1. The problem statement, all variables and given/known data (I) Explain what is meant by an 'overall heat transfer coefficient'. (II) Explain what is meant by fouling and what its effect will be on the value of the overall heat transfer coefficient. 2. Relevant equations None provided. 3. The attempt at a solution (I) The overall heat transfer coefficient (U) refers to the ‘overall’ heat transfer either by conduction or convection through a series of materials/layers. This is expressed by the equation: Q = UA(T_2-T_1) (II)Fouling references the formation of impurities; solidified process liquids and corrosion on surfaces over time. This extra layer of resistance has an adverse effect to the overall heat transfer coefficient. In some instances this newly formed fouling layer can become the largest resistance to heat transfer. The above seem to be very short answers, but, they seem to answer the questions directly. Any advise ? I don't want to write volumes if not necessary.