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Experiments have been performed to investigate the efficiency of the process of thermostabilization of a high-temperature surface with dispersed flow of a heat transfer agent at a pressure of 0.2–0.6 MPa in it and at a mass rate of flow of heat transfer agent of (3.3–6.15)·10–3 kg/s and a surface sprinkler density of 1.67–3.11 kg/(m2·s). Assessments have been made of the amount of heat transfer agent evaporating in all investigated heat transfer regimes. An equation describing various heat transfer regimes has been obtained for heat transfer from a high-temperature surface to a dispersed flow of a heat transfer agent in a criterial form. Criterial equations qualitatively describe experimental data within a small error, which indicates their satisfactory reproducibility in the said range of regime parameters of the process. [ABSTRACT FROM AUTHOR]

The development of in-chamber elements of a tokamak thermonuclear reactor is associated with a large number of challenging engineering problems, one of which is the removal of heat flows with a specific density of 10–20 MW/m2. Results of an experimental study of cooling by a two-component dispersed coolant flow directed perpendicular to the cooled surface are discussed. The study is a continuation of the research on enhancing the heat removal efficiency. The efficiency of this cooling method is due to a decrease in the proportion of convective heat transfer and an increase in heat exchange during evaporation. It is shown that the use of a two-component dispersed coolant flow makes it possible to remove heat flux densities exceeding 10 MW/m2 at a pressure of the coolant components not exceeding 0.5 MPa; the effect of the ratio of components on the efficiency of heat removal is investigated. The experimental data obtained indicate the high efficiency of the proposed cooling method. The heat transfer coefficient was found to reach 200 kW/(m2 K), a value which is significantly higher than that for conventional cooling methods based on single-phase water flow. [ABSTRACT FROM AUTHOR]

This paper presents the experimental research of factors influencing the UDS 214 excavator efficiency. The hydraulic oil flow rate is measured in hydraulic circuits for controlling the moving of the bucket of the UDS 214 ex­cavator. From the measured values, the total power losses of the individual hydraulic circuits and their efficiencies are evaluated by calculations and measurements. Furthermore, the times of the excavator cycles during a soil excavation and loading of the transport vehicle were measured. From the measured operating cycle times of the excavator, the average value of the operating cycle time was evaluated and, from this average time, the theoretical performance and the operating performance of the given excavator in the given operational states were calculated. Then, at the end of the paper, the individual calculated power losses as well as the efficiencies of the hydraulic circuits for controlling the moves of the excavator are evaluated. According to the findings, the swing hydraulic circuit of the excavator, which has the second highest power loss of 5.926 kW and its percentage in the average tested cycle time of the excavator is 48%, seems to be a suitable hydraulic circuit for the innovation.

This article describes the testing of oil filters on a laboratory test device designed to monitor changes in oil filter flow and pressure, depending on the level of engine oil contamination. The laboratory test device enables testing the suitability of using filters with different filtering capabilities, even with differently polluted engine oil. The measurement results can be used in the design of new filter materials, or in the design of changing replacement intervals, which would mean a benefit from an economic as well as an ecological point of view.

Pressure intensifiers have their utilization in hydraulic circuits, when there is a need for pressure multiplication for some period of time. Using intensifiers provides energy savings, cost reductions or smaller dimensioning. This article is about a pressure intensifier based on rotary flow dividers. Its functioning is evaluated by its pressure-multiplying efficiency. This efficiency is always calculated from values gained from measurements. However, it would be very convenient to be able to evaluate these types of intensifiers without a need to provide specific measurements for every type of intensifier and rather calculate their efficiency using the general parameters of a hydraulic circuit. Therefore, this article is about the description of a model which calculates the pressure-multiplying efficiency only with two input values: the pressure and the speed of an intensifier. Final derived formulas are also used for the efficiency prediction at pressure levels never measured before and then verified by measurements. [ABSTRACT FROM AUTHOR]

This paper presents the experimental research of factors influencing the UDS 214 excavator efficiency. The hydraulic oil flow rate is measured in hydraulic circuits for controlling the moving of the bucket of the UDS 214 excavator. From the measured values, the total power losses of the individual hydraulic circuits and their efficiencies are evaluated by calculations and measurements. Furthermore, the times of the excavator cycles during a soil excavation and loading of the transport vehicle were measured. From the measured operating cycle times of the excavator, the average value of the operating cycle time was evaluated and, from this average time, the theoretical performance and the operating performance of the given excavator in the given operational states were calculated. Then, at the end of the paper, the individual calculated power losses as well as the efficiencies of the hydraulic circuits for controlling the moves of the excavator are evaluated. According to the findings, the swing hydraulic circuit of the excavator, which has the second highest power loss of 5.926 kW and its percentage in the average tested cycle time of the excavator is 48%, seems to be a suitable hydraulic circuit for the innovation. [ABSTRACT FROM AUTHOR]

