INVESTIGATING HEAT TRANSFER ENHANCEMENT USING METAL FOAM IN DOUBLE-TUBE HEAT EXCHANGERS EXPERIMENTAL APPROACH

An experimental study is conducted to investigate the effect of adding metal-foam (MF) blocks into the annular region of a double-tube heat exchanger. The experiments were performed for different volume flow rates, from 25 to 50 LPH using hot and cold water as the working fluid. Hot water and cold water are maintained at 65 and 31 degrees C, respectively. Nickel metal foam with 10 pores per inch (PPI) and 0.9 porosity is fitted in the annular space. The primary objective of this research is to assess the impact of metal foam on key parameters such as heat transfer coefficient, effectiveness, pressure drop, and friction drop by comparing it with a conventional double-tube heat exchanger. Results demonstrate that the incorporation of metal foam leads to a significant improvement in effectiveness and efficiency, and as a consequence, the overall heat transfer coefficient values are 2.2 times compared to a conventional heat exchanger. However, this enhancement in heat transfer comes at the cost of increased pressure drop across the metal-foam heat exchanger. Following a comprehensive performance evaluation, the study reveals that the metal-foam heat exchanger exhibits a significant enhancement in heat transfer capability per unit pressure drop, showcasing a twofold increase compared to conventional heat exchangers. Additionally, the experimental results are compared with established correlations from existing literature. Overall, this research contributes to the ongoing efforts to advance solar thermal technologies by providing empirical evidence of the effectiveness of metal foam in enhancing heat transfer within flat-plate collectors. The findings offer valuable insights for the design and optimization of solar energy systems aimed at maximizing energy conversion efficiency and sustainability.