The effects of transient heat flux on the tube in contact with the natural convection, on enthalpy and entropy generation, for developed laminar flow of fluid with high Prandtl number

Heat flux is passed through the tube wall with natural convection in a tube wall of developed laminar flow. Tubes are used to find the best case with the minimum enthalpy and entropy generation. Process of heat flux pass is simulated with natural convection in several cases through the wall. By varying heat flux along the tube kept in touch with natural convection, temperature, entropy generation and enthalpy of each case change. Tubes are studied distribution of temperature, entropy generation and enthalpy along the radius and distribution of entropy generation and enthalpy along the cylinder axis, via different diagrams. Entering heat flux to the tube wall, temperature, entropy generation and enthalpy of the fluid increase significantly along the radius. The contact of heat flux to the tube wall in the direction of fluid movement, entropy generation decreases in the flow direction. Heat flux is applied to the tube wall, in parts of the tube being a heat flux, enthalpy increases in the direction of the tube wall. Enthalpy is reduced in the tube wall in parts that are associated with the natural convection. The novelty of the work is heat flux and natural convection on the pipe in various fluids and air in electric coil on the tube as heat flux and diesel furnace, solar water heaters, refrigerant tube etc. Material is not a special. Material is the fluid with high Prandtl number by number of ۱۳۴۰۰. Method of the paper is design and simulation by ansys software ۱۵.۰.۷.

Keywords:

CFD , Enthalpy , Entropy generation , heat flux , convective heat transfer