DOCSLIB.ORG

Beta Type Stirling Engine. Schmidt and Finite Physical Dimensions Thermodynamics Methods Faced to Experiments

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Beta Type Stirling Engine. Schmidt and Finite Physical Dimensions Thermodynamics Methods Faced to Experiments entropy Article Beta Type Stirling Engine. Schmidt and Finite Physical Dimensions Thermodynamics Methods Faced to Experiments Cătălina Dobre 1 , Lavinia Grosu 2, Monica Costea 1 and Mihaela Constantin 1,* 1 Department of Engineering Thermodynamics, Engines, Thermal and Refrigeration Equipments, University Politehnica of Bucharest, Splaiul Independent, ei 313, 060042 Bucharest, Romania; [email protected] (C.D.); [email protected] (M.C.) 2 Laboratory of Energy, Mechanics and Electromagnetic, Paris West Nanterre La Défense University, 50, Rue de Sèvres, 92410 Ville d’Avray, France; [email protected] * Correspondence: [email protected] Received: 10 September 2020; Accepted: 9 November 2020; Published: 11 November 2020 Abstract: The paper presents experimental tests and theoretical studies of a Stirling engine cycle applied to a β-type machine. The finite physical dimension thermodynamics (FPDT) method and 0D modeling by the imperfectly regenerated Schmidt model are used to develop analytical models for the Stirling engine cycle. The purpose of this study is to show that two simple models that take into account only the irreversibility due to temperature difference in the heat exchangers and imperfect regeneration are able to indicate engine behavior. The share of energy loss for each is determined using these two models as well as the experimental results of a particular engine. The energies exchanged by the working gas are expressed according to the practical parameters, which are necessary for the engineer during the entire project, namely the maximum pressure, the maximum volume, the compression ratio, the temperature of the heat sources, etc. The numerical model allows for evaluation of the energy processes according to the angle of the crankshaft (kinematic–thermodynamic coupling). The theoretical results are compared with the experimental research. The effect of the engine rotation speed on the power and efficiency of the actual operating machine is highlighted. The two methods show a similar variation in performance, although heat loss due to imperfect regeneration is evaluated differently. Keywords: imperfect regeneration; numerical model; Stirling engine; thermodynamic analysis 1. Introduction In the current energy economy context, many studies focus on renewable energy use and on the evaluation of thermal losses. Therefore, the Stirling engine draws the attention of the researchers for its many advantages, namely: strong potential of energy conversion, environmental-friendliness, quietness, and great adaptability to any type of heat source. Study of the Stirling engine presents great complexity because of the oscillatory character of the working fluid evolutions [1]. Various thermodynamic models of Stirling engine operations have already been presented in the literature, with various assumptions. The authors of [2] aimed to develop a numerical model for a beta Stirling engine with a rhombic drive mechanism. Considering the non-isothermal effects, the thermal resistance of the heating head, and the efficiency of the regenerative channel, the energy equations can be derived for the control volumes in the expansion chamber, the regenerative channel, and the compression chamber, and can then be solved. The machine presented in the literature [3] is overhauled in the presence of heat loss and internal irreversibility, Entropy 2020, 22, 1278; doi:10.3390/e22111278 www.mdpi.com/journal/entropy Entropy 2020, 22, 1278 2 of 15 but also shows irreversibility through heat transfer. The work of [4] can be considered a key paper for the literature on Stirling engines, as well as for the identification of design methodologies for a non-proprietary Stirling engine. The literature [5] comes with a practical validation of the practical computer simulation model of the combined plant proposed with the Otto and Stirling cycle by using finite time thermodynamics and the finite dimensional optimization methodology of thermodynamics. A model that includes frictional and mechanical losses is presented in the literature [6]—heat transfer inside the engine and other features such as auxiliary power consumption, and applies to both off-design and on-design operations. A technique for calculating the power and efficiency of Stirling machines is presented in [7]. To analyze this irreversible