Isothermal box for refrigerated vehicle

Isothermal box (100) substantially parallelepiped-shaped, comprising a lower wall (102), an upper wall (103), two side walls (102), a rear wall (105) and a front wall (104), said front wall (104) being adapted to support a refrigerating unit connected to a refrigerated air intake orifice (110) and an air suction orifice (111), said orifices (110) and (111) being formed in said front surface (104). Said isothermal box (100) further comprises at least one refrigerating diffusion device (1) adapted to be fixed to the underside of said upper wall (103) comprising a convergent nozzle (10), a first guide profile (35A) and a second guide profile (35A), the first guide profile (35A) and the second guide profile (35B) being parallel to one another and arranged at a distance from one another, the first guide profile (35A) and the second guide profile (35B) being positioned in the extension of said convergent nozzle (10), to guide the refrigerated air flow along the longitudinal axis of said isothermal box (100).