1. A method for optimizing and controlling properties of nanoparticles, wherein the properties comprises a mean particle size and a specific surface area of the nanoparticles for a scale up of nanoparticle production in an aerosol flame reactor integrated with process instruments, wherein the method comprises: determining: a) operating data for physical process parameters of a precursor or a reactant from the process instruments; b) mixing characteristics of the precursor or the reactant at a particular concentration and a stream input fed to a burner of the aerosol flame reactor; c) a flame temperature and different species mass-fractions throughout the aerosol flame reactor using a flame dynamics model coupled to a continuous particle population balance module, wherein the coupling between the flame dynamics model and the continuous particle population balance module is achieved by solving particle balance equations in each and every cell of a computational domain/flame structure; and d) data for showing influence of the burner and a design of the aerosol flame reactor on the properties of the nanoparticles; feeding the operating data, the mixing characteristics of the precursor, the flame temperature, and the determined data to a simulation tool with programmed instructions to obtain simulated data; feeding the simulated data to the continuous population balance module to obtain the mean particle size and the specific surface area of the nanoparticles by the solving of the particle balance equations in the each and every cell of the computational domain/flame structure; and processing the mean particle size and the specific surface area of the nanoparticles for optimizing and controlling the mean particle size and the specific surface area and for the scale up of the nanoparticle production in the aerosol flame reactor.