This article presents equations for air-side friction and heat transfer characteristics for bare tube air-to refrigerant heat exchangers with tube diameters ranging from 0.5 mm to 2 mm. There are no air-side correlations for such small diameter tubes in the literature. Furthermore, conventional empirical correlation development relies on testing of samples, which is inherently time consuming, expensive and has a limited range of applicability. The correlations presented in this article are developed based on comprehensive CFD simulations for a large design space and include experimental validation. The proposed correlations predict more than 80% of source data within 10% error and more than 90% of the source data within 20% error. The proposed correlations are valid for 2-40 rows of tubes. (C) 2016 Elsevier Ltd. All rights reserved.