Експериментальне визначення коефіцієнтів тепловіддачі та теплопровідності сипкого палива рослинного походження

Abstract

The work presents the results of experimental determination of heat transfer and thermal conductivity coefficients of loose fuel of plant origin. Methodological approaches to determining the thermophysical properties of materials are presented. Special attention is paid to theoretical and experimental methods that provide high accuracy in measuring properties such as heat capacity, heat transfer, and thermal conductivity. The analysis covers modern models and technological solutions that contribute to more effective research of thermophysical properties in the context of their practical application in various fields of science and technology. The most common of them allow you to obtain maximum information about the thermophysical characteristics of a material within a single experiment. A description of one of the methods for determining the coefficients of heat transfer and thermal conductivity is given. A method was chosen to estimate the coefficients of heat transfer and thermal conductivity, which provides the opportunity to conduct measurements in a regular mode. A setup has been created for experimental determination of heat transfer and thermal conductivity coefficients of a heterogeneous system based on loose fuel of plant origin. A diagram of the experimental setup is presented. The main element of the setup is an a-calorimeter and a λ-calorimeter, made of aluminum in the form of a thin-walled cylindrical beaker with a lid. The calorimeters were filled with the investigated bulk material without prior compaction, after which it was heated in a drying oven. The final stage involved cooling the material in an environment with a constant temperature. The object of the study was waste from grain processing industries of various levels of grinding, in particular sunflower husk, buckwheat husk, barley husk and spelt husk. The temperature of the material inside the calorimeters was measured using a copper-constantan differential thermocouple. A physical model of a measuring cell for implementing a method for determining the properties of materials in the form of a two-layer system is presented. Calculation formulas for determining the coefficients of heat transfer and thermal conductivity are presented. It is shown that in the calculations the heat transfer and thermal conductivity coefficients were determined taking into account the correction for the calorimeter shell. The cooling rate was established for each of the materials. The results of experimental studies of heat transfer coefficients and thermal conductivity of loose materials of plant origin are presented, taking into account the relative error