ENHANCING HEAT TRANSFER IN HEAT EXCHNAGERS BY UTILIZING METAL ORGANIC FRAMEWORKS (MOFS)

Abstract

Nanofluids in heat transfer applications have received enormous attention for their ability to enhance a systems performance and efficiency. Many nanoparticles have been utilized in heat exchangers to determine their influence on a system, except for ZIF-8 and ZIF-67. Metal organic frameworks (MOFs) are a class of nanoparticles that have porous 1D, 2D, or 3D structures created by coordinating rigid organic molecules with crystalline compounds composed of metal ions. A type of MOF that has good physical properties are zeolitic imidazolate frameworks (ZIFs) that has two types that are ZIF-8 and ZIF-67. In this study, ZIF-8 and ZIF-67 are examined in a plate and shell & tube heat exchanger setup to determine whether their performance is better than pure water. The study of ZIFs in heat transfer applications is limited and has never been done in these types of heat exchangers. The ZIFs are produced through a one-step method and stabilized utilizing tween-80 in a ratio of 1:1.06. In addition, the stability was investigated due to their hydrophobicity and it was observed that at high concentrations the nanofluid was more likely to agglomerate as observed in many analysis techniques such as zeta size, rheology, etc. ZIFs were also characterized to understand their properties and ensure that the particles were in accordance with literature. The nanofluids were optimized through Box-Behnken design and a concentration lower than 0.15 wt% had the best outcomes. Therefore, in the experimental analysis, ZIF-8 was observed to outperform ZIF-67 and water with its superior physical properties and stability. In addition, the enhancement of heat transfer was much more impressive in shell & tube heat exchangers in comparison to plate heat exchangers due to the Reynolds number attained.