heat transfer coefficient

In this study, a new method of choosing classical empirical equations for calculating heat transfer coefficients in the tubes of a shell-and-tube heat exchanger in the transient mode is proposed. This method is based on the fact that the flow is structured into a laminar boundary layer (LBL) zone and a turbulized part, and the heat transfer coefficient is calculated through the transient and turbulent heat conductivity, as well as the average thickness of the LBL and, accordingly, the average thickness of the rest of the coolant flow.

This study compares the classic calculating method of the heat transfer coefficients of the shell-and-tube heat exchanger tubes using the classic Nusselt, Reynolds, and Prandtl similarity numbers with a new method that takes into account the coefficients of surface tension of heat carriers, their transitional, turbulent viscosity and thermal conductivity, as well as the average thickness of the laminar boundary layer (LBL). The classic method shows a better efficiency of water as a heat carrier com-pared to a 45% aqueous solution of propylene glycol.

The article examines the effect of thermal insulation from autoclaved aerated concrete on the energy characteristics of a single-family house. Analysis of mathematical models of energy characteristics of external enclosing structures of buildings depending on the thickness of AEROC autoclaved concrete products according to the criteria of heat loss shows that the thermal resistance value of 7.11 m2K/W and the heat transfer coefficient of 0.141 W/(m2K) are achieved using the wall block AEROC D 300 and AEROC Energy thermal insulation panel with a thickness of 200 mm.

A promising area for the production of heat-insulating dry building mixes is the use of the microsphere of thermal power plants, that will promote the formation of thermal insulation, strength, chemically and thermally stable properties of products. To dry the microsphere, a filtration method was proposed which consists in filtering the heat agent through the porous structure of the material in the direction "material - perforated grate".

Filtration drying of grinded sunflower stems as the unit operation of the technological line for solid biofuel production has been proposed. Theoretical aspects of heat transfer processes during filtration drying have been analyzed. The effect of the drying agent velocity increase from 0.68 to 2.05 m/s on the heat transfer intensity has been established. The values of heat transfer coefficients have been calculated on the basis of the thin-layer experimental data and equation .

Filtration drying of grinded sunflower stems as the unit operation of the technological line for solid biofuel production has been proposed. Theoretical aspects of heat transfer processes during filtration drying have been analyzed. The effect of the drying agent velocity increase from 0.68 to 2.05 m/s on the heat transfer intensity has been established. The values of heat transfer coefficients have been calculated on the basis of the thin-layer experimental data and equation .

One of the main parameters that determine room climate is the internal temperature therein, which depends on projected external construction of the building. So, first of all, the article analyzes the heat resistance of the external construction of the building which is derived from thermal protection of the building, especially in the summer. Thermal effect on the external construction of the building has been analyzed primarily from the point of impact of solar radiation on the construction in the summer.