Este trabalho apresenta uma revisão dos ciclos teóricos estudados por outros autores sobre o funcionamento de uma máquina a vapor funcionando como máquina de expansão e propõe um ciclo generalizado para o estudo. Esse ciclo generalizado é equacionado e seus pontos operacionais de otimização são determinados. Ao estudar os ciclos teóricos, verificou-se que a máquina a vapor pode atingir a eficiência isentrópica igual de 100%. Um estudo experimental foi conduzido em uma máquina a vapor, a fim de verificar os fenômenos que ocorrem e que influenciam na sua eficiência, fazendo o funcionamento real se afastar do ciclo teórico. Ao fazer o estudo experimental, verificou-se que a máquina a vapor real utilizada possui baixa eficiência, atingindo um máximo de 10% de eficiência isentrópica. Essa eficiência não é do ciclo e sim do conjunto todo, e é devido a diversos fatores, como, por exemplo, atritos, problemas de lubrificação, imperfeições físicas que provocam o vazamento do fluido de trabalho. Uma simulação computacional é realizada, visando prever o comportamento real da máquina a vapor e comparar com os dados obtidos experimentalmente. Verificando assim se a simulação consegue prever os fenômenos físicos e auxiliar no projeto de uma máquina a vapor. Após analisar os dados simulados, verificou-se que as válvulas possuem grande influência na eficiência isentrópica do ciclo da máquina a vapor. Válvulas de acionamento rápido preveem uma eficiência que pode chegar a 96%, enquanto as válvulas reais provocam uma eficiência de aproximadamente 60% para as mesmas condições de simulação. Uma das principais diferenças entre a simulação e os dados reais é a restrição ao fluxo provocada pelas válvulas, e que exigem coeficientes de descarga específicos para esse tipo de válvula. / This work reviews the theoretical cycles studied by other authors on the operation of a steam engine as an expansion machine and chooses a generalized cycle for the study. This generalized cycle is modeled and the points of optimization are determined. By studying the theoretical cycles, it was found that the steam engine can reach the isentropic efficiency equal to 100%. An experimental study carried out in a steam engine in order to verify the phenomena occurring that influence their effectiveness, moving the actual operation away from the theoretical cycle. By making the experimental study, it was found that the actual steam engine has a low efficiency, reaching a maximum 10% isentropic efficiency. This efficiency is not of the cycle, but of the whole set, and is due to several factors, such as friction problems, lubrication problems, physical imperfections causing leakage of the working fluid. A computer simulation was performed in order to predict the actual behavior of the steam engine and compare with the experimental data. After analyzing the simulated data, it was found that the valves have a great influence on the isentropic efficiency of the steam cycle. Valves operating instantly can reach 96% of isentropic efficiency, while real valves cause an efficiency of approximately 60% for the same simulation conditions. A major difference between the simulation and the actual data is the flow restriction caused by valves, which requires specific discharge coefficients for this type of valve.

Este trabalho apresenta uma revisão dos ciclos teóricos estudados por outros autores sobre o funcionamento de uma máquina a vapor funcionando como máquina de expansão e propõe um ciclo generalizado para o estudo. Esse ciclo generalizado é equacionado e seus pontos operacionais de otimização são determinados. Ao estudar os ciclos teóricos, verificou-se que a máquina a vapor pode atingir a eficiência isentrópica igual de 100%. Um estudo experimental foi conduzido em uma máquina a vapor, a fim de verificar os fenômenos que ocorrem e que influenciam na sua eficiência, fazendo o funcionamento real se afastar do ciclo teórico. Ao fazer o estudo experimental, verificou-se que a máquina a vapor real utilizada possui baixa eficiência, atingindo um máximo de 10% de eficiência isentrópica. Essa eficiência não é do ciclo e sim do conjunto todo, e é devido a diversos fatores, como, por exemplo, atritos, problemas de lubrificação, imperfeições físicas que provocam o vazamento do fluido de trabalho. Uma simulação computacional é realizada, visando prever o comportamento real da máquina a vapor e comparar com os dados obtidos experimentalmente. Verificando assim se a simulação consegue prever os fenômenos físicos e auxiliar no projeto de uma máquina a vapor. Após analisar os dados simulados, verificou-se que as válvulas possuem grande influência na eficiência isentrópica do ciclo da máquina a vapor. Válvulas de acionamento rápido preveem uma eficiência que pode chegar a 96%, enquanto as válvulas reais provocam uma eficiência de aproximadamente 60% para as mesmas condições de simulação. Uma das principais diferenças entre a simulação e os dados reais é a restrição ao fluxo provocada pelas válvulas, e que exigem coeficientes de descarga específicos para esse tipo de válvula. / This work reviews the theoretical cycles studied by other authors on the operation of a steam engine as an expansion machine and chooses a generalized cycle for the study. This generalized cycle is modeled and the points of optimization are determined. By studying the theoretical cycles, it was found that the steam engine can reach the isentropic efficiency equal to 100%. An experimental study carried out in a steam engine in order to verify the phenomena occurring that influence their effectiveness, moving the actual operation away from the theoretical cycle. By making the experimental study, it was found that the actual steam engine has a low efficiency, reaching a maximum 10% isentropic efficiency. This efficiency is not of the cycle, but of the whole set, and is due to several factors, such as friction problems, lubrication problems, physical imperfections causing leakage of the working fluid. A computer simulation was performed in order to predict the actual behavior of the steam engine and compare with the experimental data. After analyzing the simulated data, it was found that the valves have a great influence on the isentropic efficiency of the steam cycle. Valves operating instantly can reach 96% of isentropic efficiency, while real valves cause an efficiency of approximately 60% for the same simulation conditions. A major difference between the simulation and the actual data is the flow restriction caused by valves, which requires specific discharge coefficients for this type of valve.

