Question

ASSIGNMENT 1 BMM35131920/1 QUESTION 3 [10 Marks] a) Briefly discuss the following terms in heat transfer: i. Blackbody ii. Absorptivity iii. Convection iv. Specific heat v. Thermal conductivity (5 Marks) b) An industrial galvanized pipe (Figure Q3) that carries SiO2 nanofluid as cooling liquid passes through a factory in which the air is at 27°C. The outside diameter of the pipe is 75 mm, and its surface temperature and emissivity are 200 °C and 0.8, respectively. If the coefficient associated with free convection heat transfer from the surface to the air is 16 W/m².K, what is the rate of heat loss from the pipe surface per unit length of pipe? (o = 5.67x10 ) (5 Marks) Nanofluid Coolant Figure Q3

Answer 1

@ @ Black body :- © Black body is the body which absorbs all the thermal radiations incident upon it Ex: Son is treated as black body Absorptivity:- fraction of radiation energy incident upon a surface which is absorbed by it, known as absorptivity of that surface Convection :- when heat is transferred from one body to another by virtue of bulk motion, then mode of heat transfer is called oy convection Specific heat :- The amount heat required to raise the temperature of body by one unit is known as specific heat of that body C Thermal conductivity The thermophysical property of material that tells about the ability of material to allow the heat energy to get conducted through the material is known as Thermal conductivity Given Ts = 200°c, € - 0 8 h To = 27°C, do = 75 mm, = 5.67X108 surface to air by 2 modes; Heat will be transferred from convection & 2) Radiation : - Q.conu + Qrod - hx As x (Ts-Too) + tu (TS" - Too") As = 16x(TTX 75 ML) (200 – 27) + 0.8 x 5.67 X168 X(T X75XL) *C (200+27334-(27+273)") 1000 - 652-195 + 448.399 1 - 1100.594 Wim