David Sánchez

David Sánchez
Universidad de Sevilla | US · Energy Engineering

PhD

About

89
Publications
15,548
Reads
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2,620
Citations
Citations since 2016
38 Research Items
1855 Citations
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300

Publications

Publications (89)
Article
Full-text available
This paper focuses on the thermodynamic comparison between pure supercritical Carbon Dioxide and blended transcritical Carbon Dioxide power cycles by means of a thorough exergy analysis, considering exergy efficiency, exergy destruction and efficiency losses from Carnot cycle as main figures of merit. A reference power plant based on a steam Rankin...
Article
Full-text available
This paper investigates the interest and potential of using working fluids based on Carbon and Sulphur Dioxide mixtures (CO2-SO2) in a transcritical Recompression cycle. In order to assess the actual thermodynamic potential of the concept proposed, the influence of dopant (SO2) content is assessed for two different turbine inlet temperatures (550 °...
Conference Paper
Full-text available
The adoption of CO2-based mixtures as power block working fluid for CSP plant can turn supercritical CO2 cycles into efficient transcritical cycles even at high ambient temperature, with significant performance improvement and potential power block cost reduction. In this work, the use of CO2+C6F6 mixture as working fluid for a power cycle coupled...
Conference Paper
Full-text available
Supercritical Carbon Dioxide (sCO2) power cycles have been proposed for Concentrated Solar Power (CSP) applications as a means to increase the performance and reduce the cost of state-of-the-art CSP systems. Nevertheless, the sensitivity of sCO2 systems to the usually hot ambient temperatures found in solar sites compromises the actual thermodynami...
Article
Full-text available
This paper provides an assessment of the expected Levelised Cost of Electricity enabled by Concentrated Solar Power plants based on Supercritical Carbon Dioxide (sCO 2 ) technology. A global approach is presented, relying on previous results by the authors in order to ascertain whether these innovative power cycles have the potential to achieve the...
Technical Report
Full-text available
The purpose of this document is to analyze the state-of-the-art of the CSP technology, focused on the solar tower configuration, and the possibility of integrating a supercritical CO2 (sCO2) cycle to substitute the traditional steam cycle. To that end, the document is divided in six sections. The first section presents a description of the fundamen...
Article
This paper presents the preliminary design and techno-economic assessment of an innovative solar system for the simultaneous production of water and electricity at small scale, based on the combination of a solar micro gas turbine and a bottoming desalination unit. To assess this system, a design model is developed to select the main design paramet...
Article
Recent research on turbomachinery design and analysis for supercritical Carbon Dioxide (sCO2) power cycles has relied on Computational Fluid Dynamics. This has produced a large number of works whose approach is mostly case-specific, rather than of general application to sCO2 turbomachinery design. As opposed to such approach, this work explores the...
Conference Paper
This paper presents the preliminary design and techno-economic assessment of an innovative solar system for the simultaneous production of water and electricity at small scale, based on the combination of a solar micro gas turbine and a bottoming desalination unit. The proposed layout is such that the former system converts solar energy into electr...
Conference Paper
Recent research on turbomachinery design and analysis for supercritical Carbon Dioxide (sCO2) power cycles has relied on Computational Fluid Dynamics. This has produced a large number of works whose approach is mostly case-specific, rather than of general application to sCO2 turbomachinery design. As opposed to such approach, this work explores the...
Article
Full-text available
Previous work by the authors has shown that broader analyses than those typically found in literature (in terms of operating pressures allowed) can yield interesting conclusions with respect to the best candidate cycles for certain applications. This has been tested for the thermodynamic performance (first and second laws) but it can also be applie...
Article
Full-text available
The aim of the paper is to find the optimum design and performance of solar microturbines powered by parabolic dish collectors using an innovative methodology which integrates the design and off-design models of the total system. In contrast to the common practice of assigning an estimated efficiency to the engine turbomachinery (generalized perfor...
Conference Paper
Full-text available
This paper presents an assessment of different control strategies to be applied in central receiver systems operating with molten salts. The objective is to identify the best control scheme to achieve a threefold objective: (i) to ensure that the outlet temperature of the receiver remains at the highest possible value, (ii) to guarantee that the te...
Article
The present paper explores the off-design performance of a CSP tower receiver due to the passage of clouds over the solar field. A quasi steady-state performance model is considered in the first part of the paper, accounting for the optical performance of the solar field and receiver only, yielding the expected incoming heat flux distribution on th...
Article
Full-text available
The interest in Supercritical Carbon Dioxide (sCO2) power cycles has grown exponentially in the last decade, thanks to distinctive features like the possibility to achieve high thermal efficiencies at intermediate temperature, small footprint and adaptability to a wide variety of energy sources. In the present work, the potential of this technology...
