3c 1018 water is boiled at sea level in a coffee

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Unformatted text preview: lished steel pan placed on top of a heating unit. The inner surface of the bottom of the pan is maintained at 110°C. If the diameter of the bottom of the pan is 25 cm, determine (a) the rate of heat transfer to the water and (b) the rate of evaporation. 1 atm 3 kW 1 atm FIGURE P10–16 110°C 10–17 Repeat Problem 10–16 for a location at an elevation of 1500 m where the atmospheric pressure is 84.5 kPa and thus the boiling temperature of water is 95°C. Answers: 100.9°C, 10.3°C 10–18 Water is boiled at sea level in a coffee maker equipped with a 20-cm long 0.4-cm-diameter immersion-type electric 1 atm FIGURE P10–11 10–12 Water is to be boiled at atmospheric pressure on a 3-cm-diameter mechanically polished steel heater. Determine the maximum heat flux that can be attained in the nucleate boiling regime and the surface temperature of the heater surface in that case. Reconsider Problem 10–12. Using EES (or other) software, investigate the effect of local atmospheric pressure on the maximum heat flux and the temperature difference Ts Tsat. Let the atmospheric pressure vary Coffee maker 1L 10–13 FIGURE P10–18 cen58933_ch10.qxd 9/4/2002 12:38 PM Page 555 555 CHAPTER 10 heating element made of mechanically polished stainless steel. The coffee maker initially contains 1 L of water at 18°C. Once boiling starts, it is observed that half of the water in the coffee maker evaporates in 25 min. Determine the power rating of the electric heating element immersed in water and the surface temperature of the heating element. Also determine how long it will take for this heater to raise the temperature of 1 L of cold water from 18°C to the boiling temperature. 10–19 Vent Boiler 150°C Repeat Problem 10–18 for a copper heating element. 10–20 A 65-cm-long, 2-cm-diameter brass heating element is to be used to boil water at 120°C. If the surface temperature of the heating element is not to exceed 125°C, determine the highest rate of steam production in the boiler,...
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