Heat Engine System Research Articles

Quantum Lenoir engine in the presence of minimal length

The effect of minimal length for quantum heat engine systems is proposed. We use a system of trapped Fermi particles in an infinite potential well. The thermodynamic cycle chosen is the reversible Lenoir cycle. We use both a single particle case and a multiparticle case. The result is that the minimum length increases the efficiency of the engine if the width of the potential well is infinitely small, and the maximum value is obtained when the width of the potential well is close to zero.

Performance of scientific law-inspired optimization algorithms for constrained engineering applications

The present work compares the performance of scientific law-inspired optimization algorithms for real-life constrained optimization applications. Ten such scientific law-inspired algorithms developed during the past decade are considered in this article. A constrained engineering application of the Stirling heat engine system is investigated with these algorithms. Four operating variables and two output constraints of the Stirling heat engine are considered for optimization. Comparative results are presented with statistical data to judge the performance of the algorithms and subsequently to identify the statistical significance and rank of each algorithm. The effects of various constraint handling methods on the performance of the algorithms are evaluated and presented. The behaviour of the constraint handling methods is analysed and presented. The effect of output constraints on the performance of the algorithms is also evaluated and presented. Finally, the convergence behaviour of the competitive algorithms is obtained and demonstrated.

Elitist Rao Algorithms and R-Method for Optimization of Energy Systems

Identifying, examining, and optimizing the impact of different parameters in a renewable energy system can significantly help determine its efficiency. Furthermore, since these systems have several objectives such as power output, system efficiency, investment cost, economic, and ecological factors, it is often not preferable to present the optimum system parameters considering just one objective. This article proposes three improved versions of recently developed Rao algorithms named elitist Rao algorithms to find optimum system parameters of renewable energy systems. In addition, a new multi-attribute decision-making method named R-method is proposed for selecting the best solution from the Pareto-fronts obtained using the elitist Rao algorithms. The proposed algorithms are tested using 30 single-objective unconstrained benchmark functions, and the significance of improvement over basic Rao algorithms is validated using the Friedman statistical test. Later, the proposed algorithms’ performances are tested in multi- and many-objective optimization scenarios of a solar-assisted Stirling heat engine system and a turbocharged direct injection diesel engine system. Furthermore, the proposed algorithms’ effectiveness is presented in terms of hypervolume, coverage, and spacing metrics. Also, the performances of the proposed algorithms in single-, multi-, and many-objective optimization are compared with the other algorithms from the literature and found to be superior or competitive.

Entransy transfer analysis methodology for energy conversion systems operating with thermodynamic cycles

The entransy transfer analysis methodology proposed in this article offers an alternative novel approach of thermodynamic analysis for assessment and optimization of various energy conversion systems operating with thermodynamic cycles. It is proved that TdU entransy and TdH enthalpy-entransy are not state functions for thermodynamic systems with non-ideal gas substances, so the entransy transfer analysis methodology is constructed based on entransy process functions for generic thermodynamic systems. Accordingly, the thermodynamic evaluation indices of entransy (transfer) dissipation, cyclic net entransy transfer, and entransy (transfer) efficiency are defined. From the case studies of an organic Rankine cycle and a vapor-compression heat pump cycle, lower entransy (transfer) dissipation and higher entransy (transfer) efficiency can be adopted as the optimization objectives for heat engine and compression heat pump systems. Besides, lower cyclic net entransy transfer is preferred for thermal energy storage systems given the charging/discharging heat. The core difference between entransy transfer analysis and exergy (entropy) analysis is that entransy transfer highlights the heat transfer phenomenon, while exergy and entropy focus on the heat–work conversion phenomenon. Moreover, thermodynamic cycles can be classified into forward and reverse cycles in the sense of entransy transfer according to positive and negative cyclic net entransy transfer.

