A comparative thermodynamic study has been carried out on R22-E181 and R134a-E181 working pairs for a vapour compression-absorption system for simultaneous heating and cooling applications. The results are obtained for a system that can be used, for example, in a dairy plant for pasteurization and chilling of milk for subsequent storage. Results show that R134a-E181 working pair gives better performance at lower solution concentration and hence at lower system capacity. At higher solution concentration and higher system capacity R22-E181 working pair is marginally better than R134a-E181 working pair. The performance trends obtained from experimental studies on a compression-absorption system working with R22-E181 are found to agree with the theoretical results, even though the actual COP is much lower than the theoretically predicted value. (c) 2006 Elsevier Ltd. All rights reserved.