Why a Fan Cools You, Not the Room - evaporation & boundary layers

A 75 W heater that makes you feel cold, and the invisible blanket it rips off.

Before you start. You need one idea from earlier in this site: cooling never needs a source of cold, only heat leaving fast enough, which is why a fridge’s refrigerant boils to soak up heat instead of pumping in something cold (Cold Is a Lie - fridge, AC, heat pump). You also need one number about yourself: sitting still, your body already makes about 100 watts of heat - a watt is just energy leaving every second, so that’s 100 joules gone every second - roughly a bright light bulb’s worth, and it never stops.

The script in Try it needs a Python library, CoolProp (pip3 install CoolProp). You do not need it: the muggy-night lab on this page runs the same balance with two sliders.