The heat transfer from a 50mm diameter incandescent bulb at 127°C to 27°C quiescent air is
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A: NOTE:- Here, we have to use correlation for find out the convection heat transfer rate.So, answer…
Q: The heat transfer from a 50mm diameter incandescent bulb at 127°C to 27°C quiescent air is [ use the…
A: Given: Ts = 127 + 273 = 400 K Tf = 27 + 273 = 300 K Pr = 0.697 k = 0.03003 W/mK v = 7.076 * 10-5…
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Q: s of the wafer are e = 0.65 an
A: Tsur,h = 1150 KTsur,c = 330 KEmmisivity, e = 0.65d = 0.78 mmT∞ = 700 Khu = 8 W/m2Khl = 4 W/m2K
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Q: Two concentric spheres with diameters of 5 cm and 10 cm are having the surface temperatures…
A: Given data: The internal diameter is: Di=5 cm The external diameter is: DO=10 cm The given…
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A: Data given - Tf = 40°C P= 1 atm Di = 3m t = 0.03 m
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A: Given Data : Surface Temperature : T1=300 KT2=1000 K Stefan Boltzmann constant : σ=1.8×10-8Wm2-K4
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A: Given:Ts=17°CT∞=22.5°Cd=1 mQ=6.6 W
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A: Given: Irradiation = 10000 W/m2
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A: Given:TG=20°CTw=100°Ch=15 W/m2.K
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Q: Question 4:Consider a person standing in a room maintained at20°C at all times. The inner surfaces…
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Q: What electrical current is required to maintain a 0.076 mm diameter, 0.6 m long vertical wire at…
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Q: 2.) Consider a flat plate solar collector placed horizontally on the flat roof of a house. The…
A: Formulas for convection and radiation heat transfer are used. Qconv=hAs(Ts-T∞)Qrad=εAsσ(Ts4-T∞4)
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A: Make a diagram as shown below of the horizontal steam pipe.
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- Question : Studies show that the major energy consumption in Fijian villages is wood which is used for cooking over open fires. Typical consumption of wood is 1 kg person–1day–1. (a) Estimate the heat energy required to boil a 2-liter pot full of water. Assuming this to be the cooking requirement of each person, compare this with the heat content of the wood, and thus estimate the thermal efficiency of the open fire. (b) How much timber has to be felled each year to cook for a village of 200 people?Assuming systematic replanting, what area of crop must the village therefore set aside for fuel use if it is not to make a net deforestation? Hint: refer to Table 10.4. (c) Comment on the realism of the assumptions made, and revise your estimates accordingly. Answer: (a) mcDT ≈ 0.6 MJ (heat losses from pot imply actual requirement is higher). h ≈ 3%. (b) 70 tonnes; 7 ha.Heat Treatment Steel plates 40 cm per side and 1 cm thick are heat treated in a static oven. Inside the oven there is a shelf where 10 separate plates are placed, in such a way that the heat treatment of one does not affect the treatment of the others. The oven is electric and emits radiation heat towards the plates. In the oven an atmosphere with nitrogen is generated to avoid the oxidation of the material, this gas acts as a convective medium on the plates. Before being placed in the oven, the plates are at room temperature of 25 ° C. The heat treatment of the plates begins with a preheating. At this stage, the combined convection and radiation heat transfer coefficient in the oven is 46 W / m2- ° C. During preheating, the oven controls the internal temperature with a quadratic compensation, therefore, the walls and the nitrogen atmosphere have a temperature Th that varies according to the expression: Th = a + bt2 where a = 750 °C, b = 3 x 10- 5°C/ s2 and t is the time in seconds.…Determine the total heat content of an outdoor air sample if the samples dry bulb temperature is 93 degrees and the wet bulb temperature is 74 degrees.
- After sunset, radiant energy can be sensed by a person standing near a brick wall, such walls frequently have surface temperatures around 44°C, and typical brick emissivity values are on the order of 0.92. What would be the radiant thermal flux per square foot from a brick wall at this temperature?You went to Target to buy some masks. As you walk up to the store, you notice the huge red balls in front of the store. Air outside is quiescent. If the sphere surface has a temperature of 17°C and the quiescent air has a temperature of 22.5°C, find the convective heat transfer rate from the sphere. The diameter of sphere is 1 m. -66wWhat are the three modes of heat transfer? Describe each briefly.
- If we neglect radiative heat transfer, what is the appropriate heat transfer coefficient value for stagnant ambient air?A solid sphere made of polished copper has a diameter of 2 cm and is at 100 C. We now expose the solid sphere to are at 50 C and 1 atm. Use the lumped capacitance method to plot the temperature of the solid sphere versus time after five minutes of exposure. The air is quiescent.(a) Calculate the rate of heat transfer by radiation from a car radiator at 110°C into a 50.0ºC environment, if the radiator has an emissivity of 0.750 and a 1.20-m^2 surface area. (b) Is this a significant fraction of the heat transfer by an automobile engine? To answer this, assume a horsepower of 200hp (1.5kW) and the efficiency of automobile engines as 25%.
- Find the amount of heat transfer transmitted through a west window (5 m2) 6 mm clear single glass window without interior shading in Amman in July at 15 pm. Assume ho=22.7 W/m2.K and the construction is heavy.In boiling water at 1 atm pressure outside a stainless-steel tube with a surface temperature of 410F, the heat-transfer coefficient h in the absence of radiation is 32 Btu/h*ft^2*F. If the emissivity of the stainless steel is 0.8, will radiation significantly augment the rate of boiling (e.g., by more than 5 percent)? Assume that the vapor film is transparent to radiation and the boiling liquid is opaque.An asphalt playground is heated in the sun all day; by sundown it reaches a temperature of 45degC. If the asphalt has an emissivity of 0.8, what is the heat flux emitted off the asphalt at night?