finite speed cycle, the direct integration of the equations based on the first law for finite speed processes is used to determine the direct power and efficiency of the cycle. There are three modeling levels of Stirling engines [1]. The ideal analysis (or first order analysis) predicts the ideal theoretical performances of an engine [7] with a nil or unlimited convective heat transfer coefficient [8]. The uncoupled analysis (or second order analysis) takes the results of the ideal analysis and corrects them, considering a certain number of finite coefficients and losses in the engine. The obtained results are much more realistic compared with those obtained based on the first order analysis. Some relevant research done by Cullen et al. [9], Bonnet S. et al. [10], Finkelstein [11], and Walker et al. [12] adopted this approach. The coupled analysis (or third order analysis) is based on a fine division of the engine in various control volumes, considering all of the main losses. Numerical methods have been applied to solve the equation system governing the process. It is worth noting that this model is defective because it does not properly simulate the fluid flow, particularly the turbulence, and it uses the empirical correlations to calculate the heat transfer and friction coefficients, which seem to be inadequate for obtaining accurate results. Some of the analyses at this level were developed by Chow [13], Urielli [14], Tew et al., [15], Organ [16], and Gedeon [17]. In the following sections, a finite physical dimensions thermodynamic method (FPDT; first order) and a 0D modeling (isothermal analysis) using the Schmidt model (second order) are presented. The FPDT model [18] is based on the irreversible thermodynamics approach, which is an old approach, but it has had some improvements and engineer adjustments, which were the aim of recent papers developed by Grosu et al. [19–21]. The Schmidt model is an isothermal analysis that considers the same irreversibilities as the FPDT model, and in addition to this, the kinematics of the pistons are considered. This model is effectively an old one (1871), but it is chosen as a starting point by many researchers for their models because of its simplicity and its reduced time of calculation, which represent an interesting advantage in comparison with the coupled analysis. The influence of fluid viscosity, leakage, or other types of source of losses is implicitly considered in the energetic balance scheme, even if it is not detailed in this paper. Empirical correlations could be used in the same way as C.H. Cheng and Y.J. Yu [2] and Y. Timoumi et al. [22]. This study relates to a beta type Stirling engine, comparing the experimental measurements with the analytical results of the two thermodynamic models. 2. β Type Stirling Engine A β-type Stirling engine characterized by the arrangement of the piston engine, displacer, and heat exchangers in a single cylinder of highly resilient glass was analyzed. The two pistons undergo a reciprocating alternative movement with an angle of 110◦. It can operate as an engine by using an electrical resistance located at the top of the cylinder, which constitutes the heat source. The cylinder is surrounded by a water jacket within which a water flow constitutes the cold sink. The displacer forces the passage of the gas from the bottom part to the top part of the cylinder, and vice versa. It also holds a highly conductive material that is used for the heat storage/release, thus playing the regenerator role. The studied hot air engine configuration is presented in Figure1. Entropy 2020, 22, 1278 3 of 15 Entropy 2020, 22, x FOR PEER REVIEW 3 of 16 FigureFigure 1. 1.SchemeScheme of ofthe the cylinder cylinder of ofthe the ββ-type-type StirlingStirling engine.engine. TheThe StirlingStirling engine engine is equippedis equipped with severalwith several sensors, sensors, namely: pressurenamely: sensor,pressure piston sensor, instantaneous piston instantaneousposition sensor, position thermocouples, sensor, thermocouples, ammeter, voltmeter, ammeter, and avoltmeter, device composed and a device of photodiodes composed and of a photodiodesdrilled disc, whichand a drilled allows disc, for flywheel which allows revolution for flywheel speed measurement. revolution speed measurement. TheThe working working fluid fluid is is air, air, which which is is assumed assumed to to behave behave as as a a perfect perfect gas. gas. Any Any change change in in the the fluid fluid is is notnot appropriate, appropriate, as as this this system system has has an an academic academic use use and and benefit. benefit. It It can can operate operate like like an an engine engine and and provideprovide mechanical work,work, or or like like a refrigeratinga refrigerating machine machine (inverse (inverse cycle), cycle), so disassembly so disassembly may be may simple. be simple.The pressure The pressure charge is 1charge bar and is should1 bar remainand should 1 bar, remain thus this 1 enginebar, thus provides this engine little mechanical provides power.little mechanicalThe rotational power. speed The of rotational the engine, speedn, is assumedof the engine, to ben constant., is assumed to be constant. The heat input to the engine
