This study involves the mathematical modelling and experimental verification of a heat exchanger accumulator. The study was initiated with a literature survey which, according to the authors, revealed that there was no published material that described how heat exchanger accumulators are designed to ensure that they are correctly sized according to the operating system and conditions. The heat exchange process that takes place within the heat accumulator was studied and a mathematical model of a heat exchanger accumulator developed. This model was used to develop a universal design procedure that correctly sized the heat exchanger accumulator according to the operating system into which it was to be installed. The model was then verified by conducting experimental tests and it was concluded that the model could be used to successfully design and implement heat exchanger accumulators into small commercially available air conditioning systems. Copyright (C) 2001 John Wiley & Sons, Ltd.