Article
This work presents a very detailed techno-economic analysis of the technology, made up of two complementary models. A performance model implemented in Thermoflex environment is used to explore alternative integration layouts in order to enable the simultaneous operation on solar and fossil energy. Then, a detailed cost analysis calculates the capit...
Conference Paper
Full-text available
The present work presents a very detailed techno-economic analysis of the technology made up of two complementary models. A performance model implemented in Thermoflex environment is used to explore alternative integration layouts to enable the simultaneous operation on solar and fossil energy. Then, a detailed cost analysis approaches the capital...
Conference Paper
Previous work by the authors has shown that broader analyses than those typically found in literature (in terms of operating pressures allowed) can yield interesting conclusions with respect to the best candidate cycles for certain applications. This has been tested for the thermodynamic performance (1st and 2nd Laws) but it can also be applied fro...
Article
Full-text available
After the renewed interest in supercritical carbon dioxide cycles, a large number of cycle layouts have been proposed in literature. These works, which are essentially theoretical, consider different operating conditions and modeling assumptions, and thus, the results are not comparable. There are also works that aim to provide a fair comparison be...
Article
Full-text available
The interest in Supercritical Carbon Dioxide (sCO2) power cycles has grown exponentially in the last decade, thanks to distinctive features like the possibility to achieve high thermal efficiencies at intermediate temperature levels, small footprint and adaptability to a wide variety of energy sources. In the present work, the potential of this tec...
Book
Full-text available
This book explores all technical aspects of solid oxide fuel cell (SOFC) hybrid systems and proposes solutions to a range of technical problems that can arise from component integration. Following a general introduction to the state-of-the-art in SOFC hybrid systems, the authors focus on fuel cell technology, including the components required to op...
Conference Paper
This paper presents a method to evaluate the off-design performance of a heat exchanger without specifying detailed heat exchanger geometry. Presently, off-design heat exchanger performance evaluation is often done by assuming one of the terms in a lumped volume approach is constant (such as UA, temperature difference, ε etc.) or by producing a dra...
Conference Paper
Since the renewed interest in supercritical carbon dioxide cycles, a large number of cycle layouts have been proposed in literature. These analyses, which are essentially theoretical, consider different operating conditions and modelling assumptions and thus the results are not comparable. There are also works that aim to provide a fair comparison...
Conference Paper
This paper provides an analysis of the Optimised Microturbine Solar Power generator (OMSoP) project, funded by the European Commission, as the most recent attempt to develop a dish and mGT Concentrated Solar Power generation system that is cost competitive against photovoltaics, at least in certain business cases. A first section presents the syste...
Article
Full-text available
Power cycles running on carbon dioxide at supercritical pressure and temperature were introduced in the late ninety-sixties but, after a warm welcome to the theoretical performance announced, they were later abandoned in favour of standard combustion gas turbines. Nevertheless, the technology was brought forward about a decade ago and has since cap...
Chapter
This chapter focuses on potential hybrid system problems and possible solutions analyzed using theoretical/computational and experimental tools, including physical systems and related available information from commercial companies. Special attention is given to the role of these kinds of power systems, using renewable sources and hydrogen as an en...
Chapter
Since fuel cell stacks are both very expensive and very susceptible to both thermal and mechanical stresses, experimental activities on hybrid systems are regularly carried out using emulator test rigs. The effective application of a range of different emulator test rigs is employed as a routine developmental tool in many associated research undert...
Chapter
The micro turbine industry is experiencing a new renaissance after several decades of idling. The operating principle of a gas turbine is based on the Brayton cycle, is based on two processes at constant entropy—compression and expansion—and two processes at constant pressure—heat addition and rejection. The preliminary design and selection of turb...
Chapter
This chapter commences with an overview of steady-state models for hybrid systems (HS). When modelling any HS plant layout (a fuel cell coupled with a traditional system), it is necessary to consider the primary requirements of the model in order to determine suitable inputs and outputs and their corresponding ranges where appropriate. The chapter...
Article
This paper presents a detailed cost analysis of a small-scale Concentrated Solar Power (CSP) generator based on parabolic dish collectors and Micro Gas Turbines (mGT), whose technical feasibility was already demonstrated in previous publications by the consortium. The system can be used for either electric power or combined heat and power generatio...
Conference Paper
Full-text available
The utilisation of supercritical bottoming cycles in gas turbine based power plants is not new at all. A number of works have already been published discussing the real potential of this configuration as compared to the standard technology using subcritical steam turbines. Nevertheless, the interest of this paper relies on the global approach to cy...
