Accounting for the Heater Inertiain the Single-Flow Non-Stationary Method to Study the Heat Transfer Surfaces

Abstract

The paper considers the problem of accounting for the heater inertia in a single-flow non-stationary method to study heat transfer in the heat transfer matrices. It shows that gas temperature at the inlet differs significantly from an ideal rectangular "step". This dependence is obtained theoretically based on the heater design and the known experimental data without using the empirical constants that should be determined in the methodological experiments. The obtained experimental data are compared with results of the analytical solutions for a cylinder during the non-stationary cooling at the boundary conditions of the third kind; their good agreement is revealed. The paper describes a mathematical model, which is based on solution to the ordinary differential equations for the heater wire temperature due to the small Bio numbers (less than 0.1) A numerical solution is obtained to assess maximum slope of the temperature time dependence taking into account the longitudinal thermal conductivity. The paper shows that accuracy of the single-flow non-stationary method is decreasing with an increase in the longitudinal thermal conductivity of the heat transfer matrix under study, and a decrease in the Ntu value, which is the dimensionless heat transfer coefficient. The obtained results are relevant for studying the heat transfer coefficient of the highly compact heat transfer surfaces. These heat transfer surfaces are widely used in various industries, including energy, oil and gas, transportation, and refrigeration

Please cite this article in English as:

Egorov K.S., Stepanova L.V. Accounting for the heater inertia in the single-flow non-stationary method to study the heat transfer surfaces. Herald of the Bauman Moscow State Technical University, Series Mechanical Engineering, 2025, no. 4 (155), pp. 118--132 (in Russ.). EDN: GBWFPL

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