Fuel cell technology has reached commercialisation of fuel cells in application areas such as residential power systems, automobile engines and driving of industrial manufacturing processes. This thesis gives an overview of the current state of fuel cell-based technology research and development, introduces a μCHP system sizing strategy and proposes methods of improving on the implementation of residential fuel cell-based μCHP technology. The three methods of controlling residential μCHP systems discussed in this thesis project are heat-led, electricity-led and cost-minimizing control. Simulations of a typical HT PEMFC -based residential μCHP unit are conducted using these control strategies. A model of a residential μCHP system is formulated upon which these simulated tests are conducted. From these simulations, equations to model the costs of running a fuel-cell based μCHP system are proposed. Having developed equations to quantify the running costs of the proposed μCHP system a method for determining the ideal size of a μCHP system is developed. A sizing technique based on industrial CHP sizing practices is developed in which the running costs and capital costs of the residential μCHP system are utilised to determine the optimal size of the system. Residential thermal and electrical load profile data of a typical Danish household are used. Having simulated the system a practical implementation of the power electronics interface between the fuel cell and household grid is done. Two topologies are proposed for the power electronics interface a three-stage topology and a two-stage topology. The efficiencies of the overall systems of both topologies are determined. The system is connected to the grid so the output of each system is phase-shifted and DC injection, harmonic distortion, voltage range and frequency range are determined for both systems to determine compliance with grid standards. Deviations between simulated results and experimental results are recorded and discussed and relevant conclusions are drawn from these.

The aim of thesis entitled steam turbine is a condensing steam turbine with steam extraction, in twin-shaft implementation for municipal waste-incineration plant. The first part of the work is focused on the design used and the selected concept turbine. The second part is engaged in thermodynamic calculation of backpressure and condensing part. The end is devoted to technical – economic comparison with other possible conceptual variants.

This thesis is devoted to the construction of new waste-to-energy plants in a territory where is already another fossil-fuel power station in operation. The aim is to create a mathematical model and prove that those two devices are able to cooperate effectively using same technology. Exactly assembled model under real operating have characteristics of a mixed integer nonlinear programming. The optimization software GAMS is used for its calculation. The complexity of the model, however, is at a level that solutions in bad initial conditions ends in local optima, or not found at all. This thesis is devoted to the elimination of non-linearity using binary variables and heuristic so the task was solved with acceptable time limits to guarantee an optimal solution.

The Brista 1 plant is a wood chip-fired combined heat and power (CHP) plant located near Märsta, northwest of Stockholm, Sweden. The primary purpose of the plant is to supply heat to the northwest district heating grid. In order to meet increasing demand for district heating, Fortum Heat is constructing a second CHP plant next to Brista 1. The Brista 2 plant will use a mixture of municipal and industrial waste as fuel. Due to changes in the European Green Certificate program, the fuel subsidies for wood chips will be significantly reduced. This will cause the Brista 1 plant to incur significantly increased operating costs. The Brista 2 plant, however, will not be affected by these changes and will therefore be much cheaper to run than Brista 1. However, due to the large demand for district heating it will be necessary to run both plants in parallel at certain times in order to meet the heating demand and/or maximize revenue during periods of high electricity demand. A computer program has been constructed using MATLAB which simulates the Brista 1 and 2 plants and their combined operation in both backpressure and direct condensing mode. The results show that the optimum allocation of heat production does not seem to be affected by electricity price assuming both plants are operated in backpressure mode. The reason for this would seem to be that the production costs (fuel, emissions, O&M) are unaffected by the electricity price. Therefore, the allocation which maximizes electrical power production, and thus revenue from electricity sales, will always be favored. In certain cases, it is more profitable to run the Brista 1 plant in direct condensing mode. The reason for this would seem to be that the thermal efficiency is somewhat higher, and that at low electricity prices the revenues from electricity sales do not offset the cost of the reduced heat production.

This thesis presents a method for reliability assessment of a power grid with distributed generation providing support to the system. The distributed generation units considered for this assessment are Combined Heat and Power (CHP) units operated by individual customers at their site. CHP refers to the simultaneous generation of useful electric and thermal energy. CHP systems have received more attention recently due to their high overall efficiency combined with decrease in costs and increase in reliability. A composite system adequacy assessment, which includes the two main components of the power grid viz., Generation and Distribution, is done using Monte Carlo simulation. The State Duration Sampling approach is used to obtain the operating history of the generation and the distribution system components from which the reliability indices are calculated. The basic data and the topology used in the analysis are based on the Institution of Electrical and Electronics Engineers - Reliability Test System (IEEE-RTS) and distribution system for bus 2 of the IEEE-Reliability Busbar Test System (IEEE-RBTS). The reliability index Loss of Energy Expectation (LOEE) is used to assess the overall system reliability and the index Average Energy Not Supplied (AENS) is used to assess the individual customer reliability. CHP reliability information was obtained from actual data for systems operating in New England and New York. The significance of the results obtained is discussed.