Selection of the cooling method for energy stressed elements, such as the divertor, limiter, and blanket, upon impact of powerful heat flows is an important issue for all research fusion reactors. At present, these elements are cooled by water under pressure, which can involve serious problems in an emergency situation related to poor tightness of elements of cooling system. This work considers an alternative cooling method of such structural elements using a two-component dispersed flow of coolant. Heating of the working segment under conditions close to stationary loads of the ITER first wall has been simulated at the test bench of the Department of General Physics and Nuclear Fusion of the National Research University Moscow Power Engineering Institute. Cooling of the working section is performed by dispersed flow of coolant over the inner surface. The temperature distribution over the wall thickness of working section has been obtained. The thermal conductivity of the material of the working section has been assessed. It is demonstrated that the proposed cooling method makes it possible to perform efficient heat removal under thermal loads in the range of 0.7–3.2 MW/m2. [ABSTRACT FROM AUTHOR]

A set of activities aimed at upgrading an experimental bench simulating heavily loaded components of thermonuclear facilities is accomplished. The design of a test section for implementing one-sided heating with high energy density is developed. A VCh-60AV high-frequency generator with operating frequencies of 30–60 kHz is the test section heating system's key component. The article describes the experimental bench schematic design, hydraulic circuit components, and the high-frequency heating system and measurement system components. The schematic design of a hydraulic atomizer with a conical insert, which generates a sprayed flow in carrying out experimental studies is presented. The results of field velocity measurements in the atomizer spray jet and of experimental study of sprayed flow distribution over the droplet radius are given, and the average diameter of droplets in the spray jet section was determined, which was found to be 34 μm. The techniques for carrying out experiments on thermal stabilization in a steady mode by spray cooling and for processing the primary experimental data are described. The effectiveness of high-temperature surface thermal stabilization by a spray of distilled water at a coolant gauge pressure of (0.2–0.6) × 106 Pa, coolant mass flowrate (3.3–6.15) × 10–3 kg/s, and spray density within the range from 1.67 to 3.11 kg/(m2 s) is studied. The obtained experimental data array is processed, and the graphic dependences of heat flux and heat-transfer coefficient on the temperature difference between the cooled wall and coolant spray are presented. The heat flux in the experimental study reached 3.2 MW/m2, and the heat-transfer coefficient in that case was equal to 77 kW/(m2 K). The obtained experimental data show satisfactory repeatability in a wide range of temperature difference from 0 to 400°C, and high heat flux and heat-transfer values have been reached. [ABSTRACT FROM AUTHOR]

Pressure intensifiers are used in specific areas of a hydraulic circuits, where increased pressure is needed, while the rest of the circuit (up to the pump) run on lower level of a working pressure. That could lead to a cheaper design of the components, while just one high pressure branch is designed on high pressure. Using pressure intensifier could also mean energy cost reductions. Rotary flow divider can be also used as a pressure intensifier. This area started to be developed in Jihostroj a.s. This paper describes specific tests, which has been running to precisely parameterize limits of use of a divider as an intensifier without design changes to follow with a development of a designs to maximize intensifier's parameters. Development also leads to compact solutions compatible with LS signals or with other hydraulic components to create compact assembly comparable to some areas of use of a piston pumps or inexpensive flow control drive. These development opportunities are also described in this paper. [ABSTRACT FROM AUTHOR]

BACKGROUND: Computed tomographic angiography (CTA) is the gold standard in the diagnosis of most vascular pathologies. The optimal method to improve this technique is the use of anthropomorphic tissue-mimicking phantoms, since CTA is accompanied by radiation exposure and the risk of allergic reactions when using contrast agents. In addition to compliance with the X-ray properties of the vessel, the pulsations occurring in the aorta in vivo must be simulated. A review of existing solutions demonstrates a small number of national developments in this area at a relatively high cost of foreign analogues. Moreover, the lack of reproducible methodology for creating pulse flow simulation devices using available and inexpensive materials is worth noting. AIM: To develop a hydraulic circuit to simulate pulse blood flow in a tissue-mimicking aortic phantom. METHODS: A literature analysis of existing pulse flow simulation devices and tissue-mimicking phantoms of the abdominal aorta was conducted. The medical and technical requirements for the designed device were formulated. The control circuit was developed, the circuit element base was determined, and the hydraulic circuit prototype was assembled. Based on a literature review, a material suitable for reproducing the biomechanical characteristics of arterial tissue was selected. A simplified phantom of the abdominal aortic segment was made. The device model included a simplified abdominal aortic phantom, a control system, a pump, a pressure sensor, a flow meter, and a flow regulator. Initial testing of the developed circuit in the basic signal mode and in the real flow profile simulation mode was performed. The basic signals were periodic rectangular signals reproduced at different frequencies, simulating normal, rapid, and slow heart rate. Using pulse-width modulation, a profile of the pressure pulse wave was obtained. RESULTS: The developed hydraulic circuit allowed successful reproduction of pressure and flow velocity profiles in a tissue-mimicking aortic phantom. Further development of the project will involve fabrication and validation of the circuit (using anthropomorphic versions of the phantom) and simulation of the angiographic study. CONCLUSIONS: The results may be useful for the improvement of CTA techniques and the development of angiosurgical training stands.

