First law of thermodynamics for open system

The first law of thermodynamics for open systems applies the transport of work dl heat dQ mass dm, with its enthalpy h and external energy (kinetic and potential energy) across the system boundaries equals the change in internal energy dtJ and external energy d a in the system. 

Alternative presentations of the derivation of the first law of thermodynamics for open systems in the Eulerian CV framework on global scales are given by [47] [54] [42]. 

In practice, pure-component molar enthalpies are employed to approximate A/7rx. This approximation is exact for ideal solutions only, when partial molar properties reduce to pure-component molar properties. In general, one accounts for more than the making and breaking of chemical bonds in (3-35). Nonidealities such as heats of solution and ionic interactions are also accounted for when partial molar enthalpies are employed. Now, the first law of thermodynamics for open systems, which contains the total differential of specific enthalpy, is written in a form that allows one to calculate temperature profiles in a tubular reactor ... 

It follows from first law of thermodynamics for open systems that the heat flow is related to the energy flow by the following relationship... 

The unsteady-state balance equation for this system (air within the engine housing) is the first law of thermodynamics for open systems with changes in kinetic and potential energies neglected. Also, the temperature and composition of the system contents are assumed independent of position and no phase changes occur. This gives the equation... 

The heat associated with a specific polymerization reaction depends on the temperatures of both the monomers and polymer. A standard basis that is consistent for treating polymerization heat effects results when the products of polymerization and the monomers are all at the same temperature. Consider a calorimeter method of measurements of heat of polymerization of monomers. The initiator is mixed with the monomer, and the system is a continuous flow CSTR. The polymerization reactions take place in the CSTR. The polymerization products enter a devolatilizer where the monomers are vaporized and removed from the product mix and recycled back to the reactors. The CSTR is water cooled to bring the monomers/polymer to the reactor temperature. There is no shaft work performed by the process. The CSTR is built, so that changes in potential and kinetic energy are negligible. The first law of thermodynamics for open systems can be written for the system as... 

Note that the energy terms in parentheses in Eq. (5.73) (internal plus macrokinetic plus potential) represent the total macroscopic energy of the fluid and, thus, Eq. (5.73) is the general differential form of the first law of thermodynamics for open systems. 

Consider that the system is an open control volume with size V that allows the transit of particles in solution through it and that, on average, remains with stationary pressure and temperature. The first law of thermodynamics for open systems states that the change of the total energy E of the system obeys the relation... 

Notice that Eq. (59) is fully compatible with Eq. (52) and with (21). However, it is important to stress that Eq. (59) is exact and a natural consequence of the first law of thermodynamics for open systems. 

THE FIRST LAW OF THERMODYNAMICS FOR OPEN SYSTEMS Material Balance... 

The first law of thermodynamics for an open system at steady state has the form... 

The first law of thermodynamics for an open system at steady state that performs no work on the surroundings other than pV work across the inlet and outlet planes of a differential control volume is written with units of energy per volume per time ... 

Energy Equation (Conservation of Energy, First Law of Thermodynamics for an Open System)... 

If the First Law is derived for an open system (constant volume see Figure 2-20) with a steady-state situation (mass flow rates in and out are equal), then the result is the First Law of Thermodynamics for an open system of a macroscopic balance ... 

The basic underlying principle governing such systems is the First Law of Thermodynamics for a control volume or open system. In Chapter 2, this approach was used to develop the Bernoulli balance used with macroscopic fluid mechanics systems. Here we will use a different form hut one that nonetheless emanates from the First Law. 

The energy balance is the result of the first law of thermodynamics. For an open system all kinds of environmental influences should be taken into account. 

Can we describe this process using our knowledge of thermodynamics We rewrite the first law of thermodynamics for an open system and, recognizing that there is no work being done on the fluid and no heat being added to the system, we find that... 

The first law of thermodynamics puts forward the principle of conservation of ener. Written for a general open system (where flow of material in and out of the system can occur) it is... 

