Spray plays an important role in many engineering and industrial processes. Therefore, it is important to investigate the heat transfer rate of particles in an environment with a wide spectrum of vortical structures resembling turbulent eddies. The interaction between these vortical structures and spherical particles significantly influences the heat transfer rate of particles and their life time. In the present study, transient heat transfer of a spherical particle interacting with random vortexes in an incompressible and viscous flow has been studied using numerical solution of the Navier-Stokes and energy equations at Re=100 by the developed computational algorithm. In order to ensure the accuracy of the calculation, the results are compared with numerical data available in literature, where good agreements were observed. The influential vortex domain around the particle was first identified with simulating two similar vortexes based on their impact on the Nusselt number. Then, using this domain of influence, effects of the number of random vortexes with different structures and positions on the heat transfer rate of the particle were considered. It was found that only 4 or 5 vortexes can well predict the influences of a vortical domain with larger number of vortexes on the heat transfer rate of a particle. The results also indicate that for 4 or more vortexes the Nu varies in a limited range of that for the case with no vortex flow. Furthermore, increasing vortexes sizes, leads to the higher heat transfer rates.