Influence of fully miscible lubrication oil on flow boiling of CO₂ inside horizontal evaporator tubes

Flow boiling heat transfer, pressure drop and flow pattern of CO₂-POE oil mixtures were experimentally investigated in smooth and micro-fin tubes. The POE oil used features full miscibility in the range of operation investigated. The experimental data was evaluated based on mixture properties, used to evaluate and improve established predictive methods. The knowledge obtained contributes to understanding the influence of oil, which is essential for achieving an efficient evaporator design.