Energy Engineering MCQ Test

An open cycle gas turbine plant is a type of gas turbine plant where the working fluid, usually air, is taken from the atmosphere and used to generate power. In an open cycle system, the working fluid is not recirculated but instead released into the atmosphere after passing through the turbine. This type of plant is commonly used in power generation and is known for its simplicity and efficiency. Single acting and double acting are not specific types of gas turbine plants, and none of the mentioned does not describe any type of gas turbine plant.

Geo-Thermal energy refers to the process of producing energy by utilizing the heat trapped inside the earth's surface. This energy is derived from the natural heat generated by the Earth's core and is harnessed through geothermal power plants. It involves drilling deep into the Earth's crust to access hot water or steam, which is then used to generate electricity or for heating purposes. Therefore, option B, Geo-Thermal energy, is the correct answer.

The correct answer is C. The alternator is a device used in power plants to convert mechanical energy into electrical energy. It does this by using a rotating magnetic field to induce an alternating current in the stator windings. This electrical energy can then be transmitted and used to power electrical devices and systems.

The thermal efficiency of an open cycle gas turbine plant can be improved by implementing inter-cooling, reheating, and regeneration. Inter-cooling involves cooling the compressed air between stages, which reduces the work required for compression and increases the overall efficiency. Reheating involves reheating the air before it enters the combustion chamber, which increases the temperature and pressure of the air and improves the overall efficiency. Regeneration involves recovering waste heat from the exhaust gases and using it to preheat the compressed air, further increasing the efficiency of the plant. Therefore, all of these methods contribute to improving the thermal efficiency of the open cycle gas turbine plant.

Gas turbines are widely used in various industries due to their versatility and efficiency. In the aviation industry, gas turbines power aircraft engines, providing the necessary thrust for flight. In the oil and gas industry, gas turbines are used for power generation, driving compressors, and operating pumps. They are also extensively used in marine propulsion systems, providing propulsion power to ships and vessels. Therefore, the correct answer is D, as gas turbines find applications in all of the mentioned fields.

The load factor refers to the ratio of the actual load on a system to the maximum load it can handle. A load factor of unity would mean that the system is operating at full capacity. However, the given correct answer states that the load factor is always less than unity. This implies that the system is not operating at its maximum capacity, suggesting that there is still room for additional load to be handled by the system.

The capital cost of a gas turbine plant is lower than that of a steam power plant of the same capacity. This is because gas turbine plants are generally smaller and simpler in design compared to steam power plants. Gas turbines have fewer components and require less infrastructure, resulting in lower construction and installation costs. Additionally, gas turbines have higher efficiency and can generate more power per unit of fuel, reducing the overall capital cost.

Demand factor is a measure of the maximum demand of a system in relation to its connected load. It is the ratio of the maximum demand to the connected load. This indicates how much of the connected load is actually being utilized at the peak demand period. A higher demand factor means that the system is operating closer to its maximum capacity, while a lower demand factor indicates that there is a greater difference between the connected load and the maximum demand.

The air standard cycle for a Gas-Turbine is called the Brayton cycle. The Brayton cycle is a thermodynamic cycle that describes the process of a gas turbine engine. It consists of four processes: compression, combustion, expansion, and exhaust. In this cycle, air is compressed, fuel is added and combusted, and the expanding gases are used to generate power. The Brayton cycle is commonly used in gas turbine engines due to its efficiency and ability to produce high power output.

In a gas turbine, an intercooler is placed between the low pressure compressor and the high pressure compressor. This is done to cool down the compressed air coming from the low pressure compressor before it enters the high pressure compressor. Cooling the air helps to increase its density, which in turn improves the efficiency of the high pressure compressor. By placing the intercooler in this location, the gas turbine can achieve better performance and reduce the overall energy consumption.

All of the options mentioned in the question are used as starters for a gas turbine. An internal combustion engine can be used as a starter to initiate the rotation of the gas turbine. A steam turbine can also be used as a starter by using steam power to rotate the gas turbine. An auxiliary electric motor can be used as a starter to provide the initial power to start the gas turbine. Therefore, all of the options mentioned (A, B, and C) are correct.

The sun is the main source for the formation of wind. The sun's heat causes the air to warm up and expand, creating areas of low pressure. As the warm air rises, cooler air rushes in to fill the void, creating wind. This process is known as convection. The uneven heating of the Earth's surface by the sun also contributes to the formation of wind. So, the sun plays a crucial role in driving the atmospheric circulation and ultimately generating wind.

