Posts Tagged ‘efficiency’

Reciprocating Engines Maximize Efficiency When They Employ Flywheels

Thursday, December 21st, 2017

   Last time we had a look inside a marvelous piece of engineering machinery known as a crankshaft.   It plays a key role in converting the reciprocating linear motion of a steam driven engine into the rotary motion required to power externally mounted devices that are attached to it.   Today we’ll finish up our blog series on flywheels when we see how using one in conjunction with a crankshaft facilitates a more even transmission of energy.   Reciprocating engines maximize efficiency when they employ flywheels.

   We learned that the energy in the steam supply decreases as the piston moves in its cylinder, which means a concurrent decrease in the engine’s horsepower and its ability to power machinery.   Without an intervening action, the reciprocating steam engine would stall.   Now, let’s see how adding a flywheel to the crankshaft can solve the problem.

Reciprocating Engines Maximize Efficiency When They Employ Flywheels

Reciprocating Engines Maximize Efficiency When They Employ Flywheels

   

   As we’ve learned before, a flywheel stores up kinetic energy while the engine powering it is performing at full horsepower, but if that power should drop off or cease to be produced, the flywheel gives up the kinetic energy stored inside it so as to keep externally mounted machinery operating until that stored energy is exhausted.   This is all made possible because flywheels are designed to have moments of inertia sufficient to positively contribute to its storage of kinetic energy.   This inertia is a numerical representation of the flywheel’s resistance to change in motion.   Please review our past blog on the subject to refresh your memory.

   The overall effect is that while the engine is operating, there’s an even flow of energy between the engine and flywheel and horsepower is supplied to keep machinery mounted to the crankshaft operating.   Any diminishment in the power supplied will be compensated for by the flywheel’s stored kinetic energy.

   Next time we’ll introduce a new topic, a phenomenon known as cavitation.

opyright 2017 – Philip J. O’Keefe, PE

Engineering Expert Witness Blog

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Superheating, Part I

Monday, August 19th, 2013

      Last time we learned that our power plant boiler as presently designed doesn’t do a good job of producing ample amounts of superheated steam, the kind of steam that turbines need to spin and power generators.   During the process of superheating the more heat energy that’s added to the steam in our boiler, the higher its temperature becomes.   However, our boiler can only produce a limited amount of superheated steam as it stands now.

Engineering expert witness power plant

      So how do we get more heat energy into the superheated steam?   Take a look at the illustration below for the solution to the problem.

coal fired power plant expert witness

      You’ll note a prominent new addition to our illustration.   It’s called a superheater.

      The superheater performs the function of raising the temperature of the steam produced in our boiler to the incredibly high temperatures required to run steam turbines and electrical generators down the line, as explained in my blog on steam turbines.   The superheater adds more heat energy to the steam than the boiler can alone.

      In fact, the amount of heat energy in the superheated steam produced with our new design is proportional to the amount of electrical energy that power plant generators produce.   Its addition to our setup will result in more energy supplied to the turbine, which in turn spins the generator.   The result is more electricity for consumers to use and a more efficiently operating power plant.

      But inefficiency isn’t the only problem addressed by the superheater.   We’ll see what else it can do next week.

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