What does an open feedwater heater do?
An open feedwater heater is basically a mixing chamber, where the steam extracted from the turbine mixes with the water exiting the pump. In an ideal condition, the water leaves the heater as a saturated liquid at the heater pressure.
What is the major purpose of using feedwater preheating in a steam cycle?
Preheating the feedwater reduces the irreversibilities involved in steam generation and therefore improves the thermodynamic efficiency of the system. This reduces plant operating costs and also helps to avoid thermal shock to the boiler metal when the feedwater is introduced back into the steam cycle.
How do feedwater heaters increase efficiency?
The Feedwater heaters increase the Rankine cycle efficiency by raising the temperature of feed water that is piped into the steam generator, in such a way that the necessary thermal energy transferred to the steam to increase the enthalpy of the system will be lower.
Why is the ideal regenerative cycle not practicable?
Although it is more efficient when compared to rankine cycle, this cycle is not practicable for the following reasons. 1) Reversible heat transfer cannot be obtained in finite time. 2) Heat exchanger in the turbine is mechanically impracticable. 3) The moisture content of the steam in the turbine is high.
What is reheat regenerative cycle?
Reheat of reheat regenerative steam power cycle increases its efficiency by increasing the average temperature of heat reception. The invention applies reversible reheating in addition to the regular reheating and uses smaller temperature differences across feed water heaters than the regular cycle.
Whose efficiency is higher when pressure ratio is kept constant?
Explanation: Otto cycle is more efficient than Diesel cycle for a given compression ratio. 6. For constant maximum pressure and heat input, the air standard efficiency of the gas power cycle is in the order.
Which is more efficient steam turbine or gas turbine?
Steam turbine Turbines produce direct rotary motion and are far more compact and weigh far less than reciprocating engines and can be controlled to within a very constant speed. As is the case with the gas turbine, the steam turbine works most efficiently at full power, and poorly at slower speeds.
What is the most efficient steam engine?
The four-cylinder “Argentina” is the most efficient steam locomotive ever built.
What is the most efficient type of engine?
Wärtsilä 31SG
What must be added to a system to decrease entropy?
When a small amount of heat ΔQ is added to a substance at temperature T, without changing its temperature appreciably, the entropy of the substance changes by ΔS = ΔQ/T. When heat is removed, the entropy decreases, when heat is added the entropy increases.
How are heat engines classified?
Heat Engines can be broadly classified into Internal and External Combustion Engines. Internal Combustion Engines are the Engines in which fuel is burned inside the cylinder. In reciprocating Engines heat is converted to the work with the help of reciprocating mechanism (e.g. piston and cylinder).