Enhancement of Thermal Performance of Counter Flow Double Pipe Heat Exchanger by Inserting Wavy-Edged Tape

This study involved numerical simulations of a double tube heat exchanger using the ANSYS FLUENT program version 22. The study aims to examine methods for minimizing pressure loss and consequently enhancing the thermal performance index (TPI) of a heat exchanger fitted with wavy edge tape that is a heat recovery system (the hot air in simulation instead of t heat from the exhaust gases of the brick factory furnaces and return it to warm the heavy fuel oil by substituting the electrical heater with a heat exchanger to recuperate waste heat from the flue gases, so elevating the temperature of Heavy fuel oil (HFO) to inject from the roof nozzles of combustion chamber of the furnace furthermore reducing cost (by finding the optimal design of wavy edge tape)) and energy consumption. Air was selected as the hot gas in the inner pipe instead of furnace exhaust gases due to their similar thermal characteristics. A numerical analysis was conducted to create a novel wavy edge tape with varying widths (50% Di, 75% Di, and 95% Di), lengths (1000, 1200, 1400) mm, amplitudes (5, 10, 15) mm, and periods of wavy length (5, 10, 15) mm. The flow rate of the outer pipe fluid (oil) ranges from (0.06 to 0.1) kg/s, while the velocity of the hot fluid (air) varies from (1 to 27) m/s, Reair (6957 to 187,837). The entrance temperature of the hot fluid can be either (200, 225, and 250)°C. The study finds that wavy edge tape tubes are more effective than smooth tubes in terms of oil outlet temperature; results revealed that an increase in the oil mass flow rate leads to a decrease in the oil outlet temperature and an increase in the heat transfer rate, at the air temperature 250°C. Additionally, the results indicate that increasing the width, length, and amplitude also leads to an increase in the oil outlet temperature of (94–94.12)°C, the pressure drop of (568.3) Pa, and the Nusselt number (65.7–66.5) respectively on the oil side. Finally, the heat exchanger’s best thermal performance index was found by investigating temperature contour at amplitude (A = 5), period (p = 15), width (w = 75% Di), and length (L = 1200 mm). The values for these parameters are, in order (1.02, 1.025, 1.02, and 1.0077).