B. Mathematical model included in the design calculation
1) Thermal equilibrium formula
c fw o mf w j w ma o Q = K F (t −t ) =α (t − t )F (1)
Where: fw k is heat transfer coefficient from cooled fluid to
water film, W/m2·K; o F is heat transfer area between fluid
inside tubes and water film outside tubes,m2 ; mf t is
logarithmic even temperature of cooled fluid, , ℃; ma t is
logarithmic even temperature of air, ℃; j
α convective heat
transfer coefficient between water film and air, W/m2·K; w t is
water film’s temperature, ℃.