In what direction does heat flow?Why do particles of matter transfer thermal energy in the direction?

Answer 1

Heat flows from warmer objects to cooler ones. That direction is spontaneous because the thermal entropy of the system is maximized when quanta of heat move from warmer to cooler objects.

Answer 2

Go research the concept of 'entropy'.

Basically states that highly organized systems (or highly energetic systems) will naturally progress to a lower organizational or energy level.