Salt hydrates such as sodium bicarbonate decahydride are use

Salt hydrates such as sodium bicarbonate decahydride are used to store energy harvested from solar or wind alternative energy sources. The process involves capturing the energy in the latent heat of melting (solid to liquid) and the re-releasing it to a steam/electric generation cycle. If the mass density is 1.50 g/cm^3 and the latent heat of melting is 3.60 times 10^2 MJ/m^3, what is the latent heat of melting in units of Btu/lbm?

Solution

Latent heat of melting is given to be L =3.6 * 10^2 MJ/m^3 and the mass density is 1.5 g/cm^3

Latent heat of melting per unit mass is L = 3.6 * 10^8 /(1.5 * 1000) J/kg

===> Latent heat of melting per unit mass is L = 240 kJ/kg

We have 1 Btu = 1055.06 J and 1 lbm = 0.453592 kg

Thus we have

Latent heat of melting per unit mass is L = 240 * 1000 kJ/kg * (0.453592 kg/lbm) * (1 Btu/1.05506 kJ)

===> Latent heat of melting per unit mass = 103.181 * 10^3 Btu/lbm