**1. Introduction**

Gas turbines are a vital and active area of research because they play a dominant role in the fields of power, propulsion and energy. They are used from the simple cycle machines employed to compress gas, pump oil and provide power, to the combined heat and power gas turbines used to provide electrical power, heating and cooling for industrial plants. Gas turbines are widely used in power plants and mechanical drive applications and, as these plants can be configured in a number of ways, the gas turbine manufacturer needs to balance the requirements of each user to optimize the design.

The conceptual design process of gas turbines is complex, involving multiple engineering disciplines. Aerodynamics, thermodynamics, heat transfer, materials science, component design, and structural analysis are a few of the fields employed when down selecting an appropriate gas turbine configuration. Because of the complexity involved, it is critical to have a process that narrows gas turbine options without missing the optimum.

The robustness of a design process is dependent on a number of factors including clear requirements and objectives, capture of the design parameters, knowledge capture and dissemination, validated procedures, repeatability, manufacturability, and the capability to consider the widest possible scope in the search for a conceptual design solution. The use of a constraint modelling technique has provided a framework where the various elements and tools involved in a design process can be integrated through various communication methods.

The design parameters of the gas turbines need to be chosen carefully to balance their influence on the reliability, maintainability, cost, efficiency and emissions of a gas turbine based power plant. Efficiency and reliability are two major parameters that should both be considered at the beginning of a new design project. To get higher efficiency means higher firing temperatures, higher pressure ratios, exotic materials, complicated cooling systems, all factors which jeopardize the cost and the reliability of the product. The aim of the product design team is to reach the optimum balance for these parameters, and for the demands and specifications of the individual customer. The gas turbine design process is not completely linear since the design steps are highly interdependent. A number of iterations are usually necessary in selecting a final configuration.

This book focuses on development and improvement of methods and techniques of analysis and diagnostics of efficiency, operation and maintenance of gas turbines. Authors from

Overview 3

increasing the output power with a little decrease in thermal efficiency. A thermo-economics algorithm is developed to estimate the economic feasibility of the cooling system. The cost of adding the air cooling system is also investigated and a cost function is derived that incorporates time-dependent meteorological data, operation characteristics of the gas turbine and the air intake cooling system and other relevant parameters such as interest rate,

**5. Energy and exergy analysis of reverse Brayton refrigerator for gas turbine** 

The use of reverse Brayton cycle to boost up the power of gas turbine power plants operating in hot humid ambiance is discussed in this chapter. The effects of irreversibilities in the system components (air compressor, combustion chamber, turbine, air cooler, expander and the mixing chamber) are evaluated along with the exergetic power gain ratio and the exergetic thermal efficiency change of the cycle. The dependency of the power gain, thermal efficiency and exergetic efficiency on the operation parameters are presented and

Unconventional gas turbine applications are discussed in this chapter. Some of engineering solutions are intended for smaller gas turbine systems, where the regenerative heat exchanger supplies energy for an additional thermal cycle. Coupling of Brayton cycle with several other thermodynamic cycles (e.g. another Brayton, Diesel or Stirling cycles) is discussed, and advantages of hybrid systems are analyzed. Large international development programmes are reviewed, and several hydrogen-fuelled gas turbine concepts are proposed. Potential combination of a hydrogen-fuelled gas turbine and a nuclear power generation unit which is used to cover peak load power demands in a power system is described.

In this chapter different techniques for recovering the exhaust heat from gas turbines are discussed, evaluating the influence of the main operating parameters on plant performance. A unified approach for the analysis of different exhaust heat recovery techniques is proposed. The methodology is based on relationships of general validity and characteristic plane for exhaust heat recovery, that indicates directly the performance obtainable with different recovery techniques, compared to a baseline non-recovery plant. An innovative scheme for external heat recovery is presented. It envisages repowering existing combined cycle power plants through injection of steam produced by an additional unit consisting of a

This chapter focuses on reliability of gas path diagnosis. New solutions are proposed to reduce the gap between simulated diagnostic process and real engine maintenance conditions. Thermodynamic models, data validation and tracking the deviations, fault classification, fault recognition techniques, multi-point diagnosis, diagnosis under transient

lifetime, and operation and maintenance costs.

**6. Gas turbines in unconventional applications** 

**7. The recovery of exhaust heat from gas turbines** 

gas turbine and a heat recovery steam generator.

**8. Gas turbine diagnostics** 

**power boosting** 

analyzed.

several countries have contributed chapters dealing with a wide range of issues related to analysis of gas turbines and their engineering applications. Gas turbine engine defect diagnostic and condition monitoring systems, operating conditions of open gas turbines, reduction of jet mixing noise, recovery of exhaust heat from gas turbines, appropriate materials and coatings, ultra micro gas turbines and applications of gas turbines are discussed. Analytical and experimental methods employed to identify failures and quantify operating conditions and efficiency of gas turbines that are encountered in engineering applications.

The book contains 11 chapters written by the specialists from various countries who are working in field of design, optimization, maintenance and diagnostics of gas turbines.
