Parallel flow evaporator with louver fins for roof top bus air conditioner was designed to replace the fin-and-tube evaporators. The capacity of parallel flow evaporator was simulated and the fin parameters were optimized by the established simulation model. Two sets of samples were experimentally investigated to verify the simulation results. The experiment results show that little condensate water was seen during the experiments

and the evaporator with 4 flow paths is of better homogeneity in refrigerant distribution and 11.2% higher in heat transfer than that with 8 flow paths. The newly designed evaporator is 38% lighter

57.6% less volume and 10.5% less refrigerant charge than the traditional fin-and-tube evaporator

and almost solved the two serious problems of the application of parallel flow evaporator in bus

i.e.

the removal of condensate water and the uniform distribution of two-phase-flow refrigerant

which indicates that the newly designed evaporator has reached the requirement of industry and can be used to replace the traditional fin-and-tube evaporator.