Work flow

In many situations, it is convenient to express the amount of chemical species in terms of moles (molar basis) rather than mass. Mass can be converted to moles using the molecular weight. 

Let s look at the contribution to the ener balance from the inlet stream labeled stream 1. Compared to the closed-system analysis we performed in Section 2.4, there are 

We conclude that the flow work of any inlet stream is given by the term (Pb)in. 

By a similar argument, we can show the flow work of any outlet stream is given by  

We can write the total energy transfer due to work in the system in terms of shaft work, W, and flow work, as follows  

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MODELLING OF STEADY-STATE VISCOMETRIC FLOW -WORKING EQUATIONS OF THE CONTINUOUS PENALTY SCHEME IN CARTESIAN COORDINATE SYSTEMS... 

The electric field and gas flow work together to provide a finely dispersed spray of charged droplets. An electric potential of about 3-5 kV is used for capillaries of about 50-100-pm diameter. 

The nonconvective energy flux across the boundary is composed of two terms a heat flux and a work term. The work term in turn is composed of two terms useful work deflvered outside the fluid, and work done by the fluid inside the control volume B on fluid outside the control volume B, the so-called flow work. The latter may be evaluated by imagining a differential surface moving with the fluid which at time 2ero coincides with a differential element of the surface, S. During the time dt the differential surface sweeps out a volume V cosdSdt and does work on the fluid outside at a rate of PV cos dS. The total flow work done on the fluid outside B by the fluid inside B is... 

Work Performed in Pumping To cause liquid to flow, work must be expended. A pump may raise the liquid to a higher elevation, force it into a vessel at higher pressure, provide the head to overcome pipe friction, or perform any combination of these. Regardless of the service required of a pump, all energy imparted to the liquid in performing this sei vice must be accounted for consistent units for all quantities must be employed in arriving at the work or power performed. 

Loeb used Lapple s compressible flow work, techniques, and reasoning to develop graphs useful for direct calculations between tw o points in a pipe. Lapple s graphs were designed for pressure drop estimations for flow from a large vessel into a length of pipe (having static velocity in the reservoir). 

The enthalpy term h includes both internal energy and flow work terms. Since dw=0 between compressor stations, the equation becomes ... 

Ti = Temperature of the gas at the point of origin, °F W = Thermodynamic flow work term... 

Eq. (2.22) may be interpreted in terms of exergy flows, work output and work potential (Fig. 2.5). The equation may be rewritten as... 

Matter may also have other forms of energy, potential or kinetic, depending on pressure, position and movement. Enthalpy is the sum of its internal energy and flow work and is given by ... 

A quantity sufficient to carry out the required tests, generally in duplicate, are filled into the containers. Most substances for which there are no concerns for either toxicity or stability are filled by weighing the appropriate quantity into antibiotic vials in a horizontal laminar flow work station. These operations are carried out in a self-contained cubicle to avoid cross-contamination. The vials are then closed with butyl rubber stoppers and sealed with an aluminium crimp seal using an automatic crimping and labelling machine. 

Here, E is the total energy of the system, Ej is the energy per mole of component i, F is the volumetric flow rate, C is the molar concentration and S is the number of components (reactants and inerts). The work term can be separated into flow work and other work Ws, according to... 

Here, h = u + P/p is the enthalpy per unit mass of fluid. Note that the inlet and exit streams include enthalpy (i.e., both internal energy, u, and flow work, P/p), whereas the system energy includes only the internal energy but no P/p flow work (for obvious reasons). If there are only one inlet stream and one exit stream (m, =m0 = m) and the system is at steady state, the energy balance becomes... 

A number of examples of limiting kinetics have been reported for reactions of [2Fe-2S] and 2[4Fe-4S] ferredoxins with inorganic complexes (11). Recent stopped-flow work has not however confirmed limiting kinetics for the reaction of azurin, ACu(I) +... 

The work term can be separated into flow work and other work Ws, according to... 

The energy Ei is the sum of the internal energy, the kinetic energy, the potential energy, and other energies in the i-component. In a CSTR, the value of Ei is equal to the internal energy. Also, in a CSTR, the work term W is reduced to the flow work and can be written as ... 

These test procedures are performed to determine average air flow velocity and uniformity of velocity within a cleanroom, clean zone, or unidirectional flow work zone, as well as to determine air supply volume uniformity. 

The work associated with pressure around the control surfaces p V V is called the flow work. As shown in Eq. 3.196, the flow work can be expanded into two terms. One is... 

What is the relevance of pV-V here. Discuss the trade-offs in introducing enthalpy as the dependent variable in the energy equation. Discuss the notion of flow work and how it is involved in going from the internal energy to the enthalpy formulation. 

Using the definition of enthalpy, h = e + p/p, we may combine the flow work with the internal-energy flux at the inlet and outlet to yield... 

Since k ordinarily is a fairly strong function of the temperature, a suitable average value must be used in Eq. (7.20) and related ones. Under adiabatic conditions the flow work may be written as ... 

Thermodynamic Diagram Method. When a thermodynamic diagram is available for the substance or mixture in question, the flow work can be found from the enthalpy change,... 

The operation of TET. First, the gas flow is cooled in heat exchanger under approximately constant pressure, then gas flow works in the turbine and is cooled further. (Note that this process is not isentropic, i.e. even in ideal case the losses are inevitable). Thus it founds itself under the condensation curve and the condensation process takes place. Further, gas again passes through heat exchanger and finally is additionally compressed by compressor. 

Adiabatic flow of a perfect gas without friction. An ideal frictionless process is represented where a gas is compressed, the area indicating the flow work, which is equal to the change in kinetic energy if no mechanical work in a machine is involved. Thus ... 

The origin of DT is interesting. We have already noted that F( + ) systems are selective for different solutes because the enrichment processes acting in a direction perpendicular to flow work in concert with (and require) nonuniform flow. However, it is the nonuniformity in flow that tends to increase DT in Eq. 9.2, thus reducing separative efficiency. The positive and negative sides of nonuniform flow require that optimization be undertaken carefully. More details are given below. 

Q = 0 Btu. (By definition, there is no transfer of heat in a constant-entropy process.) Nonflow W2 = AE = 4236 Btu (4469.2 kJ). Steady flow W2 = AH = 4902 Btu (5171.9 kJ). Note In a constant-entropy process, the nonflow work depends on the change in internal energy. The steady-flow work depends on the change in enthalpy and is larger than the nonflow work by the amount of the change in the flow work. 

Each unit of mass flow transports energy eat a rate, e = [ U + (l/2)v2 + zg]m, where z is the elevation above a datum level, andg is the acceleration of gravity. However, considering the flow work of all the entering and leaving streams in terms of the product of the pressure and volumes of each stream, we have a total energy associated with a stream i defined by... 

In an open system, flow exergy is exergy transfer due to mass flow and flow work, and the specific flow exergy exr is... 

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