Comparison of 0D and 3D Hydraulic Models for Axial Piston Pumps

Abstract In this the paper, a comparison between a 0D and a 3D model for the simulation of an axial piston pump is presented. The lumped parameter approach implements a detailed mathematical model developed in the Amesim® environment for the evaluation of the geometric features of the variable chambers. The commercial tool PumpLinx® has been used for the 3D computational fluid dynamics model. The aim is to assess the capability of the 0D model in predicting the main quantities and to evaluate the use of the three-dimensional analysis for fine tuning purposes. The comparison has been performed in conditions of fixed displacement and constant speed. A good agreement was found in the evaluation of the flow ripple and of the chamber pressure history

Volume 1 – Symposium: Tuesday, March 8

Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Components:Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Component

Volume 2 – Conference: Wednesday, March 9

10. Internationales Fluidtechnisches Kolloquium:Group 1 | 2: Novel System Structures Group 3 | 5: Pumps Group 4: Thermal Behaviour Group 6: Industrial Hydraulic

A study of the design and operation of centrifugal compressors for CO2 pipeline transportation

Carbon Capture and Storage (CCS) is one of the technological options recommended by the United Nations Inter-Governmental Panel on Climate Change (IPCC) for achieving a net reduction in CO2 emissions to the atmosphere. CCS process is made up of three aspects, namely: carbon capture, transport and storage. Historically, researchers tended to focus heavily on the capture and storage aspects of the CCS process chain with the CO2 transport aspect receiving less attention. However, in recent years, the level of research in CO2 transport has increased sharply. Research shows that pipelines are the most viable means of transporting large volumes of anthropogenic carbon dioxide from offshore and onshore sources of emission to the place of permanent storage. In pipelines, CO2 can be transported in gaseous, liquid or supercritical state. Supercritical CO2 occurs when its pressure and temperature are both above the critical point (73.76 bar; 30.97°C). Carbon dioxide in supercritical state has high density close to that of a liquid and low viscosity comparable to that of a gas. This means that a larger amount of CO2 per unit time can be transported in supercritical state than in gaseous or liquid state with low pipeline frictional pressure drop per unit mass and less energy costs. Therefore, for long distance pipeline transportation, it is economically sound to convey CO2 in supercritical state rather than in gaseous or liquid states. Pipeline infrastructure required in the CCS context is on a scale that vastly outsizes similar infrastructure commonly used for transportation of air, natural gas, petroleum, etc. CCS pipeline networks operate on an industrial scale, transporting several metric megatons of anthropogenic CO2 per annum captured from multiple power stations and other process plants to designated places of storage. A large amount of energy is consumed by compressors and booster pumps in building up and maintaining the high pressure required to ensure anthropogenic CO2 mixtures are in a supercritical state within the pipeline. Furthermore, pure and impure supercritical CO2 exhibit erratic internal flow behaviour, a consequence of large, abrupt and barely controllable changes to its fluid properties provoked by minor shifts in pressure and temperature. All these make design and operation of supercritical CO2 pipeline networks more challenging and costlier than conventional natural gas pipelines where compression pressures and volumetric delivery rates are relatively lower and neither phase change nor radical variations in thermophysical properties areexpected.A review of published literature on supercritical CO2 pipeline transportation shows a lot of effort has been made by other researchers to address design issues such as pipeline sizing, corrosion and fracture propagation and operational issues such as start-up, shut-down, rapid depressurization, valve blockage, etc. All these studies have reduced several of the technical challenges in the design and operation of the pipeline. Yet there is still a wide scope for further improvements and new developments. Compressors and booster pumps are responsible for most of the high amount of energy consumed in the operation of the pipeline. Therefore, the long-term economic feasibility of running a supercritical CO2 pipeline networks is achievable only if energy consumption and associated operating costs of both machines can be kept as low as possible. One way of reducing energy consumption is by sizing compressors and booster pumps optimally to ensure that power losses in both machines are minimized.In this PhD thesis, a new mathematical model was developed from first principles. This new mathematical model uniquely combines the geometry and working processes of a centrifugal machine with anomalous and erratic non-linear real fluid flow behavior peculiar to supercritical CO2 and its mixtures. Successfully validated with available experimental data, the model was used to carry out a detailed investigation of the performance of centrifugal compressor handling supercritical carbon dioxide of varying purity under different operating conditions. Results of the investigation showed that parameters that characterize compressor performance such as power requirement, isentropic efficiency and pressure ratio are strongly dependent on impeller size, shaft speed, mass flow rate and the chemical composition of the supercritical CO2 and its mixtures.More importantly, the work carried out in this thesis also demonstrated that the quasi-dimensional model can be used as a robust tool for optimal sizing of centrifugal compressors and booster pumps installed on a supercritical carbon dioxide transport pipeline

