ICMM2004 -xxxx CONSTRUCTAL NETWORKS FOR EFFICIENT COOLING/HEATING

ABSTRACT Channel networks designed with constructal theory are compared. The efficiency of the networks when used for cooling a uniformly heated surface is compared. Three networks are compared and it is found that the two constructal designs with two and three constructal levels have similar performance. It is shown that for a given pumping power, the constructal designs give a heat transfer coefficient of the surface which is almost a factor of magnitude higher than the one obtained for a parallel channel system

Etude et optimisaton de la distribution du fluide dans un echangeur de chaleur a plaques

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : TD 80477 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Condensation of pure and mixture of hydrocarbons in a compact heat exchanger: Experiments and modelling

International audienceThis article presents a study on heat transfer in condensation of pure and mixtures of hydrocarbons in a compact welded plate heat exchanger. Three pure fluids (pentane, butane, and propane) and two mixtures (butane + propane) have been used. The operating pressure ranges from 1.5 to 18 bar. For pure fluids, two heat transfer mechanisms have been identified. For low Reynolds numbers, the condensation occurs almost filmwise and the heat transfer coefficient decreases with increasing Reynolds number. For higher values of the Reynolds number, the heat transfer coefficient increases gently. The transition between the two regimes is between Re = 100 and 1,000 and depends on the operating conditions. For mixtures, the behavior is different. For low Reynolds numbers, mass transfer affects heat transfer and reduces the heat transfer coefficient by a factor of up to 4. Correlations for filmwise and in-tube condensation do not predict the results accurately, and a specific correlation is proposed for pure fluid condensation. For mixtures, the condensation curve method does not allow mass transfer effects to be taken into account, and more work is required to establish an accurate predictive model

Advanced sustainable energy technologies for cooling and heating applications

SUMMARY Multi-energy sources, for heating and cooling purposes, are considered to have a large potential in contributing to the penetration of renewable energy sources for domestic, building and industrial applications. But it requires that conventional heating and cooling systems have to be adapted or changed for incorporating renewable energy sources. Nowadays, the heating, ventilating and air-conditioning industries are the actors which have access to the market, and they provide services using mainly fossil fuels or electricity as energy sources. The objective is to have them using renewable energy, combining conventional and renewable sources and proposing environmental cost-effective products. The technical goal of this project is to set-up technology resource centres in Europe, with the aim of building bridges between the technology providers (research centres, universities and industry) and the technology users (manufacturers, engineering companies…). The project outputs are: • Creation of the clubs/grouping • Collection of RTD results • Development of design tools for evaluating and sizing the new technologies • Best practice and training programme • Creation of a knowledge resource centre relying on multi language search engines based on craft ontologies and terminologies • International collaboration with China For this 13 partners are collaborating to this project. The consortium is composed of centres of excellence in the area of renewable energies, energy agencies and professional associations representing industry

Micro Thermal Systems In France: From Knowledge To Technological Development

International audienceThis paper presents an overview of the research activities performed in France, and presents more precisely the work carried out by the “microthermique” group in Grenoble (“Micro thermal exchanges”), which is composed of 5 teams. Examples of fundamentals and applied research projects on micro-channel heat exchangers and systems are presented

Condensation of pure hydrocarbons and their mixture in a compact welded heat exchanger

International audienceThis article presents a study on heat transfer in condensation of pure and mixtures of hydrocarbons in a compact welded plate heat exchanger. Three pure fluids (pentane, butane, and propane) and two mixtures (butane + propane) have been used. The operating pressure ranges from 1.5 to 18 bar. For pure fluids, two heat transfer mechanisms have been identified. For low Reynolds numbers, the condensation occurs almost filmwise and the heat transfer coefficient decreases with increasing Reynolds number. For higher values of the Reynolds number, the heat transfer coefficient increases gently. The transition between the two regimes is between Re = 100 and 1,000 and depends on the operating conditions. For mixtures, the behavior is different. For low Reynolds numbers, mass transfer affects heat transfer and reduces the heat transfer coefficient by a factor of up to 4. Correlations for filmwise and in-tube condensation do not predict the results accurately, and a specific correlation is proposed for pure fluid condensation. For mixtures, the condensation curve method does not allow mass transfer effects to be taken into account, and more work is required to establish an accurate predictive model

Effects of geometrical and thermophysical parameters on heat transfer measurements in small diameter channels

International audienceAn experimental investigation of the liquid flow friction factor and heat transfer coefficient in small diameter channels is presented. Rectangular and circular mini-channels with hydraulic diameters from 0.77 to 2.01 mm were used. Literature in the 1990s showed scattered experimental results and concluded that new physical phenomena in mini-channels could occur. However, the present experimental results show that three main causes can explain how different results were obtained in mini-channels compared to macro-tubes: uncertainties on the channel dimensions, inlet and outlet singular pressure losses, and longitudinal heat conduction. When these elements are taken into account, good agreement is found with standard correlations or theories