Objective CREUSOT-LOIRE AND THE UNIVERSITY OF COMPIEGNE ARE OPTIMIZING THE PERFORMANCE OF A HEAT EXCHANGER IN AN EXTERNAL TYPE CIRCULATING FLUIDIZED BED COMBUSTOR. IN SUCH A FLUIDIZED BED GAS VELOCITIES ARE HIGHER THAN NORMAL, RESULTING IN HIGHER HEAT TRANSFER COEFFICIENTS. ANOTHER MAJOR ADVANTAGE IS THE POSSIBILITY OF INSTALLING THE HEAT EXCHANGER IN THE UPPER PART OF THE COMBUSTOR, WHERE NO COMBUSTION TAKES PLACE, THUS SEPARATING HEAT TRANSFER FROM COMBUSTION. TESTS WERE CARRIED OUT IN A CIRCULATING FLUIDIZED BED SCALE MODEL AND A 50 CM (DIAMETER) PILOT BED. SUBJECTS OF THE INVESTIGATION ARE : - THE INFLUENCE OF THE OVERALL GEOMETRICAL CONFIGURATION OF THE HEAT TRANSFER SURFACE ON THE PATTERN OF SOLID FLOW AND ON THE HEAT TRANSFER COEFFICIENT; -THE INFLUENCE OF THE TUBE SHAPE AND THE GEOMETRY OF FINNED TUBE SURFACES (LONGITUDINAL OR SPIRAL FINS). AN EQUATION TO PREDICT THE INFLUENCE OF SOLID CONCENTRATION ON THE HEAT TRANSFER COEFFICIENT (HTC) (BETWEEN THE GAS-SOLID SUSPENSION AND THE WALL) WAS ESTABLISHED. IT WAS SHOWN THAT THE HTE WAS HIGHER WHEN THE SOLIDS USED WERE FINER. AN INCREASE IN THE NUMBER OF FINS DOES NOT IMPROVE THE COEFFICIENT OF EXCHANGE AS EXPECTED. IN FACT, INTRODUCING FINS ON TUBES ALLOWS AN INCREASE OF CONTACT SURFACE BUT THE HTE PER UNIT OF EXCHANGE DECREASES RAPIDLY WHEN THE FIN PITCH IS REDUCED AND WHEN THEIR HEIGHT INCREASES. INTRODUCTION OF FINS IS MORE EFFICIENT WHEN THE AMOUNT OF SOLIDS IS SMALLER. PERFORATED FINS ARE PREFERABLE SINCE THEY PROVIDE A SMALLER DECREASE OF PARTICLE MOVEMENT AND A SMALLER DECREASE OF THEIR CONCENTRATION IN THE SPACE BETWEEN THE FINS. FURTHERMORE, FROM AN ECONOMIC POINT OF VIEW, IT IS NOT JUSTIFIED TO HAVE A TUBE WITH MORE THAN TWO FINS PER TUBE. Programme(s) PRE-ENNONUC 2C - Energy research and development programme (EEC), 1979-1983 Topic(s) Data not available Call for proposal Data not available Funding Scheme Data not available Coordinator Creusot Loire Industrie SA EU contribution No data Address 71208 Le Creusot France See on map Total cost No data Participants (1) Sort alphabetically Sort by EU Contribution Expand all Collapse all Université de Technologie de Compiègne France EU contribution No data Address 60206 Compiègne See on map Total cost No data
