Littérature scientifique sur le sujet « THROTTLING VALVE REPLACEMENT »

The results of an experimental study of the mechanic-pneumatic converter "nozzle-shutter" and the pneumatic power amplifier created on its basis are presented. Such devices can be used in the design of damping systems for a multi-bearing oscillatory system of a special-purpose vehicle intended for the transport of "delicate" goods. The algorithm for controlling the adaptive air-hydraulic spring is rather complicated and it may require expensive hydraulic equipment with electromagnetic proportional control for its implementation. A possible alternative to such equipment are pneumatic devices built on the basis of adjustable throttles "nozzle-shutter". The installation on board of vehicles on wheeled or caterpillar tracks of cargo beams or platforms with a load fixed to them may be associated with the need for their stabilization in a horizontal position in the case of a shift in the center of gravity of the cargo relative to the vertical axis. Such a problem can be solved using differential hydraulic cylinders with a cross-connection of their piston and rod cavities, and compensation for the difference in feed rates and costs should be ensured by means of pneumatic-hydraulic accumulators. In both cases, a pressure control system is required in the gas cavities of an air-hydraulic spring or an air-hydraulic accumulator, which can be implemented on the basis of a mechanic-pneumatic converter or a pneumatic power amplifier. In pneumatic continuous control systems used in mobile equipment, the directing and distribution subsystem is usually built on the basis of pneumatic throttling valves with electromagnetic proportional control. Due to the limited power of proportional electromagnets, the creation of such pneumatic directional valves is limited by their throughput. In the throttling pneumatic distributors of indirect action, the replacement of the power amplifier of the spool type with the power amplifier "nozzle-shutter" improves the dynamic characteristics of the distributor and reduces its cost. It is possible to use the obtained experimental flow-control, adjustment and power characteristics presented in dimensionless parameters when calculating the adaptive suspension of multi-axis transport systems and the cargo platforms stabilized on the horizon.

Vapour compression refrigeration system is the conventional way existing for the refrigeration these days. Although to overcome the loses in conventional method there are several ways to improve the performance of vapour compression refrigeration cycle. This paper provides an alternative method of increasing the performance by varying the area ratio of the ejector. As Ejector is the most simple and economical replacement of throttling valve. A Simulation model is developed and parametric study of ejector is done. It was found that there will be increase in performance as area ratio is changed. This cycle is named as Ejector expansion Refrigeration System.

Линейная удаленность объектов в г. Новокузнецке достигает 40 км с разницей высотных отметок 157 м. Два главных водозабора города удалены друг от друга на расстояние 20 км, что предполагает наличие зон с разным свободным напором. Управление давлением и распределение воды по районам традиционно осуществлялось дросселированием запорной арматурой, а в исходной схеме водоснабжения функционировали 119 насосных станций с агрегатами мощностью от 0,75 до 1250 кВт. По результатам анализа возможных путей решения проблемы были сформированы предложения по установке редукционных клапанов, разработана схема их установки и определены режимы работы новой системы. Установка регуляторов по всему городу решалась в два этапа. В 2016 г. в результате установки семи регуляторов были остановлены 13 повысительных насосных станций общей мощностью более 150 кВт. На втором этапе в 2017 г. были установлены еще 12 регуляторов и остановлены 8 станций общей мощностью 40 кВт, а на пяти станциях была выполнена оптимизация с заменой насосов агрегатами меньшей мощности. Окупаемость проекта составила 4 года.The linear remoteness of the water facilities in the city of Novokuznetsk reaches 40 km with a difference in elevations of 157 m. The two main water intakes of the city are located at the distance of 20 km from each other, which suggests the availability of zones with different free head. Pressure control and water distribution among the districts was traditionally carried out by throttling shutoff valves, and 119 pumping stations with pumps of 0.751250 kW capacity were operating in the initial water supply scheme. Based on the analysis of possible solutions to the problem, proposals were made for the installation of pressure reducing valves, an installation diagram was developed, and the operating modes of the new system were determined. The installation of regulators throughout the city was carried out in two stages. In 2016, as a result of the installation of 7 regulators, 13 booster pumping stations with a total energy consumption of more than 150 kW were phased out at the second stage in 2017, 12 more regulators were installed and 8 more pumping stations with a total energy consumption of 40 kW were put out of operation and 5 pumping stations were upgraded with pump replacement for lower capacity. The project payback period was 4 years.

