A parallel fiow heat exchanger has its tubes of 5cm internal and 6cm external diameter. The air flows inside the tubes and receives heat from hot gases circulated in the annular spoce of the tube at the rate of 100kW. Inside and outside heat transfer coefficients are 250W/m2K and 400W/m2K respectively. inlet temperature of hot gases is 500C, outlet temperature of hot gases is 300C, inlet temperature of air 50C, Exit temperature of air 140C. Calculate : a) Overall heat transfer coefficient based on outer surface area b) Length of the tube required to affect the heat transfer rates. Neglect the thermal resistance of the tube. c) If each tube is 3m length find the number of tubes required. GivenData:Do=6cmDi=5cmQ=100kWhi=250W/m2Kho=400W/m2Kthi=500Ctho=300Ctci=50Ctco=140CTobeCalculated:a)Uo=?b)l=?c)N=?tfl=3m