METHOD OF DETERMINING THERMOPHYSICAL PROPERTIES OF SUBSTANCES DURING CHEMICAL REACTION Russian patent published in 2025 - IPC G01N25/18 G01N25/20 G01N25/48 

FIELD: measuring.

SUBSTANCE: invention relates to thermophysical and thermochemical measurements and can be used to determine properties of solid substances, liquids and gases during chemical reactions, specifically for determining volumetric heat of chemical reaction and heat conductivity coefficient. Disclosed is a method for determining the thermophysical properties of substances during a chemical reaction, comprising steps of placing the test substance in a container with a heating element in the form of a metal wire, wherein said vessel is immersed in thermostatting fluid to maintain constant preset temperature of thermostating fluid. DC pulses are periodically supplied to ends of metal wire with such interval between them that before supply of the next pulse heat from the previous one is completely dissipated in environment. Before each pulse temperature T₀ of heating element is measured, simultaneously serving as resistance thermometer, and temperature control liquid temperature T_T and determining difference between T₀ and temperature control liquid ΔT_Φ=T₀-T_T. During each pulse, the voltage U at the ends of the metal wire and the current I are measured at equal time intervals and the heat flux density from the surface of the heating element is calculated q_L=(I⋅U/L), where L is wire length. For each heating pulse wire temperature increment values are calculated ΔT to T₀ in time τ from the beginning of the pulse and a curve of dependency is plotted ΔT=f(lnτ), according to which thermal conductivity coefficient is calculated by formula where ϕ is the inclination angle of the rectilinear portion of the obtained graph. Then thermogram is plotted ΔT_Φ=ƒ(τ^*), where τ^* is the current time of the chemical reaction, from the thermogram ΔT_Φ=ƒ(τ^*) is calculated an integral ∫ΔT_Φdτ^* and chemical reaction volumetric heat value r' is determined as per dependence r'=(λ_av∫ΔT_Φdτ^*)/F, where λ_av is average value λ, calculated as arithmetic mean of values λ for each pulse during chemical reaction, F is surface area of one meter of heating element length.

EFFECT: invention enables to determine the volumetric heat of a chemical reaction and the coefficient of heat conductivity in a single measurement with high accuracy.

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