A double-pipe, counter flow heat exchanger (co-axial inner and outer tubes with

Question

A double-pipe, counter flow heat exchanger (co-axial inner and outer tubes with hot fluid flowing through the inner tube and cooling fluid in the outer tube flowing in the opposite direction) is used to cool hot oil (specific heat = 1.9 kJ/kg.K) entering the exchanger at 165 oC and 1.8 kg/sec by water (specific heat = 4.2 kJ/kg.K) entering the exchanger at 15 oC and 1.2 kg/sec. The cooling water leaves the exchanger at 88 oC. a) Calculate the rate of heat exchange between oil and water streams b) Calculate the exit temperature of oil flow.

Explanation / Answer

Let rate of heat flow be Q`, mass flow rate =m`, Cp,c=Specific Heat for water, Tw,e= T water exit,

Tw,i= T water inlet

Q` =mw` Cp,c (Tw,e-Tw,i)= 1.2 kg/s * 4.187 kJ/kg.K * (88-15) =366.78 kJ/s

Now, Energy Balance:

mw` Cp,c (Tw,e-Tw,i)=moil` Cp,oil (Toil,i-Toil,e)

=> 1.2 * 4.187 * 73 = 1.8 * 1.9 * (165 -Toil,e)

=>107.24=165-Toil,e => Toil,e=57.75

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.