A theoretical and experimental study of horizontal air-water. Two-phase flow with a spool piece

Abstract

This Master Thesis has been carried out by Luis Mora Vallejo and Jacobo Zegrí Reiriz. We are both two Spanish students who are studying Engineering in the Universitat Politècnica de Catalunya (UPC) in the engineer‟s school Escola Tècnica Superior d‟Enginyeria Industrial de Barcelona (ETSEIB). This degree has got a common part the first two years and after that it is possible to be specialized in one sector of the industry. Then, we both decided to take part of the nuclear section in order to help our country in the energetics situation and also under the feeling of improvement that we are looking for ourselves. After sharing last three years in the same specialization we decided separately to carry out a Master Thesis abroad in order to obtain the Master Thesis of Science in Nuclear Engineering. However, there are a limited number of universities in the ENEN‟s network so it was necessary to have a good choice of what university would have been chosen. For many reasons we decided to work in the Politecnico di Torino and after knowing that we both were accepted we thought that it could be a good experience not only for us, but also for the Politecnico di Torino and the ETSEIB the possibility of carrying out together a complete thesis in our sector. Concerning the teamwork, it is important to say that this project is the result of the effort and the work of two people. As it will be seen in following lines, this Thesis has got some parts and although we have worked the same one has been more specialized in one than the other. For instance, whereas the theoretical part has been more summarized and searched by Jacobo, the code with Matlab has been more developed by Luis. This fact does not entail that one of the two members has made only one thing as we have been carrying out the Thesis together and both Luis and Jacobo have been working on theoretical part and Matlab respectively. Apart from that, other parts like the experimental analysis and the measurements have been developed by us at the same level and dedication because of the fact that working together it is possible to measure faster and with more precision and also it is easier to study the results and therefore to obtain conclusions as we are sharing our knowledge in this technology. The most important objectives that are pursued in this Thesis are related with the analysis of a horizontal air-water flow. It would be interesting to obtain an experimental and theoretical characterization of a horizontal flow using different evaluations, theories and analysis such as flow pattern analysis, pressure drop evaluations, void fraction evaluation and mass flow rate measurements. In order to achieve our goal the Department of Energetics (DENER) of the Politecnico di Torino has put at our disposal several offices, computers, software and facilities to work at our Thesis. Concerning the experimental system, which we have been working with, it will be accurately explained on next chapters. However, it can be said that it contains the necessary devices to develop our tasks related to the measurements in a correct and safety way. This Thesis is not only an analysis about the data obtained as it is also necessary to carry out a deep research work because of the difficulty of working on two-phase flow and also because of the length of the field. The experimental part consists on taking a large number of data to know, after all measurements with laboratory devices, the properties of the mixture which is flowing through a pipe only with the knowledge of some parameters. So it could be said that the aim of this work is to define an appropriate theoretical and experimental methodology that can be used in experimental apparatus, able to simulate the thermohydraulic of Nuclear Power Plant in steady state and accident (LOCA) conditions, in order to measure two-phase flow quantities as mass flow rates and velocities of water and vapour.