The ever-increasing need for more rational use of energy has led modern industry to include more energy-efficient technologies. As such, compact heat exchangers are ideally suited for condensers in the process industry. However, their proper introduction in the distillation processes means re-designing both the equipment and the processes. To improve the design of heat exchangers, there is a need to understand the fundamental issues of thermal and mechanical behaviour of this equipment with process fluids. For this reason, this project carried out a number of tests concerning the operation of heat exchangers using various pure and mixed hydrocarbons. There were in total, five sets of tests performed. Three included pure fluids, such as pentane, butane and propane while two included different mixtures of fluids, such as butane-propane mixtures. In addition, the tests involved total condensation under actual flow conditions for both downward and reflux condensers. The project resulted in an in-depth investigation of the basic mechanisms of heat and mass transfer in an idealised compact geometry. The acquired thermal performances of a compact heat exchanger during condensation on a large range of operating conditions are representative of industrial working conditions. Particularly, the local measurements of heat transfer are quite useful in establishing a predictive model for the reflux condensation process. Similarly, the new model developed on pure fluid and mixture condensation in a compact heat exchanger is expected to further the application of compact heat exchangers in the process industries.