A waste heat recovery unit is an energy recovery heat exchanger that transfers heat from process outputs at high temperature to another part of the process for some purpose, usually increased efficiency.
PROMETHEAN ENERGY builds unique waste heat recovery solutions for industrial and commercial applications. Over 50% of total input to any industrial or commercial unit is released as waste energy - we don't even realize the sources of waste energy in many cases.
Source : http://www.prometheanenergy.com/