Publications de Daniel Favrat | EPFL Graph Search

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Flow boiling experiments for two new non-azeotropic, three-component refrigerant mixtures (HP80 and HP62) and R-502 have been carried out inside a 12 mm bore, horizontal tube. Local boiling coefficients for HP62 are slightly larger that those for R-502 under the same test conditions while those for HP80 are slightly smaller. The heat transfer performances of the three fluids are accurately predicted by an existing flow boiling correlation modified here to include a nucleate pool boiling mixture equation.

In this paper the effect of systematic errors in gas temperature measurements on the thermal control of a Solid Oxide Fuel Cell system is demonstrated. Three control schemes were tested under two different conditions. First, the real gas temperature at the ...

Flow boiling experiments for two new non-azeotropic, three-component refrigerant mixtures (HP80 and HP62) and R-502, the azeotropic refrigerant binary mixture they are replacing, have been carried. Comparative results show that local flow boiling heat transfer coefficients for HP62 are slightly larger that those for R-502 under the same test conditions while those for HP80 are on average slightly smaller. The heat transfer performances of the three fluids are accurately predicted by an existing flow boiling

In this paper the first results of a new method for the configuration of district energy systems are presented. District energy systems are believed to help decreasing the CO2-emissions due to energy services (heating, cooling, electricity and hot water), ...

Rankine cycles for low to medium power and low temperature heat using water as working fluid, were almost written off. The main arguments speaking against them are reviewed in this paper and the conceptual design of the equipment entirely revisited. An adv ...

The CEPA, an Evolutionary Algorithm that preserves diversity by finding clusters in the population, has had its convergence performance improved by a technique tentatively called ‘evolutionary operator selection’. Performance is compared to results found in the literature, though at the moment it is not entirely clear how the evolutionary operator selection mechanisms work. The resulting algorithm has been applied to a number of problems - including a hybrid vehicle configuration and coke production in Shan

An improved two-phase flow pattern map is proposed for evaporation in horizontal tubes. The new map was developed based on flow pattern data for five different refrigerants covering a wide range of mass velocities and vapor qualities. The new map is valid for both adiabatic and diabatic (evaporating) flows and accurately identifies about 96% of the 702 data points. In addition, the new flow pattern map includes the prediciton of the onset of dryout at the top of the tube during evaporation inside horizontal

Dans un contexte de concurrence et de préoccupations environnementales accrues, la prise en compte des facteurs économiques et environnementaux de façon simultanée et dès les premières phases de conception des systèmes énergétiques pourrait devenir un facteur majeur de compétitivité et/ou d’aide aux décideurs. Le présent article illustre la faisabilité d’une nouvelle méthodologie holistique de conception appliquée à des centrales thermiques avec ou sans cogénération dans une gamme de puissance supérieure à

A complex heating and cogeneration plant including two 3.9 MWth ammonia heat pumps and two 3 MWel gas turbines with heat recovery boilers and three strage tanks has been in operation since 1986. This paper is a result of an expreimental evaluation during the eleventh season of heating. Energy balances throughout the season are discussed as well as the performances of one fully equipped heat pump. Results confirm the interest of this type of technology combination even if the performance of the heat pump exh

This paper presents a study of a residential (about 20kW) ORC-ORC (Organic Rankine Cycle) thermally driven heat pump. The system works with three different temperature levels similar to absorption heat pumps. The proposed concept is a hermetic system using ...

A planar solid oxide fuel cell repeating unit, 50 cm2 in total active electrode size, consisting of an anode supported electrolyte cell bearing two 7 mm holes for fuel and air injection, and contacted to two dense metal current collector plates ...

Apparatus for salt separation (2) under supercritical water conditions, comprising a heat exchanger (4) and a fluidized bed reactor (6). The fluidized bed reactor comprising a supercritical water pressure containing wall (8) defining therein a fluidized be ...

Two-phase flow pattern data were obtained with 12.0 mm bore sight glasses for five refrigerants: R-123, R-134a, R-502, R-402A and R-404A. The existing flow pattern maps of Taitel-Dukler and Hashizume poorly represented the data while the VDI map identified the flow pattern rather successfully, with the exception of mist flows. Methods used in horizontal flow boiling correlations to determine the threshold between all wet wall and partially wet wall flow were shown to be very unreliable.

