| Popis: |
The subject of this paper is turbulence modeling of fluid flow in channels of plate heat exchangers for heating domestic hot water in heating substation in Belgrade. For testing of turbulence phenomena in the channels, this paper uses the standard K-? model of turbulence. It is of particular importance that in this paper the modeling is made for different flow rates of fluids through channels, adopted in boundary conditions. The rate of flow in the input area of the channels was taken as the assumed average values of 0.01 m / sec and 0.1 m / sec, which presupposed minimum and maximum values based on the measured values of these fluid velocities in the heat substations. On the basis of these assumed speeds, the values of the exchanged kinetic energy and the character of the change in the intensity of the projections of these velocities in the direction of all three axes are obtained. On the basis of these projections, we can determine the unsteadiness of the velocity and the return currents along these channels and in their contour surfaces as well as the "dead spots" in which there is no movement of the fluid. This work presents the calculated values of the Reynolds number of the streamline for the assumption velocity of fluid in channels. These phenomena can cause different problems in the transmission of heat and dirt in the channels of the plate heat exchangers where there is no circulation. Therefore, the obtained results can serve as a basis for dimensioning and selection of heat exchangers as well as for determining their optimal working conditions. |