Load more

Recommended publications
  • Equilibrium Thermodynamics
    Equilibrium Thermodynamics Instructor: - Clare Yu (e-mail [email protected], phone: 824-6216) - office hours: Wed from 2:30 pm to 3:30 pm in Rowland Hall 210E Textbooks: - primary: Herbert Callen “Thermodynamics and an Introduction to Thermostatistics” - secondary: Frederick Reif “Statistical and Thermal Physics” - secondary: Kittel and Kroemer “Thermal Physics” - secondary: Enrico Fermi “Thermodynamics” Grading: - weekly homework: 25% - discussion problems: 10% - midterm exam: 30% - final exam: 35% Equilibrium Thermodynamics Material Covered: Equilibrium thermodynamics, phase transitions, critical phenomena (~ 10 first chapters of Callen’s textbook) Homework: - Homework assignments posted on course website Exams: - One midterm, 80 minutes, Tuesday, May 8 - Final, 2 hours, Tuesday, June 12, 10:30 am - 12:20 pm - All exams are in this room 210M RH Course website is at http://eiffel.ps.uci.edu/cyu/p115B/class.html The Subject of Thermodynamics Thermodynamics describes average properties of macroscopic matter in equilibrium. - Macroscopic matter: large objects that consist of many atoms and molecules. - Average properties: properties (such as volume, pressure, temperature etc) that do not depend on the detailed positions and velocities of atoms and molecules of macroscopic matter. Such quantities are called thermodynamic coordinates, variables or parameters. - Equilibrium: state of a macroscopic system in which all average properties do not change with time. (System is not driven by external driving force.) Why Study Thermodynamics ? - Thermodynamics predicts that the average macroscopic properties of a system in equilibrium are not independent from each other. Therefore, if we measure a subset of these properties, we can calculate the rest of them using thermodynamic relations. - Thermodynamics not only gives the exact description of the state of equilibrium but also provides an approximate description (to a very high degree of precision!) of relatively slow processes.
    [Show full text]
  • Converting an Internal Combustion Engine Vehicle to an Electric Vehicle
    AC 2011-1048: CONVERTING AN INTERNAL COMBUSTION ENGINE VEHICLE TO AN ELECTRIC VEHICLE Ali Eydgahi, Eastern Michigan University Dr. Eydgahi is an Associate Dean of the College of Technology, Coordinator of PhD in Technology program, and Professor of Engineering Technology at the Eastern Michigan University. Since 1986 and prior to joining Eastern Michigan University, he has been with the State University of New York, Oak- land University, Wayne County Community College, Wayne State University, and University of Maryland Eastern Shore. Dr. Eydgahi has received a number of awards including the Dow outstanding Young Fac- ulty Award from American Society for Engineering Education in 1990, the Silver Medal for outstanding contribution from International Conference on Automation in 1995, UNESCO Short-term Fellowship in 1996, and three faculty merit awards from the State University of New York. He is a senior member of IEEE and SME, and a member of ASEE. He is currently serving as Secretary/Treasurer of the ECE Division of ASEE and has served as a regional and chapter chairman of ASEE, SME, and IEEE, as an ASEE Campus Representative, as a Faculty Advisor for National Society of Black Engineers Chapter, as a Counselor for IEEE Student Branch, and as a session chair and a member of scientific and international committees for many international conferences. Dr. Eydgahi has been an active reviewer for a number of IEEE and ASEE and other reputedly international journals and conferences. He has published more than hundred papers in refereed international and national journals and conference proceedings such as ASEE and IEEE. Mr. Edward Lee Long IV, University of Maryland, Eastern Shore Edward Lee Long IV graduated from he University of Maryland Eastern Shore in 2010, with a Bachelors of Science in Engineering.