SIMULATION OF THE RADIANT HEAT TRANSFER PROCESS IN THE ELEMENTS OF ROASTING EQUIPMENT

The object of the research is the process of radiation heat transfer, taking into account a single reflection of rays in the IR device of food production. Investigated problem – the work is devoted to solving the problem of irregularity of radiation heat transfer during infrared roasting of food products. Main scientific results. The inverse problem of heat transfer by radiation has been solved and a technique has been developed for determining the profiles of the ray flux reflectors for uniform irradiation of receivers of a convex section. Analytical modeling of all-round uniform irradiation of an elliptical receiver has been carried out. An experimental device with low-inertia temperature sensors for infrared roasting of semi-finished meat products has been developed, which makes it possible to use a reflector shaped according to the developed analytical technique. The verification of the created technique for determining the profiles of reflectors by means of a computer experiment using the TracePro and Mathcad software systems has been carried out. The area of practical use of the research results: the use of an experimental device with a radiant flux reflector for roasting semi-finished meat products proves that the obtained technique for profiling reflectors of heat engineering systems is acceptable for the design of infrared equipment for food production and restaurant facilities. This technique allows simulating the profile of the radiant flux reflector depending on the shape of the receiver. Studies have shown that the use of a profiled reflector in the experimental device reduces the duration of roasting of natural portioned semi-finished beef products by 33 %. Innovative technological product: a technique for determining the profiles of ray flux reflectors for uniform irradiation of receivers with a convex section. Device for infrared roasting of semi-finished meat products. Scope of application of an innovative technological product. The study of an experimental device with a designed radiant flux reflector for roasting semi-finished meat products proves that the obtained technique for profiling reflectors of heat engineering systems is acceptable for the design of infrared equipment for food production and restaurant facilities. Using this approach allows to approach the solution of the problem of irregularity of irradiation of products during infrared roasting

ЭКСЕРГЕТИЧЕСКИЙ ПИНЧ-АНАЛИЗ ВСЕХ ЭЛЕМЕНТОВ КОТЕЛЬНОГО АГРЕГАТА И КОТЕЛЬНОГО АГРЕГАТА В ЦЕЛОМ

The relevance of the research is caused by the need to improve the energy efficiency of heating systems, since all types of fuel are becoming more expensive. In this regard, there is a need to create a method of thermodynamic improvement of heat engineering systems. The main aim of the research is the creation of a method for improving heating systems, the application of this method on the example of a boiler unit PP-2650-255 GM. Objects: a direct-flow boiler PP-2650-255 GM, for which a thermodynamic analysis of the processes occurring in individual elements of the boiler – an air heater, economizer, firebox, and superheater – is performed. The article analyzes all heat fluxes on each element of the boiler. Methods. An exergy method of thermodynamic analysis is used as a research tool. It allows taking into account the energy potential of thermal processes. To date, the most effective method of parametric optimization of heat and power processes is the method of integration of heat flows (pinch method). However, the pinch method is based on a change in flow enthalpy, which does not take into account the qualitative characteristics of energy. In the article, the development of the pinch method continues; flow exergy is used instead of flow enthalpy. Optimization of heat engineering parameters is carried out using an exergy pinch method. Results. Exergy pinch analysis allows you to identify unused exergy and determine in which part the loss occurs. According to the calculations and the graph, it can be seen that hot flows lost 1503,57 MW of exergy, cold flows took 1295,57 MW of exergy, taking into account cooling of the working fluid by bypass. Thus, 47,9 MW of unused exergy was detected in this boiler unit. The results of the exergy pinch analysis allow us to formulate and justify specific design measures to improve the energy efficiency of the boiler unit. This analysis allows you to effectively use the energy and resources of heating equipment.

Performance assessment of the photon enhanced thermionic emitter and heat engine system

The aim of this research is to show the potential application of a photon enhanced thermionic emitter (PETE)–irreversible heat engine (HE) hybrid system. Solar energy has the greatest potential for clean energy, and thermionic emission is the alternative way to convert heat and light into electricity. PETE is an efficient solar to electricity converter comparing to other solar converters, which its efficiency can reach above 50%. Briefly, PETE–heat engine system is analyzed, where the PETE is the main cycle and HE is the bottom cycle. Receiving temperature to PETE above 1000 K and this heat can be utilized by a bottom cycle, heat rejected by the PETE is used by the heat engine, and additional power output is obtained. In addition to basic performance evaluation consisting of power output and electricity efficiency, some exergetic parameters are considered. These exergetic parameters can be listed as: exergy efficiency, depletion ratio, waste exergy ratio, exergetic sustainability index, exergetic ecological index, and modified exergetic ecological index. According to the results, power output, energy efficiency, exergy efficiency, sustainability index, ecological exergetic index, and modified ecological index are 63.698 W cm−2, 0.637, 0.721, 2.603, 0.652, and 0.477, for the optimum cathode temperature and for the optimum anode work function are 67.295 W cm−2, 0.673, 0.764, 3.312, 0.735, and 0.616 are possible to be achieved.

