Abstract: Microcalorimetry has long been established to measure thermal power, enthalpy, and heat capacity. Our work focuses on the crystallization processes of water and KCl solution droplets using two calorimeters: a droplet-based microcalorimeter and a flow-through calorimeter. Real-time temperature changes in sessile droplets exposed to periodic heat pulses from an LED source were recorded and analyzed with high accuracy and minimal variation. Experiments involved dispensing a 400 nL droplet onto the microcalorimeter surface, observing dynamic heat capacitance (Cp) values and thermal power (P) data, and gaining detailed insights into phase transitions and energy transfer mechanisms during evaporation and crystallization. The flow-through calorimeter further complemented these observations by enabling continuous monitoring of thermal properties in flowing samples. During the evaporation of water and KCl solution droplets, the endothermic process of water evaporation and the exothermic crystallization of KCl were distinguishable. These findings highlight the study's potential in understanding complex crystallization dynamics. Decoupling thermal events during these processes is particularly beneficial for various fields such as materials science, biochemical analysis, and pharmaceutical manufacturing. This research underscores the significant role of microcalorimetry in studying crystallization, offering a robust method for dynamic thermal analysis and contributing to the broader understanding of material behavior. Comprehensive insights into the thermodynamic properties of materials facilitate advancements in energy storage, thermal management, and material characterization.
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