Engineering, 06.10.2019 11:00 kcopeland210
The boiling temperature of nitrogen at atmospheric pressure at sea level (1 atm pressure) is −196°c. therefore, nitrogen is commonly used in low-temperature scientific studies, since the temperature of liquid nitrogen in a tank open to the atmosphere will remain constant at -196°c until it is depleted. any heat transfer to the tank will result in the evaporation of some liquid nitrogen, which has a heat of vaporization of 198 kj/kg and a density of 810 kg/m3 at 1 atm. consider a 4-m-diameter spherical tank that is initially filled with liquid nitrogen at 1 atm and − 196°c. the tank is exposed to 20° c ambient air and 55 km/h winds. the temperature of the thin-shelled spherical tank is observed to be almost the same as the temperature of the nitrogen inside. disregarding any radiation heat exchange, determine the rate of evaporation of the liquid nitrogen in the tank as a result of heat transfer from the ambient air if the tank is (a) not insulated, (b) insulated with 5-cm-thick fiberglass insulation (k =0.035 w/m·k), and (c) insulated with 2-cm-thick superinsulation that has an effective thermal conductivity of 0.5 w/m·k.
Answers: 1
Engineering, 04.07.2019 18:10
Apump is used to circulate hot water in a home heating system. water enters the well-insulated pump operating at steady state at a rate of 0.42 gal/min. the inlet pressure and temperature are 14.7 lbf/in.2, and 180°f, respectively; at the exit the pressure is 60 lbf/in.2 the pump requires 1/15 hp of power input. water can be modeled as an incompressible substance with constant density of 60.58 lb/ft3 and constant specific heat of 1 btu/lb or. neglecting kinetic and potential energy effects, determine the temperature change, in °r, as the water flows through the pump.
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Engineering, 04.07.2019 18:10
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Engineering, 04.07.2019 18:10
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Engineering, 04.07.2019 18:20
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The boiling temperature of nitrogen at atmospheric pressure at sea level (1 atm pressure) is −196°c....
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