Steam engines began to play an increasingly important role in industry and transportation in the early nineteenth century. Reflections on the Motive Power of Fire were published in 1824 by Nicolas Léonard Sadi Carnot (1796-1832), a French military engineer. The book proposed a comprehensive theory of heat engines as well as an idealised model of a thermodynamic system for a heat engine known as the Carnot cycle. Carnot is widely regarded as the "Father of Thermodynamics," having laid the groundwork for the second law of thermodynamics.
Carnot heat engine: Diagram
In the diagram, the "working body" (system), a term used by Clausius in 1850, can be any fluid or vapour body through which heat Q can be injected or transferred to produce work. Carnot proposed that the fluid body may be an expandable substance, such as vapour of water, the vapour of alcohol, the vapour of mercury, a permanent gas, or air, among others. Although engines came in a variety of layouts during these early years, QH was often supplied by a boiler, wherein water was boiled over a furnace; QC was typically supplied by a stream of cold flowing water in the form of a condenser positioned on a separate section of the engine. W symbolises the movement of the output work. The output work, W, reflects the movement of the piston as it turns a crank-arm, which is then used to power a pulley, which is commonly used to push water out of flooded salt mines. Work, according to Carnot, is "weight lifted through a height."
During these carnot cycle processes, the substance can be expanded and compressed to the required point and then returned to its initial state.
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The Carnot cycle is made up of the four carnot cycle processes listed below:
1. A carnot cycle process of reversible isothermal gas expansion. The ideal gas in the system receives qin quantity of heat from a heat source at a high temperature Thigh, expands, and does work on the surroundings in this carnot cycle process.
2. An adiabatic gas expansion carnot cycle process that is reversible. The system is thermally insulated throughout this carnot cycle process. The gas continues to expand and exert influence on its surroundings, causing the system to drop to a lower temperature, Tlow.
3. An isothermal gas compression method that is reversible. In this carnot cycle process, the surroundings do work on the gas at Tlow, resulting in a loss of heat, qout.
4. An adiabatic gas compression method that is reversible. The system is thermally insulated throughout this carnot cycle process. The surroundings continue to operate on the gas, causing the temperature to increase back to Thigh.
It is the most efficient engine possible based on the premise of no accidental wasteful carnot cycle processes such as friction and no heat conduction between various sections of the engine at different temperatures. The Carnot efficiency is defined as the ratio of energy output to energy intake.
Efficiency of carnot engine = 1-T2T1 where efficiency of carnot engine of Any system working between T1 (hot reservoir) and T2 (cold reservoir)