Applying the first and second laws of thermodynamics for an open system to each of the four processes of the Brayton cycle yields ... 

The first law of thermodynamics simply says that energy cannot be created or destroyed. With respect to a chemical system, the internal energy changes if energy flows into or out of the system as heat is applied and/or if work is done on or by the system. The work referred to in this case is the PV work defined earlier, and it simply means that the system expands or contracts. The first law of thermodynamics can be modified for processes that take place under constant pressure conditions. Because reactions are generally carried out in open systems in which the pressure is constant, these conditions are of greater interest than constant volume processes. Under constant pressure conditions Equation 3 can be rewritten as... 

For a closed system the first law of thermodynamics has defined an energy function called internal energy U, which is expressed as a function of the temperature, volume, and number of moles of the constituent substances in the system U = u(t, V, n, nc). Furthermore, the second law has defined a state property, called entropy S, of the system, which is also expressed as a function of state variables S =s(T,V,nl---nc). Thermodynamics presumes that the functions t/(r,V,n, " nj and 5(7, y, I nc) exist independent of whether the system is closed or open. The energy functions of U, H, F, and G, then, apply not only to closed systems but also to open systems. 

First of all, we will touch a widely believed misunderstanding about impossibility of using the second law of thermodynamics in the analysis of open systems. Surely, the conclusion on inevitable degradation of isolated systems that follows from the second law of thermodynamics cannot be applied to open systems. And particularly unreasonable is the supposition about thermal death of the Universe that is based on the opinion of its isolation. The entropy production caused by irreversible energy dissipation is, however, positive in any system. Here we have a complete analogy with the first law of thermodynamics. Energy is fully conserved only in the isolated systems. For the open systems the balance equalities include exchange components which can lead to the entropy reduction of these systems at its increase due to internal processes as well. 

In Chap. 2 the first law of thermodynamics was applied to closed systems (nonflo processes) and to single-stream, steady-state flow processes to provide specifi equations of energy conservation for these important applications. Our purpos here is to present a more general equation applicable to an open system or to control volume. 

For an open system undergoing a chemical reaction the first law of thermodynamics may be written as dE - TdS - pdV +, ... 

Define the terras closed process system, open process system, isothermal process, and adiabatic process. Write the first law of thermodynamics (the energy balance equation) for a closed process system and state the conditions under which each of the five terms in the balance can be neglected. Given a description of a closed process system, simplify the energy balance and solve it for whichever term is not specified in the process description. 

We begin with the application of the first law of thermodynamics first to a dosed system and then to an open system. A system is any bounded portion of the universe, moving or stationary, which is chosen for the application of the various thermodynamic equations. For a closed system, in which no mass crosses the system boundaries, the change in total energy of the system, dE, is equal to the heat flow to the system. 8Q. minus the work done by the system on the surroundings. W. For a closed sy.sreni. the energy balance is... 

In this chapter we develop expressions that relate heat and work to state functions those relations constitute the first and second laws of thermodynamics. We begin by reviewing basic concepts about work ( 2.1) that discussion leads us to the first law ( 2.2) for closed systems. Our development follows the ideas of Redlich [1]. Then we rationalize the second law ( 2.3) for closed systems, basing our arguments on those originally devised by Carath odory [2-4]. Finally, by straightforward applications of the stuff equations introduced in 1.4, we extend the first and second laws to open systems ( 2.4). 

The chemical and physical changes that occur around us, such as photosynthesis in the leaves of a plant, evaporation of water from a lake, or a reaction in an open beaker in a laboratory, occur under the essentially constant pressure of Earth s atmosphere. These changes can result in the release or absorption of heat and can be accompanied by work done by or on the system. In exploring these changes, we have a number of experimental means to measure the flow of heat into and out of the system, and we therefore focus much of our discussion on what we can learn from the heat flow. (Of course, in order to apply the first law of thermodynamics to these processes, we still need to account for any work that accompanies the process.)... 

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