The liberalization of electricity markets and a growing penetration of renewables is changing operation of electrical grids. The boundary conditions for the operation of conventional power plants are changing and, as such, an improved understanding of the varying loads and prices on the electricity grid is required to assess the performance of emerging combined cycle gas turbine (CCGT) concepts and to further optimize their design for these new markets in the pursuit of increasing their profitability, especially when considering combined heat and power (CHP). To increase the flexibility of CCGT-CHP plants, three new plant layouts have been investigated by integrating different storage concepts and heat pumps in key sections of the traditional plant layout. The present study analyses the influence that market has on determining the optimum CCGT-CHP plant layout that maximizes profits (in terms of plant configuration, sizing and operation strategies) for a given location nearby Turin, Italy, for which hourly electricity and heat prices, as well as meteorological data, have been gathered. A multi-parameter approach for design and operation was followed using KTH’s and EPS’ techno-economic modeling tool DYESOPT. Results are shown by means of a comparative analysis between optimal plants found for each layout and the state-of-the art CCGT-CHP. It is shown that a plant configuration in which a cold storage unit is integrated together with a heat pump at the inlet of the gas turbine unit increases the net present value of the plant by approximately 0.3% when compared against conventional plant layouts. Using the same concept with a heat pump alone can improve lifetime profitability by 1.6%. A layout where district heating supply water is preheated with a combination of a heat pump with hot thermal tank increases plant profitability by up to 0.5%. This work has been performed as part of the PUMP-HEAT project, an EU Horizon 2020 research project in which KTH collaborates with other 13 stakeholders including industry and research institutions. The results will directly influence future work of the project.

No description available.

Micro-cogeneration is one of the technologies promoted as a response to the global call for the reduction of carbon emissions. Due to its recent application in the residential sector, the implications of its usage have not yet been fully explored, while at the same time, the available simulation tools are not designed for conducting research that focuses on the study of this technology. This thesis develops a virtual prototyping environment, using a dynamic multi-physics simulation tool. The model based procedure in its current form focuses on ICE based micro-CHP systems. In the process of developing the models, new approaches on general system, engine, heat exchanger, and dwelling thermal modelling are being introduced to cater for the special nature of the subject. The developed software is a unique modular simulation tool platform linking a number of independent energy generation systems, and presents a new approach in the study and design of the multi node distributed energy system (DES) with the option of further development into a real-time residential energy management system capable of reducing fuel consumption and CO2 emissions in the domestic sector. In the final chapters, the developed software is used to simulate various internal combustion engine based micro-CHP configurations in order to conclude on the system design characteristics, as well as the conditions, necessary to achieve a high technical, economic and environmental performance in the UK residential sector with the purpose of making micro- CHP a viable alternative to the conventional means of heat & power supply.

