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Problem #2: The surface temperature of a sphere with volume of mR", density of 8000 kg...
There is a small sphere with volume, V, surface area, As, and specific heat, c. The sphere was initially was at T, and was placed in liquid with temperature To and heat transfer coefficient h. Show the governing equation and temperature as a function of time when (i) Ti > To and (ii) Ti < T. You can use the lumped capacitance analysis. (20 pt) 3. There is a small sphere with volume, V, surface area, As, and specific heat,...
2. A separation column at a temperature of 100C is subjected for cooling for a certain period of time. If the separation column is 1500 mm high and 18 cm in diameter, and eventually exposed to an environment temperature of 35C, determine the following with a neat diagram: a) Heat Transfer Coefficient (in J/s m2C and kJ/s m2C) b) Heat transfer Rate (in W and kW) Assume the properties of air at mean temperature as density (ρ) = 1.06 kg/m3,...
7. (20 pts) A sphere with 30 mm in diameter initially at 800 K is quenched in a large bath having a constant temperature of 320 K with a convection heat transfer of 75 W/m2.K. The thermophysical properties of the sphere material are: p=400 kg/mº, c=1600 J/kg-K, and k=1.7 W/mK. (Use characteristic length Lc=VIA to determine applicability of lumped method; Use radius of the sphere for one term approximation) a) Calculate the time required for the surface of the sphere...
Heat Transfer Problem: A sphere of pure aluminum weighing 6 kg and initially at a temperature of 300°C is cooled by an air stream at 20°C with a convection coefficient of 24 W/m2 C. Calculate the time required to cool the sphere center to 100°C.
Problem 3 A portable thermocouple is used to measure the air temperature inside of a sauna. The sauna is unbearably hot and a person can only stay for 20 seconds, during which the temperature reading keeps on changing and a steady temperature is not reached. Leaving the thermocouple reader in the sauna for extended period of time has been deemed too risky for an electronics device Fortunately, a transient heat transfer model can be used to extract the temperature in...
part B ?? The heat transfer to a thermocouple bead is characterized by a heat transfer coefficient of: h- 100 W/m2C. The thermocouple bead can be approximated by a sphere with the following properties: Diameter, D = 1 mm, Density, ρ = 10,000 kg/m3, Specific Heat, Cp-1001/kgK. 5. a. Find the time constant, t b. Would you recommend using this thermocouple to make temperature measurements on a system whose temperature is oscillating at 1 Hz? The heat transfer to a...
This is for static air don't just copy from others', this is a different problem. 1. A very long horizontal cylinder of Unobtainium, of diameter 100 mm, is initially at a uniform temperature of 500 K. The cylinder is left to cool in a large room of static air at 300 K. Calculate a) the average convective heat transfer coefficient at the beginning of the cooling process when the initial temperature of the cylinder is 500 K, and 10] 15]...
A refrigerator is operating between a high pressure of 0.7 MPa and low pressure of 0.1 MPa. The Isentropic efficiency of the compressor is 0.8. The working fluid of the refrigeration cycle is R134a flowing at 0.1 kg/s. The specific heat of air is 1.005 kJ/kgk and density of air is 1.2 kg/m. Calculate a. The compressor exit temperature. b. The compressor power input. c. The evaporator cooling load. d. The coefficient of performance.e. The steam quality at the evaporator inlet.f. If the cooling load...
A gas turbine receives air at temperature T1 = 827 °C and specific volume v, -0.1 m®/kg. Air exits the turbine at P2 = 3 bar and T2 = 450 °C. The volumetric flow rate of air at the inlet is 0.5 m/s. The power output on the shaft is 1900 kW. Determine: The pressure of air at the inlet (pa) in kPa [2 marks] b) The mass flow rate in kg/s [1 mark] c) Find the rate of heat...
Problem 10.17 The temperature of a flowing gas stream is measured using a bare thermocouple, which is a spherical metal bead 1.2 mm in diameter. The properties of the metal are: denisty = 8000 kg/m^3, cp=450 J/kgK, and k= 25 W/mK. The film coefficient between the gas and the metal is 310 W/m^2K. If the gas temperature suddenly changes from 200C to 210C, how long will it take for the thermocouple to reach 209C? 10.17. The temperature of a flowing...