    [Show full text]
  • Overview of Materials Used for the Basic Elements of Hydraulic Actuators and Sealing Systems and Their Surfaces Modification Methods
    materials Review Overview of Materials Used for the Basic Elements of Hydraulic Actuators and Sealing Systems and Their Surfaces Modification Methods Justyna Skowro ´nska* , Andrzej Kosucki and Łukasz Stawi ´nski Institute of Machine Tools and Production Engineering, Lodz University of Technology, ul. Stefanowskiego 1/15, 90-924 Lodz, Poland; [email protected] (A.K.); [email protected] (Ł.S.) * Correspondence: [email protected] Abstract: The article is an overview of various materials used in power hydraulics for basic hydraulic actuators components such as cylinders, cylinder caps, pistons, piston rods, glands, and sealing systems. The aim of this review is to systematize the state of the art in the field of materials and surface modification methods used in the production of actuators. The paper discusses the requirements for the elements of actuators and analyzes the existing literature in terms of appearing failures and damages. The most frequently applied materials used in power hydraulics are described, and various surface modifications of the discussed elements, which are aimed at improving the operating parameters of actuators, are presented. The most frequently used materials for actuators elements are iron alloys. However, due to rising ecological requirements, there is a tendency to looking for modern replacements to obtain the same or even better mechanical or tribological parameters. Sealing systems are manufactured mainly from thermoplastic or elastomeric polymers, which are characterized by Citation: Skowro´nska,J.; Kosucki, low friction and ensure the best possible interaction of seals with the cooperating element. In the A.; Stawi´nski,Ł. Overview of field of surface modification, among others, the issue of chromium plating of piston rods has been Materials Used for the Basic Elements discussed, which, due, to the toxicity of hexavalent chromium, should be replaced by other methods of Hydraulic Actuators and Sealing of improving surface properties.
    [Show full text]
  • Physics 170 - Thermodynamic Lecture 40
    Physics 170 - Thermodynamic Lecture 40 ! The second law of thermodynamic 1 The Second Law of Thermodynamics and Entropy There are several diferent forms of the second law of thermodynamics: ! 1. In a thermal cycle, heat energy cannot be completely transformed into mechanical work. ! 2. It is impossible to construct an operational perpetual-motion machine. ! 3. It’s impossible for any process to have as its sole result the transfer of heat from a cooler to a hotter body ! 4. Heat flows naturally from a hot object to a cold object; heat will not flow spontaneously from a cold object to a hot object. ! ! Heat Engines and Thermal Pumps A heat engine converts heat energy into work. According to the second law of thermodynamics, however, it cannot convert *all* of the heat energy supplied to it into work. Basic heat engine: hot reservoir, cold reservoir, and a machine to convert heat energy into work. Heat Engines and Thermal Pumps 4 Heat Engines and Thermal Pumps This is a simplified diagram of a heat engine, along with its thermal cycle. Heat Engines and Thermal Pumps An important quantity characterizing a heat engine is the net work it does when going through an entire cycle. Heat Engines and Thermal Pumps Heat Engines and Thermal Pumps Thermal efciency of a heat engine: ! ! ! ! ! ! From the first law, it follows: Heat Engines and Thermal Pumps Yet another restatement of the second law of thermodynamics: No cyclic heat engine can convert its heat input completely to work. Heat Engines and Thermal Pumps A thermal pump is the opposite of a heat engine: it transfers heat energy from a cold reservoir to a hot one.