In recent years, heat pumps and refrigeration systems are widely used in both residential and industrial applications. The possibility of recovering the large throttling losses by using an expander could give a substantial contribution to the performance improvement. In this thesis, a reciprocating expander developed from a hydraulic motor was numerically and experimentally analyzed. A numerical model was developed to identify the needed small modifications to be made on the expander without change its architecture. Successively, an extensive experimental activity on the modified expander has been carried out to characterize it in detail and evaluate the effective performance. With this aim, a dedicated test rig and a measurement system have been developed. The expander was tested in a R134a heat pump cycle and in a CO2 refrigeration cycles. Despite of the mechanical losses due to the different original application of the machine, the thermodynamic cycles showed very promising results with the adoption of this solution. For this reason, a redesign and manufacturing of the machine was done in order to improve the efficiency in HFC cycles and to decrease the mechanical losses. The new version of the expander was tested in a "hot-gas bypass cycle", which has been designed and manufactured. The aim of this cycle is to obtain high stability and flexibility, and lower size due to the lack of the evaporator. The results showed improvement in both the thermodynamic behavior and mechanical losses. Finally, a 1D thermal conduction model has been developed to study the two-phase expansion with R134a with an improved accuracy.

Traditionally, a typical hydraulic circuit utilized in stationary industrial applications is based on valve operated actuation. One realization of such a system is a constant pressure circuit employing a hydraulic accumulator as an energy reserve and pressure stabilizer. The pump is used to maintain the desired pressure level, for example by using a variable displacement pump that controls the displacement setting based on the pressure level. The main benefit of this system architecture is its ability to produce high output powers with a very low response time. However, it is not the most energy efficient and in many cases, not the most space efficient solution. The efficiency of this system type is reduced mainly by the need to choke the pressure difference between the set system pressure and the actual pressure need in the actuator. By directly controlling the actuator via controlling the pump’s output flow with an electric servo motor, the throttling losses of the valve controlled system can be avoided. In addition, this enables the usage of closed circuits which in terms removes the need for a large reservoir. In this study, the replacement of a valve controlled hydraulic system with a pump controlled system in an industrial stationary material handling machine is investigated. The machine’s work cycle consist of continuous consecutive lifting and lowering motions of one end of a platform pivoted at the opposite end. The study consist of designing the replacing circuit topology, of dimensioning the hydraulic components utilizing a created Simulink-based tool and of a simulation based analysis on the dynamic properties of the designed hydraulic system.

An optimization design method is developed, which is motivated by the optimal design of a cryogenic liquid turbine (including an asymmetric volute, variable stager vane nozzles, shroud impeller and diffuser) for replacement of the Joule-Thompson throttling valve in the internal compression air-separation unit. The method involves mainly three elements: geometric parameterization, prediction of objective function, and mathematical optimization algorithm. Traditional parameterization approach is used for the geometry representation, while some novel work in the latter two aspects (i.e. objective function evaluation and optimization algorithm) is done to reduce the computing time and improve the optimization solution. A modified Cooperative Coevolution Genetic Algorithms (CCGA) is developed by incorporating a modified variable classification algorithm and some new self-adapted GA operators, which help to enhance the global search ability with an excessive number of optimization variables. Design of Experiment (DOE) is carried out to initialize the kriging approximation model, which is used to approximate the time-costly objective function. Then the CCGA is started, and once a potential superior individual is found, a decision will be made by the in-house code on whether or not it needs a updating. If required, the true objective function prediction based on the real model will be conducted and the obtained value of objective function will be used to update the kriging model. In such a way, the CCGA can complete its optimal searching with a limited number of real evaluations for objective function. All the above features are integrated into the optimization framework and encoded for the optimal turbine design. In addition, CFD software ANSYS CFX is used for the real objective function evaluations, and a well-organized batch code is developed by the authors for calling the CFD simulation which helps to promote this automation of the optimization process. For validation, the optimization method is used to solve some classical mathematical optimization problems and its effectiveness is demonstrated. The method is then used in the optimal design of the cryogenic liquid turbine stage, it is demonstrated that the optimal design method can help to reduce significantly the searching time for the optimal design and improve the design solution to the liquid turbine.