Christian Pablo Marcel

Bio: Christian Pablo Marcel is an academic researcher from National Scientific and Technical Research Council. The author has contributed to research in topics: Boiling & Natural circulation. The author has an hindex of 6, co-authored 13 publications receiving 341 citations. Previous affiliations of Christian Pablo Marcel include Balseiro Institute.

Two-phase flow instabilities: A review

Abstract: An updated review of two-phase flow instabilities including experimental and analytical results regarding density-wave and pressure-drop oscillations, as well as Ledinegg excursions, is presented. The latest findings about the main mechanisms involved in the occurrence of these phenomena are introduced. This work complements previous reviews, putting all two-phase flow instabilities in the same context and updating the information including coherently the data accumulated in recent years. The review is concluded with a discussion of the current research state and recommendations for future works.

Stability of self-pressurized, natural circulation, low thermo-dynamic quality, nuclear reactors: The stability performance of the CAREM-25 reactor

Abstract: The stability performance of self-pressurized, natural circulation, low-thermodynamic quality, nuclear reactors such as CAREM-25 is very different from existing conventional nuclear reactors. In this work, the linear stability of such a reactor is investigated in depth for both, nominal and low pressure-low power (start-up) conditions. As a result it is found that the flashing effect is crucial to correctly investigate the stability performance of the CAREM-25 reactor. In addition, it is verified that the dominant destabilizing mechanism are density waves travelling through the chimney section corresponding to Type-I instabilities. From the results it is observed that at rated conditions the unstable region is only limited to cases in which the two-phase boundary is located within a region which extends approximately from the core outlet until the middle of the chimney. It is also found that the condensation taking place in the steam dome has a great impact in defining the stability of the reactor and thus can be used to tune the CAREM-25 operational point. It is observed that the reactor shows a better stability performance when increasing the system pressure. From the steady state results it is found that the system could be pressurized without encountering instabilities if a certain minimum condensation power level is guaranteed.

Phenomenology involved in self-pressurized, natural circulation, low thermo-dynamic quality, nuclear reactors: The thermal–hydraulics of the CAREM-25 reactor

Abstract: Fil: Marcel, Christian Pablo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Patagonia Norte; Argentina. Comision Nacional de Energia Atomica. Gerencia del Area de Energia Nuclear. Instituto Balseiro; Argentina

Numerical investigation into the effect of surface wettability in pool boiling heat transfer with a stochastic-automata model

Abstract: Surface wettability is a key property in boiling heat transfer that influences heat-removal mechanisms and/or change their relative relevance. An automata model for pool boiling heat transfer is provided with rules to simulate heat transfer considering the influence of the contact angle. Free bubbles are modeled as a population of virtual spheres that change their geometric properties with simple stochastic rules. The model is validated against published experimental pool boiling data, showing excellent agreement with the boiling curve, as well as with the activation of nucleation sites, in a statistical sense. The sensitivity of the model parameters is studied to assess their influence and relevance. The model also provides information about the behavior of other near-wall relevant quantities, such as the interfacial area density and bubble detachment frequency. The computing time is around two orders of magnitude lower than the required by continuum methods to simulate pool boiling.

Two-phase flow frictional pressure drop prediction in helical coiled tubes

Abstract: Based on the construction of different experimental databases, the frictional pressure drop in helical tubes for single-phase and water-steam two-phase flow was analyzed empirically. The aim of the present study is to provide the scientific community with a reliable and simple to use predictive tool for estimating frictional pressure drop in helical tubes covering operating conditions of interest for the design and operation of coiled tube once-through steam generators, as those used in small modular advanced nuclear reactors. The single-phase database contains around 2000 data points from 14 different sources, including data measured with air and water as working fluids, covering Reynolds numbers ranging from 40 to 145,000 and curvatures between 0.0027 and 0.3. The prediction capability of some existing correlations for simple phase flow was analyzed, concluding that Ito correlations for laminar and turbulent regime (1959) are the best ones fitting the experimental data. The average difference between experimental data and Ito correlations was 3.75% for laminar regime and 2.11% for turbulent regime. The two-phase flow database was built with data available from open literature works. Due to the fact no existing correlation was found to successfully predict the available data, a new prediction tool based on the homogeneous equilibrium model was developed for water-steam flows at conditions of interest. The proposed tool, so-called FEMA correlation, converges to the Ito correlations for single phase flow, i.e. for thermodynamic qualities equal to 0 and 1. In addition, the correlation successfully fits the experimental data with an average error of 7.4% which is smaller than any other existing correlation. In addition, the new correlation is recommended for water-steam flow in vertical helical tubes with liquid only Reynolds numbers ranging from 20000 and 124000, pressures between 1 and 8 MPa, curvatures between 0.01 and 0.08, and thermodynamic qualities ranging from 0 to 1.

