Single-phase media hydrodynamics and heat transfer in heat exchangers with twisted profile tubes

A profiled heat exchanger tube is the one in which some features have been incorporated into the tube geometry for heat transfer enhancement. They offer a perspective method of steam turbine shell-and-tube heat exchangers improvement. Twisted profile tubes (TPT) are widely used in power engineering. This paper presents some results of experimental and theoretical research of hydrodynamics and heat transfer in TPTs. It is revealed that the heat transfer coefficient for water flow in a TPT increases up to 80% compared to that of a plain tube. With a rise of media Reynolds number, the heat transfer rate in a TPT decreases in comparison to that of a plain tube, but for air flow in a TPT the heat transfer coefficients ratio does not depend on the Reynolds number value. Water flow hydraulic losses in TPTs increase from 15 to 100% depending on the tube profile parameters. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen

Modern technologies for rendering information support to cogeneration steam turbine units in their design and operation stages

Application of modern information technologies in different stages of the lifecycle of cogeneration turbines is considered as one of possible ways for improving their competitiveness. Specific features relating to rendering information support for steam turbine units during the periods of their design and operation, which are the main stages of their life cycle, are presented. Three-dimension modeling, adaptive, and parametric design technologies are applied in the equipment design stages. Information support technologies developed by the authors are applied during the operation stage. Information is integrated by using a product lifecycle management (PLM) system. © 2013 Pleiades Publishing, Ltd

Heat transfer augmentation during water steam condensation on twisted profile tubes

Some results are presented of experimental and theoretical research of hydrodynamics and heat transfer during condensation of water steam (both stationary and slowly moving) on twisted profile tubes (TPT). For a heat transfer coefficient during condensation of stationary steam on TPT two characteristic areas were observed. At small values of condensate film Reynolds numbers a TPT heat transfer coefficient can be 10-15% below that of the plain tubes depending on profile parameters. With the rise of both condensate film Reynolds number and profile parameter h/s heat transfer coefficient increases up to 50% in comparison to a plain tube. During slowly moving steam condensation the TPT heat transfer coefficient increases up to 70% as compared to a plain tube. Conducted research and industrial tests results showed that the assured effect of a heat transfer coefficient increase in TPT heat exchangers could reach for turbine condensers 15%, for low cycle heaters 35-40%. The heat exchangers hydraulic resistance increases by 40-70%. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen

Development of a procedure for substantiating replacement terms for the condenser tubes of steam turbine installations

Results obtained from elaboration of a procedure for estimating replacement terms for the condenser tube systems of steam turbine installations are presented. Censored data processing methods are used in performing statistical assessment of replacement terms. The service life of condenser tubes blanked off in the course of turbine operation is assumed to be known (complete operation time), and that for tubes blanked off during the turbine repair process is assumed to be undetermined (censored operation time). The criterion for estimating the replacement term for a condenser tube system is defined as the ratio between the number of tubes blanked off during a repair and in the course of turbine operation. The procedure is validated by the results from a study on analyzing the damageability of tubes made of different materials for the condensers of 11 turbines with capacities ranging from 25 to 500 MW. © 2013 Pleiades Publishing, Ltd

Identification of corner separation modelling in axial compressor stage

The paper presents a study of corner separations in hub to blade region at various operation conditions towards compressor stall. It is known that for compressor flows with low or none separations computation fluid dynamics with RANS methods work quite well, however, for highly separated flows they are no longer entirely valid. Therefore, several criteria were applied for prediction and quantification of possible corner separation, and the main interest of this work is in predicting the separation just before it will actually happen by certain flow metrics, so these metrics can be further used as a 'pre-stall' criteria whilst the RANS CFD operating point still behave within its appropriate limits. Also the effect of shear lean is discussed in the presented context. © The Authors, published by EDP Sciences, 2020

Redesign of an axial compressor with mass flow reduction of 30%

In this paper redesign process of an axial compressor of a Gas Turbine for mechanical drive is discussed together with computational results and experimental data. The goal of the project was to reduce compressor mass flow by 30% and at the same time to increase compressor specific work by about 10%. This could not be achieved by conventional methods such as re-staggering of Inlet Guide Vanes. Throughflow and CFD calculations were performed for redesigned versions. As a result an updated compressor was produced for the real engine and achieved design objectives. This paper shows how the swept area distribution along the compressor affects stage loading distribution and surge limits. © 2019 WIT Press