Mango pulp initially 25°C and 70% wet-basis moisture is dried to 10% wet basis using95°C air. Water latent heat at 95°C is 2250 kJ/kg and pulp cp3.8 kJ/(kg·°C). Find drying energy per kg initial pulp in kJ, to one decimal.
On a 1 kg initial basis, dry solids are.30 kg. Final product mass is $.30/(1-.10)=.333333$ kg and final water is .033333 kg. Evaporated water is $.70-.033333=.666667$ kg. Heat the original pulp from 25 to 95°C: $Q_s=1(3.8)(70)=266$ kJ. Evaporation adds $.666667(2250)=1500$ kJ. Total is **1766.0 kJ/kg initial pulp**,ignoring losses as the simplified heat balance assumes.
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