Heat and Mass Transfer

Lecture $20$

$\frac{07}{12}\frac{?}{2022}$

Chapter $11$: Heat Exchangers Design Approach: Examples

Example: A dairy operation milk at $250li\frac{t}{h}r$ and temperature of $38\mathrm{.}6$ C must be chilled to a temperature of $13C$ or less. Groundwater at $10C$ is available at $0\mathrm{.}72\frac{m^3}{h}r$ and density of $1030k\frac{g}{m^3},cp=3860\frac{J}{k}g$ K respectively. Find:

UA of counter flow HE required for the chilling process

Determine outlet water temperature

For water: density is $1000k\frac{g}{m^3}$ and $cp=4187\frac{J}{k}gK$

Using U$/$A find out the outlet milk temperature if the water flow is $1\mathrm{.}44\frac{m^3}{h}r.$ What is the milk temperature if the water flow is $0\mathrm{.}36\frac{m^3}{h}r.$