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Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
A thermodynamic cycle is a continuous series of thermodynamic processes that periodically returns the working fluid of the cycle to a given state. Although cycles can be executed in closed systems, the focus here is on the cycles most frequently encountered in practice: steady-flow cycles, cycles in which each process occurs in a steady-flow manner. Practical cycles can be classified into two groups: powerproducing cycles (power cycles) and power-consuming cycles (refrigeration cycles). The working fluid typically undergoes phase changes during either a power cycle or a refrigeration cycle. Devices that operate on thermodynamic cycles are widely used in energy conversion and utilization processes since such devices operate continuously as the working fluid undergoes repeated thermodynamic cycles.
The evolution of future societies with unlimited energy supply?
Published in Kléber Ghimire, Future Courses of Human Societies, 2018
Since the discovery of fire, human societies have made very few steps in the advancement of mastering energy and energy technologies. One of the notable inventions is the internal combustion engine (ICE), which used the “fire” concept, and changed the combustible from wooden to the carbon and petrol. The understanding of the Carnot cycle on which the ICE is based led to the improvement of the gasoline engine for cars as well as the development of other systems that convert the heat produced during combustion into other useful forms of energy – for example, the turbine engines power by heated gas such as in the airplanes, and the turbine in energy production facilities powered by steam derived from fuel combustion. The Carnot cycle is a theoretical thermodynamic cycle proposed by French physicist Sadi Carnot in 1824. It provides an upper limit on the efficiency that any classical thermodynamic engine can achieve during the conversion of heat into work.
Transition Economics
Published in Susan Krumdieck, Transition Engineering, 2019
Nuclear energy has the highest resource temperature, and coal and gas combustion temperatures are higher than wood combustion, which in turn is higher than nearly all geothermal temperatures. Solar thermal temperatures can be as high as 600°C for a parabolic dish concentrator, and around 250°C for a tracking parabolic trough concentrating collector. The Carnot efficiency for high-temperature resources is necessarily higher than for low-temperature resources. The second law efficiency is the actual energy conversion performance for a plant compared to the Carnot ideal model of the plant. The thermal efficiency is the useful work produced by the thermodynamic cycle compared to the heat transfer into the cycle.
A practical approach-based technical review on effective utilization of exhaust waste heat from combustion engines
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Rajesh Ravi, Oumaima Douadi, Manoranjitham Ezhilchandran, Mustapha Faqir, Elhachmi Essadiqi, Merouan Belkasmi, Shivaprasad K. Vijayalakshmi
Stirling engines work on a regenerative thermodynamic cycle known as “the Stirling cycle.” Unlike the ICEs, the Stirling engines lack associated valves and do not contain any intake or exhaust gases (Mohd Noor et al. 2015). This characteristic helps in preventing pollution. The engine’s air is contained within itself, whereas the heat energy is converted into mechanical energy by alternate pushing of the air from cold side of the engine to the hot side (Zafer and Selenay Önal 2018). Figure 9 depicts a Stirling engine coupled with a diesel engine to recover the waste heat energy. Even small temperature differences have the ability to power a Stirling engine by a few degrees. The Stirling engines are utilized in a variety of applications, particularly when a requirement exists for a large heat source and a noise-free motor (Mahmoudzadeh Andwari et al. 2017).
Thermal performance of a single stage double inlet pulse tube refrigerator: experimental investigation and CFD simulation
Published in Experimental Heat Transfer, 2022
K.N. Sai Manoj, S. Anbarasu, S. Ghosh, S.K. Sarangi
Moldenhauer et al. [11] analyzed the thermodynamic cycle to increase the heat transfer rate in the components of the pulse tube and hot heat exchanger. The refrigeration capacity was enhanced by varying the component specifications [12]. Chen et al. [13] explained at the dissimilar frequencies of the piston, increased the pressure ratio at different parts of the configuration. Barrette and Arsalan [14] computed an axisymmetric model of the Stirling PTR with the pulse tube and regenerator of the same diameter. Celik and Ekren [15] reported the refrigeration capacity was increased by increasing the input voltages of the Stirling refrigeration system. They concluded with an increment in the voltage, the hot and cold head surface temperatures of the system were amplified and reduced. Thus, leading to extend the temperature period between the reservoirs.
Structural and magnetic properties with reversible magnetocaloric effect in PrSr1–xPbxMn2O6 (0.1 ≤ x ≤ 0.3) double perovskite manganite structures
Published in Philosophical Magazine, 2018
Another important parameter for MCE is relative cooling power (RCP) that signifies the amount of heat transfer between heat and cold parts of magnetic refrigerator in an ideal thermodynamic cycle [41]. This parameter can be defined as [42]where δTFWHM is full width at half maximum of the magnetic entropy change curve and is the absolute maximum magnetic entropy change. The calculated RCP values for the experimental data and Landau theory under 50 kOe magnetic field change are listed in Table 1. From the table, it can be said that both experimental and landau RCP values are acceptable from the view of the magnetic cooling for all samples.