Bonjour,

J'ai un examen bientôt en transfert de chaleur et ai du mal sur cet exercice,

Quelqu'un aurait t'il la gentillesse de m'aider ?

Merci infiniment,

Victoire

Water flows at 2 m s-1 through a 2.5 m length of a 25 mm diameter tube. The tube is at 320 K and
the water enters and leaves at 293 K and 295 K respectively. Taking the density of water to be 1000
kg m-3 and the specific heat capacity to be 4.18 kJ kg-1 K-1, find:

(a) The heat transfer rate Q
(b) The log mean temperature difference.
(c) The overall heat transfer coefficient.
(d) An estimate may be made of the inside heat transfer coefficient (h) from:
h = 4280(0.00488T - 1)u^0.8 / d^0.2

Where T , the mean temperature of water, is 294 K, u is the mean velocity of the flow (m s-1) and d
is the diameter of the tube (m). From this, calculate the internal heat transfer coefficient and the
thermal resistance of the scale (fouling factor) between the tube and the water inside the tube.

(e) How would the outlet temperature change if the velocity was increased by 50%? Assume a mean
water temperature of 300 K.