Effect of migrating condensate drop mode on tube bundle heat transfer performance

A condenser is an essential Organic Rankine Cycle (ORC) component. The effect of the condenser tube bundle has an important influence on the working efficiency of the condenser during actual operation. Therefore, it is of great guiding significance to study the impact of the tube bundle effect on condensation heat transfer characteristics of heat exchangers. In this paper, the condensation heat transfer performance of the heat exchanger with a triangular tube bundle in the ORC system is studied after the tube bundle rotates 20°. The difference in condensation heat transfer between the condensate from the top row of the tube dripping centrically (corresponding to before rotation) and eccentrically (corresponding to after rotation) to the bottom row of the tube is compared and analyzed. The experimental results show that the heat transfer coefficient outside the tube of each heat exchange tube decreases with the increase of heat flux. The heat transfer coefficient outside the tube increases with the rise of condensation temperature. Compared with the lower-row tube with centering drop, the external heat transfer coefficient of the lower-row tube with eccentric drop is 3%-6% higher. The tube bundle effect coefficient under the two dripping modes decreases with the increase of heat flux and finally tends to be flat. The range of centering drop’s tube bundle effect coefficient is 0.84-0.97. The range of eccentric drop’s tube bundle effect coefficient is 0.87-0.98. Therefore, the eccentric dripping method can weaken the heat transfer effect of the lower exhaust tube due to the increase in heat flux. It shows that the regular triangle arrangement after 20° rotation can improve the heat transfer performance of the condenser.