(Solved): 18:57 5G 474 EAE3701-Assessment 2 Questio... Done ASSESSMENT 2 EAE3701 2022_2 Question 1 Consider a ...
18:57 5G 474 EAE3701-Assessment 2 Questio... Done ASSESSMENT 2 EAE3701 2022_2 Question 1 Consider a house with a floor space of 200 m 2 and an average height of 3 m at sea level, where the standard atmospheric pressure is 101.3 kPa . Initially the house is at a uniform temperature of
13\deg C. Now the electric heater is turned on, and the heater runs until the air temperature in the house rises to an average value of
21\deg C. Determine how much heat is absorbed by the air assuming some air escapes through the cracks as the heated air in the house expands at constant pressure. Also, determine the cost of this heat if the unit cost of electricity in that area is R0.095/kWh. (
C_(p)=1.005k(J)/(k)g\deg C,R=0.287kPa.m3.kg.K,1kWh
=3600kJ) Question 2 An aluminium pan whose thermal conductivity is
237(W)/(m)*\deg Chas a flat bottom whose diameter is 20 cm and thickness 0.6 cm . Heat is transferred steadily to boiling water in the pan through its bottom at a rate of 750 W . If the inner surface of the bottom of the pan is
108\deg C, determine the temperature of the outer surface of the bottom of the pan [4] Question 3 Determine the maximum rate of thermal radiation that can be emitted by a surface that is at the following uniform temperatures (
\sigma =5.67\times 10^(-8)(W)/(m^(2)).K^(4)): (a) 300 K [2] (b) 600 K . [2] Question 4 Solar radiation is incident on a semi-transparent body at a rate of
900(W)/(m^(2)). If
150(W)/(m^(2))of this incident radiation is reflected back and
225(W)/(m^(2))is transmitted across the body, determine the absorptivity of the body [4] Total (20) @ Unisa 2022 Page 1 of 1