    [Show full text]
  • Internal and External Combustion Engine Classifications: Gasoline
    Internal and External Combustion Engine Classifications: Gasoline and diesel engine classifications: A gasoline (Petrol) engine or spark ignition (SI) burns gasoline, and the fuel is metered into the intake manifold. Spark plug ignites the fuel. A diesel engine or (compression ignition Cl) bums diesel oil, and the fuel is injected right into the engine combustion chamber. When fuel is injected into the cylinder, it self ignites and bums. Preparation of fuel air mixture (gasoline engine): * High calorific value: (Benzene (Gasoline) 40000 kJ/kg, Diesel 45000 kJ/kg). * Air-fuel ratio: A chemically correct air-fuel ratio is called stoichiometric mixture. It is an ideal ratio of around 14.7:1 (14.7 parts of air to 1 part fuel by weight). Under steady-state engine condition, this ratio of air to fuel would assure that all of the fuel will blend with all of the air and be burned completely. A lean fuel mixture containing a lot of air compared to fuel, will give better fuel economy and fewer exhaust emissions (i.e. 17:1). A rich fuel mixture: with a larger percentage of fuel, improves engine power and cold engine starting (i.e. 8:1). However, it will increase emissions and fuel consumption. * Gasoline density = 737.22 kg/m3, air density (at 20o) = 1.2 kg/m3 The ratio 14.7 : 1 by weight equal to 14.7/1.2 : 1/737.22 = 12.25 : 0.0013564 The ratio is 9,030 : 1 by volume (one liter of gasoline needs 9.03 m3 of air to have complete burning).
    [Show full text]
  • Abstract 1. Introduction 2. Robert Stirling
    Stirling Stuff Dr John S. Reid, Department of Physics, Meston Building, University of Aberdeen, Aberdeen AB12 3UE, Scotland Abstract Robert Stirling’s patent for what was essentially a new type of engine to create work from heat was submitted in 1816. Its reception was underwhelming and although the idea was sporadically developed, it was eclipsed by the steam engine and, later, the internal combustion engine. Today, though, the environmentally favourable credentials of the Stirling engine principles are driving a resurgence of interest, with modern designs using modern materials. These themes are woven through a historically based narrative that introduces Robert Stirling and his background, a description of his patent and the principles behind his engine, and discusses the now popular model Stirling engines readily available. These topical models, or alternatives made ‘in house’, form a good platform for investigating some of the thermodynamics governing the performance of engines in general. ---------------------------------------------------------------------------------------------------------------- 1. Introduction 2016 marks the bicentenary of the submission of Robert Stirling’s patent that described heat exchangers and the technology of the Stirling engine. James Watt was still alive in 1816 and his steam engine was gaining a foothold in mines, in mills, in a few goods railways and even in pioneering ‘steamers’. Who needed another new engine from another Scot? The Stirling engine is a markedly different machine from either the earlier steam engine or the later internal combustion engine. For reasons to be explained, after a comparatively obscure two centuries the Stirling engine is attracting new interest, for it has environmentally friendly credentials for an engine. This tribute introduces the man, his patent, the engine and how it is realised in example models readily available on the internet.
    [Show full text]
  • Feasibility Study Into Stirling Engines Application in Ship's Energy Systems
    Transactions on the Built Environment vol 42, © 1999 WIT Press, www.witpress.com, ISSN 1743-3509 Feasibility study into Stirling engines application in ship's energy systems S. Zmudzki, Faculty of Maritime Technology, Technical University of Szczecin, 71- 065 Szczecin, al Piastow 41, Poland E-mail: szmudzkia@shiptech. tuniv.szczecin.pl Abstract The possibility of utilization of solar energy as well as exhaust gas energy from main and auxiliary marine diesel engines for driving Stirling engines has been analysed. The Stirling engines are used for driving current generators. The solar dish Stirling units of 100 kW total effective power may be installed on a board of different type of ships. The system utilizing the exhaust gas energy has been provided with three-way catalyst which may lead to the reduction of emissions below limits established by appropriate regulations. 1 Introduction The Stirling engine belongs to a group of piston engines with so called external supply of heat energy, flowing then through metal walls of engine heater into working gas circulating in the working space. The heat energy supply may be realized or by means of direct effect of the high temperature energy source or by an intermediate heating system i.e. heat pipe or pool-boiler receiver. Thus, the design provides for the possibility of application of different types of heat energy of sufficiently large power. In particular, the advantages of Stirling engines are set off when using the alternative energy sources, especially waste heat energy, the operating costs for which are relatively lower in comparison with capital costs. In case of ship s energy installations, the solar energy available at appropriate geographical latitudes for ships having very large open deck surface / i.e.
