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05 Applied Thermodynamics for PSUs (Sorted from internet)

1. What is thermodynamics?
• Thermodynamics is the branch of physical science that deals with the relationship between heat and other forms of energy such as mechanical, electrical, and chemical.
2. What is the first law of thermodynamics?
• The first law of thermodynamics states that energy can neither be created nor destroyed in a system of constant mass, but it may be converted from one form to another.
3. What is the second law of thermodynamics?
• The second law of thermodynamics states that the entropy of an isolated system always increases.
4. What is the difference between an open system and a closed system?
• An open system can exchange both matter and energy with its surroundings, while a closed system can only exchange energy.
5. What is the difference between an isothermal process and an adiabatic process?
• An isothermal process occurs at a constant temperature, while an adiabatic process occurs without any heat transfer.
6. What is the Carnot cycle?
• The Carnot cycle is a theoretical thermodynamic cycle that represents the most efficient possible heat engine.
7. What is the difference between a heat engine and a heat pump?
• A heat engine converts thermal energy into mechanical work, while a heat pump transfers thermal energy from a low-temperature source to a high-temperature sink.
8. What is the difference between a refrigeration cycle and a heat pump cycle?
• A refrigeration cycle removes heat from a low-temperature source and rejects it to a high-temperature sink, while a heat pump cycle absorbs heat from a low-temperature source and delivers it to a high-temperature sink.
9. What is the difference between a compressor and a turbine?
• A compressor increases the pressure of a fluid, while a turbine extracts energy from a fluid and converts it into mechanical work.
10. What is the difference between a Rankine cycle and a Brayton cycle?
• A Rankine cycle is a steam cycle used in power generation, while a Brayton cycle is a gas cycle used in gas turbines.
11. What is the difference between a condenser and an evaporator?
• A condenser is a heat exchanger that removes heat from a fluid and transfers it to a cooling medium, while an evaporator is a heat exchanger that absorbs heat from a fluid and transfers it to a refrigerant.
12. What is the difference between a superheated vapor and a saturated vapor?
• A superheated vapor is a vapor that has been heated above its saturation temperature, while a saturated vapor is a vapor that is in equilibrium with its liquid phase.
13. What is the difference between a subcooled liquid and a saturated liquid?
• A subcooled liquid is a liquid that has been cooled below its saturation temperature, while a saturated liquid is a liquid that is in equilibrium with its vapor phase.
14. What is the difference between a throttling process and an isentropic process?
• A throttling process occurs at constant enthalpy, while an isentropic process occurs with no entropy change.
15. What is the difference between a heat exchanger and a regenerator?
• A heat exchanger transfers heat between two fluids, while a regenerator stores thermal energy in a solid matrix and releases it to a fluid during a subsequent cycle.
16. What is the difference between a single-stage compressor and a multi-stage compressor?
• A single-stage compressor compresses a fluid in a single step, while a multi-stage compressor compresses the fluid in multiple steps.
17. What is the difference between a single-effect evaporator and a multiple-effect evaporator?
• A single-effect evaporator evaporates a liquid in a single stage, while a multiple-effect evaporator evaporates the liquid in multiple stages, using the vapor from one stage to heat the liquid in the next stage.
18. What is the difference between a wet bulb temperature and a dry bulb temperature?
• A wet bulb temperature is the temperature measured by a thermometer covered in a wet wick, while a dry bulb temperature is the temperature measured by a thermometer exposed to the air.
19. What is the difference between sensible heat and latent heat?
• Sensible heat is the heat required to change the temperature of a substance, while latent heat is the heat required to change the phase of a substance.
20. What is the difference between compressor work and turbine work?

• Compressor work is the work required to compress a fluid, while turbine work is the work extracted from a fluid as it expands.                                                                                                    

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04 Material Engineering Questions for PSUs (Sorted from internet)

1. What is the difference between a ductile material and a brittle material?
• Ductile materials can undergo significant plastic deformation before failure, while brittle materials fail without undergoing appreciable plastic deformation.
2. Explain the concept of stress and strain.
• Stress is the internal resistance of a material to external forces, while strain is the measure of deformation resulting from the applied stress.
3. What are the different types of material testing methods?
• The different types of material testing methods include tensile testing, hardness testing, impact testing, and fatigue testing.
4. How does the microstructure of a material affect its properties?
• The microstructure of a material, which includes its grain size, phase distribution, and defects, can significantly influence its mechanical, thermal, and electrical properties.
5. What is the difference between a composite material and a homogeneous material?
• A composite material is made up of two or more distinct constituents with different properties, while a homogeneous material has the same properties throughout.
6. Explain the concept of fatigue failure in materials.
• Fatigue failure occurs when a material fails under repeated or fluctuating loading, even though the applied stress may be below its ultimate strength.
7. What are the different types of corrosion?
• The different types of corrosion include uniform corrosion, galvanic corrosion, pitting corrosion, and crevice corrosion.
8. How does the addition of alloying elements affect the properties of a material?
• The addition of alloying elements can alter the mechanical, thermal, and electrical properties of a material by changing its microstructure and phase distribution.
9. What is the difference between a thermoplastic and a thermosetting material?
• A thermoplastic material can be melted and re-molded multiple times without significant degradation, while a thermosetting material undergoes a chemical reaction during curing and cannot be re-molded.
10. Explain the concept of creep in materials.
• Creep is the time-dependent deformation that occurs in a material under a constant load or stress, typically at high temperatures.
11. What are the different methods of heat treatment for steels?
• The different methods of heat treatment for steels include annealing, quenching, tempering, and normalizing, each used to achieve specific properties.
12. How does the presence of impurities affect the properties of a material?
• The presence of impurities can weaken the mechanical properties of a material, increase its susceptibility to corrosion, and alter its electrical conductivity.
13. What is the difference between a ferrous material and a non-ferrous material?
• A ferrous material contains iron as its main constituent, while a non-ferrous material does not contain iron.
14. Explain the concept of phase diagrams in materials.
• Phase diagrams represent the relationships between the different phases of a material (such as solid, liquid, and gas) as a function of temperature and composition.
15. What is the role of grain boundaries in materials?
• Grain boundaries can influence the mechanical properties of a material by acting as barriers to dislocation movement and affecting the material's strength and ductility.
16. How does the presence of defects, such as dislocations and vacancies, affect the properties of a material?
• The presence of defects can significantly influence the mechanical, thermal, and electrical properties of a material by affecting its strength, ductility, and conductivity.
17. What are the different types of non-destructive testing methods?
• The different types of non-destructive testing methods include ultrasonic testing, radiographic testing, magnetic particle testing, and liquid penetrant testing.
18. Explain the concept of work hardening in materials.
• Work hardening, also known as strain hardening, is the process by which a material becomes stronger and more brittle as it is plastically deformed.
19. What is the difference between a primary and a secondary phase in a material?
• A primary phase is the first phase to form during solidification or phase transformation, while a secondary phase forms after the primary phase has already formed.
20. How does the composition of a material affect its corrosion resistance?

• The composition of a material can affect its corrosion resistance by influencing the formation of protective oxide layers and its ability to passivate in a corrosive environment. 

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