Kallesoe C.S.,Grundfos |
Jensen T.N.,University of Aalborg |
Wisniewski R.,University of Aalborg
2015 European Control Conference, ECC 2015 | Year: 2015
Water scarcity is an increasing problem worldwide and at the same time a huge amount of water is lost through leakages in the distribution network. It is well known that improved pressure control can lower the leakage problems. In this work water networks with a single pressure actuator and several consumers are considered. Under mild assumptions on the consumption pattern and hydraulic resistances of pipes we use properties of the network graph and Kirchhoffs node and mesh laws to show that simple relations exist between the actuator pressure and critical point pressures inside the network. Subsequently, these relations are exploited in an adaptive reference control scheme for the actuator pressure that ensures constant pressure at the critical points. Numerical experiments underpin the results. © 2015 EUCA.
Darula R.,University of Aalborg |
Stein G.J.,Slovak Academy of Sciences |
Kallesoe C.S.,Grundfos |
Sorokin S.,University of Aalborg
ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis, ESDA 2012 | Year: 2012
An electro-magneto-mechanical system, composed of the electromagnet, having an iron core with a coil and a movable yoke, is analyzed in the paper. Exposing the yoke to mechanical motion, the variation of the magnetic flux due to change of the air gap height induces alternating voltage at the coil terminals. If the electrical circuit is closed, the so generated electrical power is dissipated via the internal coil losses, treated in this paper. Thanks to the interaction between the electrical and mechanical system (i.e. via magnetic force), the power dissipation in electrical circuit influences the dynamical response of the mechanical system. And so the mechanical vibrations can be controlled by these means. The mathematical model of the simplified dynamical system, which describes behavior of the experimental set-up, is derived using a lumped parameter approach. The aim of the article is to identify parameters of the derived mathematical model, focused mainly on electrical circuit. Based on measured experimental data, the static constants as well as dynamic losses were analyzed. Copyright © 2012 by ASME.
Kallesoe C.S.,Grundfos |
Wisniewski R.,University of Aalborg |
Jensen T.N.,University of Aalborg
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2014
An industrial case study in the form of a large-scale hydraulic network underlying a district heating system is considered. A distributed control is developed that minimizes the aggregated electrical energy consumption of the pumps in the network without violating the control demands. The algorithm is distributed in the sense that all calculations are implemented where the necessary information is available, including both parameters and measurements. A communication network between the pumps is implemented for global optimization. The local implementation of the algorithm means that the system becomes a Plug & Play control system as most commissioning can be done during the manufacture of the pumps. Only information on the graph-structure of the hydraulic network is needed during installation. © IFAC.
Sveegaard S.G.,University of Aalborg |
Keiding K.,Grundfos |
Christensen M.L.,University of Aalborg
Water Research | Year: 2012
A drainage/filtration apparatus was developed for automatically determining sedimentation velocity and dewatering rate. Pressure-step testing was used to study filter cake compressibility, resistance, and swelling. Activated sludge was analysed, and the data indicate that the sludge is highly compressible even at low pressures (10 kPa). Furthermore, compressed sludge cakes swell if the pressure is released. Hence, the average specific cake resistance decreases if the pressure is released, though the resistance is higher after the compression cycle than before. Sludge must be dewatered under low pressure, because higher pressure only compresses the cake and does not improve the dewatering rate. © 2012 Elsevier Ltd.
Olsson G.,Lund University |
Carlsson B.,Uppsala University |
Comas J.,University of Girona |
Copp J.,Primodal Inc. |
And 12 more authors.
Water Science and Technology | Year: 2014
Key developments of instrumentation, control and automation (ICA) applications in wastewater systems during the past 40 years are highlighted in this paper. From the first ICA conference in 1973 through to today there has been a tremendous increase in the understanding of the processes, instrumentation, computer systems and control theory. However, many developments have not been addressed here, such as sewer control, drinking water treatment and water distribution control. It is hoped that this review can stimulate new attempts to more effectively apply control and automation in water systems in the coming years. © IWA Publishing 2014.
Towsley G.,Grundfos |
Benavente A.,ConocoPhillips |
Dougherty R.L.,University of Kansas
ASHRAE Transactions | Year: 2013
Bypass orifices are used to reduce pressure in fluid flow for a variety of situations, specifically wherein variable flow rates are not available. As compared to studies regarding venturis, square-edged orifices, and similar devices, much less is known about performance of orifices configured similar to pipe nipples or nipple orifices. Thus, in most cases, the system designer chooses a nipple orifice based on assumed losses, which has a discharge coefficient of about 0.6. However, it is important in such situations to have additional information in order to optimally design these systems for minimum energy consumption. Herein, data and design information are presented for pressure drop as a function of flow rate for nipple orifices ranging from 1/8 to 7/8 in. (3.2 to 22.2 mm) diameter in pipes ranging from nominal 1/2 to 1 1/2 in. (12.7 to 38.1 mm) diameter. Curve fits accuracies for the data given are within ±25% for flow rates above 20 gpm (4.54 m3/h), and range as high as ±40% for lower flow rates. Discharge coefficients are also presented as a function of Reynolds Number. It is shown that there appears to be no clear trend in the data as a function of Reynolds Number. However, multiplying Reynolds Number by factors of diameter ratio and orifice diameter yields a trend that could be used in nipple orifice system design. Discharge coefficients can be predicted reasonably well, with the general error for all orifice-line sizes studied herein being ±5% (with 77% confidence). The results presented herein can be used to develop discharge coefficient predictions with other errors and confidence levels. For future work, more data are needed on large orifice-line combinations. Needed then are theoretical studies to understand the basis for modifying pressure drop and/or Reynolds Number by functions of diameter ratio and/or orifice and line diameters. This and future work will then be able to provide basic data to develop modeling and software tools to allow the optimum orifice to be selected to minimize energy waste. In addition, future effort should be focused on the comparison of variable speed pump system design, that does not need flow restrictors like nipple orifices, with constant speed pump system design with some type of flow restrictor. ©2013 ASHRAE.