Across-flow air-to-water heat exchanger (both fluids unmixed) with an effectiveness of 0.65 is used to heat water (cp 4180 j/kg. k) with hot air (c 1010 j/kg. k). water enters the heat exchanger at 20°c at a rate of 4 kg/s, while air enters at 100 c at a rate of 9 kg/s. if the overall heat transfer coefficient based on the water side is 260 w/m2.k, determine the heat transfer surface area of the heat exchanger.

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