Meaningful and Physically Consistent Efficiency Definition for Positive Displacement Pumps - Continuation of the Critical Review of ISO 4391 and ISO 4409

2021 ◽  
Author(s):  
Christian Schänzle ◽  
Peter F. Pelz
Keyword(s):  
Critical Review ◽  
Volumetric Efficiency ◽  
Dead Volume ◽  
Specific Enthalpy ◽  
Positive Displacement ◽  
Displacement Pump ◽  
Fluid Properties ◽  
The Common ◽  
Isentropic Efficiency ◽  
The Ideal

Abstract ISO 4391:1984 gives the common efficiency definition for positive displacement machines. ISO 4409:2019 uses this efficiency definition to specify the procedure for efficiency measurements. If the machine conditions do not correspond with an incompressible flow due to operation at high pressure levels, the compressibility of the fluid and the dead volume of a pump must be taken into account. On this point, ISO 4391:1984 is physically inconsistent. Achten et. al. address this issue in their paper at FPMC 2019 presenting a critical review of ISO 4409:2007. They introduce new definitions of the overall efficiency as well as the mechanical-hydraulic efficiency. At the same time, they question the validity of the volumetric efficiency definition. Li and Barkei continue on this issue in their paper at FPMC 2020 and give a new efficiency definition based on the introduction of a new quantity Φ which describes the volume specific enthalpy of the conveyed fluid. The motivation of this paper is to contribute to the ongoing and fruitful discussion. Our approach starts with the most general efficiency definition, namely the isentropic efficiency. Subsequently, we make assumptions concerning the fluid properties with respect to the compressibility of the conveyed fluid. On the basis of the ideal cycle of a positive displacement pump and the p-v diagram, we derive physically consistent and more meaningful representations of the overall, the mechanical-hydraulic and the volumetric efficiency that address the inconsistency of ISO 4391:1984. Furthermore, we compare our findings with the existing results of Achten et. al. and Li and Barkei.

scholarly journals Thermal Modelling of External Gear Machines and Experimental Validation

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2920 ◽  
Author(s):  
Rituraj Rituraj ◽  
Andrea Vacca ◽  
Mario Antonio Morselli
Keyword(s):  
Thermal Model ◽  
Experimental Validation ◽  
Volumetric Efficiency ◽  
Outlet Temperature ◽  
Fluid Temperature ◽  
Power Losses ◽  
Internal Flows ◽  
Lumped Parameter ◽  
Fluid Properties ◽  
The Common

The flow of energy within external gear machines (EGMs) leads to the variation of fluid temperature in the EGMs, which affects their performance. However, the common approaches for the simulation of EGMs assume isothermal conditions. This isothermal assumption negatively impacts their modelling accuracy in terms of the internal flows which are dependent on the fluid temperature (via fluid properties). This paper presents a lumped parameter based thermal model of EGMs where the fluid temperature in the EGM is evaluated considering the effects of compression/expansion, internal flows, and power losses. Further, numerical techniques are developed to model each of these three aspects. The thermal model is validated via the outlet temperature and volumetric efficiency measurements obtained from experiments conducted on six units of an EGM taken as a reference with different internal clearances. The results from the model show that the fluid temperature increases as it is carried from the inlet side to the outlet side during the pumping operation. However, the fluid at the ends of the shafts has the highest temperature. By comparing the isothermal simulation results with the proposed thermal model, the results also point out how the isothermal assumption becomes inaccurate, particularly in conditions of low volumetric efficiency.

Measuring the Losses of Hydrostatic Pumps and Motors: A Critical Review of ISO4409:2007

2019 ◽  
Author(s):  
Peter Achten ◽  
Robin Mommers ◽  
Takao Nishiumi ◽  
Hubertus Murrenhoff ◽  
Nariman Sepehri ◽  
...  
Keyword(s):  
Measurement Data ◽  
Mechanical Efficiency ◽  
Energy Conversion Efficiency ◽  
Volumetric Efficiency ◽  
Total Loss ◽  
Loss Analysis ◽  
The Road ◽  
Positive Displacement ◽  
Displacement Pump ◽  
Steady State Performance

