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Thermodynamic Processes
Published in S. Bobby Rauf, Thermodynamics Made Simple for Energy Engineers, 2021
An isothermal process is a thermodynamic process in which the temperature stays constant. In isothermal processes, there is no change in internal energy because internal energy is directly related to temperature. This is validated by Eq. 8-17. Furthermore, as stipulated by Eq. 8-18, there is no change in enthalpy.
The Ideal Gas
Published in Irving Granet, Jorge Luis Alvarado, Maurice Bluestein, Thermodynamics and Heat Power, 2020
Irving Granet, Jorge Luis Alvarado, Maurice Bluestein
and from the first law, it can be deduced that both the changes in enthalpy and internal energy for this process are zero (q−w=0) because the temperature is constant. Therefore, the work of the isothermal process must exactly equal the heat transferred. Thus, q=wJ
The First Law of Thermodynamics
Published in David R. Gaskell, David E. Laughlin, Introduction to the Thermodynamics of Materials, 2017
Thus, for an ideal gas, an isothermal process is one of constant internal energy, during which the work done by the system equals the thermal energy absorbed by the system, both of which are given by Equation 2.10.
Elitist Rao Algorithms and R-Method for Optimization of Energy Systems
Published in Heat Transfer Engineering, 2023
Ravipudi Venkata Rao, Hameer Singh Keesari, Jan Taler, Pawel Oclon, David Taler
The TS diagram of the solar-assisted Stirling heat engine system considered in this case study is shown in Figure 3. The decision variables considered are internal irreversibility parameter (ϕ), heat transfer area ratio (Ar), temperature ratio (χ), the temperature of the heat source (TH), and the temperature of the working fluid in the high-temperature isothermal process (Th). Let Tc be the temperature of the working fluid in the low-temperature isothermal process, TL be the heat sink temperature, TH be the heat source temperature, AH be the heat transfer area for the heat exchanger of the hot side, hc be the convection heat transfer coefficient for the low-temperature side, f be the relative investment cost parameter of the heat exchanger hot side, hh be the convection heat transfer coefficient for the high-temperature side, then the thermo-economic objective function is given by the following equation:
A Dynamic Mesh Study of Series and Parallel Bladder Pressure Pulsation Attenuators
Published in International Journal of Computational Fluid Dynamics, 2021
According to the work principles of the attenuator, some assumptions are made plausibly in the simulative modelling to simplify the modelling process as follows: The bladder contains an ideal gas whose pressure and volume vary in an isothermal process.Nitrogen in the elastic bladder mainly bears the axial load. The outside diameter of the bladder remains unchanged by deformation, and the load-bearing model of the bladder could be simplified into a ‘gas spring-damper model’. Moreover, there is only horizontal movement.Oil compressibility is ignorable compared with gas.The fluid keeps a constant temperature since heat transfer is ignored (Nakazawa et al. 1987; Ho and Ahn 2010).
Transient phenomena during the emptying process of a single pipe with water–air interaction
Published in Journal of Hydraulic Research, 2019
Vicente S. Fuertes-Miquel, Oscar E. Coronado-Hernández, Pedro L. Iglesias-Rey, Daniel Mora-Meliá
Therefore, this paper presents a new mathematical model to be used for emptying processes. The proposed model simulates the liquid column with a rigid model using the mass oscillation equation (Cabrera, Abreu, Pérez, & Vela, 1992; Izquierdo et al., 1999; Lee, 2005; Liou & Hunt, 1996), which provides sufficient accuracy by using a moving air–water interface (Izquierdo et al., 1999; Zhou et al., 2013). Additionally, it is possible to consider thermodynamic behaviours such as: (a) an isothermal process, where the temperature remains constant inside the hydraulic installation; (b) an adiabatic process, where the hydraulic installation exchanges no heat with its surroundings; and (c) an intermediate processes, which involves temperature change and heat transfer. In this sense, the relationship between the absolute pressure and total volume of entrapped air characterizes the behaviour of air, which is known as a polytropic process. If the transient process occurs slowly enough, it is considered isothermal, and the polytropic coefficient is 1.0. In contrast, if the transient process is fast enough, it is considered adiabatic, and the polytropic coefficient is 1.4 (Fuertes-Miquel, López-Jiménez, Martínez-Solano, & López-Patiño, 2016; Izquierdo et al., 1999; Martin, 1976; Martins et al., 2015; Zhou et al., 2013). In actual installations, isothermal or adiabatic processes are rare, so an intermediate situation occurs.