Investigating subcooled flow boiling heat transfer and fluid dynamics within a shell-and-plate heat exchanger

Abstract

The study experimentally investigates subcooled flow boiling in a single channel of a shell-and-plate heat exchanger. Experiments on single-phase and boiling heat transfer were conducted under varying mass flux (61.442 to 199.326 kg/m2·s), preheating (20 to 42℃), and heating temperatures (30 to 60℃), using the refrigerant R365mfc. Key findings include that microscale boiling is the dominant heat transfer mechanism, with macroscale boiling occurring at high mass flux and preheating temperatures. The boiling heat transfer coefficient and friction pressure drop increase with mass flux, while optimal heat transfer occurs with an inlet subcooling of 4–6 °C. Flow patterns—bubbly, bubbly-slug, and churn flows—were identified, with bubbly flow offering superior heat transfer performance at the cost of higher pressure drop. The prediction model for friction pressure drop and heat transfer coefficient, using the Weber and boiling numbers, shows a prediction error within ±20 % of experimental data.