Last time we ran our basic power plant steam turbine without a condenser. In that configuration the steam from the turbine exhaust was simply discharged to the surrounding atmosphere. Today we’ll connect it to a condenser to see how it improves the turbine’s efficiency. As discussed in a previous blog, enthalpy his,_{1 }
If the condenser vacuum exists at a pressure of 0.6 PSI, a realistic value for a power plant condenser, then referring to the steam tables in the Van Wylen and Sonntag thermodynamics book, we find that the enthalpy
and the amount of useful work that the turbine can perform with the condenser in place would therefore be,
h1474 BTU/lb – 847 BTU/lb = 627 BTU/lb_{2} = So essentially with the condenser present, the work of the turbine is increased by 168 BTU/lb (627 BTU/lb – 459 BTU/lb). To put this increase into terms we can relate to, consider this. Suppose there’s one million pounds of steam flowing through the turbine each hour. Knowing this, the turbine power increase,
Now according to
A typical automobile has a 120 HP engine, so this equation tells us that the turbine horsepower output was increased a great deal simply by adding a condenser to the turbine exhaust. In fact, it was increased to the tune of the power behind approximately 550 cars! What all this means is that the stronger the vacuum within the condenser, the greater the difference between h will be. This results in increased turbine efficiency and work output, as evidenced by the greater numeric value for _{2}W. Put another way, the turbine’s increased efficiency is a direct result of the condenser’s vacuum forming action and its recapturing of the steam that would otherwise escape from the turbine’s exhaust into the atmosphere.This wraps up our series on the power plant water-to-steam cycle. Next time we’ll use the power of 3D animation to turn a static 2D image of a centrifugal clutch into a moving portrayal to see how it works. ________________________________________ |

## Posts Tagged ‘work’

### How Condensers Increase Efficiency Inside Power Plants

Wednesday, December 4th, 2013### Enthalpy Values in the Absence of a Condenser

Tuesday, November 26th, 2013
Last time we learned that the amount of useful work, To better gauge the effects of a condenser, let’s look at the differences between its being present and not present. Let’s first take a look at how much work is produced by a steam turbine without a condenser. The steam entering the turbine inlet has a pressure of 2000 pounds per square inch (PSI) and a temperature of 1000°F. Knowing these turbine inlet conditions, we can go to the steam tables in any thermodynamics book to find the enthalpy, by Gordon J. Van Wylen and Richard E. Sonntag list enthalpy values over a wide range of temperatures and pressures. For our example this volume tells us that,Fundamentals of Classical Thermodynamics
where Since there is no condenser attached to the steam turbine’s exhaust in our illustration, the turbine discharges its spent steam into the surrounding atmosphere. The atmosphere in our scenario exists at 14.7 PSI because our power plant happens to be at sea level. Knowing these facts, the steam tables inform us that the value of the exhausted steam’s enthalpy,
Combining the two equations we are able to calculate the useful work the turbine is able to perform as:
h1474 BTU/lb – 1015 BTU/lb = 459 BTU/lb_{2} = This equation tells us that for every pound of steam flowing through it, the turbine converts 459 BTUs of the steam’s heat energy into mechanical energy to run the electrical generator. Next week we’ll connect a condenser to the steam turbine to see how its efficiency can be improved.
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### Enthalpy and the Potential for More Work

Monday, November 18th, 2013
Last time we learned how enthalpy is used to measure heat energy contained in the steam inside a power plant. The higher the steam pressure, the higher the enthalpy, and vice versa, and we touched upon the concept of Let’s revisit the equation introduced last time, which allows us to determine the amount of useful work output:
h_{2} Applied to a power plant’s water-to-steam cycle, enthalpy As for enthalpy Next week we’ll see how the condenser, and more specifically the vacuum inside of it, sets the platform for increased energy production, a/k/a
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