Thermodynamic Analysis of Steady-State Flow Processes

1 THERMODYNAMIC ANALYSIS OF STEADY-STATE FLOW PROCESSES 

Many processes consist of a number of steps, and lost-work calculations are then made for each step separately. By Eq. (5.34), 

Fora single surroundings temperature Ta, summing over the steps of a process gives Dividing the former equation by the latter yields  

Thus an analysis of the lost work, made by calculationof the fraction that each individual lost-work term represents of the total, is the same as an analysis of the rate of entropy generation, made by expressing each individual entropy-generation term as a fraction of the snm of all entropy-generationtenns. Recall that all terms in these equations are positive. 

An alternative to tire lost-work or entropy-generation analysis is a work analysis. For this, Eq. (5.31) becomes  

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Thermodynamic Analysis of Steady-State Flow Processes... 

Real irreversible processes can be subjected to thermodynamic analysis. The goal is to calciilate the efficiency of energy use or production and to show how energy loss is apportioned among the steps of a process. The treatment here is limited to steady-state, steady-flow processes, because of their predominance in chemical technology. 

This analysis of living systems uses concepts of thermodynamics, information theory, cybernetics, and systems engineering, as well as the classical concepts appropriate to each level. The purpose is to produce a description of living structure and process in terms of input and output, flows through systems, steady states, and feedbacks, which will clarify and unify the facts of life. The approach generates hypotheses relevant to sin e individuals, types, and levels of living systems, or relevant across individuals, types, and levels. These hypotheses can be confirmed, disconfirmed, or evaluated by experiments and other empirical evidence. 

We have used this chapter to illustrate how thermodynamics can contribute to the analysis and design of selected engineering processes. The applications considered here included calculations for phase equilibria, solubilities, heat effects in steady-flow processes, and the response of certain variables to changes of state. 

For analysis purposes, the equations for conservation mass and the first law of thermodynamics are simplified with some assumptions. Two such common cases are (i) the steady-state steady-flow process and (ii) the uniform-flow uniform-state process. 

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