Abstract ISO 4409 is the most important international standard for measuring the efficiency of hydraulic pumps and motors, the latest edition being 4409:2007. The standard describes methods for determining the steady-state performance in terms of overall efficiency. It also defines equations for calculating the volumetric efficiency of pumps and motors. The hydro-mechanical efficiency is only defined for motors, not for pumps. This paper analyses the efficiency and losses of pumps and motors in an alternative way. The preference is on loss analysis instead of efficiencies. Especially the effects of the bulk modulus are considered in a different and more inclusive manner. The new methodology results in a higher total loss for motor and a lower total loss for pumps than the current ISO 4409 standard. Furthermore, it results in significant changes of the hydro-mechanical and volumetric losses. The differences between the new methodology and ISO 4409 become larger for high load pressures. The new methodology demands knowledge about the minimum volume of the displacement chamber. The ratio between this volume and the full displacement of a single displacement chamber strongly influences the hydro-mechanical and volumetric losses of the pump or motor. The new methodology is valid for all positive displacement hydrostatic pumps and motors. The volumetric efficiency, as defined in ISO 4409, can still be used as a flow rate factor, but should not be regarded as an energy conversion efficiency. The importance of adopting the proposed methodology is further demonstrated by analyzing and comparing the measurement data about a fixed displacement pump and motor, showing the differences in the loss analysis by means of ISO 4409 and the new equations. The methodology, observations and validation results presented in this paper are significant and can pave the road for improving the current ISO 4409:2007 standard, which would ultimately benefit the industry.

Introduction

2017 ◽  
Author(s):  
Erika Fischer-Lichte
Keyword(s):  
Middle Class ◽  
Social Group ◽  
Family Values ◽  
Court Culture ◽  
Common Root ◽  
New Family ◽  
The Common ◽  
German Court ◽  
The Ideal

The introduction ‘Philhellenism and Theatromania’ retraces the emergence of these two phenomena in the German middle class. The year 1755 marks a watershed in this regard: it saw the publication of J. J. Winckelmann’s treatise Reflections on the Painting and Sculpture of the Greeks and the premiere of G. E. Lessing’s first domestic tragedy Miß Sara Sampson. Both share the common root and motivation once and for all to banish Frenchified German court culture. While Winckelmann’s treatise praised the ‘noble simplicity’ and ‘quiet greatness’ of the Greek masterpieces, Lessing’s play advocated new family values and the ideal of ‘naturalness’ as the true virtues of the middle class. The merging of Philhellenism as the cult of beauty with theatromania as the quest for identifying in a social group and as an individual provided the basic condition for staging Greek tragedies.

scholarly journals From Norms to Facts: The Realization of Rights in Common and Civil Private Law

2011 ◽  
Vol 56 (1) ◽  
pp. 77-114 ◽  
Author(s):  
Helge Dedek
Keyword(s):  
Legal System ◽  
Deep Structure ◽  
Common Law ◽  
Social Reality ◽  
Judicial Decision Making ◽  
Legal Traditions ◽  
The United Kingdom ◽  
The Common ◽  
Legal Concepts ◽  
The Ideal

Every legal system that ties judicial decision making to a body of preconceived norms has to face the tension between the normative formulation of the ideal and its approximation in social reality. In the parlance of the common law, it is, more concretely, the remedy that bridges the gap between the ideal and the real, or, rather, between norms and facts. In the common law world—particularly in the United Kingdom and the Commonwealth—a lively discourse has developed around the question of how rights relate to remedies. To the civilian legal scholar—used to thinking within a framework that strictly categorizes terms like substance and procedure, subjective right, action, and execution—the concept of remedy remains a mystery. The lack of “remedy” in the vocabulary of the civil law is more than just a matter of attaching different labels to functional equivalents, it is the expression of a different way of thinking about law. Only if a legal system is capable of satisfactorily transposing the abstract discourse of the law into social reality does the legal machinery fulfill its purpose: due to the pivotal importance of this translational process, the way it is cast in legal concepts thus allows for an insight into the deep structure of a legal culture, and, convergence notwithstanding, the remaining epistemological differences between the legal traditions of the West. A mixed jurisdiction must reflect upon these differences in order to understand its own condition and to define its future course.

Light-duty single and multi-shaft boosting and compounding studies with in-cylinder insulation

2020 ◽  
pp. 146808742098058
Author(s):  
Peter Andruskiewicz ◽  
Russell Durrett ◽  
Venkatesh Gopalakrishnan ◽  
Kushal Narayanaswamy ◽  
Paul Najt
Keyword(s):  
Engine Performance ◽  
Volumetric Efficiency ◽  
Expansion Process ◽  
Exhaust Gases ◽  
Positive Displacement ◽  
Brake Power ◽  
Light Duty ◽  
Insight Into

A set of two-cylinder engine concepts utilizing a supercharger and piston- or turbine-compounding were compared to a turbocharged engine modeled with a consistent methodology developed in previous works. In-cylinder insulation was added to each of the engines to evaluate the effects on performance. The goals of this simulation were to utilize energy that otherwise would be bypassed around the turbine side of a turbocharger and redirect it to the crankshaft, as well as to redirect energy that would previously have entered the coolant into the exhaust gases where it could be reclaimed by a second expansion process. Gains in performance and efficiency were thoroughly analyzed to provide insight into the magnitudes and mechanisms responsible. It was found that the second expansion process from exhaust-compounding was able to significantly improve engine performance at moderate to high loads, as well as compensate for the loss in volumetric efficiency that accompanies in-cylinder insulation. The piston-compounded single-shaft DCDE was able to outperform the turbocharged multi-shaft DCDE at mid to high loads, and in maximum brake power due to the low losses in the coupled nature of the second expansion, while the turbine-compounded engine suffers higher losses due to the turbomachinery mismatch with the positive displacement power cylinders.

