Experiments were conducted to study the condensation heat transfer and pressure drop characteristics of refrigerant R32 in aluminum herringbone tubes

ripple tubes

and smooth tubes. The experimental refrigerant mass flow rate is 100-350 kg/(m2·s). The saturation temperature is 308 K

313 K

and 318 K

respectively

while the vapor quality is 0.2-0.8. The experimental results show that the herringbone tube has the highest coefficient of heat transfer

followed by the ripple tube

while the smooth tube is the worst. The friction pressure drop is highest for the ripple tube

and the pressure drop of the herringbone tube is higher than that of the smooth tube. The surface coefficient of heat transfer and friction pressure drop decrease with an increasing saturation temperature and increase with an increasing mass flow rate. The performance evaluation factor

PEF

was introduced to evaluate the heat transfer performance of the heat transfer tube. The herringbone tube has the best heat transfer performance with PEF values ranging from 2.07 to 2.72

while the ripple tube has PEF values ranging from 0.68 to 0.90. A new heat transfer correlation was proposed following the form of classical heat transfer correlations

and the error of the new correlation formula was within ±20%.