Nanofluids for heat transfer: an engineering approach

Table 1 Systems engineering approach to nanofluid design.

	ENGINEERING PARAMETERS	Nanoparticle material	Nanoparticle concentration	Nanoparticle shape	Nanoparticle size	Base fluid	Zeta potential/fluid pH	Kapitza resistance	Additives	Temperature
NANOFLUID PROPERTIES
Stability	⇑	▲	▲	▲	■↓	○	■	x	■	?
Density	⇑	■	■↑	x	x	■	x	x	x	x
Specific Heat	⇑	■	■↓	x	x	■	x	x	x	▲
Thermal Conductivity	⇑	○	■↑	○	■↑	▲	○	■↓	▲	○
Viscosity	⇓	▲	■↓	■	■↓	■↑	■	x	○	■
Heat Transfer Coefficient	⇑	■	■↑*	■	■↑	■	■	■↓	○	■
Pumping Power Penalty	⇓	x	■	■	■↑	■	■	x	○	■
Relative Importance		4.0	6.25	3.75	5.0	5.25	4.0	2.0	2.75	3.75

Symbols:
■- strong dependence; ○- medium dependence; ▲- weak dependence; x - no dependence; ? - unknown or varies from system to system; ⇑ - larger the better;⇓ - smaller the better; ↑- increase with increase in parameter; ↓- decrease with increase in parameter; *-within the linear property increase.