The ornamental design for a heatdissipationdevice, as shown and described.
FIG. 1 is a perspective view of a heat dissipation device of our new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 shows the heat dissipation device of FIG. 1 having fans mounted thereon, wherein the fans are shown for illustrative purpose only and form no part of the claimed design.