The effect of airflow on the heat transfer of the air-to-refrigerant airfoil heat exchanger was experimentally investigated. The average Nusselt number for air was estimated using wind tunnel experiments and an inverse heat transfer method. The correlations of the Nusselt number for air by use of the Reynolds or Mach number for air were estimated for an airfoil with a chord length of 44 mm at a refrigerant mass flow rate of 7.2 g/s. Furthermore, the correlation of the ratio of the average temperature difference to the logarithmic mean temperature difference was also obtained.