Ji Song

SIMULATION-BASED DESIGN METHOD FOR ROOM AIR CONDITIONER WITH SMALLER DIAMETER COPPER TUBES

Promoting the use of smaller diameter tube in room air conditioner is beneficial to reduce copper consumption and refrigerant charge, but may cause reduction of air conditioner performance, so a design method is needed. This paper presents a simulation-based design method for air conditioner with smaller diameter tube. The new method combines heat exchanger simulator and knowledge-based evolution method optimizer for designing air conditioner heat exchanger with smaller diameter tube. The simulation-based design method is illustrated in detail by an air conditioner of replacing 7 mm tube indoor unit heat exchanger and 9.52 mm tube outdoor unit heat exchanger with 5 mm tube. Case study shows that the cost of the designed air conditioner with 5 mm copper tube is 17.3% lower than that of the original one while the performance deviation between these two air conditioners is less than 0.7%.

Fin design for an evaporator with small diameter microgroove tubes

The application of fin-and-tube heat exchangers with small diameter microgroove tubes in room air conditioners has rapidly increased recently, and fins suitable for such heat exchangers should be developed. In the present study, a louver fin suitable for the evaporator with small diameter microgroove tubes was designed by applying computational fluid dynamics method, and the performance of the optimized and existing louver fins were experimentally investigated. Experimental results show that water bridge occurs at the bottom of the optimized fins for small diameter tubes, which is not the same as that for larger diameter tubes; for the fins of the evaporator with small diameter tubes, the increase of the fin pitch leads to the decrease of Colburn j factors. Based on the experimental data, a correlation of the Colburn j factor was developed to predict the heat transfer rate of the evaporator with small diameter microgroove tubes, and agrees with 85% of the experimental data within a deviation of ±20%.