Der integrierte Gas-Dampf (GiD-) Prozess mit Wasserrückgewinnung ist ein flexibler Kraft-Wärme-Kopplungsprozess, der die gleichzeitige Bereitstellung von Strom und Wärme teilweise entkoppeln kann. Der effiziente und sparsame Einsatz von fossilen Brennstoffen ist aus ökonomischer wie auch ökologischer Sicht geboten. Die Kraft-Wärme-Kopplung (KWK), die gleichzeitige Erzeugung von Strom und Wärme, ist eine Möglichkeit dafür. Allerdings erfordert die KWK auch eine gleichzeitige Abnahme von Strom und Wärme beziehungsweise deren Speicherung. Sowohl Strom als auch Prozessdampf lassen sich nur aufwendig und damit relativ teuer speichern, weshalb Alternativen gefragt sind. Der GiD-Prozess besteht aus einer Gasturbine mit nachgeschaltetem Abhitzedampfkessel. Die Gasturbine verfügt als Besonderheit über eine Dampfinjektion, die vor, nach oder direkt in die Brennkammer erfolgen kann. Der Abhitzekessel hat zusätzliche Wärmeübertragerflächen um das Abgas bis unter den Taupunkt abzukühlen. Somit kann ein Teil des injizierten Dampfes aus dem Abgas zurückgewonnen und wiederverwendet werden. Der in die Gasturbine injizierte Dampf führt dieser weitere Energie zu. Diese kann entweder zur Leistungssteigerung der Anlage oder zur Reduzierung des fossilen Brennstoffbedarfes genutzt werden. Die erste Option der Leistungssteigerung ist auch als Cheng-Prozess bekannt. Diese Arbeit widmet sich der weniger untersuchten zweiten Möglichkeit der Brennstoffreduzierung. Beim Vergleich des GiD-Prozesses mit verschiedenen anderen Kraftwerks-Prozessen zeigt sich, dass dieser besonders gut für industrielle Anlagen mit Prozessdampfbedarf und einer elektrischen Leistung kleiner 20 MW el geeignet ist. Im Rahmen dieser Arbeit wurde der GiD-Prozess mittels einer Versuchsanlage auf Basis einer Industriegasturbine mit 650 kW el untersucht. Die Arbeit dokumentiert verschiedene Versuchsfahrten und Untersuchungen an dieser Anlage. Die Injektion von Dampf reduziert die Schadstoffemissionen in den zulässigen Bereich und kann sehr flexibel zu einer Steigerung des Anlagenwirkungsgrades von bis zu zwei Prozent führen. Dabei wird der Dampf sehr gleichmäßig in die Versuchsanlage eingebracht, so dass keine signifikanten Änderungen der Abgastemperaturverteilung erkennbar sind. Die Überhitzung des Dampfes kann zu einer weiteren Steigerung des Anlagenwirkungsgrades führen. Die Rückgewinnung des eingebrachten Dampfes ist mit den entsprechenden Wärmeübertragern möglich. Das zurückgewonnene Wasser ist durch die Stickoxide des Abgases verunreinigt und muss entsprechend aufbereitet werden.

Le concentrateur à réflecteur linéaire de Fresnel (LFR) est une technologie solaire thermodynamique en plein essor : petites applications industrielles (chaleur, froid, électricité) à centrales électriques (10-100 MWel). Ce travail de thèse établit un modèle global du procédé solaire, en régime permanent, pour un prédimensionnement du système. Le modèle comprend trois parties chaînées : (i) les transferts radiatifs dans le concentrateur optique, modélisés précisément par une méthode de Monte Carlo (environnement EDStar) ; (ii) les transferts thermiques dans le récepteur, évalués analytiquement (puissances, températures) ; (iii) le cycle thermodynamique, avec Thermoptim. L’application étudiée couple un concentrateur LFR à un moteur Ericsson. L’air est fluide caloporteur et de travail. Un prototype est en construction. L’hybridation et le stockage thermique sont des options clés. Un modèle systémique permettrait d’optimiser l’opération du procédé, en étudiant son comportement dynamique. / Linear Fresnel Reflector (LFR) is a promising Concentrating Solar Power technology. Research is booming and industrial applications are emerging. Applications range from small production units (heat, cold, electricity) to utility scale power plants (several tenths of MW). This PhD work establishes a global model of the solar process, in order to improve our knowledge of the system’s performances. It is a static model suited for a pre-design of the system. The model is chaining three parts. Radiative heat transfer in the optical concentrator is modelled by Monte Carlo statistical Method. The algorithm enables a detailed study of any geometrical configuration, especially through absorbed power flux maps on the receiver. The simulation tool is using the environment of development EDStar. The thermal model calculates analytically the useful thermal power, losses and temperature profiles along the receiver (glass cover, fluid, pipe...). The thermodynamic cycle is simulated analytically using the software Thermoptim. The studied application uses air as heat transfer and working fluid. Air directly feeds an Ericsson engine. The engine developed by LaTEP laboratory is promising for small scale cogeneration (1 to several tenths of kWel). The prototype Linear Fresnel Reflector built in Ecole des Mines d’Albi will enable experimental study of a solar process coupling an LFR concentrator and an Ericsson engine. The technology under study can feed a power plant or a cogeneration system in the industry, producing electricity and heat at 100 to 250°C. Hybridisation with an other energy source (biomass, gas...) and thermal storage (molten salt?) are key features to investigate. To optimise the operating strategy of the process, dynamic behaviour must be studied: a systemic or agent based model is a very relevant approach.