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Utility and Process System Optimization
Published in Albert Thumann, Scott Dunning, Plant Engineers and Managers Guide to Energy Conservation, 2020
The Carnot cycle is of interest because it is used as a comparison of the efficiency of equipment performance. The Carnot cycle offers the maximum thermal efficiency attainable between any given temperatures of heat source and sink. A thermodynamic cycle is a series of processes forming a closed curve on any system of thermodynamic coordinates. The Carnot cycle is illustrated on a temperature-entropy diagram (Figure 5-2A) and on the Mollier Diagram for super-heated steam (Figure 5-2B).
Vapor and Advanced Power Cycles
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
The Carnot cycle has the maximum efficiency because heat is added isothermally at the source temperature (highest temperature) and rejected isothermally at the sink temperature (lowest temperature). Figure 10.1a shows the steady-flow Carnot cycle operating on wet steam (a liquid-vapor mixture). The working fluid is heated reversibly and isothermally in the boiler (1-2); it is then expanded reversibly and adiabatically in the turbine (2-3), condensed reversibly and isothermally in the condenser (3-4), and compressed reversibly and adiabatically in the compressor (4-1) and the cycle repeats. The temperature of steam during processes 1-2 and 3-4 can be maintained constant by maintaining the pressure constant since temperature and pressure are two dependent properties in the saturation region.
Lexicon
Published in Samuel C. Sugarman, HVAC Fundamentals, 2020
Carnot cycle: (Heat) An ideal heat engine cycle of maximum thermal efficiency. The Carnot cycle is the most efficient cycle possible for converting a given amount of thermal energy into work or, conversely, for using a given amount of work for refrigeration purposes. See heat engine.
Climate change and extreme weather: A review focusing on the continental United States
Published in Journal of the Air & Waste Management Association, 2021
While the increased rain rate in tropical cyclones stems directly from thermodynamics associated with warmer sea surface temperatures, this warming also influences the dynamics of storms. This is best understood by viewing tropical cyclones as Carnot cycle heat engines (Emanuel 1987). The efficiency of a Carnot cycle in converting thermodynamic energy into the kinetic energy is proportional to the difference in temperatures between the warm and cold side of the engine. For a tropical cyclone (Figure 5, from Emanuel 2006) the warm side is the sea surface and the cold side is the tropopause, the coldest region of the lower atmosphere. This Carnot efficiency imposes an upper bound, denoted the potential intensity, on the strengths of tropical cyclones. With climate change, the temperature of the tropopause is not expected to change substantially, so the maximum potential efficiency of a tropical cyclone increases with the temperature of the underlying ocean, and, therefore, with climate change. It is important to bear in mind, however, that this represents the maximum, or potential, intensity of a storm. Most storms fall short of this potential strength, because they move over colder waters before they achieve it or because they are disrupted by vertical shear in the prevailing winds.
Efficiency limits of evaporative fabric drying methods
Published in Drying Technology, 2021
Kyle R. Gluesenkamp, Viral K. Patel, Ayyoub M. Momen
A Carnot cycle is defined as operating between a high-temperature reservoir and a low-temperature reservoir. In the following discussion, the high-temperature reservoir temperature is referred to as TH and the low-temperature reservoir temperature as TC. The difference between them (called the heat pump temperature lift, or simply “lift”) is referred to as ΔTlift ≡ TH – TC.