Recent Advances in Heat Transfer Enhancements: A Review Report

Table 4

Estimated the highest recorded heat transfer enhancement level due to each enhancer.

Heat Transfer Enhancer Type	(Heattransferduepresenceoftheenhancer)Heattransferinabsenceoftheenhancer
Fins inside tubes	2.0, [37]
Microfins inside tubes	4.0 for laminar, [70]
	1.4 for turbulent, [70]
Porous media	≈12.0(𝑘eff/𝑘𝑓), [78]
Nanofluids	3.5, [10]
Flexible seals	2.0, [151]
Flexible complex seals	3.0, [153]
Vortex generators	2.5, [157]
Protrusions	2.0, [165, 166]
Ultra high thermal conductivity composite materials	6, [167]