Special Issue "Modelling of Thermal and Energy Systems"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Thermal Management".

Deadline for manuscript submissions: 20 August 2020.

Special Issue Editor

Prof. Dr. Francisco Vera García
Website
Guest Editor
Univ Politecn Cartagena, Escuela Tecn Super Ingn Ind, Dept Ingn Term & Fluidos, Cartagena, Spain
Interests: internal combustion engines; two-phase flow; heat exchangers design; evaporation & condensation processes; efficiency use of energy; thermal & PV solar energy; water desalinization

Special Issue Information

Dear Colleagues,

At present, in the Industry 4.0 era, it is possible to respond to the behavior of several real systems with a very good adjustment. Modelling tools are present in the majority of engineering disciplines, including energy, manufacturing, reliability, business, etc. However, it is interesting to define Modelling properly, to separate from and not confuse Modelling with simulation.

A correct model solves the physical equations representing the real phenomena that are going to take place in a real system. The fidelity of the model will be strongly determined by the correct physical laws included in the model, the simplifying assumptions, and subjected validation process for the model. A model is able to obtain parameters from different integrated parts of a complex system. In addition, a model is a powerful tool to optimize and to predict a real system.

Meanwhile, a simulation is the statistical response of a system; therefore, the reliability of a simulation is based on the amount of disposable data for the simulated system. In fact, Big Data techniques simulate a known system, but they are not able to get a response from new systems.

Utilizing Modelling tools, we are able to accurately predict the energy flows, power requirements, energy consumption, temperature, humidity, pressure, etc. for several components and their interconnections to develop complex Modelling systems. It is possible to evaluate the impact of a specific measure on a component (i.e., a partial optimization, changes of an environmental/internal parameter, etc.) and to obtain the impact of the whole system. Furthermore, the combination of Modelling and experimentation is the best strategy for the analysis, acquisition of knowledge, optimization, and control of a thermal or energy system.

This Special Issue focuses on the analysis, design, validation, response, and implementation of Modelling of Thermal and Energy Systems. The topics of interest for the Special Issue include (but are not limited to):

  • Modelling of thermal systems;
  • Modelling of complex energy systems;
  • Thermal correlations Modelling;
  • Two-phase flow Modelling;
  • Heat exchangers Modelling and design.;
  • Modelling of internal combustion engines;
  • Reliability and failure detection Modelling;
  • Air conditioning and refrigerant systems;
  • Computational fluid dynamics (CFD) for thermal and energy systems;
  • Modelling of thermal processes (evaporation and condensation);
  • Modelling of energy flows.;
  • Optimization and efficiency use of energy systems;
  • Renewable energy models, thermal and PV solar energy, wind, biomass, biofuels, etc.;
  • Modelling of the desalinization process;
  • Thermal energy storage Modelling;
  • Modelling of building energy consumption, isolation of buildings, etc.

Prof. Dr. Francisco Vera García
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

 

Keywords

  • Thermal systems
  • Energy systems
  • Thermal correlations
  • Heat exchangers
  • Internal combustion engines
  • Reliability
  • Failure detection
  • Air conditioning systems
  • Refrigerant systems
  • Computational fluid dynamics (CFD)
  • Evaporation
  • Condensation
  • Energy flows
  • Optimization of energy systems
  • Renewable energies
  • Desalinization process
  • Thermal energy storage
  • Building energy consumption

Published Papers (11 papers)

