Q3 a) A rectangular duct with width of 0.3 m and height of 0.2 m is used to deliver cold fresh air to a medium size master bedroom. Heat from roof causes the internal surface temperature of the duct to be 40°C. The fresh cold air enters the duct at 17°C and exits at 23°C. Given the volumetric flow rate of the fresh cold air which enters the duct is 0.15 m/s, assuming the flow inside the duct is fully developed: i) State two assumptions for analyzing this problem ii) Calculate the Reynolds number for the flow inside the duct iii) Calculate the heat transfer rate to the fresh cold air inside the duct, kW iv) What is the minimum length of the duct to keep the exit temperature at 23°C, m b) Will the exit temperature remain the same which is at 23°C, if the length of the duct is increased 5 times of the length calculated in iv)? Explain and sketch a temperature variation along the length of the duct to justify your answer.

Q3 a) A rectangular duct with width of 0.3 m and height of 0.2 m is used to deliver cold fresh air to a medium size master bedroom. Heat from roof causes the internal surface temperature of the duct to be 40°C. The fresh cold air enters the duct at 17°C and exits at 23°C. Given the volumetric flow rate of the fresh cold air which enters the duct is 0.15 m/s, assuming the flow inside the duct is fully developed: i) State two assumptions for analyzing this problem ii) Calculate the Reynolds number for the flow inside the duct iii) Calculate the heat transfer rate to the fresh cold air inside the duct, kW iv) What is the minimum length of the duct to keep the exit temperature at 23°C, m b) Will the exit temperature remain the same which is at 23°C, if the length of the duct is increased 5 times of the length calculated in iv)? Explain and sketch a temperature variation along the length of the duct to justify your answer.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

See similar textbooks

Similar questions

consider a flow of water in a cylinder maintained at constant temperature of hundred degree Celsius the diameter of the cylinder is 15 and the length of the tube is 6 metre the inlet and outlet temperature of the water is TI equal to 15 degree Celsius and equal 57 degrees celsius find the average heat transfer Coefficient associated with the flow of water mass flow rate is 2.25 kilogram per second and cp=4.178KJ/aKg.K
An electric generator at a power plant produces energy by passing superheated steam from a high temperature container (reservoir), through a pipe connected to a series of fans, and then into a low temperature reservoir. As the steam passes across the blades of the fans some of the heat energy of the steam is transformed into mechanical energy, which turns the fans which in turn are connected to a generator, which in turn converts the mechanical energy into electrical energy. If the high temperature steam has a temperature of 436.7 K and the low temperature reservoir has a temperature of 106.7 K, what is the Carnot efficiency of this process?
Water (cp=4.182 kJ/kg.K, k=0.6405 W/m.K, Pr=3.57, ν=0.5537x10-6 m2/s, ρ=998 kg/m3) flows through a tube (D=0.5 cm) with an average velocity of 0.2 m/s. The average temperatures of the water at the inlet and outlet cross-sections are 26,03 oC and 86,92 oC, respectively. The uniform heat flux of 0,82 W/cm2 is subjected to the surface of the tube for heating process. Determine the tube length [m].
Q2) Air at 20°C flows over a flat plate having a uniform heat flux of 800 W/m². The flow velocity is 4m/s and the length of the plate is 1.2 m. Determine the value of heat transfer coefficient and also the temperature of the plate as the air leaves the plate.
Shown in the figure,a card is cooled with water. To cool the cardWater 0.4 m / s in the circular pipe system placed on the bottomaverage speed and entering at a temperature of 20 oC, at a temperature of 24 oCcomes out. Electronic components on the board of 1.5 kWthey produce energy. At the same time, from the card surface to the mediumApproximately 0.05 kW of heat loss occurs by convection. Continuous flowFind the mass flow rate of the water for the conditions. Specific heat of waterYou can get = 4.22 as ?? / ???.
Moist air at 20°C dry-bulb and 8°C thermodynamic wet-bulb temperature is to be processed to a final dew-point temperature of 13°C by adiabatic injection of saturated steam at 110°C. The rate of dry airflow is 2 kg/s. Find the final dry-bulb temperature of the moist air and the rate of steam flow.
Q 2- The Nusselt number for flow in a tube is given by Nu = C₁ Rea Prb where the constants, C1, a, and b are 0.023, 0.8, and 0.3, respectively. Estimate a mass-transfer coefficient for moist air flowing in a 30 cm tube with a diameter of 10 cm at the rate of 0.3 m3/s. Assume standard air, Prandtl number is 0.7 and unity Lewis number.
7.120
An air duct heater with an electric heating element in an industrial plant is used. 12 m/s velocity perpendicular to the elements from above to the atmospheric air heater and enters at 27 oC. In the duct heater, each row consists of 3 pipes in the flow direction. It consists of 4 rows. In this air duct heater any two pipes The distance between the centers is 22 mm. Each element in the heater is 12 mm outside diameter, 220 mm length and a uniform surface temperature of 330 oC. Air duct Find the heat transfer rate in the heater and the temperature of the air leaving the heater.
Consider a 10-m-long smooth rectangular tube, with a = 50 mm and b= 25 mm, that is maintained at a constant surface temperature. Liquid water enters the tube at 20°C with a mass flow rate of 0.027 kg/s. Determine the tube surface temperature necessary to heat the water to the desired outlet temperature of 80°C. (Nu = 3.39) "C
how the heat transfer coefficient on the boiler side changes with 50% increase in mass flow rate and how the heat transfer coefficient on the tube side is affected with 50% increase in mass flow rate (without using numerical values) ) show it mathematically.
A steam power plant is located in the northern part of the country. Steam in the plant flows steadily through a 0.203-m diameter pipeline from the steam generating unit (SGU) to the steam turbine. At the SGU end, the steam conditions are determined to be P= 4 mPa, t - 400 celsius, h =3,264.9kJ/kg, and specififc volume = 0.121 m3/kg. At the steam turbine end, the conditions are found to be P=3.5 mPa, t = 392 celsius, h = 3,133.9 kJ/kg, specific volume 0.261m3/kg. Heat loss from the pipeline is 6.92kJ/kg. Determine the steam mass flow rate in kg/s.