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Expansion of steam in either the saturated or superheated state is generally not isothermal. When steam expands from a high pressure to a lower pressure the temperature will be reduced, unless energy is added during the process. When steam expands in an engine such as a steam turbine, the temperature reduction is greater than during free expansion
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Which type of steam is imparted on the blades of turbine?
Superheated steam.
Why is superheated steam preferred in a turbine?
among other things, to improve thermal efficiency and minimize ( transmission losses) as the steam cycles through the turbines, these are often l00% Heavy Duty cycles as in Powerhouse service and Nuclear submarines. turbines use superheated steam in order to avoid condensation inside, and, as a result, erosion of the blades. Superheated steam also contains more potential energy (expressed as an enthalpy).
What is a direct expansion evaporator?
Refrigerant enters a direct expansion evaporator as a saturated liquid vapor mix and leaves as a superheated vapor.
What is a desuperheater?
HiSuperheated steam is steam that is at a temperature higher than the saturation temperature for the steam pressure. For example, steam at a pressure of 3 bar g has a saturation temperature of 143.762°C. If further heat were to be added to this steam and the pressure remained at 3 bar g, it would become superheated.So, desuperheating is the process by which superheated steam is restored to its saturated state, or the superheat temperature is reduced.The idea behind desuperheating is that saturated steam has a better energy exchange capacity (U coefficient) than superheated steam.Superheated steam must cool down before condensing, therefore it is less efficient than saturated steam in appliances such as heat exchangers.Also, superheated steam is a thermal insulator, just like air.
Difference between saturated and superheated steam?
Saturated steam occurs when steam and water are in equilibrium. If you have a closed container of water and heat it, above 100 celsius the steam pressure will start to rise, and as the temperature continues to rise, the pressure will go on rising. What is happening is that steam is being evolved to match the temperature (steam tables will give this relation) and the steam conditions are said to be saturated because if the pressure is raised by external means, some of the steam will start to condense back to water.If the steam pressure is held at a lower level than that achieved at saturation, by taking steam off to feed a turbine or other steam usage, there is effectively an excess temperature for that pressure, and the steam is said to be superheated. It in fact then becomes dry, and behaves as a gas. The amount of superheat can be quantified as so many degrees of superheat (celsius or fahrenheit). Turbine designers want steam to be superheated before reaching the turbine, to avoid condensation causing blade erosion, and steam producing boilers in power plants are designed to produce superheated steam.
What is a Binary Vapour Cycle?
A binary vapour cycle is a representation of a mercury cycle and a steam cycle on a same scale.In this vapour cycle there is comparison between the mercury cycle and steam cycle. In mercury cycle there occurs isothermal expansion of saturated water from boiler into dry saturated steam followed by isentropic expansion followed by condensation of steam and at last heating of steam and thus mercury has completed the cycle in 4 way process. In steam cycle first ther is isothermal expansion which results in converting of saturated water into dry saturated steam followed by superheated process where the steam is superheated followed by isentropic expansion of superheated steam followed by condensation of exhaust steam and at last heating of steam thus completing the cycle.
Define isothermal expansion?
Isothermal expansion is what keeps gas at a constant temperature. It works by absorbing heat in order to conserve energy.
In which of the following processes is it possible that entropy would stay constant: isothermal expansion?
In an isothermal expansion process, it is possible for entropy to stay constant.
In order for a high temperature boiler or steam engine to produce superheated steam?
In order for a high temperature boiler or steam engine to produce superheated water, or steam?
Which type of steam is imparted on the blades of turbine?
Superheated steam.
What is the relationship between enthalpy and the isothermal expansion process?
In an isothermal expansion process, the enthalpy remains constant. This means that the heat energy exchanged during the expansion is equal to the work done by the system.
What does the PV diagram of an isothermal expansion illustrate?
The PV diagram of an isothermal expansion illustrates the relationship between pressure and volume during a process where the temperature remains constant.
Does a parcel of air that rises undergo isothermal expansion?
No, a parcel of air that rises undergoes adiabatic expansion, not isothermal expansion. This is because adiabatic processes involve changes in temperature due to the parcel's expansion or compression without any heat exchange with the surroundings, while isothermal processes involve constant temperature.
What happens when superheated steam pressure is reduced?
steam quality increase
How much energy is used per kilogram of steam?
That would depend on if the steam is superheated dry steam or not and if superheated dry steam its temperature. It should be possible to google "boiler equations" or "boiler design" to get details.
What is the relationship between the work done during an isothermal expansion and the change in internal energy of a system?
During an isothermal expansion, the work done is equal to the change in internal energy of the system.
Is steam superheated water?
No, steam is not superheated water. Steam is the gaseous form of water that is created when water is heated to its boiling point and vaporizes. Superheated water is water that has been heated beyond its boiling point and exists in a state where it is hotter than its boiling point.
