<Dd> U f (\ displaystyle U_ (f)) = overall heat transfer coefficient for a fouled heat exchanger, W m 2 K (\ displaystyle (\ frac (W) (m ^ (2) K))) </Dd> <Dd> P (\ displaystyle P) = perimeter of the heat exchanger, may be either the hot or cold side perimeter however, it must be the same perimeter on both sides of the equation, m (\ displaystyle m) </Dd> <Dd> U (\ displaystyle U) = overall heat transfer coefficient for an unfouled heat exchanger, W m 2 K (\ displaystyle (\ frac (W) (m ^ (2) K))) </Dd> <Dd> R f C (\ displaystyle R_ (fC)) = fouling resistance on the cold side of the heat exchanger, m 2 K W (\ displaystyle (\ frac (m ^ (2) K) (W))) </Dd>

What are the influences of mass flow rate on the coefficient of heat transmission