NOMENCLATURE

Q = heat loss rate, W

Ø = volume fraction

K = Thermal Conductivity, W/m∙K

h = Convective heat transfer coefficient, W/m2∙K

T = Temperature, K

c = specific heat capacity, J/kg∙K

Î = effectiveness

Nu = Nusselt Number

C = heat capacity, J/K∙s

Pr = Prandtl Number

m = mass flow rate, kg/s

U = overall heat transfer coefficient, W/m2∙K

r2 = inner diameter of spiral tube, m

r1 = outer diameter of spiral tube, m

d = average diameter of tube, m

A1 = inner surface area of spiral tube, m2

A2 = outer surface area of spiral tube, m2

L = Length of the tube, m

Re = Reynolds Number

NTU = Numbers of Transfer Units

μ = Viscosity, m2/s

ρ = Density, kg/m3

Subscripts

a = air

w = water

p = nanoparticle

f = fluid

i = inlet

o = outlet

m = mean

t = spiral tube

min = minimum

max = maximum