Advances in Continuous Flow Calorimetry

Abstract

Calorimetric data from chemical reactions such as reaction enthalpy, adiabatic temperature rise, and activation energy are essential for reaction safety and scale-up from laboratory investigations to reactor design and operation. Typically, these data are gained from batch calorimeters with sophisticated setups and elaborate measurement procedures. Continuous flow calorimeters, compared with batch setups, have different mixing and heat transfer characteristics and enable harsh reaction conditions, particularly within microstructured reactors with their enhanced heat transfer capability. This review provides an overview of currently investigated and applied flow calorimeters in research and development in relation to existing concepts. Novel approaches for heat flux measurements as well as integrated sensors are presented. Safety aspects of flow chemistry are a main driver, but additionally, low material consumption is important in early process development. Limitations of the concepts are presented with a comprehensive literature overview of flow calorimetry to show that continuous flow calorimeters form a new tool in process development and safety engineering, particularly with microstructured devices and novel sensing techniques.

Liquizald─Thermally Stable N-Nitrosamine Precursor for Diazomethane

“…Although rearrangement of the isothermality reactor design guideline (eq 1−4) (eq 21) has been postulated for calculating the maximum allowable temperature increase, ΔT max , at a given hydraulic channel diameter of a reactor, d h , 61 the presence of ΔT in the exponential term of safety factor makes this approach impractical.…”

Thermal characterization of highly exothermic flash chemistry in a continuous flow calorimeter

“…Continuous flow calorimetry is receiving increasing attention in recent years. 28 The miniaturization of calorimeters that operate in a continuous flow fashion potentially enables the safe investigation of fast and highly exothermic reactions at high reactant concentrations along with minimal material consumption. 29 There are three types of flow calorimeters based on different calorimetric methods that have been reported:…”

Simultaneous Characterization of Reaction Kinetics and Enthalpy by Calorimetry Based on Spatially Resolved Temperature Profile in Flow Reactors

“…Recently, the combination of a continuous flow reactor and in-line thermal sensing, viz. continuous flow calorimetry (Figure c), has been attracting attention because it enables simpler, quicker, and safer screening of process conditions than batch calorimetry does. − Continuous flow calorimetry uses eq to calculate the enthalpy of reaction Δ H or fractional conversion X to determine the reaction kinetics by measuring the heat flux at a volumetric flow rate of F and initial reactant concentration of c 0 …”