Numerical investigation of subsonic steam injection in subcooled water pool is carried out to understand flow and heat transfer phenomenon during its various phases. Physical phenomena of bubble elongation, its necking, detachment and collapse are successfully captured. Bubble cycle frequency and heat transfer coefficient during these phases of the bubble evolution are determined and compared with the experimental data reported in literature. Heat transfer coefficient obtained from the simulation compared well with the experimental results for the bubble elongation phase. The pressure variations due to the oscillatory behavior of the bubble are also captured and compared with the literature data. Subsequently, the effect of water bulk sub-cooling is studied and it is found that the bubble cycle frequency decreases with decreasing sub-cooling levels. This is attributed due to the reduced interfacial heat transfer at lower water subcooling.