The portable table fan that I use at my home and office is the Geek Aire Rechargeable Table Fan - 16 Inch (Black).
Some of the features of this Mini table fan are:
RECHARGEABLE: Driven by 15600mAh large Lithium-ion battery with 3 - 24 hrs (varied by speed setting) standby timer covers your whole day without electricity support. Average charging time of 3 - 4 hours proving to be best portable fan for outdoor use.
HIGH VELOCITY FAN WITH 120° VERTICAL TILT: The battery powered outdoor fan possesses an adjustable 360°tilt head providing widespread coverage. Unique 16 inch metal fan blade design, Built with brushless DC motor, max 2000 CFM high performance airflow perfect for camping travel and home use.
VARIABLE SPEED CONTROL & LED BATTERY INDICATOR: Step less speed control, Radiant Red light LED battery gauge indicator, which can tell battery life, help you ration the battery life however you want and avoid any nasty surprises.
IDEAL FOR OUTDOOR USE: Modern style, high-tech look, Large carrying portable design is perfect for home, outdoors, camping, and sporting scenarios. Built-in USB port for re-charging smart phones or other digital devices you may need.
WORRY FREE SAFETY: Geek Aire 16 inch Outdoor portable fan is built to IPX4 water resistant, 24V power charger, Equipped with metal frame and anti-slip rubber feet to ensure safety.
This is one of the best portable table fans that I've ever used and I recommend you all to check out this product!