Experimental and numerical study on heat transfer characteristics of three-row slotted fins with small diameters

Heat transfer and fluid flow characteristics on the air side in three-row slotted fin-and-tube heat transfer surfaces with small diameters applied in a trans-critical CO₂ air-conditioning or refrigeration cycle are studied experimentally and numerically. All the numerical results are in agreement with the related test data within 10% deviation. Besides, influences of a slotted inclination angle on heat transfer are analyzed with four different methods. It is found that the slotted inclination angle could enhance heat transfer with more evident pressure drop.