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The research effort on the Coil Designer tool was aimed at developing a generalized simulation and optimization tool for design of air-cooled coils or microchannel heat exchangers. The tool is featured with:
- User-friendly interface
- Flexibility for circuitry design
- Multiple independent streams
- Variety of refrigerants that are available in NIST Refprop 7.0 and AWMix 1.0
- Non-uniform air distribution/fin spacing
- Built-in or user-provided correlations for heat transfer coefficient and pressure drop on both the refrigerant side and air side
The refrigerant flow circuitry can be accomplished by connecting the tube ends at the front side and rear side of the coil. A segment-by-segment approach within each tube is adopted to increase the accuracy of the simulation results. The GUI allows non-uniform air distribution by assigning individual temperature, velocity and humidity value to each segment of the frontal face area of the coil. Dehumidification issues can be handled. The calculated refrigerant and air properties at each segment can be exported to a spreadsheet.
Validation of this tool is in progress. The deviation of the simulated heat duty, outlet air temperature/humidity has been found to be within 5-10% from the experimental data of water coils and micro channel CO2 heat exchangers.
Heat exchanger design involves a set of independent design variables with discrete nature and non-analytical solution space. Genetic Optimization Algorithm is implemented and integrated with the simulation tool as an effective optimization scheme. The performance objectives of heat capacity, exchange effectiveness, pump power, and fan power, together with cost, space, are met by optimizing the coil configuration, geometric sizes, tube circuiting, and flow rates of the air and refrigerants.
Via modeling, validation, and optimization, the tool intends to reduce the amount of prototyping and enhance productivity in heat exchanger design.
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