Tesis doctoral de José Zambrana González
The present thesis analyscs in detall the process of water evaporation for convective upward flows in vertical tubes, used in industrial applications. Both, the heat transfer process and the pressure drop mechanism, are considered. However, special attcntion has been put on the heat transfer process in the transition from puré liquid to two-pha.Se flow, known as subcooled íiow boiling región. the empirical correlations for the heat transfer coefficient on the water side for subcooled flow boiling región, provided by the usual bibliography, do not ensure continuity between this región and the puré liquid and two-phasc íiow regions. This is, in fact, opposite to the physics of the phenomenon. in order to get continuity between the subcooled flow boiling región and its extremes, ensuring consequently physical coherence, this thesis proposes to use an analytical corrclation of elliptical type for the water heat transfer coefficient in the subcooled flow boiling región. using this correlation in the transition región for the water heat transfer coefficient together with other empirical correlations commonly used for puré liquid and two-phase flow, has allowed developing a method of calculation for a single tube. Similar methods or correlations for the pressure drop determination in each of the regions have been used. at the same time, to extend the method developed for a single tube to a bank of tubes has ailowed to develop an crigineering tool valid for performance analyses and/or sizing of industrial evaporators. the tool here developed has severa! Advantages when it is compared to the ones used commonly in the industry, the e-ntu methods. The first advantage is the fact itself of being able to analyse evaporators where phase change occurs inside them, determining dynainically where each región begins and cnds (puré liquid, subcooled flow boiling región and two-phasc flow región). The second advantage is that this tool allows a local analysis of the heat exchanger instead of a global one, as usual. It is possiblc theu for the designer a better evaluation of the evaporator under study.
Datos académicos de la tesis doctoral «Water evaporation in vertical tubes: an analytical approach for the subcooled flow boiling region and development of a method for evaluation and sizing evaporators«
- Título de la tesis: Water evaporation in vertical tubes: an analytical approach for the subcooled flow boiling region and development of a method for evaluation and sizing evaporators
- Autor: José Zambrana González
- Universidad: Politécnica de Madrid
- Fecha de lectura de la tesis: 05/03/2010
Dirección y tribunal
- Director de la tesis
- Pedro Perez Del Notario Martinez Marañon
- Tribunal
- Presidente del tribunal: isidoro Martinez herranz
- pedro acisclo Rodriguez aumente (vocal)
- Mª desamparados Ribes greus (vocal)
- José ignacio Nogueira goriba (vocal)