Question

In a counter flow heat exchanger, hot fluid has heat capacity of 2kJ/kgk, mass flow rate 5kg/s, inlet temperature ${150}^{\circ }C$ and outlet temperature ${20}^{\circ }C$. Assuming heat transfer to take place in. an adiabatic chamber, the outlet temperature of the cold fluid is

• A. ${26.25}^{\circ }C$
• B. ${20}^{\circ }C$
• C. ${70}^{\circ }C$
• D. ${32.5}^{\circ }C$

Answer 1

The correct option is D ${32.5}^{\circ }C$


From energy balance
$Q_{hot}=Q_{cold}$
$m_h.C_h.(T_{hi}-T_{ho})=m_c.C_c.(T_{\infty }-T_{ci})$
$5\times 2\times (150-100)=10\times 4\times (T_{\infty }-20)$
$T_{co}={32.5}^{\circ }$