Optimised Liquid Flooded Gas Cycle for Heat Pump and External Heat Engine Applications

Gas cycles, in their ideal form, promise the highest efficiency heat pump and external heat engine systems. The Ericsson and Stirling cycle promise Carnot efficiency, yet their seeming simplicity present significant engineering challenges in implementation. The primary challenge of both cycles is isothermal compression and expansion where finite time and the mechanical system’s insufficient surface area prevent ideal performance. Liquid flooding of the Ericsson cycle has been explored previously. Flooding with a high heat capacity liquid in effect increases the surface area for heat exchange, yet the experimental mechanical system uncounted significant losses, preventing suitable performance. This paper models a novel gas cycle system that combines aspects of the reverse Brayton air cycle and the Liquid Flooded Ericsson cycle. The enthalpy model in EES (Engineering Equation Solver) allows optimization of possible cycle arrangements and yields an optimal arrangement that constitutes a new gas cycle utilizing liquid flooding to achieve superior performance in a simpler cycle that previously envisioned. Possible applications of the new cycle include heat pump and external heat engines.

Rao algorithms for multi-objective optimization of selected thermodynamic cycles

This work proposes multi-objective Rao algorithms. The basic Rao algorithms are modified for solving multi-objective optimization problems. The proposed algorithms have no algorithm-specific parameters and no metaphorical meaning. Based on the interaction of the population with best, worst, and randomly selected solutions, the proposed algorithms explore the search space. The proposed algorithms handle multiple objectives simultaneously based on dominance principles and crowding distance evaluation. In addition, multi-attribute decision-making method-based selection scheme for identifying the best solutions from the Pareto fronts is included. The proposed algorithm performances are investigated on a case study of solar-assisted Brayton heat engine system and a case study of Stirling heat engine system to see whether there can be any improvement in the performances of the considered systems. Furthermore, the efficiencies of the Rao algorithms are evaluated in terms of spacing, hypervolume, and coverage metrics. The results obtained by the proposed algorithms are compared with those obtained by the latest advanced optimization algorithms. It is observed that the results obtained by the proposed algorithms are superior. The performances of the considered case studies are improved by the application of the proposed optimization algorithms. The proposed optimization algorithms are simple, robust, and can be easily implemented to solve different engineering optimization problems.

Solar assisted heat engine systems: multi-objective optimisation and decision making

Identifying, analysing and optimising the effect of various parameters of a solar assisted heat engine system contribute significantly in assessing the system's performance. Optimum parameters can be identified by performing multi-objective optimisation (MOO) considering multiple performance factors. Usually, non-dominated solutions set can be found for these MOO problems and selecting a most suitable solution from non-dominated solutions set is difficult. Hence, in this study, the applicability of multi attribute decision-making methods in MOO problems has been discussed and a decision making procedure is suggested on the basis of average rank to identify the best solution in a Pareto front. Two MOO case-studies of solar-assisted engine systems are optimised by using the multi-objective-Jaya-algorithm and its variants known as multi-team perturbation guiding Jaya algorithm and adaptive multi-team prturbation guiding Jaya algorithm. In both the case studies, the proposed algorithms have improved the performance of the considered systems. Furthermore, the performances of the proposed algorithms are compared using the coverage, spacing, and hypervolume indicators.

Improved multi-objective Jaya optimization algorithm for a solar dish Stirling engine

This study proposes an adaptive multi-team perturbation guiding Jaya (AMTPG Jaya) algorithm. The proposed approach uses multiple teams to explore the search space. Depending on the percentage of consumed function evaluations, the AMTPG Jaya algorithm adjusts the number of teams in the search. Furthermore, all teams move from a single population set and are simultaneously guided by different perturbation equations to different regions of search space. As each team has a different perturbation scheme, the set of moves to new positions by each team is unique. During the search process, the perturbation equations are exchanged depending on the quality of the solutions produced by them. The proposed algorithm employs dominance principles and the crowding distance estimation method to handle the multiple objectives simultaneously. The proposed algorithm is examined using two multi-objective optimization case studies of a solar dish Stirling heat engine system and a multi-objective optimization case study of the Stirling heat pump. Also, the Technique for Order of Preference by Similarity to Ideal Solution decision-making method is employed for identifying an optimal solution. The computational results obtained by the proposed AMTPG Jaya algorithm are superior to those achieved by the other algorithms presented in this work.

