Steam Engine Nasser ALHashimi Abdulaziz mohammed Abdulaziz Nasser Ahmad ALShamsi 11.11

Steam Engine A steam engine is a heat engine that performs mechanical work using steam as its working fluid. Steam engines are external combustion engines, where the working fluid is separate from the combustion products.

The history of steam engine The history of the steam engine stretches back as far as the first century AD; the first recorded rudimentary steam engine being the aeolipile described by Greek mathematician Hero of Alexandria. In the following centuries, the few steam-powered 'engines' known about were essentially experimental devices used by inventors to demonstrate the properties of steam. A rudimentary steam turbine device was described by Taqi al-Din in 1551 and by Giovanni Branca in Denis Papin a Huguenot refugee did some useful work on the steam digester in 1679, and first used a piston to raise weights in 1690.

The history of steam engine The first practical steam-powered 'engine' was a water pump, developed in 1698 by Thomas Savery. It used a vacuum to raise water from below, then used steam pressure to raise it higher. Small engines were effective though larger models were problematic. They proved only to have a limited lift height and were prone to boiler explosions. It received some use in mines and pumping stations.

The first commercially successful engine was the atmospheric engine, invented by Thomas Newcomen around It made use of technologies discovered by Savery and Papin. Newcomen's engine was relatively inefficient, and in most cases was used for pumping water. It worked by creating a partial vacuum by condensing steam in a cylinder. It was employed for draining mine workings at depths hitherto impossible. also for providing a reusable water supply for driving waterwheels at factories sited away from a suitable 'head'. Water that had passed over the wheel was pumped back up into a storage reservoir above the wheel.

The idea of how they use steam to produce work The idea of using boiling water to produce mechanical motion has a very long history, going back about 2,000 years. Early devices were not practical power producers, but more advanced designs producing usable power have become a major source of mechanical power over the last 300 years, beginning with applications for removing water from mines using vacuum engines. Subsequent developments used pressurized steam and converted linear to rotational motion which enabled the powering of a wide range of manufacturing machinery. These engines could be sited anywhere that water and coal or Wood fuel could be obtained, whereas previous installations were limited to locations where water wheels or windmills could be used. Significantly, this power source would later be applied to vehicles such as steam tractors and railway locomotives. The steam engine was a critical component of the Industrial Revolution, providing the prime mover for modern mass-production manufacturing methods. Modern steam turbines generate about 90% of the electric power in the United States using a variety of heat sources.

Steam cycle The Rankine cycle is the fundamental thermodynamic underpinning of the steam engine. The Rankine cycle is a cycle that converts heat into work. The heat is supplied externally to a closed loop, which in steam engines contains water and steam. This cycle generates about 90% of all electric power used throughout the world, including virtually all solar thermal, biomass, coal and nuclear power plants.

Steam cycle The Rankine cycle is sometimes referred to as a practical Carnot cyclebecause, when an efficient turbine is used, the TS diagram begins to resemble the Carnot cycle. The main difference is that heat addition (in the boiler) and rejection (in the condenser) are isobaric (constant pressure) in the Rankine cycle and isothermal (constant temperature) in the theoretical Carnot cycle. In this cycle a pump is also used to pressurize the working fluid received from the condenser as a liquid instead of as a gas. Pumping the working fluid through the cycle as a liquid requires a very small fraction of the energy needed to transport it as compared to compressing the working fluid as a gas in a compressor (as in the Carnot cycle).

Steam cycle It is also useful to introduce the historical measure of a steam engine's energy efficiency, its "duty". The concept of duty was first introduced by Watt in order to illustrate how much more efficient his engines were over the earlier Newcomen designs. Duty is the number of foot-pounds of work delivered by burning one bushel (94 pounds) of coal. The best examples of Newcomen designs had a duty of about 7 million, but most were closer to 5 million. Watt's original low-pressure designs were able to deliver duty as high as 25 million, but averaged about 17. This was a three-fold improvement over the average Newcomen design. Early Watt engines equipped with high-pressure steam improved this to 65 million.

Steam cycle The working fluid in a Rankine cycle follows a closed loop and is reused constantly. While many substances could be used in the Rankine cycle, water is usually the fluid of choice due to its favourable properties, such as non-toxic and unreactive chemistry, abundance, and low cost, as well as its thermodynamic properties.

Applications in Automobile Engines The foundation of second law of thermodynamics was laid by the inventions made by Sadi Carnot, a young French scientist considered to be the father of thermodynamics.. Before the findings of Carnot it was considered that the efficiency of heat engine was dependent on the type of working fluid used in the engine. In his book “Reflections on the Motive Power of Fire” published in the year 1824, Carnot said that the efficiency of the heat engine was independent on the type of fluid used in the engine. As per him efficiency of the heat engine is dependent just on two temperatures: the temperature of the source (hot body) from where the engine absorbs heat and the temperature of the sink (atmosphere) where the engine gives up the exhaust heat.