Heat transfer characteristics of CO₂ condensation on common heat exchanger materials: Method development and experimental results

Understanding condensation of CO₂ is essential for e.g designing compact heat exchangers or processes involved in Carbon Capture and Storage. However, a consistent experimental campaign for condensation of CO₂ on common materials is lacking. In this work, we present an experimental method and an associated laboratory setup for measuring the heat transfer properties of CO₂ condensation on materials commonly used in heat exchangers for the liquefaction of CO₂. We have investigated the heat transfer during CO₂ condensation on copper, aluminum, stainless steel (316) to reveal the heat transfer dependency on surface properties. The experiments are conducted at three saturation pressures, 10, 15, and 20 bar and at substrate subcooling between 0 and 5K. The results show that the heat transfer coefficients decrease with increasing surface subcooling. It was also found that increasing the saturation pressure increases the heat transfer coefficient. The results indicate that surface roughness and surface energy affect the condensation heat transfer coefficient, and an increased roughness results in reduced heat transfer coefficients. The highest heat transfer coefficient is found for condensation on copper, for which the lowest surface roughness has been measured.