Optimal performance regions of an irreversible energy selective electron heat engine with double resonances

A theoretical model for irreversible double resonance ESE (energy selective electron) device with phonon induced bypass heat leakage which is operating as heat engine system is proposed. The thermodynamic performance is optimized and the impacts of heat leakage and structure parameters of the electron system on its performance are discussed in detail by using FTT (finite time thermodynamics). Moreover, performances of the ESE system with multiple optimization objective functions, including power output, thermal efficiency, ecological function and efficient power, are explored by numerical examples. New optimal performance regions and the selection plans of optimization objective functions of the ESE system are obtained. It reveals that the characteristic of power versus efficiency behave as loop-shaped curves in spite of the heat leakage which will always decrease the efficiency of the electron engine. By properly choosing the design parameters, the ESE engine can be designed to operate at optimal conditions according to different design purpose. The preferred design area should be located between the optimal effective power condition and the optimal ecological function condition.

Thermo-environmental performance analysis of irreversible solid oxide fuel cell – Stirling heat engine

ABSTRACTA hybrid, irreversible solid oxide fuel cell – Stirling heat engine system is taken into account. Thermoenvironmental criterion approach, which enables to evaluate environmental impact of any thermal cycle, is applied to the considered system for the first time. Power density, exergy density, thermoenvironmental function density, energy and exergy efficiencies are considered. Results are presented and discussed to determine optimum operating conditions. Some important results for the hybrid system are ordered: maximum power density is 7489.92 (A m−2), maximum energy and exergy efficiencies are 0.800 and 0.887, respectively, and finally, thermoenvironmental function density is 0.0276 (W mpts−1 m−2).

Reverse electrodialysis with NH4HCO3-water systems for heat-to-power conversion

A Reverse ElectroDialysis Heat Engine (REDHE) system operating with “thermolytic” ammonium hydrogen-carbonate (NH4HCO3) aqueous solutions as working fluids is studied. The engine is constituted by (i) a RED unit to produce electric power by mixing the solutions at different salinity and (ii) a thermally-driven regeneration unit including a stripping and an absorption column to restore the initial salinity gradient thus closing the cycle. In the present work only the RED unit and the stripping column are taken into account. In particular, a simplified integrated process model for the whole cycle was developed: it consists of (i) a lumped parameter model for the RED unit validated with experimental data and (ii) a model developed via a process simulator to assess the thermal duty of the stripping column. The effect of operating conditions as solution concentrations and velocities was investigated by a sensitivity analysis. Under the best conditions (among those investigated), a power density of about 9 W/m2 of cell pair was predicted for the RED unit, and a maximum exergetic efficiency of about 22% was found for the whole cycle. A preliminary economic analysis of the process is also provided.

Network Analysis of Fuel Cell Heat Engine Distributed Energy Systems

A thermodynamic and electrochemical framework transformed into an electrical network is used to analyze the power output and efficiency of high-temperature, ceramic fuel cell heat engine systems for the hydrogen oxidation reaction. It is interesting that the heat engine combustor subsystem performance was able to be recast in electrochemical and electrical network terms. The analysis includes the effect of temperature on the operation and performance of these ceramic, high-temperature systems. The power and efficiency responses of a distributed energy system operated at constant voltage to protect the fuel cell, using supplemental firing of the heat engine, and subjected to a cyclic load demand is presented. These systems are of interest to the emerging renewable energy grid. While the perfect fuel cell would undergo no degradation, practical fuel cells will degrade. The partition of power in a degrading distributed energy system is examined.

Performance analysis of irreversible solid oxide fuel cell – Brayton heat engine with ecological based thermo-environmental criterion

An irreversible hybrid solid oxide fuel cell (SOFC)-Brayton heat engine system is taken into account in this study. Ecological based thermoenvironmental function is considered to assess the performance of the system as well as the power, exergy destruction, energy and exergy efficiencies. This function enables someone to determine environmental impact of any thermal cycle. Optimum operating conditions for all investigated parameters are obtained. Results are presented numerically and discussed. Some important results are; maximum power density of the hybrid system is 15260.9 (Wm−2) at i=17,000 (Am−2), maximum energy efficiency of the hybrid system is 0.841 at i=7200 (Am−2), exergy efficiency of the hybrid system is 0.676 at i=5200 (Am−2) and ecological based thermoenvironmental function density of the hybrid system reaches maximum value at i=5800 (Am−2) and it is equal to 0.00603 (Wmpts−1m2). Finally, environmental friendly and efficient operation conditions, if≤i≤iP, is suggested for the hybrid system.

