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Valorisation of resources with the cogeneration of electricity and heat from the incineration of wastes is an important issue in modern societies. Present decision models aiming with minimizing the total costs associated with the optimum choice of configuration (synthesis), component design (dimensioning), and operation of waste incineration/cogeneration units. In fact, the time factor which greatly affects certain key decision parameters such as the amount of wastes to eliminate and the electrical and heat

From the standpoint of waste elimination and the design and operation of the systems installed, the cogeneration of electricity and heat from the incineration of wastes has become today an important issue in Switzerland. Decision models developed to minimize the total costs associated with such systems respond only partially to the problems associated with the choice of configuration (synthesis), component design, and the operation of the waste incineration/cogeneration unit. In fact, the time factor which

A combined thermal and simple kinetic model is applied to a small single solid oxide fuel cell (SOFC, 20 cm2 square cell of anode supported electrolyte with 1 cm2 active area). The aim was to compute the temperature field to analyze the operating conditions of the active area of the cell. The cell is simulated in the conditions used for electrochemical characterization, i.e. at negligible fuel utilization and thermally non-adiabatic. Though using a very simple kinetic model, the simulated polarization curve

This paper presents the experimental investigation of a concept of Thermally Driven Heat Pump (TDHP), based on the coupling of a vapor compression heat pump cycle and an Organic Rankine Cycle (ORC). The studied concept uses a single stage centrifugal compr ...

Combined cycles are inherently modular, since they are composed of one or several gas turbines cycles coupled with a steam cycle. Thus, it is often possible to consider repowering of conventional steam power plants by replacing the boiler with a gas turbine and a heat recovery steam generator. It constitutes an interesting option to increase power outputs and efficiencies and reduce specific emissions at moderate costs due to the reuse of existing parts and plant infrastructure. The goal of this study was t

Compact district energy networks in a temperature range of 10 to 16°C have a great potential for energy savings by providing a heat source for decentralized heating heat pumps, a cold source for air-conditioning and a heat sink for refrigeration or cogener ...

A small cogeneration system based on a Solid Oxide Fuel Cell (SOFC) fed on the renewable energy source biogas is presented. An existing farm biogas production site (35 m3 per day), currently equipped with a SOFC demonstration stack, is taken for reference. A process flow diagram was defined in a software package allowing to vary system operating parameters like the fuel inlet composition, reforming technology, stack temperature and stack current (or fuel conversion). For system reforming simplicity, a base

The vaporization of an entrapped mass of saturated water suddenly allowed to expand is studied both experimentally and theoretically. In the experimental set-up, the water is initially pressurized by a piston at the closed end of a cylinder and heated to the onset of vaporization, at which time the expansion is initiated by releasing the gas counterpressure acting on the back face of the piston. The initial depressurization rate is mainly controlled by the gas pressure releasing mechanism, which, in the pre

Test of the unscavenged prechamber ignition system on a 150kW cogeneration engine fed with biogas are presented. The objective was to reach at least 36% in fuel conversion efficiency with exhaust gas emissions lower than the Swiss regulations limits (NOx, ...

At our laboratory extensive research has been conducted on the conversion of conventional Diesel cogeneration engines to operation on natural gas and biogas. In the framework of this research, a numerical simulation of a prechamber autoignition gas engine ...

Among renewable energy sources biomass plays a major role. Several paths for improving the conversion of biomass with minimum burden on the environment are being pursued worldwide. This paper reviews some of the most recent results from research at the Swiss Federal Institute of Technology of Lausanne. On the theoretical and experimental sides it covers the improvement of biogas combustion engines using combustion prechambers both with spark ignition or autoignition in order to reduce the emissions while ke

The present book is the result of more than half a century of teaching and research in thermodynamics at the Swiss Federal Institute of Technology (Ecole Polytechnique Fédérale of Lausanne), known as the EPFL, in Switzerland. Its objective is to facilitate the teaching of thermodynamics to engineering students and to allow engineers from industry to update their knowledge in this domain. It deals primarily with the study of problems of energy conversion of chemical, mechanical and thermal energies in an app

The integration of a solar collector field generating steam into a conventional combined cycle in order to partially replace the fossil fuel required by the latter results in a substantial reduction in greenhouse gases, in an increase in the return on investments associated with the solar field and in an almost complete elimination of the need for solar energy storage. This paper discusses the design of such an integrated hybrid solar-fossil combined cycle with maximum daily and nightly power outputs of 88

Although heat pump based district heating is often an obvious solution from an energy standpoint, adapting the delivery temperature to the most exigent users is detrimental to overall system performance. This pitfall can be avoided with a centralized plant of heat pumps, cogeneration units and an auxiliary furnace, supplemented by decentralized heat pumps. However, the problem of mixed energy production and delivery which this poses is complex and presents for the engineer the daunting if not impossible tas

In recent times the interest in electricity production with Organic Rankine Cycles (ORC) has increased. A look into recent publications shows that the identification of suitable working fluids is in general done by a look at a more or less small number of ...

