Heat transfer measurements and correlation of refrigerant flow boiling in tube filled with copper foam

• Flow boiling heat transfer in tube filled with low PPI metal foam was investigated.
• Metal foam promotes the transition from stratified flow to stratified-wavy flow.
• Metal foam also promotes the transition from stratified-wavy flow to annular flow.
• Metal foam enhances the flow boiling heat transfer by a maximum of 220%.
• A heat transfer correlation with good accuracy was proposed.

Flow boiling heat transfer characteristics of refrigerant in tubes filled with metal foams were experimentally investigated at a saturation temperature of 7 °C, mass flux from 10 to 90 kg m−2 s−1, vapor quality from 0.1 to 0.8 and heat flux from 3.1 to 18.3 kW m−2. The refrigerant is R410A. The test sections are tubes with inner diameter of 23.4 or 13.8 mm, filled with 5 or 10 PPI copper foam. The experimental results reveal that, metal foam enhances the flow boiling heat transfer by a maximum of 220% and promotes the flow pattern transition from stratified flow to stratified-wavy flow and from stratified-wavy flow to annular flow. The heat transfer coefficient decreases with vapor quality under low mass flux, while it increases with vapor quality under high mass flux. A correlation for predicting the flow boiling heat transfer was developed and it agrees well with the experimental data.