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Published in Splinter Robert, Illustrated Encyclopedia of Applied and Engineering Physics, 2017
[thermodynamics] A graphical representation of the locus of states in a system showing lines for processes that have the same temperature in a state diagram (pressure versus volume) or in a T–S diagram (temperature vs. entropy). Specifically, the phase changes of vaporization, sublimation, and solidification/fusion (respectively, their inverse processes) take place at constant temperature (see Figure I.39).
Thermo-economic analysis and multi-objective optimization of a solar dish Stirling engine
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Mohsen Rostami, Ehsanolah Assareh, Rahim Moltames, Tohid Jafarinejad
Also, Figure 3 shows the Entropy-Temperature (T-S) diagram of the engine. The presented model is comprised of two isothermal and two isochoric processes. Through (1–2) process, the fluid is isothermally compressed and its temperature is decreased due to the convection heat transfer in the TC condenser heat exchanger. In the process, the temperature of the low-temperature source is increased from TL1 to TL2. Through the process (2–3), the operating fluid’s temperature is increased through an isochoric process during the passage within the regenerator. As for the isothermal process (3–4), the operating fluid is expanded by absorbing solar energy. During the process, the temperature of the high-temperature source is decreased from TH2 to TH1. Finally, as work is produced within the expansion chamber, the fluid’s high temperature is decreased (absorbed) by passing through the regenerator.
Thermodynamic Analysis on the Reversibility of Compressor-expander
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Dwi Setiawan, Rifan Adi Kusuma, I Dewa Made Subrata, Y. Aris Purwanto, Armansyah H. Tambunan
Table 4 below indicates that the temperature and pressure entering the expander are in a superheated state at each scenario. The superheated state also confirmed in the temperature-entropy (T-S) diagram at expander inlet temperature of 53.76°C as shown in Figure 5. Therefore, it can be ascertained that the operating conditions were suitable for ORC operation. At the same pressure ratio of 1.34, the theoretical work of the expansion process is 223.59 watts lower than the theoretical work of the compression process. The theoretical work relationship of the compression and expansion processes to the pressure ratio is presented in Figure 6. As the ratio of pressure generated by the compression and expansion processes increases, greater theoretical work is required and produced. However, at the pressure ratio above 1.45, the theoretical work required by the compressor tends to be constant. This also applies to the theoretical work of the expansion process at a pressure ratio above 1.33.
Analysis of a combined proton exchange membrane fuel cell and organic Rankine cycle system for waste heat recovery
Published in International Journal of Green Energy, 2021
Can Liu, Guokun Liu, Yanzhou Qin, Yuan Zhuang
Figure 2 presents the T-s diagram of a typical thermodynamic process of an ORC system. Process 1–3 is the constant pressure heat absorption, where the temperature and entropy of the organic working fluid increase. Usually, at Condition 3, the working fluid has been completely transformed into vapor state. When the vapor enters the turbine, the isentropic expansion occurs during Process 3–4 under assumed ideal conditions. The high-efficiency gas turbine drives the generator to produce electricity. During the Process 4–5, the exhaust vapor is condensed under a constant lower pressure, and the working fluid is converted from vapor phased to liquid phase. During the Process 5–1, the liquid working fluid is pressurized by a pump (assuming isentropic compression), and the pumped liquid enters the evaporator to complete the cycle (Quoilin et al. 2013).