The object of research is a pump of dynamic principle of action, namely a TFP «TURO» type (Switzerland). The main TFP disadvantage is a lower value of the efficiency compared with centrifugal pumps. This is due to the peculiarity of their working process – the formation of a longitudinal vortex in the free chamber of the pump, the maintenance of which consumes part of the power consumed by the pump. The analysis of a priori information indicates the expediency of using a change in the geometry of the flowing part of the pump as a means of influencing its pressure and energy characteristics. Extending the part of the blades of the impeller to the free chamber allows the combined working process (blade and vortex) to be used in the pump, which will increase the efficiency of the pump without losing the significant advantages inherent in this type of pumps. Experimental impellers were made and a test was carried out on an experimental bench. The obtained results indicate the possibility of increasing the head and efficiency of the pump while maintaining the location of the optimal regime. The nomenclature of quality indicators is determined, according to which the comparison of the created pump and the analog pump is carried out. The Harrington method (the «desired function» method) was chosen to determine the basic quality measure. The weight coefficients for quality indicators are determined and the integral indicator of the technical level of the created pump and analog pump is calculated. The use of the SST model of turbulence for the numerical simulation of flow in the TFP flowing part is substantiated. Numerical calculation is performed and integral values of the pump are obtained. The proposed design allows to create new pumping equipment with improved performance and a higher technological level, or increase the relevant indicators of existing equipment by making changes to the impeller design. These changes do not require significant costs and do not require the use of complex equipment and can be implemented directly at the site of operation by the company's own forces or the operating organization.

Due to a simple design and hydraulic passage that is the least susceptible to clogging, torque flow pumps (TFP) of Turo type are the most common pumps used for pumping various hydraulic mixtures. These pumps are referred to vortex pumps, operation of which is accompanied by energy loss and vortex formation resulting in low economic efficiency. Since the TFP is a vortex hydraulic machine, the ratio of the fluid velocity in the free pump passage to the impeller rotational speed ω_fluid /ω is an indicator of the TFP efficiency. The higher the value of ω_fluid , the more efficient the pump is. The mechanism of the energy transfer in the TFP is caused by both blade and vortex operating process, or a combined operating process. The efficiency of the pump can be improved by increasing the portion of blade operating process. The aim of the study is to improve the efficiency of the TFP of Turo type by modifying the impeller design, to obtain a basic equation of the TFP with a new impeller which has several extended blades, and to study the influence of the impeller geometry on the pump performance experimentally. The study was carried out by analytical and experimental methods. The equation describing the head dependence on the hydraulic passage dimensions of the pump with a new impeller was obtained analytically. This equation can be used to clarify the methodological recommendations for designing the pump. The energy balance in the TFP was analyzed. During the testing on a test rig, the characteristics of the pump were obtained, which confirmed the advantages of using the modified impeller with extended blades resulting in increase of the portion of the blade operating process.

We consider the influence of vapor content in the mixed flow leaving a liquid-vapor ejector on the energy efficiency of a vacuum unit. As shown by numerical studies of liquid-vapor ejectors, this issue is important as vapor overproduction, which accompanies the process of secondary flow ejection, directly impacts the efficiency of the working process of both the liquid-vapor ejector and the vacuum unit as a whole. The greater the degree of vapor overproduction, the greater the load on the vapor phase of the separator, which is part of the vacuum unit. In addition, the liquid phase must be returned to the cycle to ensure the constancy of the mass flow rate of the working fluid of the primary flow. Our numerical study results revealed the rational value of the degree of vapor overproduction at which the efficiency of the liquid–vapor ejector was maximized, and the amount of additional working fluid that needed to enter the cycle of the vacuum unit was minimal. Experimental condition monitoring studies on the liquid–vapor ejector were carried out on plane-parallel transparent models with different flow path geometries. Through experimental studies, we confirmed and adjusted the values of the achievable efficiency of the working process of a liquid–vapor ejector, depending on the degree of vapor overproduction. Using a comparative analysis of liquid–vapor ejectors with different flow path geometries, differences were revealed in their working processes, which consisted of the degree of completion of the mixing of the working media of primary and secondary flows. To determine the feasibility of using liquid–vapor ejectors with different flow path geometries, exergy analysis was performed, resulting in achievable efficiency indicators.

Author(s): Sharapov S. O.1, Bocko J.2, Yevtushenko S. O.1*, Panchenko V. O.3, Skydanenko M. S.4 Affiliation(s): 1 Department of Technical Thermophysics, Sumy

Simulation of the thermal state of the premises with the heating system «Heat-insulated floor»

This paper considers the possibility of using liquid-vapor ejectors in condensing units of steam turbines. This unit is designed for pumping out a steam-air mixture from a steam turbine condenser, in which the process occurs at a pressure lower than atmospheric. In the traditional scheme, this is provided by a two-stage steam-jet ejector unit. The proposed scheme involves the use of a single-stage liquid-vapor ejector and its possible pre-vacuum mode of operation in conjunction with a liquid-ring vacuum pump. A working process of the liquid-vapor ejector does not require the supply of working steam from the outside since its generation occurs in the active nozzle of the liquid-vapor ejector. A description of the traditional scheme and the proposed options is given, which are different both in the scheme solution and in the operating parameters. The object of this study is a liquid-vapor ejector, which is used in the condensing system of a steam turbine. Thermodynamic calculation of the proposed circuit solutions was carried out. As a result, the necessary mode parameters of the schemes were determined. To assess the feasibility of using a liquid-vapor ejector in the condensation systems of steam turbines, an exergy analysis was performed. The proposed scheme makes it possible to increase efficiency by 2.3 times, and when used with a liquid-ring vacuum pump – by 2.44 times. To assess the economic efficiency of the modernization of the condensing system, thermoeconomic analysis was performed. The use of the proposed scheme makes it possible to reduce the cost of generating boiler steam and reduce the cost of the resulting product of the steam turbine unit by about 51 %. The estimated cost of a unit of the amount of boiler steam consumed per ton of product and the unit cost of steam were established.