1. A 8000 W electric resistance heater is being used to heat water in an insulated,...

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1. A 8000 W electric resistance heater is being used to heat water in an insulated, constant diameter tube. Calculate the mass flow rate if the water enters the tube steadily at 30C and leaves at 100C. (30 Points) 2. The inner and outer surfaces of a 0.5m thick and 5m x 9m north wall of an electrically heated home are maintained at temperatures of 50C and 20C, respectively. The rate of heat transfer through this wall is 2500W. (a) Determine the thermal conductivity of that wall if the temperatures of the surfaces are maintained constant for a period of 6h. (b) determine the total heat loss through the wall for that period, and (c) the cost of that heat loss if the cost of electricity is 0.09$/kWh. (40 Points) 3. A pipe transports superheated vapor at a rate of 2000Kg/hr. The diameter and length of the pipe are 0.1m and 100m respectively. The pipe, which is located in a power plant at 300 K, has a uniform surface temperature of 350 K. If the temperature drop between the inlet and outlet of the pipe is 30K, determine the heat transfer coefficient as a result of convection between the pipe surface and the surroundings. Assume, the specific heat of the vapour is 2190 J/kg.K. (30 Points) 1. A 8000 W electric resistance heater is being used to heat water in an insulated, constant diameter tube. Calculate the mass flow rate if the water enters the tube steadily at 30C and leaves at 100C. (30 Points) 2. The inner and outer surfaces of a 0.5m thick and 5m x 9m north wall of an electrically heated home are maintained at temperatures of 50C and 20C, respectively. The rate of heat transfer through this wall is 2500W. (a) Determine the thermal conductivity of that wall if the temperatures of the surfaces are maintained constant for a period of 6h. (b) determine the total heat loss through the wall for that period, and (c) the cost of that heat loss if the cost of electricity is 0.09$/kWh. (40 Points) 3. A pipe transports superheated vapor at a rate of 2000Kg/hr. The diameter and length of the pipe are 0.1m and 100m respectively. The pipe, which is located in a power plant at 300 K, has a uniform surface temperature of 350 K. If the temperature drop between the inlet and outlet of the pipe is 30K, determine the heat transfer coefficient as a result of convection between the pipe surface and the surroundings. Assume, the specific heat of the vapour is 2190 J/kg.K. (30 Points)

Answer rating: 100% (QA)

1 To calculate the mass flow rate of water in the tube we can use the energy balance equation Power in Power out The power in is the electrical power ... View the full answer