Abstract
• Heat transfer intensification of heat exchanger can be achieved using nanofluids. • The effect of using nanofluids on heat exchangers performance is reviewed. • Different nanofluids employed in heat exchangers are studied. • The impacts of using nanofluids with other enhancement systems are introduced. • Nanofluids improve the effectiveness of different types of heat exchangers. Heat exchangers are widely utilized in different thermal systems for diverse industrial aspects. The selection of HEx depends on the thermal efficiency, operating load, size, flexibility in operation, compatibility with working fluids, better temperature and flow controls, and comparatively low capital and maintenance costs. Heat transfer intensification of heat exchangers can be fulfilled using passive, active, or combined approaches. Utilizing nanofluids as working fluids for heat exchangers have evolved recently. The performance of heat exchangers employed different nanofluids depends mainly on the characteristics and improvement of thermophysical properties. Regarding the unique behavior of different nanofluids, researchers have attended noteworthy progress. The current study reviews and summarizes the recent implementations carried out on utilizing nanofluids in different types of heat exchangers, including plate heat exchangers, double-pipe heat exchangers, shell and tube heat exchangers, and cross-flow heat exchangers. The results showed that nanofluids with enhanced thermal conductivity, although accompanied by a considerable decrease in the heat capacity and raising viscosity, has resulted in performance enhancement of different heat exchangers types. So, the performance evaluation criterion that combines the thermal enhancement and increases the pumping power for any type of heat exchangers is requisite to evaluate the overall performance properly. The challenges and opportunities for future work of heat transfer and fluid flow for different types of heat exchangers utilizing nanofluids are discussed and presented.
Highlights
Nowadays, the rapid progress in thermal technologies for different heat exchangers (HExs) applications, associated with power-saving and intensification of heat transfer, is a critical issue for scientists
The results revealed that applying an external magnetic field intensified the heat transfer up to 320% with an inconsiderable pressure drop increase, which was attributed to the generated swirling flow disrupted the thermal boundary layer and improved the inside flow mixing of the HEx, as shown in Fig. 9 Alternatively, Singh and Sarkar proposed a novel enhancing technique in a double-pipe heat exchangers (DPHExs) using wire coil turbulator and Al2O3ÀMgO/water hybrid NF for turbulent flow [96]
The impact of utilizing different nanoparticles of Al2O3, CuO, SiO2, and ZnO with different thermophysical properties at various ’ of 1 - 4 vol.% dispersed into different base fluids such as water, ethylene glycol, and engine oil on the performance of the shell and helically coiled tube HEx (SHCTHEx) was numerically investigated by Narrein and Mohammed [130]
Summary
The rapid progress in thermal technologies for different heat exchangers (HExs) applications, associated with power-saving and intensification of heat transfer, is a critical issue for scientists. Nanofluids (NFs), as formed by dispersing nanoparticle (NPs) to conventional heat transfer fluids, i.e., base fluids (BF), have higher thermal conductivity compared and high intensity of the thermal performance, should be employed to achieve the thermal engineering requirements in various application such as water desalination, heat storage, heat exchangers [19À24]. This is in return provides a very promising approach to increase the energy efficiency in many applications at lower environmental impacts [25]. The challenges and future work for the intensification of heat transfer and fluid flow for different types of HExs utilizing NFs are thoroughly discussed and presented
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