Article
Organic Rankine Cycle (ORC) have principally been used in the past couple of decades to recover medium grade heat from sources such as geothermal, biomass and the exhaust of a realm of different industrial processes (waste heat recovery). In the past few years, this power generation technology has also been proposed in concentrating solar thermal p...
Article
A hybrid energy system comprising a parabolic dish solar energy concentrator (Solar Dish) and a micro gas turbine is investigated in the study. A thermodynamic model of the system is presented, able to simulate both on-design and off-design performance of the system and accounting for the main technical aspects of the concentrator, receiver and gas...
Article
This paper presents an innovative methodology to perform market analysis of a new solar power generation technology based on parabolic dish and micro gas turbine engines. Technical, economic, social and political parameters of influence are combined together into a single figure of merit: index of market potential. This index is an original approac...
Conference Paper
Full-text available
The advantage to using supercritical carbon dioxide (sCO2) in a power cycle (whether Rankine or Brayton) over other fluids is justified on the basis of cycle performance simulations. These simulations are influenced by the assumptions and resolution of turbomachinery and heat exchanger models. For turbomachinery, isentropic or polytropic efficienci...
Article
This paper investigates different strategies for the reduction of peak heat fluxes on the receiver of a solar tower plant through the variation of the heliostats aiming points. The analysis is performed for two different solar tower receivers and heliostat field layouts. The innovative aspect of the work is in the methodology proposed: the effect o...
Article
Energy storage is a cutting edge front for renewable and sustainable energy research. In fact, a massive exploitation of intermittent renewable sources, such as wind and sun, requires the introduction of effective mechanical energy storage systems. In this paper we introduce the concept of a trigenerative energy storage based on a compressed air sy...
Conference Paper
The development of the supercritical Carbon Dioxide power cycle has relied on parallel tracks along which theoretical and experimental works have successfully complemented each other in the last few years. Following this approach, intensive work on the development of critical components has enabled the demonstration of the technology in small-scale...
Article
The international scientific community researching the supercritical carbon dioxide power cycle has already developed the first turbomachinery designs, which are currently operating in reference laboratories worldwide. Nevertheless, the performance of this equipment is still quite far from the target values yielding fairly disappointing system effi...
Article
Molten Carbonate Fuel Cells are an efficient solution to capture carbon dioxide emitted by conventional power plants operating on fossil-fuels. With respect to the currently available technologies (e.g. amine-based chemical absorption), which need significant amounts of heat and electricity to be operated, MCFCs are regarded as active capture syste...
Article
Wastewater treatment stations take advantage of the biogas produced from sludge in anaerobic digesters to generate electricity (reciprocating gas engines) and heat (cooling water and engine exhaust gases). A fraction of this electricity is used to operate the plant while the remaining is sold to the grid. Heat is almost entirely used to support the...
Article
Wastewater treatment produces biogas fuel, commonly used for cogeneration in reciprocating engines, though small scale gas turbines can also be employed. In all cases, the carbon dioxide released through combustion is not regarded as a net greenhouse gas emission since the carbon content in the biogas has a natural origin. In light of that, it is p...
Article
The design of efficient supercritical carbon dioxide (S-CO2) turbomachinery to be used for power generation (and also for CO2 capture facilities) has gained interest in recent years due to the compactness and good performance of the S-CO2 recuperative Brayton cycle in nuclear, waste heat and solar applications. Presently, in addition to a large amo...
Conference Paper
A rapidly growing interest in the supercritical carbon dioxide power cycle has been observed in the last years due to the superb performance of this system in concentrated solar and nuclear applications; a sample of this interest is the number of technical publications submitted to Turbo Expo in the last couple of years. As active members of the su...
Conference Paper
This work compares different approaches (i.e. fault distribution patterns) that aim to explain how a gas turbine compressor gets fouled and how its corresponding performance map deteriorates. To do so, a series of such maps is first developed based on an updated “stage-stacking” methodology. Then, the maps so developed are affected by fouling using...
Conference Paper
The number of people researching the supercritical CO2 power cycle has largely increased in the last few years. Just to mention, in contrast to the one or two technical papers in the topic submitted yearly to Turbo Expo until 2011, the number of contributions in the topic has rocketed to twenty in the last conference held in Copenhagen. Such astoun...
Conference Paper
This work presents a non-conventional combined cycle comprising a topping supercritical Brayton cycle working with carbon dioxide (S-CO2) and a bottoming organic Rankine cycle (ORC). As shown by previous authors in the field of nuclear energy, carbon dioxide cycles are characterised by lower turbine inlet temperatures (around 1100 K) than conventio...
Article
One of the most promising technologies for stationary power applications is the Molten Carbonate Fuel Cell (MCFC). This is due to its high efficiency, low emissions and the medium–high operating temperature. This high temperature allows for hybridization with other power generation technologies where the bottoming cycle recovers part of the heat in...
