In current years, the warmth switch enhancement developed with the aid of the usage of nanofluid. A nanofluid is a kind of fluid that organized by means of dispraised of nanoparticles of metal, oxides or carbides with 100 nm size that depressed in water, ethylene glycol or oil. The enhancement of warmness transfer overall performance through expending nanofluid primarily relies upon on the type of nanoparticles, kind of base fluid, form of nanoparticles, size of nanoparticles and nanoparticles attention in the base fluid. In this paper, several newly massive numbers of studied have been being provided to discover the nanofluid enhancement the warmth switch charge in several heat exchangers kinds such as double-pipe warmth exchangers, plate heat exchangers, cross-flow warmth exchangers and shell and tube warmth exchangers. In existing review article, it presents quite a few experimental and numerical research studies that investigated the impact of using nanoparticles in the single and hybrid nanofluids to acquire greater overall performance of enhancement of warmness switch in the double pipe warmness exchangers conferring to relative route of movement of fluids (Parallel flow and Counter flow) and the nature of warmth trade process. The current study showed that there is a wide use of nanofluids in double pipe heat exchangers in all dimensions. Where the comparison showed that the use of nanofluids, whether inside the inner tube or in the annular tube of the heat exchanger, will effectively lead to heat transfer, reduce the size of the heat exchanger and reduce the cost of manufacturing and materials


Nanofluids, Nanoparticles, Hybrid Nanofluids, Double-Pipe Heat Exchangers