Saturated vapor is condensed to saturated liquid in a condenser. The heat capacity ratio is $C_r = \displaystyle{\frac{C_{min}}{C_{max}}}$. The effectiveness ($\varepsilon$) of the condenser is
1. $\displaystyle{\frac{1-exp[-NTU(1+C_r)]}{1+C_r}}$
2. $\displaystyle{\frac{1-exp[-NTU(1-C_r)]}{1-C_rexp[-NTU(1-C_r)]}}$
3. $\displaystyle{\frac{NTU}{1+NTU}}$
4. $1-exp(-NTU)$