Say there's a torture technique that hangs people by metal chains (gruesome, I know; stay with me) and the room slowly heats at a steady rate. (Like boiling a frog in an increasingly hot pot of water.) The rate of the temperature increase can either be controlled automatically or by a dial in case the torturer wants to draw out the pain or kill the victim quickly. The room slowly increases in heat until the person dies.
What kind of changes would the human body undergo? Would the outside flesh char and burn before the person became unconscious or died? Can the human body combust into flames by heated air alone, or does it need something to ignite it? In this scenario, what effect would the chains have on this person?