Two-phase flow instabilities: A review

Abstract: An updated review of two-phase flow instabilities including experimental and analytical results regarding density-wave and pressure-drop oscillations, as well as Ledinegg excursions, is presented. The latest findings about the main mechanisms involved in the occurrence of these phenomena are introduced. This work complements previous reviews, putting all two-phase flow instabilities in the same context and updating the information including coherently the data accumulated in recent years. The review is concluded with a discussion of the current research state and recommendations for future works.

Review of applications and developments of ultra-thin micro heat pipes for electronic cooling

Abstract: The development of miniaturization and high-density packaging of electronic components demands heat dissipation components that are compact and exhibit high performance. An ultra-thin micro heat pipe (UTHP), as a novel heat pipe with a flat shape that is highly suitable for application with high power and limited heat dissipation space, has been extensively investigated and widely used in mobile electronics. Understanding the influence of the manufacturing processes, capillary wick structures and flattened thickness on the thermal performance of UTHPs has been the aim of numerous studies. This paper presents a comprehensive review of the recent developments and applications of UTHPs for thermal management of electronics. The different types and applications of UTHPs are introduced, and the packaging technologies of UTHPs are summarized and compared. Furthermore, the fabrication methodology and heat transfer characteristics of various wick structures used for UTHPs are reviewed and analysed in detail. Finally, the challenges affecting the development and application of UTHPs are outlined, and recommendations for future research are presented.

Applications of artificial neural networks for thermal analysis of heat exchangers – A review

Abstract: Artificial neural networks (ANN) have been widely used for thermal analysis of heat exchangers during the last two decades. In this paper, the applications of ANN for thermal analysis of heat exchangers are reviewed. The reported investigations on thermal analysis of heat exchangers are categorized into four major groups, namely (i) modeling of heat exchangers, (ii) estimation of heat exchanger parameters, (iii) estimation of phase change characteristics in heat exchangers and (iv) control of heat exchangers. Most of the papers related to the applications of ANN for thermal analysis of heat exchangers are discussed. The limitations of ANN for thermal analysis of heat exchangers and its further research needs in this field are highlighted. ANN is gaining popularity as a tool, which can be successfully used for the thermal analysis of heat exchangers with acceptable accuracy.

Progress in dynamic simulation of thermal power plants

Abstract: While the conventional design of thermal power plants is mainly focused on high process efficiency, market requirements increasingly target operating flexibility due to the continuing shift towards renewables. Dynamic simulation is a cost-efficient tool for improving the flexibility of dispatchable power generation in transient operation such as load changes and start-up procedures. Specific applications include the optimisation of control structures, stress assessment for critical components and plant safety analysis in malfunction cases. This work is a comprehensive review of dynamic simulation, its development and application to various thermal power plants. The required mathematical models and various components for description the basic process, automation and electrical systems of thermal power plants are explained with the support of practical example models. The underlying flow models and their fundamental assumptions are discussed, complemented by an overview of commonly used simulation codes. Relevant studies are summarised and placed in context for different thermal power plant technologies: combined-cycle power, coal-fired power, nuclear power, concentrated solar power, geothermal power, municipal waste incineration and thermal desalination. Particular attention is given to those studies that include measurement validation in order to analyse the influence of model simplifications on simulation results. In conclusion, the study highlights current research efforts and future development potential of dynamic simulation in the field of thermal power generation.