The article refers to the proposed test equipment used to monitor the service life of hydrostatic transducers and fluids under constant or dynamic operating pressure loading. The proposed laboratory test equipment enables simultaneous testing of hydrostatic transducers and energy carriers in two hydraulic circuits and is designed to measure the flow characteristics and technical life of hydrostatic transducers with different energy carriers. The benefit of the proposed device is the possibility of simultaneous testing of the transducers as well as the performance of verification measurements of individual circuits, which was preceded by the development of a theoretical design. This includes the calculations necessary to determine the power of the drive, the cooling power as well as the definition of other parameters and elements of the hydraulic system. The design of the device was based on technical characteristics, load characteristics obtained by own measurements, and characteristics of individual hydraulic and electrohydraulic elements. On the basis of the prepared laboratory test equipment, it is possible to significantly shorten the time of operational tests and perform repeated tests under the same operational load with different types of energy carriers. The hydraulic circuit (primary or secondary) can be loaded through a proportional electrohydraulic pressure valve, which is able to simulate the load with the operational pressure curve obtained by measurement, as well as the cyclic stress, the frequency, amplitude, and rate of increase of which can be defined according to the selected methodology. A verification measurement of the flow characteristics of the used transducers was also carried out, which confirmed the correct function and design of the test laboratory equipment. The achieved results can be used in mechanical engineering for the accelerated life test of hydrostatic transducers, which are often used in mobile energy devices working in environmentally sensitive areas. The proposed laboratory test equipment will be used for testing ecological energy carriers, increasing the efficiency of energy conversion in agricultural facilities using biomass. [ABSTRACT FROM AUTHOR]

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At present, Mosenergo is carrying out computations and experiments to substantiate the possibility of reducing the minimum load for a group of natural-gas fired boilers (live steam pressure = 130 kgf/cm2) and ensuring continuous, without restrictions, operation of the main and auxiliary equipment. According to the operating documentation, the minimum load of Mosenergo boilers is 50 to 60%. To preliminarily assess the minimum permissible load, thermal and hydraulic analyses were carried out using specially developed mathematical models. To confirm that boilers can operate at a reduced load, to adjust the operating modes, and to determine the performance indicators, tests at various Mosenergo boilers were conducted. In the tests, the load of these boilers (TGME-464, TP-80, TP-80M, TP-87, TGM-84B, TGM-96) was reduced to 40 – 45% of the rating while maintaining the required reliability criteria, permissible environmental performance, and rated steam parameters. [ABSTRACT FROM AUTHOR]

The article refers to the proposed test equipment used to monitor the service life of hydrostatic transducers and fluids under constant or dynamic operating pressure loading. The proposed laboratory test equipment enables simultaneous testing of hydrostatic transducers and energy carriers in two hydraulic circuits and is designed to measure the flow characteristics and technical life of hydrostatic transducers with different energy carriers. The benefit of the proposed device is the possibility of simultaneous testing of the transducers as well as the performance of verification measurements of individual circuits, which was preceded by the development of a theoretical design. This includes the calculations necessary to determine the power of the drive, the cooling power as well as the definition of other parameters and elements of the hydraulic system. The design of the device was based on technical characteristics, load characteristics obtained by own measurements, and characteristics of individual hydraulic and electrohydraulic elements. On the basis of the prepared laboratory test equipment, it is possible to significantly shorten the time of operational tests and perform repeated tests under the same operational load with different types of energy carriers. The hydraulic circuit (primary or secondary) can be loaded through a proportional electrohydraulic pressure valve, which is able to simulate the load with the operational pressure curve obtained by measurement, as well as the cyclic stress, the frequency, amplitude, and rate of increase of which can be defined according to the selected methodology. A verification measurement of the flow characteristics of the used transducers was also carried out, which confirmed the correct function and design of the test laboratory equipment. The achieved results can be used in mechanical engineering for the accelerated life test of hydrostatic transducers, which are often used in mobile energy devices working in environmentally sensitive areas. The proposed laboratory test equipment will be used for testing ecological energy carriers, increasing the efficiency of energy conversion in agricultural facilities using biomass.