Question

A brine solution is heated from 10°C to 35°C in a one-shell-pass (hot water) two-tube- pass (brine) heat exchanger. The hot water enters at 60°C and exits at 45°C. The water flow rate is 0.30 kg/s and the overall heat transfer coefficient is U = 950 W/m2 · °C. What heat exchanger area is required?

Answer 1

The area of heat exchanger
`A=0.00218\ m^2`

Step-by-step explanation:

Given that

Brine heated from 10°C to 35°C and water cools from 60°C to 45°C.

`U=950\ (W)/(m^2K)`

Lets take these are act as counter flow heat exchanger.

So

`\Delta T_1=35^(\circ)C,\Delta T_2=25^(\circ)C`

As we know that

`Q=m_wC_p\Delta T_w=U* A* LMTD`

Here

`LMTD=(\Delta T_1-\Delta T_2)/(\ln (\Delta T_1)/(\Delta T_2))`

`LMTD=(35-25)/(\ln (35)/(25))`

LMTD=29.7°C.

`m_wC_p\Delta T_w=U* A* LMTD`

`C_p=4.187(KJ)/(kg.K)` for water

0.3 x 4.187 x 15 = 950 x A x 29.7

`A=0.00218\ m^2`

So the area of heat exchanger
`A=0.00218\ m^2`