The correct answer is B. Natural draught. Natural draught refers to the draught or airflow produced in a chimney without the use of any mechanical devices. It occurs due to the temperature difference between the inside and outside of the chimney. As the hot air inside the chimney rises, it creates a pressure difference that draws in fresh air from the surroundings, resulting in a natural draught. This type of draught is commonly found in traditional fireplaces and wood-burning stoves.

Diesel plants are mainly used as both peak load and standby power plants. Peak load plants are used during periods of high electricity demand when additional power generation is required. Standby power plants, on the other hand, are used as backup in case of power outages or emergencies. Diesel plants are suitable for both purposes due to their ability to quickly start up and provide power when needed.

Binary vapor cycles are used to increase the efficiency of the plant. This is because binary vapor cycles involve the use of two different working fluids, allowing for better heat transfer and energy conversion. By utilizing two fluids with different boiling points, binary vapor cycles can effectively recover waste heat and optimize the overall efficiency of the plant.

A solar collector is a device that captures and absorbs solar energy from the sun. It converts this solar energy into thermal energy, which can be used for various purposes such as heating water or space heating. The solar collector does not convert solar energy into electricity, mechanical energy, or radiation. Therefore, the correct answer is C. Solar Energy thermal energy.

In a fuel cell, chemical energy is converted into electrical energy. Fuel cells work by combining hydrogen and oxygen to produce electricity through an electrochemical reaction. The hydrogen fuel is fed into the anode side of the fuel cell, while oxygen (usually from the air) is supplied to the cathode side. The chemical reaction between hydrogen and oxygen generates an electric current that can be used to power various devices or systems. Therefore, the correct answer is B. Electrical energy.

A flat-plate collector is a type of solar thermal collector that is used to absorb sunlight and convert it into heat energy. The temperature attained by a flat-plate collector is typically around 90 degrees Celsius. This temperature range is considered optimal for many applications such as heating water or space heating. It is not as high as the range of 100 to 150 degrees Celsius mentioned in option B, and it is also not above 150 degrees Celsius as mentioned in option C. Therefore, option A is the correct answer.

The most common type of geothermal plant is the flash type. Flash plants utilize high-pressure hot water from underground reservoirs to generate steam. The steam is then used to drive turbines and generate electricity. Flash plants are efficient and widely used because they can operate with a wide range of temperatures and produce a high amount of power. They are particularly suitable for areas with high-temperature geothermal resources.

The power output from a hydro-electric power plant depends on three parameters: head, discharge, and efficiency of the system. The head refers to the height difference between the water source and the turbine, which determines the potential energy available. The discharge is the amount of water flowing through the turbine, which affects the kinetic energy available. The efficiency of the system measures how effectively the turbine converts the potential and kinetic energy into electrical energy. Therefore, these three parameters play a crucial role in determining the power output of a hydro-electric power plant.

Hydro-electric power plants are considered the cheapest in terms of operation and maintenance because they rely on the natural flow of water to generate electricity. Once the infrastructure is in place, the ongoing costs are relatively low compared to other power plants. Additionally, hydro-electric power plants have a longer lifespan compared to other types of plants, reducing the need for frequent maintenance and replacement.

In geothermal power plants, waste water is discharged back to earth. This is because geothermal power plants use hot water or steam from deep within the earth to generate electricity. After the water is used, it is cooled and then returned to the earth through injection wells. This process ensures that the water is recycled and reused, minimizing the environmental impact and conserving water resources.

The value of diversity factor in practice is greater than unity. This means that the actual load on a system is less than the sum of individual loads. Diversity factor takes into account the fact that not all loads operate at their maximum capacity simultaneously. By considering this factor, system designers can allocate resources more efficiently and avoid overloading the system.

The correct answer is D. Heat gases coming out of high pressure turbine. In a gas turbine, the re-heater is used to reheat the gases that are coming out of the high-pressure turbine. After the gases pass through the high-pressure turbine, their temperature drops significantly. The re-heater then heats up these gases again before they enter the low-pressure turbine. This helps to increase the efficiency of the turbine by maintaining a high temperature of the working fluid throughout the process.

A regenerator in a gas turbine plant increases the thermal efficiency. This is because a regenerator recovers waste heat from the exhaust gases and uses it to preheat the incoming air before it enters the combustion chamber. By preheating the air, the regenerator reduces the amount of fuel needed to reach the desired temperature, thus increasing the overall thermal efficiency of the plant. This improvement in thermal efficiency leads to a more efficient conversion of fuel into useful work, resulting in higher energy output for the same amount of fuel consumed.