Network Analysis of Fuel Cell Heat Engine Distributed Energy Systems

A thermodynamic and electrochemical framework transformed into an electrical network is used to analyze the power output and efficiency of fuel cell heat engine systems for the hydrogen oxidation working reaction. The analysis includes operation of these systems at constant voltage with constant power operation through supplemental firing of the heat engine. It is interesting that the heat engine combustor performance was able to be recast in electrochemical and electrical network terms. The analysis includes the power and efficiency responses of a cyclic load distributed energy system of interest to the renewable energy grid. While the perfect fuel cell would undergo no degradation, practical fuel cells will degrade. The partition of power in a degrading distributed energy system at constant voltage with constant power is examined. Network topology is an important parameter which the electrical network approach is best suited to analyze. For high heat engine exergetic efficiency and low fuel cell operating voltage parallel fuel cell network topology design gives the best performance while for poor heat engine exergetic efficiency and high operating voltage a series fuel cell network topology design gives the best performance design.

Combustion Characterization and Model Fuel Development for Micro-tubular Flame-assisted Fuel Cells.

Combustion based power generation has been accomplished for many years through a number of heat engine systems. Recently, a move towards small scale power generation and micro combustion as well as development in fuel cell research has created new means of power generation that combine solid oxide fuel cells with open flames and combustion exhaust. Instead of relying upon the heat of combustion, these solid oxide fuel cell systems rely on reforming of the fuel via combustion to generate syngas for electrochemical power generation. Procedures were developed to assess the combustion by-products under a wide range of conditions. While theoretical and computational procedures have been developed for assessing fuel-rich combustion exhaust in these applications, experimental techniques have also emerged. The experimental procedures often rely upon a gas chromatograph or mass spectrometer analysis of the flame and exhaust to assess the combustion process as a fuel reformer and means of heat generation. The experimental techniques developed in these areas have been applied anew for the development of the micro-tubular flame-assisted fuel cell. The protocol discussed in this work builds on past techniques to specify a procedure for characterizing fuel-rich combustion exhaust and developing a model fuel-rich combustion exhaust for use in flame-assisted fuel cell testing. The development of the procedure and its applications and limitations are discussed.

Analysis and optimization with ecological objective function of irreversible single resonance energy selective electron heat engines

Ecological performance of a single resonance ESE heat engine with heat leakage is conducted by applying finite time thermodynamics. By introducing Nielsen function and numerical calculations, expressions about power output, efficiency, entropy generation rate and ecological objective function are derived; relationships between ecological objective function and power output, between ecological objective function and efficiency as well as between power output and efficiency are demonstrated; influences of system parameters of heat leakage, boundary energy and resonance width on the optimal performances are investigated in detail; a specific range of boundary energy is given as a compromise to make ESE heat engine system work at optimal operation regions. Comparing performance characteristics with different optimization objective functions, the significance of selecting ecological objective function as the design objective is clarified specifically: when changing the design objective from maximum power output into maximum ecological objective function, the improvement of efficiency is 4.56%, while the power output drop is only 2.68%; when changing the design objective from maximum efficiency to maximum ecological objective function, the improvement of power output is 229.13%, and the efficiency drop is only 13.53%.

Model for evaluating degradation of high-temperature fuel cell heat engine systems

A thermodynamic and electrochemical framework with a composite fuel cell for the analysis of the degrading fuel cell heat engine hybrid is used to investigate the effect of temperature and voltage on the performance of high-temperature fuel cell heat engine hybrid systems. In this composite fuel cell a Tafel nickel cermet anode is combined with a ceramic electrolyte and mixed electronic ionic conduction (MIEC) cathode. Activation polarizations are described by three models – Butler–Volmer, Tafel, and MIEC. It is verified from simulation that for hydrogen direct oxidation working reaction (WR) the MIEC-containing fuel cell functions well in the hybrid system. It has found that there is an optimal constant voltage that maximizes power for a hybrid operating at the constant voltage. This simulation method in this paper is a first step in a screening procedure for determining and exploring the system behavior of new fuel cell materials for use in hybrid systems.