In the realm of microscale electronic cooling systems, enhancing the thermal efficiency of working fluids has emerged as a pivotal area of research, addressing the inadequacies of traditional cooling systems in managing the heat generated by increasingly compact and powerful electronics. Introducing nanoparticles into working fluids has been recognized as a transformative approach to augmenting their thermal properties. Nanodiamonds, particularly with their exceptional material properties, including high thermal conductivity, have garnered significant interest for their potential in nanofluid heat transfer applications. This study delves into the effects of diamond nanoparticles on the thermal properties of working fluids, tailored explicitly for microscale heat transfer. It further investigates how incorporating a nozzle can amplify the fluid's random motion, thereby enhancing the heat transfer coefficient at the microscale. A specialized experimental setup was developed to assess the influence of the nozzle-shaped connector on the heat transfer coefficient of diamond nanofluids within a microchannel. The research examines the enhancement of heat transfer in relation to the Reynolds number and compares it to that of deionized water. Results showed that the addition of a nozzle-shaped connector greatly enhances the heat transfer coefficient in the second microchannel for both deionized water and deionized water-nanodiamond nanofluid.