In CO2 cycles with high-temperature heat sources that are used in applications such as nuclear power, concentrated solar power, and combustion, partial condensation transcritical CO2 (T-CO2) cycles or recompression supercritical CO2 (S-CO2) cycles are cons ...

A new type of district energy network capable of providing simultaneously heating and cooling is being investigated. It is based on the use of CO2 as a heat transfer fluid by taking advantage of the latent heat of vaporization, to store and transfer heat a ...

In this paper, a district heating, cooling and power generation unit has been evaluated from the viewpoints of cost and CO2 emissions. The superstructure considered includes a solid oxide fuel cell and gas turbine (SOFC-GT) combined cycle, a compression heat pump, an absorption chiller, a compression chiller and an additional boiler. Both physical and costing modeling has been developed for evaluating the economics and environmental benefits associated with the design and the operation of several possible c

In the context of resource conservation, incineration of domestic wastes is a technique allowing an interesting potential in energy valorization. However, because of the variability (annual, monthly) in quality and quantity of raw material, one of the characteristics of waste incineration cogeneration power plants is their frequent partial or excess loading. In order to describe their behaviour at these non-nominal loads, there is a need for simulation tools which predict with accuracy the behaviour of the

In order to extend the application range of air-water heat pumps to high temperature residential heating systems, new small hermetic compressors with remodeled injection ports for vapor injection have successfully been tested in laboratory. The injection flow has been controlled by means of either an electronically regulated expansion valve or of a capillary tube. Extreme load and operating conditions could be achieved (air –12°C / water 65°C), using R-407C, while keeping the limits in discharge temperature

Daniel Favrat

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Time-dependent Thermoeconomic Modeling and Optimization of the Synthesis, Design and Operation of a Waste Incineration Cogeneration Power Plant.

An Approach for the Time–Dependent Thermoeconomic Modeling and Optimization of Energy System Synthesis, Design and Operation.

Thermal modeling of a small anode supported solid oxide fuel cell

Experimental investigation of a Thermally Driven Heat Pump based on a double Organic Rankine Cycle and an oil-free Compressor-Turbine Unit

Thermoeconomic optimization of the retrofit of an existing steam cycle power plant.

Novel district heating and cooling energy network using CO2 as a heat and mass transfer fluid

Energy balance model of a SOFC cogenerator operated with biogas

Non-equilibrium effects during the sudden vaporization of saturated water / Vaporization of superheated water under sudden depressurization

Improving performances of a lean burn cogeneration biogas engine equipped with combustion prechambers

Numerical Simulations of a Prechamber Autoignition Engine Operating on Natural Gas

Selected pathways for a more efficient conversion of biomass in cogeneration or fuel production

Thermodynamics and Energy Systems Analysis; From Energy to Exergy

CO2 Mitigation Through the Use of Hybrid Solar-Combined Cycles.

An Environomic Approach for the Modeling and Optimization of a District Heating Network Based on Centralized and Decentralized Heat Pumps, Cogeneration and/or Gas Furnace (Part II: Application)

Methodology for Identification of Suitable ORC-Cycle and Working-Fluid using Integration with Multiple Objectives

Transcritical or supercritical CO2 cycles using both low- and high-temperature heat sources

Performance and Profitability Perspectives of a CO2 based District Energy Network in Geneva’s City Center

Optimization of a Heating, Cooling and Power Generation District Unit based on a Solid Oxide Fuel Cell - Gas Turbine Combined Cycle from the Viewpoints of Cost and CO2 Emissions

Transfert de chaleur par rayonnement dans un four d'incinération industriel: Application de la méthode des zones [Radiative heat transfer in an industrial waste incinerator: Application of the zone method]

Experiences with Hermetic Scroll Compressors with Intermediate Vapor Injection Port in Heat Pumps for High Temperature Lift Heating Applications