The reversible intercooled cycle

In the ultimate version of the reheated and intercooled reversible cycle [CICICIC- HTHTHT- XJr, both the compression and expansion are divided into a large number of small processes, and a heat exchanger is also used (Fig. 3.6). Then the efficiency approaches that of a Carnot cycle since all the heat is supplied at the maximum temperature Tr = T ax and all the heat is rejected at the minimum temperature = r,nin. 

Before moving on to the aJs analyses of irreversible gas turbine cycles we need to define various criteria for the performance of some components, all of which have been assumed to be perfect (reversible) in the analyses of Section 3.2.1. The criteria used are listed in Table 3.1. 

In addition to the irreversibilities associated with these components, pressure losses (Ap) may occur in various parts of the plant (e.g. in the entry and exit ducting, the combustion chamber, and the heat exchanger). These are usually expressed in terms of non-dimensional pressure loss coefficients, Ap/(p) N, where (/ )in is the pressure at entry to the duct. (Mach numbers are assumed to be low, with static and stagnation pressures and their loss coefficients approximately the same.) 

As alternatives to the isentropic efficiencies for the turbomachinery components, tjt and Tjc. which relate the overall enthalpy changes, small-stage or poly tropic efficiencies (Tjpj and Tjpc) are often used. The pressure-temperature relationship along an expansion line is then p T = constant, where z = [y y OtJpt]- 

Turbine Isentropic efHciency Tfr = Enthalpy drop/i.sentropic enthalpy drop 

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