One of the most common appliances used on a daily basis is the hair dryer. A hair dryer is basically a duct in which a few layers of electric resistors are placed. A small fan at the back of the device pulls the air in and forces it through the resistors where it is heated (see Fig. 1). The power consumed by the heating elements (i.e. electric resistors) of the hair dryer is 12 58 Watts. Air enters the hair dryer at 95 kPa and 25°C and leaves at 50°C. The cross-sectional area of the hair dryer at the exit is 55 cm². The power consumed by the fan is 2 Watts and the heat loss through the walls of the hair dryer is 5 Watts. By clearly stating your assumptions throughout, 1.Analytically describe the Fluid Mechanics and Thermodynamics working principles of the hairdryer; 2. Provide a schematic diagram of the hair dryer clearly indicating the system's boundaries, mass flows and energy/heat flows; 3. Determine the volumetric flow rate of the air at the inlet; 4. Determine the velocity of the air at the exit.

One of the most common appliances used on a daily basis is the hair dryer. A hair dryer is basically a duct in which a few layers of electric resistors are placed. A small fan at the back of the device pulls the air in and forces it through the resistors where it is heated (see Fig. 1). The power consumed by the heating elements (i.e. electric resistors) of the hair dryer is 12 58 Watts. Air enters the hair dryer at 95 kPa and 25°C and leaves at 50°C. The cross-sectional area of the hair dryer at the exit is 55 cm². The power consumed by the fan is 2 Watts and the heat loss through the walls of the hair dryer is 5 Watts. By clearly stating your assumptions throughout, 1.Analytically describe the Fluid Mechanics and Thermodynamics working principles of the hairdryer; 2. Provide a schematic diagram of the hair dryer clearly indicating the system's boundaries, mass flows and energy/heat flows; 3. Determine the volumetric flow rate of the air at the inlet; 4. Determine the velocity of the air at the exit.

Sustainable Energy

2nd Edition

ISBN:9781337551663

Author:DUNLAP, Richard A.

Publisher:DUNLAP, Richard A.

Chapter19: Battery Electric Vehicles (bevs)

Section: Chapter Questions

Problem 8P

See similar textbooks

Similar questions

A heat pump supplies heat energy to a house at the rate of 140,000 kJ/h when the house is maintained at 25°C. Over a period of one month, the heat pump operates for 100 hours to transfer energy from a heat source outside the house to inside the house. Consider a heat pump receiving heat from two different outside energy sources. In one application the heat pump receives heat from the outside air at 0°C. In a second application the heat pump receives heat from a lake having a water temperature of 10°C. If electricity costs $0.105/kWh, determine the maximum money saved by using the lake water rather than the outside air as the outside energy source.
The electric resistance of a light bulb is 145 Ω . Determine the value of currentflowing through the lamp when it is connected to a 120-volt source.Using Ohm’s law, as shown , we have V = RI I = V/R = 120/145 = 0.83 A
A 35 hp air compressor handles 300 ft3/min of air with a density of 0.079 lbm/ft3 and pressure of 14.7 psia, and discharges at a pressure of 75 psig with a density of 0.305 lbm/ft3. The change in specific internal energy across the compressor is 35 Btu/lbm. Neglecting the changes in kinetic and potential energies, calculate (a) work in Btu/lbm (b) the heat transfer in Btu/lbm
15.) Conduct research to find the specific heat capacity of water ___________________ and iron ________________________ Based on your observations & analysis from above explain what you would expect to see when you research the Specific Heat Capacity value for copper. Clay bricks are used as building materials in construction. Do some research on specific heat capacities of brick, concrete, stone etc. and advise on what this means for society.
ENERGY CONSERVATION - BERNOULLI EQUATION. 3. Kerosene flows at 25 ° C, at a rate of 1200 L / min, from the lower tank (A) to the upper tank (B) through a 2 ”copper tube. type K. Calculate the air pressure over the fluid.
The horizontal pump in Fig.1 discharges water at 57 m3/h. Neglecting Losses,What power in KW is delivered to the water by the pump? A-836 watt B-8360 watt C-8362 watt D-83600 watt
Assume 40% of the light emitted by a 1000 W metal halide lamp (110,000 lm) illuminates a surface with the area of a 32-ft diameter. 1. Determine the average illuminance of the surface in foot candles. 2. Determine the average illuminance of the surface in lux.
A refrigerator absorbs 5 kJ of energy from a cold reservoir and rejects 8 kJ to a hot reservoir. (a) Find the coefficient of performance of the refrigerator. (b) The refrigerator is reversible and is run backward as a heat engine between the same two reservoirs. What is its efficiency?
The Energy Efficiency Rating (EER) of an air-conditioning unit is defined asthe ratio of the heat removed in Btu/h divided by the energy used in watts.The EEI (Edison Electric Institute) names an air-conditioning unit as anEnergy Star unit if it has an EER of 13 or greater. A 21⁄2-ton air-conditioningunit uses 2.41 kilowatts (2,410 watts) of energy. One ton is equivalent to12,000 Btu/h. Can this unit be termed an Energy Star unit?
A cylindrical tank 1m in diameter and 3m tall weighs 3.86kN. Given: ylead = 100kN/m3. 14. Which of the following most nearly gives the weight of the lead that must be placed inside the tank to make the top of the tank flushed with water surface?
Liquid weighing 0.98 gram and containing 90% of carbon and 8% of hydrogen give the following result in the bomb calorimeter experiment amount of water taken in the calorimeter equal to 450 gram water equivalent of the calorimeter equal to 450 gram rise in temperature of water equal to 1.8 degree centigrade if the latent heat of steam is 587 calorie per gram calculate the cross and net calorific value of the fuel
We have exposed 1 kg of water, 1 kg of brick, and 1 kg of concrete each to a heat source that puts out 100 J every second. Assuming that all of the supplied energy goes to each material and they were all initially at the same temperature, which one of these materials will have a greater temperature rise after 10 s? We can answer this question using Equation as shown . We will first look up the values of the specific heat for water, brick, and concrete, which are cwater = 4180 J⁄kg K, cbrick = 960 J⁄kg K and cconcrete = 880 J⁄kg K . Now applying as shown , Ethermal = mc(Tfinal Tinitial) to each situation, it should be clear that although each material has the same amount of mass and is exposed to the same amount of thermal energy, the concrete will experience a higher temperature rise because it has the lowest heat capacity value among the three given materials.