Air is heated in a duct as it flows over resistance wires. consider a 20 kw electric heating system. air enters the heating section at 100 kpa and 15°c with a volumetric flow rate of 140 m/min. if heat is lost from air in the duct to the surroundings at a rate of 150 w, determine (a) the exit temperature (72) of air and (b) the energetic efficiency (ou). use the pg model for air and neglect the power consumed by the fan. (c) draw an energy flow diagram for the system.

Ahot wire operates at a temperature of 200°c while the air temperature is 20°c. the hot wire element is a tungsten wire of 5 um diameter and 2 mm in length. plot using excel current, heat transfer and heat generated by the wire for air velocity varying from 1-10 m/s in steps of lm/s? matlab the sensor voltage output, resistance, or assume nu 0.989 re033pr13 take air properties at tr (200°c20°c)/2 = 110°c properties of tungsten: c 0.13 kj/kg.k 3 p 19250 kg/m k (thermal conductivity) = 174 w/m.k