Question

Consider the springtime melting of ice in the mountains, which gives cold water running in a river at 2°C while the air temperature is 20°C. What is the availability of the water relative to the temperature of the ambient?

Answer 1

ψ = h1 - h0 - T0(s1 - s0)

flow availability from Eq.

Approximate both states as saturated liquid from

ψ = 8.392 - 83.96 - 293.15(0.03044 - 0.2966) = 2.457 kJ/kg

Why is it positive? As the water is brought to 20°C it can be heated with qL from a heat engine using qH from atmosphere TH = T0 thus giving out work.