Influence of Water Droplet Size and Temperature on Wet Compression

In the last years, among all different gas turbine inlet air cooling techniques, an increasing attention to fogging approach is dedicated. The various fogging strategies seem to be a good solution to improve gas turbine or combined cycle produced power with low initial investment cost and less installation downtime. In particular, overspray fogging and interstage injection involve two-phase flow consideration and water evaporation during compression process (also known as wet compression). According to the Author’s knowledge, the field of wet compression is not completely studied and understood. In the present paper, all the principal aspects of wet compression and in particular the influence of injected water droplet diameter and surface temperature, and their effect on gas turbine performance and on the behavior of the axial compressor (change in axial compressor performance map due to the water injection, redistribution of stage load, etc.) are analyzed by using a calculation code, named IN.FO.G.T.E. (INterstage FOgging Gas Turbine Evaluation), developed and validated by the Authors.

Evaluation of Energy Efficiency for a CCHP System With Available Microturbine

This paper deals with the problem of energy utilization efficiency evaluation of a microturbine system for Combined Cooling, Heating and Power production (CCHP). The CCHP system integrates power generation, cooling and heating, which is a type of total energy system on the basis of energy cascade utilization principle, and has a large potential of energy saving and economical efficiency. A typical CCHP system has several options to fulfill energy requirements of its application, the electrical energy can be produced by a gas turbine, the heat can be generated by the waste heat of a gas turbine, and the cooling load can be satisfied by an absorption chiller driven by the waste heat of a gas turbine. The energy problem of the CCHP system is so large and complex that the existing engineering cannot provide satisfactory solutions. The decisive values for energetic efficiency evaluation of such systems are the primary energy generation cost. In this paper, in order to reveal internal essence of CCHP, we have analyzed typical CCHP systems and compared them with individual systems. The optimal operation of this system is dependent upon load conditions to be satisfied. The results indicate that CCHP brings 38.7 percent decrease in energy consumption comparing with the individual systems. A CCHP system saves fuel resources and has the assurance of economic benefits. Moreover, two basic CCHP models are presented for determining the optimum energy combination for the CCHP system with 100kW microturbine, and the more practical performances of various units are introduced, then Primary Energy Ratio (PER) and exergy efficiency (α) of various types and sizes systems are analyzed. Through exergy comparison performed for two kinds of CCHP systems, we have identified the essential principle for high performance of the CCHP system, and consequently pointed out the promising features for further development.

An Integrated Software Procedure to Support Teaching of Radial Inflow Turbine Design

The authors decided to organize their design/analysis computational tools in an integrated software suite in order to help teaching radial turbine, taking advantage of their research background and a set of codes previously developed. The software is proposed for use during class works and the student can either use a single design/analysis tool or face a complete design loop consisting of iterations between design and analysis tools. The intended users are final year students in mechanical engineering. The codes output are discussed with two practical examples in order to highlight the turbomachinery performance at design and off-design conditions. The above suite gives the student the opportunity of getting used to different concepts (choking, blade loading, performance maps, …) that are encountered in turbomachinery design and of understanding the effects of the main design parameters.

Training Future Gas Turbine Performance Engineers

The performance analysis of modern gas turbine engine systems has led industry to the development of sophisticated gas turbine performance simulation tools and the utilization of skilled operators who must possess the ability to balance environmental, performance and economic requirements. Academic institutions, in their training of potential gas turbine performance engineers have to be able to meet these new challenges, at least at a postgraduate level. This paper describes in detail the “Gas Turbine Performance Simulation” module of the “Thermal Power” MSc course at Cranfield University in the UK, and particularly its practical content. This covers a laboratory test of a small Auxiliary Power Unit (APU) gas turbine engine, the simulation of the ‘clean’ engine performance using a sophisticated gas turbine performance simulation tool, as well as the simulation of the degraded performance of the engine. Through this exercise students are expected to gain a basic understanding of compressor and turbine operation, gain experience in gas turbine engine testing and test data collection and assessment, develop a clear, analytical approach to gas turbine performance simulation issues, improve their technical communication skills and finally gain experience in writing a proper technical report.

