H-S diagram

Plots of the properties of various substances as well as tables and charts are extremely useful in solving engineering thermodynamic problems. Two-dimensional representations of processes on P-V, T-S, or H-S diagrams are especially useful in analyzing cyclical processes. The use of the P-V diagram was illustrated earlier. A typical T-S diagram for a Rankine vapor power cycle is depicted in Figure 2-36. 

Since the fluid properties are defined by the entropy and enthalpy, Eqs. (9-50) represent a curve on an h—s diagram, which is called a Fanno line. 

Rapidly diverging pressure lines on the h-s diagram—to minimize the back-work ratio and to make reheat modification most effective. 

The h-S diagram becomes most convenient in following rocket motor processes and this is the reason for its introduction. The conveniences obtained are generally hidden by machine computation programs which essentially deal with the enthalpy-entropy process for the expansion process, h is the sensible enthalpy only. Theoretical performance calculations are performed in terms of the total enthalpy which is here defined as the sum of the sensible and chemical enthalpies only. 

Figure 4.4 Changes of state in a steam jet compressor, shown in h,s-diagram (h = enthalpy and s = entropy).

Although the T-s diagram is veiy useful for thermodynamic analysis, the pressure enthalpy diagram is used much more in refrigeration practice due to the fact that both evaporation and condensation are isobaric processes so that heat exchanged is equal to enthalpy difference A( = Ah. For the ideal, isentropic compression, the work could be also presented as enthalpy difference AW = Ah. The vapor compression cycle (Ranldne) is presented in Fig. H-73 in p-h coordinates. 

HG. 16-51 UOP nine-bed polybed PSA Ho unit a) flow scheme (h) cycle diagram. (Reference Fuderer and Rudelstotfer, U.S. Fatent numbef- 3,986,849, 1976.)... 

Fig. 4.1 Block diagram of a closed-loop control system. R s) = Laplace transform of reference input r(t) C(s) = Laplace transform of controlled output c(t) B s) = Primary feedback signal, of value H(s)C(s) E s) = Actuating or error signal, of value R s) - B s), G s) = Product of all transfer functions along the forward path H s) = Product of all transfer functions along the feedback path G s)H s) = Open-loop transfer function = summing point symbol, used to denote algebraic summation = Signal take-off point Direction of information flow.

A reversible cycle with turbine expansion split into two steps (high pressure, HP, and low pressure, LP) is illustrated in the T, s diagram of Fig. 4.3. The mass flow through the heater is still unity and the temperature rises from T2 to Tt, = Tq hence the heat supplied (3b is unchanged, as is the overall isentropic temperature ratio (x). But cooling air of mass flow i//H is used at entry to the first HP turbine (of isentropic temperature ratio. xh) and additional cooling of mass flow is introduced subsequently into the LP turbine (of isentropic temperature ratio Xl)- The total cooling flow is then i/( = i/ h + >h.-... 

We describe a parametric point calculation of the efficiency of a simple CCGT plant, firstly with no feed heating. It is supposed that the main parameters of the gas turbine upper plant (pressure ratio, maximum temperature, and component efficiencies) have been specified and its performance (t)o)h determined (Fig. 7.3 shows the T,s diagram for the two plants and the various state points). 

This is essentially the approach adopted by Ruffi [9] in a comprehensive set of calculations, but he assumed that the economiser entry water temperature 7b is raised above the condenser temperature by feed heating, which was specified for all his calculations. The T,s diagram is shown in Fig. 7.6 the feed pump work terms are neglected so that h.j, = hy and h. = /ib. 

The hydrogen effect on ductility and the flow stress will be considered first on the example of non-alloyed titanium. The Ti - H phase diagram is given in Fig. 1, and Fig. 2 shows the temperature dependence of ductility of Ti-a H alloys, A , for several X values. Tensile tests were run at a rate e 10" s . Ductility of the commercial... 

The H-S plot is called a Mollier diagram and is particularly useful in analyzing throttling devices, steam turbines, and other fluid flow devices. A Mollier diagram for steam is presented in Figure 2-37 (standard engineering units) and in Figure 2-38 in SI units. 

At its best, the study of solvent kies by the formalism given can be used to learn about proton content and activation in the transition state. For this reason it is known as the proton inventory technique. The kinetics of decay of the lowest-energy electronic excited state of 7-azaindole illustrates the technique.25 Laser flash photolysis techniques (Section 11.6) were used to evaluate the rate constant for this very fast reaction. From the results it was suggested that, in alcohol, a double-proton tautomerism was mediated by a single molecule of solvent such that only two protons are involved in the transition state. In water, on the other hand, the excited state tautomerism is frustrated such that two water molecules may play separate roles. Diagrams for possible transition states that can be suggested from the data are shown, where of course any of the H s might be D s. 

Figure 1.93. /02-pH diagram with the stability fields of aqueous species in Na-K-H-S-Se-0 system for the conditions SS = 10 mol/kg H2O, ESe = 10 mol/kg H2O, ionic strength = 1, and temperature = 150°C. Dashed lines are the ratio ho-a i- /a i- in logarithmic units. Stability fields for native sulfur and native selenium and the boundaries between predominance regions of oxidized and reduced selenium species are omitted for clarity (Shikazono, 1978b). 

FIGURE 28.5 Flow diagram of the selected treatment system. (From Eroglu, V. and Erturk, F., in Handbook of Industrial Waste Treatment, Wang, L.K. and Wang, M.H.S., Eds, Marcel Dekker, New York, 1991, pp. 293-306 Eroglu, V., Topacik, D., and Ozturk, I., Wastewater Treatment Plant for Cayirova Pipe Factory, Environmental Engineering Department, Istanbul Technical University, Turkey, 1989. With permission.)... 

Electrochemical mechanism of copper activating marmatite is investigated by using voltammetric method. The voltammogram of the marmatite electrode in the presence of 10 mol/L Cu is presented in Fig. 6.7. It can be seen that in the presence of cupric ion marmatite surface exhibits the electrochemical character of activation products. In the light of E h-pH diagram of the CU-S-H2O system... 

Figure 13. Diagram showing how dynamical instability characterized by the sum of positive Lyapunov exponents > o contributes to dynamical randomness characterized by the Kolmogorov-Sinai entropy per unit time h s and to the escape y due to transport according to the chaos-transport formula (95).

Then, from fig.lc it is seen that SC transition onset points Tconset(H)(= Tk(H)) are at the Bloch-Gruneisen curve (dashed curve). On the other hand, such a picture is characteristic for low temperature superconductors described by s-wave BCS theory. From this analogy it may be concluded that in the cuprates the SC order parameter is of s-wave symmetry, also. Moreover, as seen from magnetic phase H-T diagram, the... 

Both authors would like to thank Professor J.H.S. Blaxter for the original invitation to write this review and Professor A. J. Southward for his assistance through many revisions. Mr C. Silver generously helped in conversion of the early computer files to IBM format, and redrafted many of the diagrams. Dr Eve Southward helped correct the references and taxonomic details. Last but not least, both authors thank their wives, Svetlana and Muriel, for their support during this arduous undertaking. 

The thermodynamic process can be indicated both on a P-V (pressure-volume) diagram and on a h-S(enthalpy-entropy) diagram as shown in figure n. A. 2. The propellants enter the chamber at point i and are gasified. They react as a constant pressure, pc, and then they are expanded isentropically through the nozzle to the exhaust pressure pe. The throat conditions are noted with the subscript t. 

---