STUDY OF THE INFLUENCE OF DETERMINING FACTORS ON THE HEAT TRANSFER COEFFICIENT UNDER FORCED CONVECTION CONDITIONS USING A PROGRAMMED ALGORITHM IN VISUAL BASIC FOR APPLICATIONS

When designing thermal power systems, engineering calculations of equipment use the convective heat transfer coefficient to further determine heat flows. The value of this coefficient depends on many factors and physical quantities, such as heat capacity; pressure; density; phase state; heat or coolant flow mode; characteristics of the contacted surface, i.e. sizes, shapes, wall roughness; coefficients of kinematic and dynamic viscosity, etc. To calculate heat flows, heat transfer coefficient and analyze its dependence on the above values, an algorithm for step-by-step automatic calculation of parameters of interest to the user was developed in Excel based on the Visual Basic for Applications programming language using existing engineering techniques. In engineering techniques, only a few quantities are mainly used: surface and fluid temperatures; fluid velocity and defining geometric characteristics of the surface in contact with a gaseous or liquid substance. The program provides the following corrections: temperature, for hydrodynamic stabilization of the flow in the initial section, for the narrowing of the flow in the narrowest section of the channel, for the angle of attack of the oncoming flow and for the relative position of the pipes in the bundle. As a fluid, you can choose air, water, transformer oil, MS-20 and MK oils, liquid ammonia and flue gases.