Efficiency Camot engine

Carnot stated that the efficiency of a reversible Camot engine depends only on the temperatures of the heat reservoirs and is independent of the nature of the working substance. This theorem can be proved by showing that the assumption of a reversible engine with any but the known efficiency of a reversible Camot engine leads to a contradiction of the Clausius statement of the second law. 

As the efficiency of a Camot engine is independent of the working substance, the efficiency given in Equation (6.42) for an ideal gas must be equal to that given in Equation (6.29) for any reversible Camot engine operating between the same heat reservoirs. Thus,... 

Curzon, F.L. Ahlborn, B. Efficiency of a Camot engine at maximum power output. Am.. Phys. 1975, 43, 22. 

A particular power plant operates with a heat-source reservoir at 300°C and a heat-sink reservoir at 25°C. It has a thermal efficiency equal to 60 percent of the Camot-engine thermal efficiency for the same temperatures. 

To what temperature must the heat-source reservoir be raised to increase the thermal efficiency of the plant to 40 percent Again 17 is 60 percent of the Camot-engine value. 

Perhaps one of the earliest attempts at representing fluid properties centered around the concept of the ideal gas. Experiments on gases at low pressures and densities had led to the following observations at a given temperature, the volume of a gas is inversely proportional to its absolute pressure and, at a given pressure, the volume of a gas is directly proportional to its temperature, if the latter is measured on an appropriate scale. Later work showed that this scale coincides with the absolute temperature scale associated with the Camot engine efficiency (Section 1.1.1). The two observations were combined to form the ideal gas equation of state. An equation of state is a fluid behavior model that relates the temperature, pressure, and volume of the fluid in an equation form. The ideal gas equation of state takes the form... 

Thus, the efficiency of a Camot engine must depend only on the values of Tc and Th and not on the properties of the working substance. Since the efficiency is given by e = 1 + Qc/qh, the ratio c/ h must be a unique function of Tc and Ti, only. To find this function for temperatures on the ideal-gas temperature scale, it is simplest to choose as the working substance an ideal gas. 

In comparison the theoretical efficiency of a conventional combustion engine is limited by the Camot-cycle efficiency. This efficiency (Equation 6.5) is a function of the operating temperature (T2) and the temperature of the surroundings (Ti). 

If the actual coefficient of performance of the refrigerator is cmaJ I -5 and if the thermal efficiency of the engine is i) = i)camot/l-5, how much heat does the engine absorb from the 500-K reservoir ... 

Just as the Carnot cycle C of Fig. 4.3 can be claimed to be the most efficient possible heat engine ( reai < camot = 1 — Itfc/tfhlX so t0° can reverse Carnot cycle C be claimed to be the most efficient possible refrigerator ... 

Whenever energy is transformed from one form to another, an inefficiency of conversion occurs. Electrochemical reactions having efficiencies of 90% or greater are common. In contrast, Camot heat engine conversions operate at about 40% efficiency. The operation of practical cells always results in less than theoretical thermodynamic prediction for release of useful energy because of irreversible (polarization) losses of the electrode reactions. The overall electrochemical efficiency is, therefore, defined by ... 

Rankine Cycle Thermodynamics, Carnot cycles provide the highest theoretical efficiency possible, but these are entirely gas phase. A drawback to a Camot cycle is the need for gas compression. Producing efficient, laige-volume compressors has been such a problem that combustion turbines and jet engines were not practical until the late 1940s. 

Nicolas Leonard Sadi Carnot, the French engineer and physicist, was bom in Paris in 1796. His father, Lazare Nicolas Marguerite Carnot, was in the French military service. Sadi Camot is considered as the founder of modem thermodynamics. Famous for his invaluable contributions to science and thermodynamics, Sadi Camot was honored with the title Father of Thermodynamics. Some of his noteworthy contributions to thermodynamics are the concepts of Camot heat engine, Camot cycle, Carnot s theorem, Camot efficiency, and reversible cycle. 

Camot cycle - A sequence of reversible changes in a heat engine using a perfect gas as tbe working substance, which is used to demonstrate that entropy is a state function. The Camot cycle dso provides a means to calculate tbe efficiency of a beat engine. 

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