Remote Monitoring and Failure Diagnosis for a Microturbine Cogeneration System

This paper presents the implementation of failure detection and diagnosis, and predictive maintenance for a microturbine cogeneration system. It also introduces a remote monitoring system with capabilities for high-capacity high-speed data acquisition and storage, as well as data sharing via the Internet. Additionally, this paper provides failure diagnosis that uses high-speed transient data in order to determine the root cause of microturbine emergency shutdown or start failure, as well as failure prediction that uses long-range trend data in order to carry out the appropriate maintenance with some examples.

An Integrated Experimental-Numerical Case Study for a University Course About Dynamic Design of Turbomachinery

In the paper, the development of an integrated experimental-numerical case study for a university course of Fluid Dynamic Design of Turbomachinery (FDDT) is presented. Since 2004, a FDDT course has been held at the Engineering Department of the University of Ferrara (Italy). The basic idea of the FDDT course is to introduce the basic and advanced ideas beyond the design of turbomachinery supported by the use of integrated three-dimensional tools. Within the course, great effort has been devoted to practical experience, both numerical and experimental. In particular, the study of a simple but exhaustive geometry may represent a good exercise where students can practically and effectively train. For this reason, during the FDDT course, a centrifugal pump has been studied both experimentally and numerically as a test geometry. In the paper, the phases necessary to carry out this kind of project are presented and discussed.

Time Characterisation of the Anodic Loop of a Pressurized Solid Oxide Fuel Cell System

A dynamic Solid Oxide Fuel Cell (SOFC) model was integrated with other system components (i.e.: reformer, anodic off-gas burner, anodic ejector) to build a system model that can simulate the time response of the anode side of an integrated 250 kW pressurized SOFC hybrid system. After model description and data on previous validation work, this paper describes the results obtained for the dynamic analysis of the anodic loop, taking into account two different conditions for the fuel flow input: in the first Case (I), the fuel flow follows with no delay the value provided by the control system, while in the second Case (II) the flow is delayed by a volume between the regulating valve and the anode ejector, this being a more realistic case. The step analysis was used to obtain information about the time scales of the investigated phenomena: such characteristic times were successfully correlated to the results of the subsequent frequency analysis. This is expected to provide useful indications for designing robust anodic loop controllers. In the frequency analysis, most phase values remained in the 0–180° range, thus showing the expected delay-dominated behavior in the anodic loop response to the input variations in the fuel and current. In Case I, a threshold frequency of 5Hz for the pressure and STCR, and a threshold frequency of 31Hz for the anodic flow were obtained. In the more realistic Case II, natural gas pipe delay dominates, and a threshold frequency of 1.2Hz was identified, after which property oscillations start to decrease towards null values.

Lycoming T-53 Gas Turbine Engine Modification for Industrial Application

This paper describes a development program active at Magellan Aerospace Corporation since 2003, whereby specific modifications are incorporated into an Avco Lycoming T-53 helicopter gas turbine engine to enable it to function as a ground based Industrial unit for distributed power generation. The Lycoming T-53 is a very well proven and reliable two shaft gas turbine engine whose design can be traced back to the 1950s and the fact of its continued service to the present day is a tribute to the original design/development team. Phase 1 of the Program introduces abradable rotor path linings, blade coatings and changes to seal and blade tip clearances. Magellan has built a test cell to run the power generation units to full speed and full power in compliance with ISO 2314. In co-operation with Zorya-Mashproekt, Ukraine, the exhaust emissions of the existing combustion system for natural gas was reduced by 30%. New nozzles for low heat value fuels and for high hydrogen content fuels (up to 60% H2) have been developed. The T-53 gas turbine engine exhaust gas temperature is typically around 620 deg C, which makes it a very good candidate for co-generation and recuperated applications. As per Phase 2 of the program, the existing helicopter integral gearbox and separate industrial step-down gearbox will be replaced with single integral gearbox that will use the same lubrication oil system as the gas turbine engine. The engine power output will increase to 1200 kW at the generator terminals with an improvement to 25% efficiency ISO. Phase 3 of the Program will see the introduction of a new silo type combustion system, developed in order to utilize alternative fuels such as bio-diesel, biofuel (product of wood pyrolysis), land fill gases, syn gases etc. Phase 4 of the Program in cooperation with ORMA, Russia will introduce a recuperator into the package and is expected to realize a boost in overall efficiency to 37%. The results of testing the first two T-53 industrial gas turbine engines modified per Phase 1 will be presented.