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Research

Open AccessArticle
Convective Drying of Ceramic Bricks by CFD: Transport Phenomena and Process Parameters Analysis
Energies 2020, 13(8), 2073; https://doi.org/10.3390/en13082073 - 21 Apr 2020
Cited by 1
Abstract
In the manufacturing process of ceramic brick, the step of drying needs the control of process variables to uniformly dry the porous material, producing a good end-product. The majority of numerical simulations involving drying of ceramic materials is performed considering only the solid [...] Read more.
In the manufacturing process of ceramic brick, the step of drying needs the control of process variables to uniformly dry the porous material, producing a good end-product. The majority of numerical simulations involving drying of ceramic materials is performed considering only the solid domain, resulting in a very simplified and limited study. This way, the objective of this work is the analysis of the drying process with hot air of an industrial hollow clay brick inside the oven at different temperatures by using computational fluid dynamic (CFD). The results of the temperature and water mass distribution inside the brick and of air in the oven at different times of the drying process are shown, analyzed and checked with experimental data, and it was obtained in a concordance with the data. An equation to calculate the brick water mass diffusivity depending on the drying air temperature was proposed. Full article
(This article belongs to the Special Issue Modelling of Thermal and Energy Systems)
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Open AccessFeature PaperArticle
System Characteristics Analysis for Energy Management of Power-Split Hydraulic Hybrids
Energies 2020, 13(7), 1837; https://doi.org/10.3390/en13071837 - 10 Apr 2020
Abstract
Hydraulic hybrid powertrains provide an opportunity for specific applications, such as heavy-duty vehicles based on high-power density, which has not been included in other types of hybrid powertrains. Among the various architectures of hybrid vehicles, power-split hybrids have a greater possibility of producing [...] Read more.
Hydraulic hybrid powertrains provide an opportunity for specific applications, such as heavy-duty vehicles based on high-power density, which has not been included in other types of hybrid powertrains. Among the various architectures of hybrid vehicles, power-split hybrids have a greater possibility of producing better fuel efficiency than other hybrid architectures. This study analyzed the possible energy-saving characteristics of power-split hydraulic hybrid vehicles (HHVs); this has not been comprehensively described in previous studies. A typical configuration of power-split HHVs was modeled with the FTP-72 driving cycle using a novel simulation method that considered the dynamic and thermal behaviors together. The characteristics were analyzed in comparison to a power-split hydrostatic transmission (HST), which is designed with the same conditions except for hydraulic energy storage. The power-split HHV not only has a better fuel efficiency, but it also shows system energy-saving characteristics. The power-split HHV has more chances for engine idling, which is directly related to fuel consumption savings due to engine stop. Additionally, more engine idling time enables the system to operate in a more efficient area on the engine map by load leveling. The results for the system temperature show that the power-split HHV offers the possibility to deliver better thermal management because it prevents the waste of braking power, which is especially crucial for hydraulic systems in comparison to other power systems such as electric or mechanical power systems. The ease of thermal management results in less energy consumption for cooling down the system temperature by minimizing the cooling system, as well as in a better thermal stability for the hydraulic system. The power-split HHV characteristics analyzed in this study can be used to design and organize the system control logic while developing power-split HHVs. Full article
(This article belongs to the Special Issue Modelling of Thermal and Energy Systems)
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Open AccessArticle
Study of the Miller Cycle on a Turbocharged DI Gasoline Engine Regarding Fuel Economy Improvement at Part Load
Energies 2020, 13(6), 1500; https://doi.org/10.3390/en13061500 - 22 Mar 2020
Abstract
This contribution is focused on the fuel economy improvement of the Miller cycle under part-load characteristics on a supercharged DI (Direct Injection) gasoline engine. Firstly, based on the engine bench test, the effects with the Miller cycle application under 3000 rpm were studied. [...] Read more.
This contribution is focused on the fuel economy improvement of the Miller cycle under part-load characteristics on a supercharged DI (Direct Injection) gasoline engine. Firstly, based on the engine bench test, the effects with the Miller cycle application under 3000 rpm were studied. The results show that the Miller cycle has different extents of improvement on pumping loss, combustion and friction loss. For low, medium and high loads, the brake thermal efficiency of the baseline engine is increased by 2.8%, 2.5% and 2.6%, respectively. Besides, the baseline variable valve timing (VVT) is optimized by the test. Subsequently, the 1D CFD (Computational Fluid Dynamics) model of the Miller cycle engine after the test optimization at the working condition of 3000 rpm and BMEP (Brake Mean Effective Pressure) = 10 bar was established, and the influence of the combined change of intake and exhaust valve timing on Miller cycle was studied by simulation. The results show that as the effect of the Miller cycle deepens, the engine’s knocking tendency decreases, so the ignition timing can be further advanced, and the economy of the engine can be improved. Compared with the brake thermal efficiency of the baseline engine, the final result after simulation optimization is increased from 34.6% to 35.6%, which is an improvement of 2.9%. Full article
(This article belongs to the Special Issue Modelling of Thermal and Energy Systems)
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Open AccessArticle
Studying the Role of System Aggregation in Energy Targeting: A Case Study of a Swedish Oil Refinery
Energies 2020, 13(4), 958; https://doi.org/10.3390/en13040958 - 20 Feb 2020
Abstract
The definition of appropriate energy targets for large industrial processes is a difficult task since operability, safety and plant layout aspects represent important limitations to direct process integration. The role of heat exchange limitations in the definition of appropriate energy targets for large [...] Read more.
