Thermally-induced recirculation of printing fluid

A non-transitory computer-readable storage medium having computer executable instructions stored thereon to operate a printing fluid delivery system to recirculate printing fluid to a printing fluid applicator, the instructions are executable by a processor to:

• transport printing fluid between a reservoir and a printing fluid applicator through a conduit system;
• heat a first conduit segment of the conduit system by a first heating module;
• and
• increase a temperature of the printing fluid in the first conduit segment to a first temperature which is greater than a second temperature of the printing fluid in a second conduit segment of the conduit system to thermally induce recirculation of the printing fluid from the printing fluid applicator through the conduit system and back to the printing fluid applicator, and to maintain the printing fluid in the printing fluid applicator within a target temperature range.