CYRANO - A COMPUTATIONAL MODEL FOR THE DETAILED DESIGN OF PLATE-FIN-AND-TUBE HEAT-EXCHANGERS USING PURE AND MIXED REFRIGERANTS

A computational model for the detailed design of finned coils has been developed. This programme discretises heat exchangers into tube eleme nts for which the governing equations are solved using local values of temperature, pressure, physical properties and heat transfer coeffici ents. Single-phase, condenser and evaporator cases can be automaticall y treated using water, R22, R134a, and refrigerant mixtures based on R 32, R125, and R134a. The software can handle non-conventional coil cir cuits with different numbers of inlets and outlets, non-uniform air di stribution at the coil inlet face, using smooth, wavy and louvered fin s, and smooth and internally finned tubes. The programme has been vali dated on seven finned coils using pure fluids, with and without moistu re condensation on the fins. Comparisons with tests show errors of les s than 5% on the coil duty and of the order of 30% on the refrigerant pressure drop. A performance simulation of a coil using R22 and a tern ary mixture is presented to validate the programme algorithms develope d for mixtures. (C) 1997 Elsevier Science Ltd and IIR.