The definition of appropriate energy targets for large industrial processes is a difficult task since operability, safety and plant layout aspects represent important limitations to direct process integration. The role of heat exchange limitations in the definition of appropriate energy targets for large process sites was studied in this work. A computational framework was used which allows to estimate the optimal distribution of process stream heat loads in different subsystems and to select and size a site wide utility system. A complex Swedish refinery site is used as a case study. Various system aggregations, representing different patterns of heat exchange limitations between process units and utility configurations were explored to identify trade-offs and bottlenecks for energy saving opportunities. The results show that in spite of the aforementioned limitations direct heat integration still plays a significant role for the refinery energy efficiency. For example, the targeted hot utility demand is reduced by 50–65% by allowing process-to-process heat exchange within process units even when a steam utility system is available for indirect heat recovery. Furthermore, it was found that direct process heat integration is motivated primarily at process unit level, since the heat savings that can be achieved by allowing direct heat recovery between adjacent process units (25–42%) are in the same range as those that can be obtained by combining unit process-to-process integration with site-wide indirect heat recovery via the steam system (27–42%). Full article
(This article belongs to the Special Issue Modelling of Thermal and Energy Systems)
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Open AccessArticle
Planned Heating Control Strategy and Thermodynamic Modeling of a Natural Gas Thermal Desorption System for Contaminated Soil
Energies 2020, 13(3), 642; https://doi.org/10.3390/en13030642 - 03 Feb 2020
Abstract
This paper presents a planned heating control strategy applied for a natural gas thermal desorption system for polluted soil to achieve the dynamic adjustment of the heating time and energy consumption. A lumped-parameter model for the proposed system is established to examine effects [...] Read more.
This paper presents a planned heating control strategy applied for a natural gas thermal desorption system for polluted soil to achieve the dynamic adjustment of the heating time and energy consumption. A lumped-parameter model for the proposed system is established to examine effects of the natural gas mass flow rate and the excess air coefficient on the heating performance of the target soil. The control strategy is explored to accomplish the heating process as expected with constant temperature change rate or constant volumetric water content change rate at different phases by adapting the natural gas flow. The results demonstrate that the heating plan can be realized within the scheduled 36 days and the total natural gas consumption can be reduced by 24% (1487 kg) compared to that of the open-loop reference condition, which may be widely applied for other thermal remediation systems of the polluted soil. Full article
(This article belongs to the Special Issue Modelling of Thermal and Energy Systems)
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Open AccessArticle
Thermo-Economic Analysis of a Hybrid Ejector Refrigerating System Based on a Low Grade Heat Source
Energies 2020, 13(3), 562; https://doi.org/10.3390/en13030562 - 23 Jan 2020
Cited by 1
Abstract
The rising of the global energy demand requires the use of alternative energy conversion systems employing renewable sources. In the refrigeration and air conditioning fields, heat driven ejector systems represent a promising way to produce the cooling effect by using available low-grade temperature [...] Read more.
The rising of the global energy demand requires the use of alternative energy conversion systems employing renewable sources. In the refrigeration and air conditioning fields, heat driven ejector systems represent a promising way to produce the cooling effect by using available low-grade temperature sources. In this paper, a thermo-economic analysis of a waste heat recovery hybrid ejector cycle (WHRHEC) was carried out. A thermodynamic model was firstly developed to simulate a WHRHEC able to obtain chilled water with a cooling load of 20 kW, by varying the working fluids and the pinch point values in the heat exchangers. Specific single- and two-phase heat transfer correlations were used to estimate the heat transfer surface and therefore the investment costs. The operative ranges that provide a reasonable compromise between the set-up costs and the cycle performances were then defined and compared to the current waste heat-driven technologies, such as absorption chillers and organic Rankine cycles (ORCs) coupled with vapor compression cycles (VCCs). The last part of the paper presents an economic analysis providing the map of the design (plant size) and contingent (specific cost of energy, waste heat availability) variables that lead to the economic convenience of a WHRHEC system when integrated to a conventional VCC plant. Full article
(This article belongs to the Special Issue Modelling of Thermal and Energy Systems)
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Open AccessArticle
Improvements of a Failure Database for Marine Diesel Engines Using the RCM and Simulations
Energies 2020, 13(1), 104; https://doi.org/10.3390/en13010104 - 24 Dec 2019
Abstract
Diesel engines are widely used in marine transportation as a direct connection to the propeller and as electrical principal or auxiliary generator sets. The engine is the most critical piece of equipment on a vessel platform; therefore, the engine’s reliability is paramount in [...] Read more.
Diesel engines are widely used in marine transportation as a direct connection to the propeller and as electrical principal or auxiliary generator sets. The engine is the most critical piece of equipment on a vessel platform; therefore, the engine’s reliability is paramount in order to optimize safety, life cycle costs, and energy of the boat, and hence, vessel availability. In this paper, the improvements of a failure database used for a four-stroke high-speed marine diesel engine are discussed. This type of engine is normally used in military and civil vessels as the main engine of small patrols and yachts and as an auxiliary generator set (GENSET) for larger vessels. This database was assembled by considering “failure modes, effects, and criticality analysis (FMECA),” as well as an analysis of the symptoms obtained in an engine failure simulator. The FMECA was performed following the methodology of reliability-centered maintenance (RCM), while the engine response against failures was obtained from a failure simulator based on a thermodynamic one-dimensional model created by the authors, which was adjusted and validated with experimental data. The novelty of this work is the methodology applied, which combines expert knowledge of the asset, the RCM methodology, and the failure simulation to obtain an accurate and reliable database for the prediction of failures, which serves as a key element of a diesel engine failure diagnosis system. Full article
(This article belongs to the Special Issue Modelling of Thermal and Energy Systems)
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Open AccessArticle
An Energetic Model for Detonation of Granulated Solid Propellants
Energies 2019, 12(23), 4459; https://doi.org/10.3390/en12234459 - 22 Nov 2019
Abstract
Unexpected detonation of granular solid energetic materials is a key safety issue in the propellants manufacturing industry. In this work, a model developed for the characterization of the early stages of the detonation process of granular solid energetic materials is presented. The model [...] Read more.
