工程熱力學(xué)和傳熱學(xué)(雙語)第9章習(xí)題課-資料下載頁
2025-10-10 16:53本頁面
【正文】 n oil bath at a temperature of 50℃ . If the quenching occurs when the ball reaches a temperature of 100℃ and the heat transfer coefficient between the oil and the sphere is 500W/m2.℃ , determine how long the ball should be kept in the oil bath. If 100 balls are to be quenched per minute, determine the rate at which heat must be removed from the oil bath in order to maintain the bath temperature at 50℃ . 18. A thermocouple is to be used to measure the temperature in a gas stream. The junction is approximated as a sphere with thermal conductivity of 25W/(m.℃ ), density of 9000kg/m3, and specific heat of (kg.℃ ). The heat transfer coefficient between the junction and the gas is 250W/(m2.℃ ). Calculate the diameter of the junction if the thermocouple should measure 95 percent of the applied temperature difference in 3s. Tutorial Lumped system analysis Tutorial Lumped system analysis 19. The temperature of a gas steam is to be measured by a thermocouple whose junction can be approximated as a 1mmdiameter sphere, The properties of the junction are λ=35W/(m.℃ ), ρ=8500kg/m3, and cp=320kJ/(kg.℃ ), and the convection heat transfer coefficient between the junction and the gas is h=210 W/(m2.℃ ). Determine how long it will take for the thermocouple to read 99 percent of the initial temperature difference.
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