    [Show full text]
  • Robosuite: a Modular Simulation Framework and Benchmark for Robot Learning
    robosuite: A Modular Simulation Framework and Benchmark for Robot Learning Yuke Zhu Josiah Wong Ajay Mandlekar Roberto Mart´ın-Mart´ın robosuite.ai Abstract robosuite is a simulation framework for robot learning powered by the MuJoCo physics engine. It offers a modular design for creating robotic tasks as well as a suite of benchmark environments for reproducible re- search. This paper discusses the key system modules and the benchmark environments of our new release robosuite v1.0. 1 Introduction We introduce robosuite, a modular simulation framework and benchmark for robot learning. This framework is powered by the MuJoCo physics engine [15], which performs fast physical simulation of contact dynamics. The overarching goal of this framework is to facilitate research and development of data-driven robotic algorithms and techniques. The development of this framework was initiated from the SURREAL project [3] on distributed reinforcement learning for robot manipulation, and is now part of the broader Advancing Robot In- telligence through Simulated Environments (ARISE) Initiative, with the aim of lowering the barriers of entry for cutting-edge research at the intersection of AI and Robotics. Data-driven algorithms [9], such as reinforcement learning [13,7] and imita- tion learning [12], provide a powerful and generic tool in robotics. These learning arXiv:2009.12293v1 [cs.RO] 25 Sep 2020 paradigms, fueled by new advances in deep learning, have achieved some excit- ing successes in a variety of robot control problems. Nonetheless, the challenges of reproducibility and the limited accessibility of robot hardware have impaired research progress [5]. In recent years, advances in physics-based simulations and graphics have led to a series of simulated platforms and toolkits [1, 14,8,2, 16] that have accelerated scientific progress on robotics and embodied AI.
    [Show full text]
  • Isobaric Expansion Engines: New Opportunities in Energy Conversion for Heat Engines, Pumps and Compressors
    energies Concept Paper Isobaric Expansion Engines: New Opportunities in Energy Conversion for Heat Engines, Pumps and Compressors Maxim Glushenkov 1, Alexander Kronberg 1,*, Torben Knoke 2 and Eugeny Y. Kenig 2,3 1 Encontech B.V. ET/TE, P.O. Box 217, 7500 AE Enschede, The Netherlands; [email protected] 2 Chair of Fluid Process Engineering, Paderborn University, Pohlweg 55, 33098 Paderborn, Germany; [email protected] (T.K.); [email protected] (E.Y.K.) 3 Chair of Thermodynamics and Heat Engines, Gubkin Russian State University of Oil and Gas, Leninsky Prospekt 65, Moscow 119991, Russia * Correspondence: [email protected] or [email protected]; Tel.: +31-53-489-1088 Received: 12 December 2017; Accepted: 4 January 2018; Published: 8 January 2018 Abstract: Isobaric expansion (IE) engines are a very uncommon type of heat-to-mechanical-power converters, radically different from all well-known heat engines. Useful work is extracted during an isobaric expansion process, i.e., without a polytropic gas/vapour expansion accompanied by a pressure decrease typical of state-of-the-art piston engines, turbines, etc. This distinctive feature permits isobaric expansion machines to serve as very simple and inexpensive heat-driven pumps and compressors as well as heat-to-shaft-power converters with desired speed/torque. Commercial application of such machines, however, is scarce, mainly due to a low efficiency. This article aims to revive the long-known concept by proposing important modifications to make IE machines competitive and cost-effective alternatives to state-of-the-art heat conversion technologies. Experimental and theoretical results supporting the isobaric expansion technology are presented and promising potential applications, including emerging power generation methods, are discussed.
