To investigate the convective heat transfer characteristics in the dispersed flow region downstream of the quenching front during the reflooding stage of a Large Loss-of-Coolant Accident (LOCA) in rectangular narrow gap channels between plate-type fuels. This study employs numerical simulation methods by utilizing the Discrete Phase Model (DPM) to simulate droplets stripped and carried downstream by the steam entrainment effect in the quenching front region. The study focuses on the convective heat transfer performance in rectangular narrow gap channels under the condition of a normal distribution of droplet diameters. By altering relevant boundary conditions, the impacts of different droplets in various distribution scenarios on convective heat transfer within the narrow gap channels are analyzed. The relevant results can provide a basis for ensuring the safe and stable operation of reactors.