Article
The utilisation of low-calorific syngas fuels in conventional gas turbines and gas and steam combined cycle equipments has been studied by the authors over the last years. In the present work, the effects of using different fuels of the referred type on the performance of a gas and steam combined cycle performance are assessed. The main bottle-neck...
Article
This work presents a comparative analysis of hybrid systems based on molten carbonate fuel cells and making use of closed-cycle extemally-heated bottoming systems. Two options are considered: reciprocating (Stirling) engines and supercritical carbon dioxide turbines. These two engines share the common feature of working on closed cycles with pure f...
Article
In spite of its slow commercial deployment, fuel cells are amongst the most efficient and environmentally friendly electric power generators. The case of Molten Carbonate Fuel Cells is even more interesting since, in addition to these features that are common to all fuel cells, these systems can be used as active carbon capture devices due to their...
Article
The use of gasified fuels for electricity production is of increasing interest as an alternative to traditional fuels especially in regions with abundant biomass or coal resources. Nevertheless, its use in current gas turbine technologies is challenging due to the differences in fuel composition with respect to conventional natural gas. In this pap...
Article
The use of gasified fuels for electricity generation is gaining interest as an alternative to traditional fuels especially in regions with abundant biomass or coal resources. However their use in some of the most extended power generation technologies like gas turbines and combined cycles is not straightforward. The authors have studied the use of...
Conference Paper
The channels formed between adjacent blades in a turbine/compressor are nothing more than a variable section duct. Hence, the first step of turbomachinery design is to understand the physical processes experienced by a certain fluid when flowing through these nozzles and diffusers. In the main, nozzles are easier to understand since the fluid flows...
Conference Paper
This work presents a detailed model of performance of Stirling engines which is expected to be of interest for the Concentrated Solar Power community. In effect, gas turbines of different types have been proposed for small and medium scale solar applications based on their reduced (even inexistent) water consumption and modularity. In the medium to...
Article
Organic Rankine Cycles (ORC) are considered to be effective solutions for low and medium temperature heat recovery for power production. In such applications where the temperature of waste heat is in the 300-450 degrees C range, they stand as a more interesting option to enhance system performance than the more complex steam cycles typically used i...
Article
This work is divided into two main sections. First, a review of the most frequently used approaches to molten carbonate fuel cell modelling is presented. The models available in literature are found to be classified in three different groups which are carefully described in the paper. Then the models are compared and their ability to predict fuel c...
Article
The authors have previously presented a proposal for hybrid cycles comprising a high temperature fuel cell, either MCFC or SOFC, and a bottoming closed supercritical Brayton cycle working on carbon dioxide, whose expected performance has already been reported. As a continuation, this work presents an assessment on the expected part load performance...
Article
This article presents a novel proposal for complex hybrid systems comprising high temperature fuel cells and thermal engines. In this case, the system is composed by a molten carbonate fuel cell with cascaded hot air turbine and Organic Rankine Cycle (ORC), a layout that is based on subsequent waste heat recovery for additional power production. Th...
Article
A proposal for high efficiency hybrid systems based on molten carbonate fuel cells is presented in this paper. This proposal is based on adopting a closed cycle bottoming gas turbine using supercritical carbon dioxide as working fluid as opposed to open cycle hot air turbines typically used in this type of power generators. First, both bottoming cy...
Article
Research in concentrated thermal solar power plants of all types and, in particular, those based on central receiver, namely solar tower plants, has experienced great impetus in the last decade, reaching full commercial operation with the PS10 plant in Spain. In spite of previous demonstration plants testing different receivers and power cycle layo...
Article
An analysis of the premature failure in a high number of crankshafts from the same model of a four cylinder reciprocating compressor used in bus climate control systems has been carried out.The analysis included visual examination, crankshaft chemical composition and hardness analysis and a dynamical model of the system. The simulation included sev...
Article
This work presents the development of a simple analytical model of performance for heavy duty gas turbine combustors and its use for the analysis of main emissions for a set of syngas fuels. This set of syngas fuels has been selected as a wide representation of different compositions of syngas fuels, from fossil or vegetal origins. Their combustion...
Article
A tool for gas turbine dynamic simulation is presented in this work. First, a thermodynamic model of the engine is presented, capable of predicting engine performance at full and part load conditions. This model considers modern features as variable geometry compressor and air cooled turbine expansion. Then, two different control techniques are ass...
Conference Paper
In this work, a tool to predict the performance of fossil fuel steam power plants under variable operating conditions or under maintenance operations has been developed. This tool is based on the Spencer-Cotton-Cannon method for large steam turbine generator units. The tool has been validated by comparing the predicted results at different loads wi...