Unexpected detonation of granular solid energetic materials is a key safety issue in the propellants manufacturing industry. In this work, a model developed for the characterization of the early stages of the detonation process of granular solid energetic materials is presented. The model relies on a two-phase approach which considers the conservation equations of mass, momentum, and energy and constitutive relations for mass generation, gas-solid particle interaction, interphase heat transfer, and particle-particle stress. The work considers an extension of approximated Riemann solvers and Total Variation Diminishing (TVD) schemes to the solid phase for the numerical integration of the problem. The results obtained with this model show a good agreement with data available in the literature and confirm the potential of the numerical schemes applied to this type of model. The results also permit to assess the effectiveness of different numerical schemes to predict the early stages of this transient combustion process. Full article
(This article belongs to the Special Issue Modelling of Thermal and Energy Systems)
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Open AccessArticle
Fast Heating Model for the Aircraft Cabin Air
Energies 2019, 12(18), 3565; https://doi.org/10.3390/en12183565 - 18 Sep 2019
Cited by 1
Abstract
Maintaining a suitable cabin air temperature distribution is essential for providing an acceptable thermal environment for passengers and crew. However, cabin air may be very cold for the first flight in winter morning. It could be difficult to heat quickly the cabin air [...] Read more.
Maintaining a suitable cabin air temperature distribution is essential for providing an acceptable thermal environment for passengers and crew. However, cabin air may be very cold for the first flight in winter morning. It could be difficult to heat quickly the cabin air and to maintain an acceptable temperature gradient before boarding with the existing environmental control system. This study developed numerical model for predicting the heating process that coupled airflow and heat transfer in a cabin. The model was validated by using the experimental data obtained from an MD-82 airliner. With the validated numerical model, this investigation proposed to use an electric blanket to heat cabin air quickly and to reduce the air temperature gradient. Full article
(This article belongs to the Special Issue Modelling of Thermal and Energy Systems)
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Open AccessFeature PaperArticle
Analysis of Thermodynamic Models for Simulation and Optimisation of Organic Rankine Cycles
Energies 2019, 12(17), 3307; https://doi.org/10.3390/en12173307 - 27 Aug 2019
Cited by 1
Abstract
Equations of state (EOSs) form the base of every thermodynamic model used in the design of industrial processes, but little work has been done to evaluate these in the context of such models. This work evaluates 13 EOSs for their accuracy, computational time [...] Read more.
Equations of state (EOSs) form the base of every thermodynamic model used in the design of industrial processes, but little work has been done to evaluate these in the context of such models. This work evaluates 13 EOSs for their accuracy, computational time and robustness when used in an in-house optimisation program that finds the maximum power output of an organic Rankine cycle. The EOSs represent popular choices in the industry, such as the simple cubic EOSs, and more complex EOSs such as the ones based on corresponding state principles (CSP). These results were compared with results from using the Groupe Européen de Recherches Gazières (GERG) EOS, whose error is within experimental uncertainty. It appears that the corresponding state EOSs find a solution to the optimisation problem notably faster than GERG without significant loss of accuracy. A corresponding state method which used the Peng–Robinson EOS to calculate the shape factors and a highly accurate EOS for propane as the reference EOS, was shown to have a total deviation of just 0.6% as compared to GERG while also being 10 times as fast. The CSP implementation was also more robust, being able to converge successfully more often. Full article
(This article belongs to the Special Issue Modelling of Thermal and Energy Systems)
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Open AccessArticle
Diesel Mean Value Engine Modeling Based on Thermodynamic Cycle Simulation Using Artificial Neural Network
Energies 2019, 12(14), 2823; https://doi.org/10.3390/en12142823 - 22 Jul 2019
Cited by 1
Abstract
This study aims to construct a reduced thermodynamic cycle model with high accuracy and high model execution speed based on artificial neural network training for real-time numerical analysis. This paper proposes a method of constructing a fast average-value model by combining a 1D [...] Read more.
This study aims to construct a reduced thermodynamic cycle model with high accuracy and high model execution speed based on artificial neural network training for real-time numerical analysis. This paper proposes a method of constructing a fast average-value model by combining a 1D plant model and exhaust gas recirculation (EGR) control logic. The combustion model of the detailed model uses a direct-injection diesel multi-pulse (DI-pulse) method similar to diesel combustion characteristics. The DI-pulse combustion method divides the volume of the cylinder into three zones, predicting combustion- and emission-related variables, and each combustion step comprises different correction variables. This detailed model is estimated to be within 5% of the reference engine test results. To reduce the analysis time while maintaining the accuracy of engine performance prediction, the cylinder volumetric efficiency and the exhaust gas temperature were predicted using an artificial neural network. Owing to the lack of input variables in the training of artificial neural networks, it was not possible to predict the 0.6–0.7 range for volumetric efficiency and the 1000–1200 K range for exhaust gas temperature. This is because the mean value model changes the fuel injection method from the common rail fuel injection mode to the single injection mode in the model reduction process and changes the in-cylinder combustion according to the injection timing of the fuel amount injected. In addition, the mean value model combined with EGR logic, i.e., the single-input single-output (SISO) coupled mean value model, verifies the accuracy and responsiveness of the EGR control logic model through a step-transient process. By comparing the engine performance results of the SISO coupled mean value model with those of the mean value model, it is observed that the SISO coupled mean value model achieves the desired target EGR rate within 10 s. The EGR rate is predicted to be similar to the response of volumetric efficiency. This process intuitively predicted the main performance parameters of the engine model through artificial neural networks. Full article
(This article belongs to the Special Issue Modelling of Thermal and Energy Systems)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Development of a variable valve actuation control to improve engine efficiency and emissions in a light duty diesel engine
Authors: Serrano, J.R.; Arnau, F.J.; Martín, J.; Auñón, A.
Affiliation: Universitat Politècnica de València. CMT-Motores Térmicos
Abstract: Due to the need to fulfill the pollutant emission regulations, a growing interest has arisen to adopt Variable Valve Actuation (VVA) technology for automotive engines. Several VVA strategies, such as the exhaust re-opening and the late exhaust closing, can be used to achieve an increment in the after-treatment upstream temperature by increasing the residual gas amount.

