Calculate Heat Transfer To Crystallizer

Question

An aqueous solution of sodium acetate (20.0 mol% NaC₂H₃O₂) flows at a rate of 100 kg/h into an evaporative crystallizer at 60°C. When the solution is exposed to the low pressure in the evaporator 16.9% of the water evaporates, concentrating the remaining solution and causing crystals of sodium acetate trihydrate (NaC₂H₃O₂^.3H₂O) to form. The product is an equilibrium mixture of crystals and a saturated aqueous solution containing 15.4 mol% NaC2H3O2. The effluents (crystals, solution, and water vapor) are all at 50°C.

Estimate the rate at which heat must be transferred to or from the crystallizer (state which), using the following physical property data:

C_{p, all solutions} = 3.5 kJ/(kg °C)

C_{p, crystals} = 1.2 kJ/(kg °C)

C_{p, H2O(v)} = 32.4 kJ/(kmol °C)

ΔĤ_v,H2O = 4.39 x 10⁴ kJ/kmol

Heat of solution of anhydrous sodium acetate: ΔĤ_s(25 °C) = -1.71 x 10⁴ kJ/kmol NaC₂H₃O₂

Heat of Hydration: NaC₂H₃O₂(s) + 3 H₂O (l) à NaC₂H₃O₂^.3H₂O (s) ΔĤ(25 °C) = -3.66 x 10⁴ kJ/kmol NaC₂H₃O₂

Summary

The question belongs to Chemistry and it discusses about calculating the rate at which heat must be transferred to or from the crystallizer. This has been discussed in the solution detail.

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