Heat Transfer Enhancement in a Cross-Flow Heat Exchanger with Modified Air Angles of Attack

The technique of heat transfer enhancement of a nonfin cross-flow heat exchanger by a modified air angle of attack is investigated experimentally in this study. Six air angles of attack (i.e.,0 degrees, 30 degrees, 60 degrees, 90 degrees, 120 degrees, and 150 degrees) with the same perimeter are examined to determine their relationships to the overall heat transfer coefficient and the pressure drop; the heat exchanger performance are also tested. In the experiment, hot water (at a temperature of 75 degrees C) with a constant flow rate and air at ambient conditions with various velocities (ranging from 2 to 7m/s) flows through the heat exchanger. The results indicate that the modified air angle of attack technique can enhance the overall heat transfer coefficient; however, the pressure drop is also increased.