Abstract
One of a major objective is to analyze the effect of internal and external convection coefficients in the heat transfer generated by electric motors and characterize intervals of feasible values, in practical terms, for these coefficients. Another objective is to determine the motor core temperature, considering the environmental and operational conditions of the motor installation and the heat flux Q0 (fixed) in the fins. To achieve the objectives were developed analytical solutions for determining the temperature variations in the fins, performance and electric motor efficiency, considering heat flow constant at the base of the fins and the possible variations in temperature of surround media. The heat flux at the base of the fins, in this case, is the minimum necessary for satisfactory electric motor performance and the core temperature is within the safety range stipulated by the manufacturer. The obtained results characterize a range of possible values for the inner and outer heat transfer coefficients.
Highlights
The electric motor is responsible for the transformation of electric energy into mechanical energy, which is the main end-use of electric energy in industries in general, and its wide use in this sector is due to its simple construction and wide versatility in applying loads
The motor core temperature was computationally simulated by varying the internal (h1) and external (h2) convection heat transfer coefficients and the ambient temperature
The results demonstrated two things: the importance of the internal heat transfer coefficients and their physical limitations
Summary
Global Journal of Researches in Engineering (A ) Volume XIxX Issue III Version I transfer generated by electric motors and characterize of overheating (Santos, Rafael Simões, 2011). Ventilation depends directly on the internal and external convection heat transfer to which the motor is subjected This dependence is because the heat exchange occurs between a moving fluid (air) and the motor surface (housing), which are at different. The contact interface between the motor wall 28 and its insulation is promoted by a mechanical union that generates a thermal resistance due to imperfect contact, resulting from small roughness and undulation In this region, conduction occurs at the contact points and conduction through the trapped fluids in the interstices of roughness and undulation. We have to determine two convection coefficients, one of them referring to the external region and the other to the internal part of the motor housing, the latter is dependent on the microscopic imperfections on the surfaces and the contact pressure of the materials, the fluid contained in the interstices, of the applied oxide film and the metallic shim involved. The calculated value of Q0 for the motor studied is 7709.7 W / m2
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