Analysis of Deep Sea Umbilical in Steep Wave Configuration

2016 ◽  
Author(s):  
Akash A. Nair ◽  
Gnanaraj A. Anbu ◽  
Panneer Selvam Rajamanickam ◽  
Gopakumar Kuttikrishnan ◽  
Ramadass Gidugu Ananda
Keyword(s):  
Deep Sea ◽  
Mining Machine ◽  
Optimum Number ◽  
Suitable Material ◽  
Static And Dynamic Analysis ◽  
Positive Displacement ◽  
Displacement Pump ◽  
Umbilical Cable ◽  
Steep Wave ◽  
Mother Ship

Deep sea mining is mineral retrieval process that takes place on the ocean floor wherein global industries are actively exploring and experimenting of different techniques in this relatively new concept of mining for extracting it economically from depths of 5000–5500 m below the ocean’s surface. National Institute of Ocean Technology (NIOT), India has been working on a mining concept for ∼6000 m water depth where a crawler based mining machine collects, crushes and pumps nodules to the mother ship using a positive displacement pump through a flexible riser (umbilical) system. The umbilical also serve as the weight supporting member for the miner and pump. In this paper, static and dynamic analysis of the umbilical system in steep wave configuration and the miner is carried out using ORCAFLEX for launching and touchdown conditions. Three different materials are considered and the best suitable material for umbilical is selected as the first step based on the tension. Then umbilical with Single Miner System is analyzed for the launching and touchdown conditions. Based on the analysis the optimum number and spacing of buoyancy tanks that will keep the stresses within the allowable limits in the umbilical cable are recommended.

Study on Electromagnetic Vibration Pump

2013 ◽  
Vol 774-776 ◽  
pp. 312-315
Author(s):  
Zhan Xiong Lu
Keyword(s):  
Research Field ◽  
Pump Design ◽  
Positive Displacement ◽  
Low Viscosity ◽  
Electromagnetic Vibration ◽  
Displacement Pump ◽  
Small Flow ◽  
Working Principle ◽  
Low Specific Speed ◽  
Specific Speed

Electromagnetic vibration pump is one type of first proposed new household positive displacement pump.It is mainly used to transport water and other low viscosity liquid. It has many advantages including small flow, high head, simple structure,good self-priming performance. Electromagnetic driving method was combined with displacement pump in vibration pump for the first time. Its specific speed can reach below 10,and this is a breakthrough in super-low specific speed pump design. The working principle of electromagnetic vibration pump and its performance were studied in the paper. each of these problems is further discussed and explained in order to point out the research field for the development of electromagnetic vibration pump later.

scholarly journals GLOBALIZATION AND GLOBAL GOVERNANCE

2013 ◽  
pp. 16-23
Author(s):  
A. A. Gromyko
Keyword(s):  
Global Governance ◽  
Common Good ◽  
Global Market ◽  
State University ◽  
The Sustainable Development ◽  
Private Interests ◽  
The Common ◽  
Academy Of Sciences ◽  
Moscow State University ◽  
The Ideal

Anatoly Andreevich Gromyko, a professor of the Moscow State University, a corresponding member of the Russian Academy of Sciences reflects in his article on the destinies of mankind and the most complex problems facing the world community at the early 21 century under globalization and increased demand in global governance. In his analysis the author concedes that after numerous pieces of research on various aspects of these two phenomena, there are still more questions than answers. He believes that globalization might become a force serving not only private interests of big corporations but also the common good of humanity. Since interdependence is the main feature of our world we should not fall prey to the ideal images of global governance because there is no one size fit all global governance. The article elaborates the three most pressing world problems:– the need in a new way of thinking about globalization. According to the author the problems of globalization must be approached with knowledge of history and acknowledgement of social justice;– the need in morally acceptable balance among unifying potential of globalization, unchained global market and the state as the last resort of its nation;– the need to make United Nations a platform, where political and social democracy should lay ground for global governance so craved for by the mankind. The author pays special attention to the dichotomy between the force of law and the law of force as well as to the prospects for the new democratic global order accommodating the sustainable development of human civilization.

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