Thermal energy heat engines

No creation of entropy and uncompensated heat occurs in the reversible heat engine and pomp, and hence Eq. 3.45 gives the maximum efficiency theoretically attainable for heat engines and heat pumps. This equation also shows that thermal energy (heat) can not be... 

In 1824 a French engineer, Sadi Carnot, investigated the principles governing the transformation of thermal energy, heat, into mechanical energy, work. He based his discussion on a cyclical transformation of a system that is now called the Carnot cycle. The... 

Fig. 3.32 Flow diagram of energy and entropy in an ideal thermal motor (heat engine) (gray circle).

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 ... 

Peter J Loftus, D PhlL, Arihur D. Little, Inc. Member, American Society of Mechanical Engineers. (Heat Generation, Thermal Energy Conversion and Utilization, Heat Recovery)... 

In a practical sense, all operations that are carried out in metallurgy, chemical, engineering and many other disciplines involve the production or absorption of energy in the form of heat. The laws directing the transfer of heat and the types of systems that have for their main aim the control of heat flow are therefore of great consequential. When two bodies at different temperatures are brought into thermal communication, heat transfers from the... 

Although fuel cells are not heat engines, heat is still produced and must be removed in a fuel cell power system. Depending upon the size of the system, the temperature of the available heat, and the requirements of the particular site, this thermal energy can be either rejected, used to produce steam or hot water, or converted to electricity via a gas turbine or steam bottoming cycle or some combination thereof... 

Incident solar energy is absorbed by the surface water of the oceans. Ocean surface temperatures in excess of 26°C occur near the equator. Pure water has a maximum density at a temperature of 4°C. The chilled water tends to settle to the depths of the ocean. The combination of the warmed ocean surface water and cold deep ocean water provides the thermodynamic condition needed to operate a heat engine called ocean thermal energy conversion (OTEC). A typical closed-cycle OTEC Rankine cycle using a working fluid such as ammonia or a freon is suggested. 

The abundance of incident solar energy, particularly in large desert regions with few interruptions due to cloud cover, lends to the appeal of solar heat engines. Electrical power produced via thermal conversion of solar energy by means of a conventional Rankine cycle is technically achievable. 

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