Energy converter, thermal heat engines. Carnot cycle

The conventional generation of electrical energy from a fuel requires the use of a heat engine which converts thermal energy to mechanical energy. All heat engines operate by the Carnot cycle, and their maximum efficiency is about 40-50% (for the modern gas-fired power stations, the efficiency is about 55%). 

The most elRcient means of converting thermal energy into work or electricity is the Carnot cycle. The Carnot cycle represents an idealized heat engine that is unachievable in practical systems but that sets a useful standard for heat engine performance and comparisons. The Carnot elRciency is given by... 

The direct combustion of hydrogen in an oxygen atmosphere follows the same reaction as in Equation 1.7. In this process, AH is transformed completely into thermal energy (heat), which can be converted into mechanical work using a steam turbine. Thereafter, it can be transformed into electrical work in an electric generator. The upper limit of the thermodynamic efficiency for any heat or steam cycle corresponds to the efficiency of the hypothetical Carnot heat engine ... 

The unique feature of batteries and fuel cells is that in them electrical energy is produced directly from chemical energy, bypassing the need to convert it first to heat and then construct a heat engine of one type or another, to convert the thermal energy to electrical energy. The efficiency of conversion of the latter is limited by the second law of thermodynamic expressed by the Carnot cycle ... 

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