This report is a bachelor thesis at Karlstad University in collaboration with Invencon AB and Ranotor AB. The goal was to analyze a rotating valve leading water vapor through an inlet and five outlets. The quantifiable results that were addressed in this project are the mass flow through the outlets and the forces affecting the valve and its shaft (primarily radial forces). The tools used for this project are PTC Creo and ANSA for modelling and mesh as well as ANSYS-CFX and Matlab for computational help. The results show that the specified rotational speed of 4600 rpm doesn’t work for this model. The rotational speed was chosen because of an interest in this specific operating condition. A 3 mm radial gap between the rotating valve and the valve housing proved to cause a leakage in the form of pressure loss inside the valve. The boundary conditions that were laid out for this project are not valid for this operating condition. Since the difference in pressure is large (100 down to 1 bar) the flow is choked. A large difference in pressure also makes it important to adjust the total area of the outlets, since the pressure drop affects the density of the vapor. The forces on the rotating valve that were calculated (using ANSYS-CFX) create a foundation for choosing bearings for the valve. If the construction is modified, and/or the rotating valve will operate at a different rotational speed these forces will be subject to change. / Denna rapport är ett examensarbete på Karlstads Universitet i samband med Invencon AB och Ranotor AB. Målet var att analysera en roterande ventil som leder trycksatt vattenånga via ett inlopp och ut genom fem olika utlopp. De kvantifierbara resultaten som söktes var massflödet ut ur utloppen och krafterna som påverkar ventilen och axeln (främst radiellt). Verktyg som har använts för att analysera ventilen är PTC Creo och ANSA för modellering och mesh, samt ANSYS-CFX och Matlab för beräkningshjälp. Resultaten tyder på att det valda varvtalet, 4600 rpm, inte fungerar så bra. Varvtalet valdes pågrund av att man var intresserad av driftsfallet. Ett 3 mm radiellt avstånd mellan ventil ochventilhus visade sig även ge läckage i form av tryckfall inuti ventilen. Randvillkoren som är specificerade är inte giltiga vid detta driftsfall. Eftersom tryckförhållandet är så högt (100 till 1 bar) så är flödet chokat. Stor tryckskillnad gör det viktigt att anpassa arean på utloppen, då tryckfall påverkar densiteten. Krafterna på den roterande ventilen som beräknades (i ANSYS-CFX) är ett underlag vid val av lager för ventilen. Om konstruktionen modifieras, och/eller ventilen kommer att användas vid ett annat varvtal så kommer dessa krafter att ändras.

This master’s thesis deals with utilization of biomass for micro cogeneration. The theoretical part of the master’s thesis defines main terms of the master’s thesis, which is biomass and cogeneration. The practical part of the master’s thesis is focused on the design and manufacturing of small micro cogeneration unit based on a small membrane steam engine. It means design of two steam generators to produce steam for the membrane steam engine. It will be also carried out design and production of membrane steam engine which is fitted with a small BLDC generator including electrical part for power output and measuring parameters. It will be made several measurements with the steam engine including measuring power output characteristic of the steam engine and measuring loading characteristics of the generator.

Object of this document is possibility of using piston steam engine (later only SE) in steam boiler plant, heating plant and steam reduction station. There is implemented a thermodynamic suggestion of SE for defined parameters of mechanical power 20 kW, frequency 1500 cpm, input steam pressure 1,5 MPa and warmth inside steam condenser 105 °C. There are implemented the main construction segments of SE with a view to steam distribution system. For determine a shape of work diagram SE (p-V diagram), there was created a supportive programme in Excel. The programme serves as the basis of determination of motor stroke volume and basis of determination of main dimensions.

This thesis deals with a technical economic analysis of the midrange biomass units use. The main output product of the thesis is the computational system based on balance models of cogeneration key nodes. The computational system is suited for cogeneration technologies based on the Rankin steam cycle. The computational system was used for a particular case study calculation focused on a 1 MW biomass boiler extension by an expansion engine (a steam turbine or steam engine).