    [Show full text]
  • The Atmospheric Steam Engine As Energy Converter for Low and Medium Temperature Thermal Energy
    The atmospheric steam engine as energy converter for low and medium temperature thermal energy Author: Gerald Müller, Faculty of Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ, UK. Te;: +44 2380 592465, email: [email protected] Key words : low and medium temperature, thermal energy, steam engine, desalination. Abstract Many industrial processes and renewable energy sources produce thermal energy with temperatures below 100°C. The cost-effective generation of mechanical energy from this thermal energy still constitutes an engineering problem. The atmospheric steam engine is a very simple machine which employs the steam generated by boiling water at atmospheric pressures. Its main disadvantage is the low theoretical efficiency of 0.064. In this article, first the theory of the atmospheric steam engine is extended to show that operation for temperatures between 60°C and 100°C is possible although efficiencies are further reduced. Second, the addition of a forced expansion stroke, where the steam volume is increased using external energy, is shown to lead to significantly increased overall efficiencies ranging from 0.084 for a boiler temperature of T0 = 60°C to 0.25 for T0 = 100°C. The simplicity of the machine indicates cost-effectiveness. The theoretical work shows that the atmospheric steam engine still has development potential. 1. Introduction The cost-effective utilisation of thermal energy with temperatures below 100°C to generate mechanical power still constitutes an engineering problem. In the same time, energy within this temperature range is widely available as waste heat from industrial processes, from biomass plants, from geothermal sources or as thermal energy from solar thermal converters [1].
    [Show full text]
  • Recording and Evaluating the Pv Diagram with CASSY
    LD Heat Physics Thermodynamic cycle Leaflets P2.6.2.4 Hot-air engine: quantitative experiments The hot-air engine as a heat engine: Recording and evaluating the pV diagram with CASSY Objects of the experiment Recording the pV diagram for different heating voltages. Determining the mechanical work per revolution from the enclosed area. Principles The cycle of a heat engine is frequently represented as a closed curve in a pV diagram (p: pressure, V: volume). Here the mechanical work taken from the system is given by the en- closed area: W = − ͛ p ⋅ dV (I) The cycle of the hot-air engine is often described in an idealised form as a Stirling cycle (see Fig. 1), i.e., a succession of isochoric heating (a), isothermal expansion (b), isochoric cooling (c) and isothermal compression (d). This description, however, is a rough approximation because the working piston moves sinusoidally and therefore an isochoric change of state cannot be expected. In this experiment, the pV diagram is recorded with the computer-assisted data acquisition system CASSY for comparison with the real behaviour of the hot-air engine. A pressure sensor measures the pressure p in the cylinder and a displacement sensor measures the position s of the working piston, from which the volume V is calculated. The measured values are immediately displayed on the monitor in a pV diagram. Fig. 1 pV diagram of the Stirling cycle 0210-Wei 1 P2.6.2.4 LD Physics Leaflets Setup Apparatus The experimental setup is illustrated in Fig. 2. 1 hot-air engine . 388 182 1 U-core with yoke .
    [Show full text]
  • Novel Hot Air Engine and Its Mathematical Model – Experimental Measurements and Numerical Analysis
    POLLACK PERIODICA An International Journal for Engineering and Information Sciences DOI: 10.1556/606.2019.14.1.5 Vol. 14, No. 1, pp. 47–58 (2019) www.akademiai.com NOVEL HOT AIR ENGINE AND ITS MATHEMATICAL MODEL – EXPERIMENTAL MEASUREMENTS AND NUMERICAL ANALYSIS 1 Gyula KRAMER, 2 Gabor SZEPESI *, 3 Zoltán SIMÉNFALVI 1,2,3 Department of Chemical Machinery, Institute of Energy and Chemical Machinery University of Miskolc, Miskolc-Egyetemváros 3515, Hungary e-mail: [email protected], [email protected], [email protected] Received 11 December 2017; accepted 25 June 2018 Abstract: In the relevant literature there are many types of heat engines. One of those is the group of the so called hot air engines. This paper introduces their world, also introduces the new kind of machine that was developed and built at Department of Chemical Machinery, Institute of Energy and Chemical Machinery, University of Miskolc. Emphasizing the novelty of construction and the working principle are explained. Also the mathematical model of this new engine was prepared and compared to the real model of engine. Keywords: Hot, Air, Engine, Mathematical model 1. Introduction There are three types of volumetric heat engines: the internal combustion engines; steam engines; and hot air engines. The first one is well known, because it is on zenith nowadays. The steam machines are also well known, because their time has just passed, even the elder ones could see those in use. But the hot air engines are forgotten. Our aim is to consider that one. The history of hot air engines is 200 years old.
    [Show full text]