In mid-2014, Figener began its studies in mathematical modeling of fluid dynamics and heat flow (CFD). The flow of atmospheric air in Thermoelectric Plants was simulated.
The study consisted of analyzing the flow of atmospheric wind around thermoelectric plants and determining the recirculation of hot air from their cooling systems. At the same time, he learned the OpenFOAM software, a finite volume calculation program capable of iteratively solving several partial derivative equations such as the Navier-Stokes, the transport and the Poisson equations, which have a large number of variables and require calculation several parameters simultaneously.
This study aimed to diagnose the loss of the production capacity of the motor generators and the overheating of the refrigeration fluid due to the inefficiency of the radiators, and with this the reduction of the electric energy production of the plants. The work of FIGENER's engineers comprised field data surveys, modeling, simulations and analysis of alternatives.
Modeling and Simulations
FIGENER performed the simulations calculations with the OpenFOAM software, a program that has a robust mathematical model capable of simulating the flow of fluids around complex geometries and the fluid-heat transfer interaction. The software was executed in a Linux environment due to its greater stability and speed of communication with hardware.
In the adopted models, the plant operates in a permanent regime and the atmospheric air is maintained with constant speed and direction. The full load of all systems was considered in the preliminary calculations of the input data of the simulations, to verify the proper functioning of these same systems.
The following items are taken into account:
- Wind speed and direction;
- Radiator cooling air speeds and temperatures;
- Flue gas speed and temperature;
- Geometry and location of the engine room and radiators
- Geometry and location of warehouses around the engine room which can influence the flow of atmospheric air.
The software performs the mass and thermal balances of each volume created, in order to respect the Navier-Stokes equations and the transport and the boundary conditions imposed, identifying the current lines and the variation of the temperature of the fluid air that by them pass. As a result, it was possible to determine the temperature increase in the various control groups, such as the combustion air intake of the engines and the cooling air intake of the radiators.
The calculations after the data processing of the simulations were performed directly in Excel spreadsheets, which basically consist of:
- Estimates of energy flow from combustion;
- Fan calculations;
- Mass and energy balances;
- Calculations of average temperature of the air intakes of the radiators and the engine room and of the combustion air intakes.
Diagnostics and Alternatives
Based on these simulations, it was possible to characterize the current operating conditions of the plant, identify the heat sources that cause the loss of engine power due to the high temperature of the combustion air and thus elaborate technical alternatives to reduce the temperature of the radiator inlets and motorcycle generators.
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