Intercooled regenerative

The Intercooled Regenerative Reheat Cycle The Carnot cycle is the optimum cycle between two temperatures, and all cycles try to approach this optimum. Maximum thermal efficiency is achieved by approaching the isothermal compression and expansion of the Carnot cycle or by intercoohng in compression and reheating in the expansion process. The intercooled regenerative reheat cycle approaches this optimum cycle in a practical fashion. This cycle achieves the maximum efficiency and work output of any of the cycles described to this point. With the insertion of an intercooler in the compressor, the pressure ratio for maximum efficiency moves to a much higher ratio, as indicated in Fig. 29-36. 

This cycle produces an increase of 30% in work output, but the overall efficiency is slightly decreased as seen in Figure 2-15. An intercooling regenerative cycle can increase the power output and the thermal efficiency. This combination provides an increase in efficiency of about 12% and an increase in power output of about 30%, as indicated in Figure 2-16. Maximum efficiency, however, occurs at lower pressure ratios, as compared with the simple or reheat cycles. 

Figure 2-16. Performance map showing the effect of pressure ratio and turbine inlet temperature on an intercooled regenerative cycle.

Figure 2-18. The intercooled regenerative reheat split-shaft gas turbine cycle.

The addition of an intercooler to a regenerative gas turbine cycle increases the cycle s thermal efficiency and output work because a larger portion of the heat required for the process c-3 in Figure 2-7 can be obtained from the hot turbine exhaust gas passing through the regenerator instead of from burning additional fuel. 

The CHAT cycle may be seen as a low loss evaporative development of the dry intercooled, reheated regenerative cycle [CICBTBTX]. It offers some thermodynamic advantage—increase in turbine work (and heat supplied ) with little or no change in the compressor work, leading to an increased thermal efficiency and specific work output. 

The second step is to develop several conceptual plants (e.g., cycles A, B, and C) to meet the identified need. One of the several plants is described in Example 5.14. In this example, a three-stage regenerative steam Rankine cycle and a four-stage intercool and four-stage reheat air Brayton cycle are combined to meet the need. 

The intercooler is used to reduce power consumption for the compressors and improve the efficiency of the regenerative gas turbine system. In this section, helium in the pressure rise process of the compressors is cooled by the cooling water rurming through a wavy-firmed flat tube. The system design has been done on the basis of installation of two intercoolers, and Table 5 shows the specification of the first stage of the intercooler. 

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