Intube flow boiling experiments for two new zeotropic refrigerant mixtures and R-502 have been carried out at three saturation temperatures over a wide range of local vapor qualities. The zeotropic mixtures tested were HP80 and HP62. Local flow boiling coefficients for HP62 are slightly larger than those for R-502 under the same test conditions while those for HP80 are slightly smaller. The heat transfer performances of the three fluids are generally quite accurately predicted by an existing flow boiling co

A new heat transfer model for intube flow boiling in horizontal plain tubes is proposed that incorporates the effects of local two-phase flow patterns, flow stratification and partial dryout in annular flow. Significantly, the local peak in the heat transfer coefficient versus vapor quality can now be determined from the prediction of the location of onset of partial dryout in annular flow. The new method accurately predicts a large, new database of flow boiling data, and is perticularly better than existin

A multicriteria decision support system has been developed to evaluate alternatives for sustainable and integrated energy centres for rural development in the Mediterranean area. The search for the most suitable solution for a fixed site is a complex problem, due to the variety of the plausible alternatives, the changing points of view and the diversity of the different interest groups that are responsible for the choice. By using a participative approach, combining optimisation and multicriteria methods an

Simulation of a pure-solar combined-cycle solar thermal power was performed in order to analyse the thermodynamic and economic performance. An open volumetric receiver and packed-bed storage concept was considered. For a 15 MWe power plant, an exergetic ef ...

Subtile alliance de haute technologie et d’empirisme, le concept de rozière a démontré toute son efficacité pendant le vol autour du monde. Deux modifications majeures ont été réalisées entre les ballons Orbiter 2 et 3. Soulevons un coin du voile.

Numerous degrees of freedom are often available for the heat integration of batch processes. Usually, only few of these are actually considered and optimized. Time slice-dependant Tmin have been investigated and optimized using a supertargeting procedure originally developed for multiple base case design. The trade-off direct indirect heat exchanges has also been studied and tools for the preliminary assessment of the heat storage system are proposed. Further improvements are being considered for both t

A method of optimising the thermodynamic and economic performance of heliostat field within a solar tower thermal power plant has been developed. The method includes the generation of a heliostat field given a set of design variables, the assessment of its ...

Daniel Favrat

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Intube Flow Boiling of R–502 and Two Near-Azeotropic Alternatives.

The effect of bias in gas temperature measurements on the control of a Solid Oxide Fuel Cells system

R–502 and Two Near-Azeotropic Alternatives. Part I: Intube Flow Boiling Tests.

Network synthesis for district heating with multiple heat plants

Can steam play a role in low to medium power from low temperature heat?

A Fast Multi-Objective Evolutionary Algorithm applied to Industrial Problems

Flow Boiling in Horizontal Tubes. Part 1; Development of a Diabatic Two–Phase Flow Pattern Map

Optimisation thermo-économique et environomique de nouvelles centrales de production d’électricité à cycles combinés

Performances of 3.9 MWTH Ammonia Heat Pumps within a District Heating Cogeneration Power Plant: Status After Eleven Years of Operation.

Low power ORC-ORC systems for heat pump applications

Local current measurement in a solid oxide fuel cell repeat element

Apparatus for salt separation under supercritical water conditions

Two-Phase Flow Patterns for New Refrigerants Inside Horizontal Tubes.

Boiling of Two Zeotrope Mixtures and R–502 Inside a Plain Horizontal Tube.

Flow Boiling in Horizontal Tubes. Part 3; Development of a New Heat Transfer Model Based on Flow Pattern

Multicriteria Decision Support System Applied to Sustainable and Integrated Energy Centres for Rural Development in the Mediterranean Area

Evaluation of a combined-cycle setup for Solar Tower Power Plants

Piccard et Jones. Tout sur leur réussite. Les dessous de la rozière.

Improving Pinch Analysis based heat integration of single & multi-product batch plants

Thermo-economic Optimisation of the Heliostat Field of Solar Tower Thermal Power Plants