In this masters thesis are discusses the possibilities of increasing the electrical efficiency of cogeneration units with an internal combustion engine with the power output 800 kWe. Technical and economical aspect the connection with steam turbine, steam engine and ORC turbine is compared. It include the design of heat exchanger for ORC cycle.

In this thesis a method for determining optimal dead space in an axial-type expander is developed. The axial-type expander in question is for use in a steam engine, a environmental friendly and fuel-agnostic alternative to the ICE-engine. Optimal dead space is of importance as an increase in the dead space lowers the efficiency of the engine, however, is needed to ensure operation of expander as the piston could otherwise collide with the expander chamber top surface. The model for determining the optimal dead space in this thesis is based on vectorial tolerance models used for kinematic assemblies, and include the effect of thermal expansion, clearances at joints, manufacturing tolerances and deformations. With resulting tolerances and safety factors, a safe position of the expansion chamber top surface can then be established by Monte Carlo analysis. With input of design variables and the effect from factors mentioned and their effect on the minimal safe distance is calculated using the model in this thesis. From numerical analysis, the factors having the most contribution on the dead space are concluded to be thermal expansion of piston and piston rod, dimensional manufacturing tolerances of piston and piston rod, clearance at ball joints, axial clearance at shaft and bending of Z-shaft. / I detta examensarbete har en metod för att bestämma det optimala avståndet mellan kolv och expansionskammarens högsta yta tagits fram. Axial-kolvmotorn avses för bruk i en ångmotor, ett miljövänligt alternativ till bensin och dieselmotorer som kan drivas med många drivmedel, t.ex. biomassa. Att bestämma detta optimala avstånd är viktigt eftersom en ökning i detta avstånd minskar motorns effektivitet. Dock behövs ett visst avstånd för att säkerställa att ingen kontakt mellan de två ytorna sker under drift. Modellen framtagen i detta examensarbete baserar sig på tolerans analys-modeller med vektorer som används för mekanismer under rörelse. I denna modell inkluderas effekten av termisk expansion, glapp i kontakt mellan komponenter, tillverkningstoleranser och deformationer på kolvens rörelse. Med hjälp av resulterande toleranser och säkerhetsfaktorer kan genom Monte Carlo simulationer ett optimalt avstånd mellan kolv och expansionkammaren bestämmas. Genom inmatning av designvariabler och undersökta effekter kunde genom numerisk analys konstateras att de viktigaste parametrarna att undersöka med störst effekt på axial-kolvmotorn var termisk expansion av kolv och kolvstång, dimensionella toleranser av kolv och kolvstång, glapp i kul-kontakter, axial rörelsefrihet vid kulled och böjning av Z-axel.

The topic of this thesis is the designing of two load bearing surfaces in a modern high-speed steam expander. One of the surfaces is a synchronizing gear structure and the other a conical surface. The goal besides the design is to calculate the contact pressure these surfaces experience during operation. This is achieved by using a machine element design software called KISSsoft for the gear’s more complex geometry. The design process for the conical surfaces is based on analytical calculations that utilizes Hertzian contact theory and the contact pressures the designs amount to is investigated by the use of FEA. The designing process used for the surfaces with regards to placement and geometry resulted in two different concepts. The main difference between the two resulting concepts were how the surfaces were located relative to each other. The gear structure for both concepts were so-called spiral bevel gears, which are conical gears with spiral teeth. The conical surfaces of each concept utilizes crowing of one of the surfaces. The crowing was deemed as a necessary design detail and the magnitude of the crowning radius was used to control the resulting contact pressure. / Ämnet för denna avhandling är utformningen av två lastbärande ytor i en högvarvig modern ångmotor. En av ytorna är en synkroniserande kuggkonstruktion och den andra en konisk yta. Målet förutom utformningen är att beräkna det kontakttryck som dessa ytor upplever under drift. Detta uppnås genom att använda en mjukvara som är specialiserat på design av maskinelement som heter KISSsoft för kuggkonstruktionens mer komplexa geometri. Designprocessen för de koniska ytorna är baserad på analytiska beräkningar som använder Hertz kontaktteori och kontakttrycken i dessa ytor undersöks närmare med hjälp av FEA. Designprocessen som användes for placeringen av ytorna men också deras geometri resulterade i två vinnande koncept. Den största skillnaden mellan dessa koncept var hur ytorna är placerade relativt till varandra. Kuggkonstruktionen var för båda koncepten koniska kuggväxlar med spiralformade tänder. De koniska ytorna for båda koncepten använde bombering av en av ytorna. Bomberingen ansågs som ett nödvändigt detalj i utformningen and dess krökningsradie kunde användas för att kontrollera kontakttrycket mellan ytorna.

In some applications, the piston steam engine may be more suitable than the technology currently used. The thesis deals with the analysis of its advantages, weaknesses and possibilities of use, which are offered. Introduces the principles and functions of piston steam engines. It also contains a thermodynamic design based on a specific assignment and a feasibility assessment.