Investigation and Control of a Regional Steam-Distribution Network under Two-phase Flow Conditions
Department of Information Technology, Pollack Mihály Faculty of Engineering
University of Pécs, Pécs, Hungary
Abstract: Measurement and simulation techniques have been developed for a two-phase flow to quantify and qualify a steam network and to determine the flow regime in the network. The development of these techniques makes it possible to create an intelligent monitoring system, which ensures that:
- By the execution of the computational model the different states of the network can be simulated;
- By using the principal of the local dynamic pressure measurement the distribution of the velocity in the cross-section of the pipes near the measurement points can be determined;
- The mass transfer in the condense vessels can be determined in the backbone pipes;
- By using mobile communication the measured data can be transferred immediately to the monitoring system; and
- Algorithms and formulas can be created to determine the quality of the two-phase flow.
Keywords: Two-phase flow, identification, modelling, mass transfer network
Lajos Szakonyi is the head of the Department of Information Technology of the Faculty of Engineering at University of Pécs since 1992. His research interests are the mathematical modelling of technological systems, mass and energy flow systems, control, measurement and signal processing. His works for the industry and the utilization of the same results in the education is documented in the form of publications. He is the author or co-author of 15 books and 50 papers published in conference proceedings and journals.
CITE THIS PAPER AS:
Lajos SZAKONYI, Investigation and Control of a Regional Steam-Distribution Network under Two-phase Flow Conditions, Studies in Informatics and Control, ISSN 1220-1766, vol. 18 (2), pp. 119-126, 2009.
The basis of the research is a 13 km long citywide steam network with pipe diameters between DN50 and DN450. The network distributes approximately 130 thousand tonnes of steam to different parts of the city . To reduce the loss of energy the measurement of the losses and the determination of their spatial and temporal distribution is required, thus suggestions can be made for a more energy efficient operation of the network . The monitoring system installed on the steam network is shown in Figure 1.
After the preliminary studies of the steam network it became obvious that some active experiments and measurements must be performed to develop a reliable simulation model for the flow and heat characteristics [3,4,5]. To perform these measurements some special pressure sensors (flow sensors) had to be designed, manufactured and installed. The main reason for the special sensors is that during condensation, the development of the two-phase flow the fluid phase aggregates at the bottom of the pipe and the flow pattern is dominated by this layered flow pattern .
The other, basic task for the measurements was to determine and record the topology of the network and to identify sources, passive elements, junctions and the number of consumer points. A geographic information system provides the basis for this survey of a citywide mass and energy network and for the modelling and simulation of the network [7,8,9].
The requirements of the investigation of the two-phase flow in order to ensure the correct scoring of energy are the following:
- development and operation of special flow meters (Pitot-pipe type, capable of following the local velocity distribution),
- developing of computational methods for the processing and evaluation of the data provided by the above devices,
- calculation methods, in order to obtain information about the flow regime, and for the estimation of the characteristic values of the flow.
The construction and development of the above devices and methods have provided the strategic background for the establishment of an intelligent monitoring and expert system.
- Szakonyi, L., Identification of the Municipal Water-steam Network, Elaboration of its Computer Controlled System, Acta Agraria Kaposváriensis, University of Kaposvár, Hungary (in Hungarian) , Vol. 10, No. 1, 2006, pp. 157-162.
- Szakonyi, L., Elaboration of Infocommunication Technology and its Utilization in the Region’s Energy Distribution, Symposium on Informatics in Higher Education, Debrecen, Hungary (in Hungarian) , 24-25. August, 2005, p.12.
- Szakonyi, L., Jancskar, I. A., Sari, Z., Energetic Model for an Elementary Unit of a Steam Network, Pollack Periodica, An International Journal for Engineering and InformationSciences, 1994, Akadémiai Kiadó, Budapest 2006,Vol. 1, No. 3, pp. 91-102.
- Szakonyi, L., Jancskar, I. A., Sari, Z., Numerical Study of Condensation in a Wet Steam Flow under Dynamic Loading, Proceedings of the Fifth International Conference on Engineering Computational Technology, Las Palmas de Gran Canaria, Spain, 12-15. September, 2006, pp. 1-13.
- Szakonyi, L., Sari, Z., Identification and Modeling of Condensation Phenomena in a Regional Steam Network, 5th International Symposium on Turbulence, Heat Transfer Dubrovnik, Croatia, 25-29. September, 2006, pp. 643-646.
- Huhn, J., Wolf, J., Two-phase Flow (Vapour-liquid Systems), Műszaki Könyvkiadó, Budapest (in Hungarian), 1978.
- Szakonyi, L., Energetic Model of an Elementary Pipe-segment of a Steam-water Network, Pollack Periodica, An International Journal for Engineering and Information Sciences, 1994, Akadémiai Kiadó, Budapest 2007, Vol. 2, No. 1, pp. 63-78.
- Jancskar, I. A., Sari, Z., Szakonyi, L., Ivanyi, A., Diffuse Interface Modeling of Liquid-Vapor Phase Transition with Hysteresis, Physica B, Vol. 403, pp. 505-508, 2008.
- Sari, Z, Jancskar, I. A., Szakonyi, L., Ivanyi, A., Phenomenological Transient FEM Modelling of a Two-phase Flow with Dynamic Phase Change, Proceedings of the Eleventh International Conference on Civil Structural and Environmental Engineering Computing, St. Julians, Malta, 18-21. September, 2007, pp. 217.