A systematic analysis of the dispersion characteristics of a selectively liquid-filled dual-core PCF by varying different geometrical parameters towards achieving ultra negative dispersion values around a desired wavelength has been carried out. The dependence of PCF parameters along with the infiltrating liquid upon dispersion has been investigated. Our analysis establishes that with the increase of Λ, the total dispersion is red-shifted with a reduction of the negative dispersion. Again, the dispersion is red-shifted but with an increment of negative dispersion and narrower FWHM for an increase of d. In contrary to the above dependence of Λ and d, with an increase of n_L, the dispersion gets blue-shifted with an increase of negative dispersion at the cost of reduced FWHM. Our numerical study establishes a high negative dispersion of −52,100 ps/nm/km around 1550 nm through an optimized design. Three such designs of selectively liquid filled dual-core PCF demonstrating a negative dispersion from −28,700 ps/nm/km to −52,100 ps/nm/km around the wavelength of 1550 nm with available practical liquids have been presented to demonstrate the effectiveness of the method. Our optimized structures demonstrate excellent tunable properties with temperatures for various optical communication systems based devices. Our proposed PCF will be an excellent candidate for dispersion compensation in long-haul data transmission as being thousand times more than the available DCFs. Our approach of dispersion engineering will be helpful for dispersion engineering related applications like true time delay instruments, Raman amplifier, ASE suppression, Four-wave mixing etc.