the further testing of a new double calorimeter. We earlier reported initial development of the calorimeter and thereafter inferred rates coefficients for adsorption of moisture under a “large pressure jump.” (The test materials were silica gel type A and water.) The paper presents a further check on the calorimeter by demonstrating that measured desorption and adsorption rates were compatible. A disappointing aspect was an unintended near step change in condenser pressure at the start of the experiment. The condenser design was deficient, and better drainage is needed in the future to maintain vapor in immediate contact with cold surfaces. Notwithstanding the lower than intended pressure driving force, the heat addition to the silica gel was measurable, following an exponential pattern against time with regression coefficient better than 99%. The rate coefficients that fitted each data set were broadly in line with coefficients reported for adsorption (within the limits of experimental error).