TUTORIAL – 3 (03/02/2017) Thermodynamics for …amitk/AS1300/AS1300_TUTORIAL3_2017.pdf ·...
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TUTORIAL – 3 (03/02/2017) Thermodynamics for Aerospace Engineers (AS1300) Temperature and Heat 1. A relation between the resistance and the temperature T of a resistance is given as R=R 0 [1+α(T-T 0 )], where R 0 is the resistance measured in ohms at temperature T0 (in °C) and α is a material constant. The thermometer reads temperatures of 0°C and 91°C corresponding to resistance values of 51.39 and 51.72 ohms respectively. What would be the resistance corresponding to a temperature of 50°C in this thermometer? 2. The readings T A and T B in °C of 2 thermometers A and B agree well at ice and steam points. At other points, their temperature are related as T A = p + qT B + rT B 2 , where p, q and r are constants. When A reads 51°C, B reads 50°C. Determine what A reads when B reads 30°C. 3. A thermometer is constructed by arranging an aluminum rod so that its length can be measured by using a scale made of different material. The thermometer is calibrated at 0°C and 100°C and the distance between these points is divided uniformly into 100 degrees of equal length of the scale. What is the true temperature when this thermometer reads 40°C? The coefficient of linear expansion of aluminum in this temperature range is 0.2221x10 -4 cm/(cm.K) while that of the material of the scale is 10 -5 cm/(cm.K). 4. Two mercury-in-glass thermometers are made of identical materials and are accurately calibrated at 0°C and 100°C. One has a tube of constant diameter, while the other has a tube of conical bore, 10 % greater in diameter at 100°C than at 0°C. Both thermometers have the length between 0 and 100 subdivided uniformly. What will be the straight bore thermometer read in a place where the conical bore thermometer reads 50°C. 5. It is desired to melt aluminum (melting point 660°C) with solid state specific heat capacity 0.9 kJ/kg K and latent heat 390 kJ/kg. The initial temperature of solid aluminum is 15°C and the final temperature of molten aluminum is 700°C. The specific heat capacity of molten metal is 1.11 kJ/kg K and density is 2400 kg/m 3 .Find how much metal can be melted to the required state per hour in a 2.17 MW furnace.
Transcript of TUTORIAL – 3 (03/02/2017) Thermodynamics for …amitk/AS1300/AS1300_TUTORIAL3_2017.pdf ·...
TUTORIAL – 3 (03/02/2017)
Thermodynamics for Aerospace Engineers (AS1300)
Temperature and Heat
1. A relation between the resistance and the temperature T of a resistance is given as R=R0[1+α(T-T0)], where R0 is the resistance measured in ohms at temperature T0 (in °C) and α is a material constant. The thermometer reads temperatures of 0°C and 91°C corresponding to resistance values of 51.39 and 51.72 ohms respectively. What would be the resistance corresponding to a temperature of 50°C in this thermometer?
2. The readings TA and TB in °C of 2 thermometers A and B agree well at ice and steam points. At other points, their temperature are related as TA= p + qTB + rTB
2, where p, q and r are constants. When A reads 51°C, B reads 50°C. Determine what A reads when B reads 30°C.
3. A thermometer is constructed by arranging an aluminum rod so that its length can be measured by using a scale made of different material. The thermometer is calibrated at 0°C and 100°C and the distance between these points is divided uniformly into 100 degrees of equal length of the scale. What is the true temperature when this thermometer reads 40°C? The coefficient of linear expansion of aluminum in this temperature range is 0.2221x10-4 cm/(cm.K) while that of the material of the scale is 10-5 cm/(cm.K).
4. Two mercury-in-glass thermometers are made of identical materials and are accurately calibrated at 0°C and 100°C. One has a tube of constant diameter, while the other has a tube of conical bore, 10 % greater in diameter at 100°C than at 0°C. Both thermometers have the length between 0 and 100 subdivided uniformly. What will be the straight bore thermometer read in a place where the conical bore thermometer reads 50°C.
5. It is desired to melt aluminum (melting point 660°C) with solid state specific heat capacity 0.9 kJ/kg K and latent heat 390 kJ/kg. The initial temperature of solid aluminum is 15°C and the final temperature of molten aluminum is 700°C. The specific heat capacity of molten metal is 1.11 kJ/kg K and density is 2400 kg/m3.Find how much metal can be melted to the required state per hour in a 2.17 MW furnace.
