Table of Contents


    • Exergy analysis of a complex four-cylinder steam turbine

      pg(s) 3-7

      This paper presents an exergy analysis of a complex four-cylinder steam turbine, which operate in a coal-fired power plant. Analyzed steam turbine consists of high pressure single flow cylinder (HPC), intermediate pressure dual flow cylinder (IPC) and two low pressure dual flow cylinders (LPC1 and LPC2). The highest part of cumulative mechanical power (787.87 MW) is developed in IPC (389.85 MW) and HPC (254.67 MW), while both low pressure cylinders develop a small part of cumulative mechanical power (70.29 MW in LPC1 and 73.06 MW in LPC2). Cylinder exergy destruction (cylinder exergy power loss) continuously increases as the steam expands through the turbine. The lowest exergy destruction has HPC (13.07 MW), followed by the IPC (20.95 MW), while the highest exergy destructions are noted in low pressure cylinders (24.37 MW in LPC1 and 27.17 MW in LPC2). Cylinder exergy efficiency continuously decreases as the steam expands through the turbine. The highest exergy efficiency has HPC (95.12%), followed by the IPC (94.90%) and LPC1 (74.25%), while the lowest exergy efficiency of all cylinders is obtained in LPC2 (72.89%). Exergy efficiencies of LPC1 and LPC2 are much lower in comparison to other low pressure dual flow cylinders from comparable steam power plants. The whole observed steam turbine has exergy
      efficiency equal to 90.20%.

    • On the study of some characteristics ensuring loading capacity of rack drives

      pg(s) 8-12

      This research deals with the study of some kinematic characteristics, which can be used to ensure the loading capacity of the rack drives, including its hydrodynamic component. A brief analysis of the spatial rack drives in terms of their load capacity is realized. When mutually enveloping tooth surfaces are synthesized, it is possible to appear singular contact points appear on the active tooth surfaces. Two kinds of singular points exist, depending on the normal vector to the meshed tooth surfaces in their common points: singular points of firstorder (called ordinary nodes), and singular points of second-order. Singular points of first order should be registered and eliminated from the mesh region since increased specific friction, worsen lubrication, and heat transfer are present, which result in a decreased loading
      capacity of the gear set A special accent is placed on the registration and elimination of singular points on the tooth surfaces of the synthesized rack drives. Analytical expressions are written defining total transference velocity and its normal component to an instantaneous contact line at an arbitrary contact point.