Water enters at 20 ℃ at a rate of 0.1 kg/s in a double-pipe counter flow heat exchanger is to be heated by hot air that enters the heat exchanger at 90 ℃ at a rate of 0.3 kg/s. The overall heat...

Water enters at 20 ℃ at a rate of 0.1 kg/s in a double-pipe counter flow heat exchanger is to be heated by hot air that enters the heat exchanger at 90 ℃ at a rate of 0.3 kg/s. The overall heat transfer coefficient based on the inner side of the tube to be 100 W/m2. ℃. The length of the tube is 14 m and the internal diameter of the tube is 1.4 cm. Determine the outlet temperature of the water. The specific heats of the water and air are given to be 4.18 and 1.01 kJ/kg.℃, respectively. Select one: a. 32.7 ℃ b. 30.5 ℃ c. 24.3 ℃ d. 28.8 ℃

Extracted text: Water enters at 20 °C at a rate of 0.1 kg/s in a double-pipe counter flow heat exchanger is to be heated by hot air that enters the heat exchanger at 90 °C at a rate of 0.3 kg/s. The overall heat transfer coefficient based on the inner side of the tube to be 100 W/m2. °C. The length of the tube is 14 m and the internal diameter of the tube is 1.4 cm. Determine the outlet temperature of the water. The specific heats of the water and air are given to be 4.18 and 1.01 kJ/ kg.°C, respectively.