Exergy loss

Fig. 2.9. Work output and exergy losses in CBT ga.s turbine plant (all. as I ractions of fuel exergy).

Therefore, plots of exergy loss or irreversibility like Fig. 2.9, for a particular plant operating condition, do not always provide the complete picture of gas turbine performance. 

Horlock, J.H. (1998), The relationship between effectiveness and exergy loss in counterflow heat exchangers, ASME Paper 1998-GT-32. 

Subsequently, we refer briefly to other comparable studies, including the calculations of exergy losses and rational efficiency. Finally, we show the real gas exergy calculations for two practical plants—[CBT]i and [CBTX]i. 

Once the state points are known round a cycle in a computer calculation of performance, the local values of availability and/or exergy may be obtained. The procedure for e.stimating exergy losses or irreversibilities was outlined in Chapter 2. Here we. show such calculations made by Manfrida et al. [13] which were also presented in Ref. [14]. 

Fig. 5.10 shows the exergy losses as a fraction of the fuel exergy (including the partial pressure terms referred to in Section 2.4) for the General Electric LM 2500 [CBT]ic plant. 

Fig. 5.10. Calculated exergy losses as fractions of fuel exergy for the General Electric LM 2500 CBT plant, for varying combustion temperatures (K) (after Ref. [13 ).

Another water injection cycle proposed is the TOPHAT cycle [12] (see Fig. 6.16). As for the HAT cycle, the purpose is to introduce water into the cycle with low exergy loss and this is achieved by injecting water continuously in the compressor in an attempt to... 

In both cases heat is taken from the exhaust gases to feed the reaction process, enhancing the heating value of the resulting modified fuel, which is then fed to the combustion chamber. But the main thermodynamic feature is that the exergy loss in the final exhaust gas is thus reduced and the efficiency increased. 

Exergy input — [Exergy recovered + Exergy loss] — Exergy consumption = Exergy accumulation (9)... 

The exergy loss associated with heat infiltration during the three storage periods can be expressed as... 

A parametric study was conducted using the Engineering Equation Solver (EES) software. Figure 4 illustrates the variation of the exit temperature of the heat pump (or supply temperature of the heat distribution system) in the heating mode versus COP. Normally, in heating systems, the supply temperature of the heat distribution network plays a key role in terms of exergy loss. This temperature is determined via an optimization procedure. 

Comparison of Exergy Loss during Storage and Transportation of Hydrogen... 

The convenience of the exergy concept houses the possibility to discuss energy issues on a clear and quantitative basis, in particular if the exergy values assigned to process streams are combined with exergy losses incurred in the processes in which these streams participate, either actively or passively, as the next chapter illustrates. 

A noteworthy point is, however, that the heat for the reboiler is supplied at 377 K, which is often available as waste heat in a chemical plant. Waste heat is usually rejected (hence the term "waste"), so heat integration could improve the process efficiency and reduce total exergy losses for the entire chemical plant (see Figure 10.14). Now, what Figure 10.14 shows is that heat integration can sometimes reduce the exergy losses of a chemical plant as well as reduce... 

Pie chart of main exergy losses in the HP LDPE process. 

Unit Exergy Loss (%) Exergy Loss (MJ/kgPE) Exergy Loss ( /kgPE)... 

The losses in the reactor are chemical exergy losses, whereas the cooler losses can be attributed to physical exergy losses. Mixing constitutes physical losses as do the losses in the extruder due to the dissipation of mechanical energy to heat. The losses in the purge vessel (V3) are due to the fact that the gas is incinerated. The sum of all losses equals 4.73MJ/kg PE, or US 0.0465 per kg PE. 

Coupling reactions to reduce the chemical exergy loss in the reactor... 

Exergy Loss Reduction by Recovering Butylene and Ethylene from Purge Gas... 

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