In beauty salons and in homes, a ubiquitous device is the hairdryer. The front end of a typical hairdryer is idealized as a thin-walled cylindrical duct with a 6-cm diameter with a fan at the inlet that blows air over an electric heating coil as schematically shown in the figure. The design of this appliance requires two power settings, with which the air blown over the electric heating coil is heated from the ambient temperature of
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Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
- A steam power plant is located in the northern part of the country. Steam in the plant flows steadily through a 0.17-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°C, h = 3,247 kJ/kg, and specific volume = 0.181 m³/kg. At the steam turbine end, the conditions are found to be P = 3.5 MPa, t = 392°C, h = 3,178.3 kJ kg, and specific volume = 0.248 m³/kg. Heat loss from the pipeline is 7.86 kJ/kg. Determine the steam mass flow rate in kg/s.arrow_forwardA water tube boiler has a capacity of 1000 kg/hr of steam. The factor of evaporation is 1.3, boiler rating is 200%, boiler efficiency is 5%, heating surface area is 0.91 m2/boiler Hp, and the heating value of fuel is 18,400 Kcal/kg. The total coal available in the bunker is 50,000 kg. Determine total number of hours to consume the available fuel.arrow_forwardA Carnot engine operating on air (k = 1.4) accepts 50 kJ/kg of heat and rejects20 kJ/kg. Calculate the high and low reservoir temperatures if the maximum specificvolume is 10 m3/kg and the pressure after the isothermal expansion is 200 kPa. Assumean ideal gas constant for air of 0.287 kJ/kg-K.arrow_forward
- The sun generates an average of 1.958 kW/m2 when tapped as source of energy wherein a flat-plate collector with an area of 1.006 m2 is used. If the flow rate of water inside the collector is 50.1 liters per hour, compute for the possible temperature rise of working fluid in K.arrow_forwardIn a refrigerator the pressure in the evaporator us 2.72 kg/cm sq. and the refrigerant entry is 0.12 dry while at the exit 0.91 dry. During the compression, the work done per kg is 17,033 kg-m/kg. Calculate the COP. The rate of refrigerant circulation is 5.64 kg/min. The given latent heat and specific volume at 2.72 kg/cm sq are 320 kcal/kg ang 0.436 cu m/kg.arrow_forwardA 550 W redrigerator working at a 25 °C room temlerature ejects 340 J of heat from a region. Estimate the temperature of the cooling space.arrow_forward
- Question 4: An insulated room is heated by burning candles. Is this a heat or work interaction? Take the entire room, including the candles, as the system Question 5: Is the energy required to heat air from 295 to 305 K the same as the energy required to heat it from 345 to 355 K? Assume the pressure remains constant in both cases.arrow_forwardAn auditorium is designed to seat 4500 people. The ventilation rate is 1.62 x 107 ft3/hr of outside air. The outside temperature is 0oF dry bulb, and outside pressure is 14.6 psia. Air leaves the auditorium at 70oF dry bulb. There is no recirculation. The furnace has a capacity of 1,250,000 Btu/hr. The temperature at which the air should enter the auditorium is most nearlyarrow_forwardSOLVE THE PROBLEM AND SHOW THE DETAILED SOLUTION A steam condenser receives 10 kg per second of steam with an enthalpy of 2,570-kJ/kg. The steam condenses into liquid and leaves with an enthalpy of 160kJ/kg. Cooling water passes through the condenser with temperature increases from 13 to 24 Calculate the cooling water flow rate in kg/s.arrow_forward
- It is common knowledge that the temperature of air rises as it is compressed. An inventor thought about using this high-temperature air to heat buildings. He used a compressor driven by an electric motor. The inventor claims that the compressed hot-air system is 25 percent more efficient than a resistance heating system that provides an equivalent amount of heating. Is this claim valid, or is this just another perpetualmotion machine? Explain.arrow_forwardIn refrigeration process, a region is cooled and the temperature was maintained at -15oC. The cooling water used in the refrigeration is 25oC. If the refrigerant is HFC-134a, and the heat transfer temperature difference is 10oC, (a) calculate the COP of the Carnot Refrigerator. (b) What is the COP and (c) mass flowrate if the rating of the refrigeration process is 100,000 kJ/h and the efficiency of the compression is 0.75arrow_forwardA six-cylinder refrigerant 22 compressor operating at 29 r/s indicate a refrigerating capacity of 96.4 kW and a power requirement of 28.9 kW at an evaporating temperature of 5°C and condensing temperature of 50°C. The performance data are based on 3°C liquid sub-cooling and 8°C superheating of the suction gas entering the compressor. The cylinder bore is 67 mm and the piston stroke is 57 mm. Compute (a) the clearance volumetric efficiency if the clearance volume is 4.8 percent, (b) the actual volumetric efficiency, and (c) the compression efficiency.arrow_forward
- Refrigeration and Air Conditioning Technology (Mi...Mechanical EngineeringISBN:9781305578296Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill JohnsonPublisher:Cengage Learning