Analysis of Indirectly Fired Gas Turbine Power Systems

This paper describes the results of modelling the performance of several indirectly fired gas turbine (IFGT) power generation system configurations based on four gas turbine class sizes, namely 5 kW, 50 kW, 5 MW and 100 MW. These class sizes were selected to cover a wide range of installations in residential, commercial, industrial and large utility power generation installations. Because the IFGT configurations modelled consist of a gas turbine engine, one or two recuperators and a furnace; for comparison purpose this study also included simulations of simple cycle and recuperated gas turbine engines. Part-load, synchronous-speed simulations were carried out with generic compressor and turbine maps scaled for each engine design point conditions. The turbine inlet temperature (TIT) was varied from the design specification to a practical value for a metallic high-temperature heat exchanger in an IFGT system. As expected, the results showed that the reduced TIT can have dramatic impact on the power output and thermal efficiency when compared to that in conventional gas turbines. However, the simulations also indicated that several configurations can lead to higher performance, even with the reduced TIT. Although the focus of the study is on evaluation of thermodynamic performance, the implications of varying configurations on cost and durability are also discussed.

Development of a Partial Oxidation Gas Turbine (POGT) for Innovative Gas Turbine Systems

Gas Technology Institute (GTI) has been advancing the POGT concept since 1995. The progress to date of a GTI-led team on the development and testing of a POGT prototype, and POGT-based systems are presented. There are two main features that distinguish a POGT from a conventional gas turbine: the design arrangement and the thermodynamic processes used in operation. One unique feature is utilization of a non-catalytic partial oxidation reactor (POR) in place of a typical combustor. An important secondary distinction is that a much smaller compressor is required, one that typically supplies less than half of the air flow required in a conventional gas turbine. From a thermodynamic point of view, the working fluid provided by the POR (a secondary fuel gas) has much higher specific heat than complete combustion products. This allows higher energy per unit mass of fluid to be extracted by the POGT expander than is the conventional case. A POR operates at fuel rich conditions, typically at equivalence ratios on the order of 2.5, and virtually any hydrocarbon fuel can be combusted. Because of these fuel rich conditions, incomplete combustion products are used as the hot section working fluid. A POGT thus produces two products: power and a secondary fuel that usually is a H2 rich gas. This characteristic can lead to high efficiencies and ultra-low emissions (single digit NOx and CO levels) when the secondary fuel is burned cleanly in a bottoming cycle. When compared to the equivalent standard gas turbine bottoming cycle combination, the POGT provides an increase of about 10 percentage points in overall system efficiency. Two areas of recent development are addressed in the paper: POGT development and experimental evaluation of a 7 MWth pressurized non-catalytic POR installed at GTI; and examples of POGT-based systems for combined generation of power, heat, syngas, hydrogen, etc. The POGT design approach to convert an existing engine into a POGT by replacing its combustor with a POR together with concomitant modifications of other engine components is discussed. Experimental results of the POR operation include descriptions of major operating conditions: start up, light off conditions, lean combustion mode, lean-to-rich transition, and operation in rich partial oxidation mode at different loads and air to fuel ratios. The overall efficiency of a POGT two-stage power system is typically high and can approach 70% depending on the POGT operating conditions and the chosen bottoming cycle. The bottoming-cycle can be either a low pressure (or vacuum) combustion turbine, or an internal combustion engine, or a solid oxide fuel cell, or any combination of them. In addition, the POGT can be used as the driver for cogeneration systems. In such cogeneration systems the bottoming cycle can be a fuel-fired boiler, an absorption chiller, or an industrial furnace. The POGT is ideally suited for the co-production of power and either hydrogen, or synthesis gas (syngas), or chemicals. Some of these important applications are discussed.