Performance analysis and optimization of organic Rankine cycle (ORC) for waste heat recovery

https://research.birmingham.ac.uk/portal/files/53643809/APEN2017.pdf

Performance-based health monitoring, diagnostics and prognostics for condition-based maintenance of gas turbines: A review

The effects of surface roughness on gas turbine performance are reviewed based on publications in the open literature over the past 60 years. Empirical roughness correlations routinely employed for drag and heat transfer estimates are summarized and found wanting. No single correlation appears to capture all of the relevant physics for both engineered and service-related (e.g., wear or environmentally induced) roughness. Roughness influences engine performance by causing earlier boundary layer transition, increased boundary layer momentum loss (i.e., thickness), and/or flow separation. Roughness effects in the compressor and turbine are dependent on Reynolds number, roughness size, and to a lesser extent Mach number. At low Re, roughness can eliminate laminar separation bubbles (thus reducing loss) while at high Re (when the boundary layer is already turbulent), roughness can thicken the boundary layer to the point of separation (thus increasing loss). In the turbine, roughness has the added effect of augmenting convective heat transfer. While this is desirable in an internal turbine coolant channel, it is clearly undesirable on the external turbine surface. Recent advances in roughness modeling for computational fluid dynamics are also reviewed. The conclusion remains that considerable research is yet necessary to fully understand the role of roughness in gas turbines.

A Review of Surface Roughness Effects in Gas Turbines

Clearance control is of paramount importance to turbomachinery designers and is required to meet today's aggressive power output, efficiency, and operational life goals. Excessive clearances lead to losses in cycle efficiency, flow instabilities, and hot gas ingestion into disk cavities. Insufficient clearances limit coolant flows and cause interface rubbing, overheating downstream components and damaging interfaces, thus limiting component life. Designers have put renewed attention on clearance control, as it is often the most cost effective method to enhance system performance. Advanced concepts and proper material selection continue to play important roles in maintaining interface clearances to enable the system to meet design goals. This work presents an overview of turbomachinery sealing to control clearances. Areas covered include: characteristics of gas and steam turbine sealing applications and environments, benefits of sealing, types of standard static and dynamics seals, advanced seal designs, as well as life and limitations issues.

Sealing in Turbomachinery

Any prime mover exhibits the effects of wear and tear over time. The problem of predicting the effects of wear and tear on the performance of any engine is still a matter of discussion. Because the function of a gas turbine is the result of the fine-tuned cooperation of many different components, the emphasis of this paper is on the gas turbine and its driven equipment (compressor or pump) as a system, rather than on isolated components. We will discuss the effect of degradation on the package as part of a complex system (e.g., a pipeline, a reinjection station, etc.). Treating the gas turbine package as a system reveals the effects of degradation on the match of the components as well as on the match with the driven equipment. This article will contribute insights into the problem of gas turbine systent degradation. Based on some detailed studies on the mechanisms that cause engine degradation, namely, changes in blade surfaces due to erosion or fouling, and the effect on the blade aerodynamics; changes in seal geometries and clearances, and the effect on parasitic flows; and changes in the combustion system (e.g., which result in different pattern factors), the effects of degradation will be discussed. The study includes a methodology to simulate the effects of engine and driven equipment degradation. With a relatively simple set of equations that describe the engine behavior, and a number of linear deviation factors which can easily be obtained from engine maps or test data, the equipment behavior for various degrees of degradation will be studied. A second model, using a stage by stage model for the engine compressor, is used to model the compressor deterioration. The authors have avoided to present figures about the speed of degradation, because it is subject to a variety of operational and design factors that typically cannot be controlled entirely.

Degradation in Gas Turbine Systems

This paper describes the most important factors affecting the industrial gas turbine engine performance deterioration with service time and provides some approximate data on the prediction of the rate of deterioration. Recommendations are made on how to detect and monitor the performance deterioration. Preventative measures, which can be taken to avoid or retard the performance deterioration, are described in some detail.

Performance Deterioration in Industrial Gas Turbines

This paper describes the most important factors affecting the industrial gas turbine engine performance deterioration with service time and provides some approximate data on the prediction of the rate of deterioration. Recommendations are made on how to detect and monitor the performance deterioration. Preventative measures, which can be taken to avoid or retard the performance deterioration, are described in some detail.Copyright © 1991 by ASME

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In cooperation with the US Department of Energy`s Morgantown Energy Technology Center, Westinghouse is working on Phase 2 of an 8-year Advanced Turbine Systems Program to develop the technologies required to provide a significant increase in natural gas-fired combined cycle power generation plant efficiency. In this paper, the technologies required to yield an energy conversion efficiency greater than the Advanced Turbine Systems Program target value of 60% are discussed. The goal of 60% efficiency is achievable through an improvement in operating process parameters for both the combustion turbine and steam turbine, raising the rotor inlet temperature to 2,600 F (1,427 C), incorporation of advanced cooling techniques in the combustion turbine expander, and utilization of other cycle enhancements obtainable through greater integration between the combustion turbine and steam turbine.

A combined cycle designed to achieve greater than 60 percent efficiency

In cooperation with the US Department of Energy`s Morgantown Energy Technology Center, Westinghouse is working on Phase 2 of an 8-year Advanced Turbine Systems Program to develop the technologies required to provide a significant increase in natural gas-fired combined cycle power generation plant efficiency In this paper, the technologies required to yield an energy conversion efficiency greater than the Advanced Turbine Systems Program target value of 60% are discussed The goal of 60% efficiency is achievable through an improvement in operating process parameters for both the combustion turbine and steam turbine, raising the rotor inlet temperature to 2,600 F (1,427 C), incorporation of advanced cooling techniques in the combustion turbine expander, and utilization of other cycle enhancements obtainable through greater integration between the combustion turbine and steam turbine

A sealing system for reducing a gap between a tip of a shrouded turbine blade and a stationary shroud of a turbine engine. The sealing system includes one or more seal lands extending from a shrouded turbine blade toward a stationary shroud of a turbine engine. During operation of the turbine engine, the seal lands straighten and extend towards the stationary shroud of the turbine engine, thereby reducing the leakage of air past the shrouded turbine blades and increasing the efficiency of the turbine engine. The sealing system may also include one or more protrusions extending from the stationary shroud towards the tips of the shrouded turbine blades.

Ihor S. Diakunchak

Papers

Performance Deterioration in Industrial Gas Turbines

Performance Deterioration in Industrial Gas Turbines

A combined cycle designed to achieve greater than 60 percent efficiency

A combined cycle designed to achieve greater than 60 percent efficiency

Turbine blade tip clearance control device