In this study, a one-dimensional gas dynamics engine model has been used to simulate several VVA strategies and develop a control system to actuate over the valves timing to increase the engine efficiency and reduce the exhaust pollutant emissions.

 

Title: Passive heating and cooling of photovoltaic greenhouses including thermochromic materials
Authors: Javier Padilla1, Carlos Toledo2,3, Rodolfo López3, Raquel Montoya1, José-Ramón Navarro1, José Abad1 and Antonio Urbina3
Affiliation: 1 Department of Applied Physics, Technical University of Cartagena, Plaza Hospital 1, 30202, Cartagena. Spain. 2 ENEA Centro Ricerche Portici, Energy Technologies Department, Photovoltaics and Smart Devices Division, Innovative Devices Lab, largo Enrico Fermi 1, 80055 Portici (NA), Italy. 3 Department of Electronics, Technical University of Cartagena, Plaza Hospital 1, 30202, Cartagena. Spain.
Abstract: The light transmittance and thermal characteristics of envelope materials are crucial to control or modify the inside temperature and light spectrum of a living/working/cultivation space. In particular, photovoltaic modules are now broadly used as structural components of greenhouses for agronomical applications. In this study an analytical thermal model has been used to fit experimental temperature data measured during two years on four structures built with photovoltaic modules of four different technologies (mono-crystalline Si, amorphous Si, CdTe and an organic technology); additionally data have also been collected in structures in which the thermal effect of colour tuning has been quantified on several common construction materials (glass, wood, concrete on brick and plasterboard). In all cases, temperature differences of several degrees between external and internal ambient have been observed, paving the way to use passive cooling and heating methods to control the temperature and light spectrum of the greenhouses by simply modifying the colour of the structural components, including the photovoltaic modules, its level of solar cell coverage and its light absorption properties.

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