Electrical Engineering XYZ MCQs
Direct conversion of heat energy into electrical energy is possible through:
- MHD generator
- Thermal converters
- Both of the above
- Fuel or solar cell
Correct answer: 3. Both of the above
Explanation: Both MHD generator and thermal converters are correct answers.
- MHD Generator (MagnetoHydroDynamic Generator): MHD generators directly convert heat energy into electrical energy using the principles of magnetohydrodynamics. In this process, a conducting fluid, often a plasma, is passed through a magnetic field at high velocities. The interaction between the moving fluid and the magnetic field induces electric currents, which can be collected to generate electricity. MHD generators are particularly suited for high-temperature and high-velocity fluid flows, such as those found in certain types of power plants.
- Thermal Converters: Thermal converters encompass various technologies that directly convert heat energy into electricity. These include thermoelectric generators, thermionic converters, and thermophotovoltaic cells. Each of these technologies operates on different principles, but they all utilize the temperature difference between a heat source and a heat sink to generate electricity. For example, thermoelectric generators exploit the Seebeck effect, where a temperature gradient across a semiconductor material induces an electric voltage. Thermionic converters utilize the emission of electrons from a heated cathode and their collection at an anode to generate electricity. Thermophotovoltaic cells convert thermal radiation directly into electricity using photovoltaic cells optimized for infrared wavelengths.