Q: A 4-kW resistance heater in a water heater runs for
A 4-kW resistance heater in a water heater runs for 3 hours to raise the water temperature to the desired level. Determine the amount of electric energy used in both kWh and kJ.
See AnswerQ: A typical household pays about $1200 a year on energy bills
A typical household pays about $1200 a year on energy bills, and the U.S. Department of Energy estimates that 46 percent of this energy is used for heating and cooling, 15 percent for heating water, 1...
See AnswerQ: A transistor with a height of 0.32 in and a
A transistor with a height of 0.32 in and a diameter of 0.22 in is mounted on a circuit board. The transistor is cooled by air flowing over it at a velocity of 600 ft/min. If the air temperature is 12...
See AnswerQ: Steam at 250°C flows in a stainless steel pipe (
Steam at 250°C flows in a stainless steel pipe (k = 15 W/m⋅K) whose inner and outer diameters are 4 cm and 4.6 cm, respectively. The pipe is covered with 3.5-cm-thick glass wool insulation (k = 0.038...
See AnswerQ: In an annealing process, a 50-mm-thick stainless
In an annealing process, a 50-mm-thick stainless steel plate (ρ = 8238 kg/m3, cp = 468 J/kg⋅K, k = 13.4 W/m⋅K, and α = 3.48 × 10−6 m2/s ) was reheated in a furnace from an initial uniform temperatur...
See AnswerQ: A 0.55-m-internal-diameter spherical tank
A 0.55-m-internal-diameter spherical tank made of 1-cm-thick stainless steel (k = 15 W/mâ‹…K) is used to store iced water at 0°C. The tank is located outdoors at 30Â&d...
See AnswerQ: During a fire, the trunks of some dry oak trees (
During a fire, the trunks of some dry oak trees (k = 0.17 W/m⋅K and α = 1.28 × 10−7 m2/s) that are initially at a uniform temperature of...
See AnswerQ: Repeat Prob. 19–108, assuming the inner surface of
Repeat Prob. 19–108, assuming the inner surface of the tank to be at 0°C but by taking the thermal resistance of the tank and heat transfer by radiation into consideration...
See AnswerQ: Consider airflow over a plate surface maintained at a temperature of 220
Consider airflow over a plate surface maintained at a temperature of 220°C. The temperature profile of the airflow is given as The airflow at 1 atm has a free stream velocity and temperatur...
See AnswerQ: A fluid (ρ = 1000 kg/m3, μ =
A fluid (ρ = 1000 kg/m3, μ = 1.4 × 10−3 kg/m⋅s, cp = 4.2 kJ/kg⋅K, and k = 0.58 W/m⋅K) flows with an average velocity of 0.3 m/s through a 14-m-long tube with inside diameter of 0.01 m. Heat is uniform...
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