Numerical investigation of cavitation in twin-screw pumps

In order to investigate the flow characteristics and the formation process of cavitation in twin-screw pumps, three-dimensional computational fluid dynamics numerical analysis has been carried out. A conformal structured moving mesh generated by an in-house code SCORG was applied for the rotor domain. The volume of fluid method has been adopted for dealing with the liquid-gas two-phase flow, while the bubble dynamics was handled by a homogenous cavitation model. By changing the rotation speed and discharge pressure, the intensity, distribution area and variation of cavitation at different rotor angle were obtained. The effects of rotation speed and discharge pressure on cavitation characteristics have been analysed. Calculation results with cavitation model are compared with the results without cavitation and the experimentally obtained values. The influence of cavitation on the performance of a screw pump in terms of the mass flow rate, pressure distribution, rotor torque and the shaft power has been analysed and discussed. For analysis of cavitation in clearances, a 2D numerical model which includes radial and inter-lobe clearances was used. The relationship between volumetric efficiency and cavitation intensity was developed by variation of boundary conditions

Models for Flow Rate Simulation in Gear Pumps: A Review

Gear pumps represent the majority of the fixed displacement machines used for flow generation in fluid power systems. In this context, the paper presents a review of the different methodologies used in the last years for the simulation of the flow rates generated by gerotor, external gear and crescent pumps. As far as the lumped parameter models are concerned, different ways of selecting the control volumes into which the pump is split are analyzed and the main governing equations are presented. The principles and the applications of distributed models from 1D to 3D are reported. A specific section is dedicated to the methods for the evaluation of the necessary geometric quantities: analytic, numerical and Computer-Aided Design (CAD)-based. The more recent studies taking into account the influence on leakages of the interactions between the fluid and the mechanical parts are explained. Finally the models for the simulation of the fluid aeration are described. The review brings to evidence the increasing effort for improving the simulation models used for the design and the optimization of the gear machines

Volume 1 – Symposium

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group A: Materials Group B: System design & integration Group C: Novel system solutions Group D: Additive manufacturing Group E: Components Group F: Intelligent control Group G: Fluids Group H | K: Pumps Group I | L: Mobile applications Group J: Fundamental

Volume 2 – Conference

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group 1 | 2: Digital systems Group 3: Novel displacement machines Group 4: Industrial applications Group 5: Components Group 6: Predictive maintenance Group 7: Electro-hydraulic actuatorsDer Download des Gesamtbandes wird erst nach der Konferenz ab 15. Oktober 2020 möglich sein.:Group 1 | 2: Digital systems Group 3: Novel displacement machines Group 4: Industrial applications Group 5: Components Group 6: Predictive maintenance Group 7: Electro-hydraulic actuator

One-dimensional modelling of a trilateral flash cycle system with two-phase twin-screw expanders for industrial low-grade heat to power conversion

This paper provides an overview of a one-dimensional modelling methodology for equipment and systems for heat to power conversion based on a staggered grid space discretization and implemented in the commercial software GT-SUITE®. Particular attention is given to a newly developed modelling procedure for twin-screw machines that is based on a chamber modelling approach and considers leakage paths between cells and with the casing. This methodology is then applied to a low-grade heat to power conversion system based on a Trilateral Flash Cycle (TFC) equipped with two parallel two-phase twin-screw expanders and a control valve upstream of the machines to adapt the fluid quality for an optimal expander operation. The standalone expander model is used to generate performance maps of the machine, which serve as inputs for the TFC system model. Parametric analyses are eventually carried out to assess the impact of several operating parameters of the TFC unit on the recovered power and cycle thermal efficiency. The study shows that the most influencing factors on the TFC system’s performance are the inlet temperature of the heat source and the expander speed. While the first depends on the topping industrial process, the expander speed can be used to optimize and control the TFC system operation also in transient or off-design operating conditions