A spherical vessel, 1.2 m diameter is to be used for the storage of liquid nitrogen at 77K in an area where the surrounding air will have a temperature of 305K with a dew-point of 301K What thickness of insulation, k = 0.02 W/mK, will be necessary to prevent condensation on the insulation surface? The heat transfer coefficient at the insulation surface may betaken as 12W/m2 K Answer: 82 mm STEPS ON HOW TO REACH THIS

A spherical vessel, 1.2 m diameter is to be used for the storage of liquid nitrogen at 77K in an area where the surrounding air will have a temperature of 305K with a dew-point of 301K What thickness of insulation, k = 0.02 W/mK, will be necessary to prevent condensation on the insulation surface? The heat transfer coefficient at the insulation surface may betaken as 12W/m2 K Answer: 82 mm STEPS ON HOW TO REACH THIS

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.20P: A 2.5-cm-OD, 2-cm-ID copper pipe carries liquid oxygen to the storage site of a space shuttle at...

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1.15 A thermocouple (0.8-mm-diameter wire) used to measure the temperature of the quiescent gas in a furnace gives a reading of . It is known, however, that the rate of radiant heat flow per meter length from the hotter furnace walls to the thermocouple wire is 1.1 W/m and the convection heat transfer coefficient between the wire and the gas is K. With this information, estimate the true gas temperature. State your assumptions and indicate the equations used.
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Required information Heat dissipated from an engine in operation can cause hot spots on its surface. If the outer surface of an engine is situated in a place where oil leakage is possible, then when leaked oil comes in contact with hot spots above the oil's autoignition temperature, it can ignite spontaneously. Consider an engine cover that is made of a stainless-steel plate with a thickness of 1 cm and a thermal conductivity of 14 W/m.K. The stainless-steel plate is covered with a 5-mm-thick insulation (k=0.5 W/m.K). The inner surface of the engine cover is exposed to hot air at 350°C with a convection heat transfer coefficient of 5 W/m².K as shown in the figure. The 2-m-long engine outer surface is cooled by air blowing in parallel over it at 7 m/s in an environment where the ambient air is at 60°C. To prevent fire hazard in the event of oil leak on the engine cover, the engine cover surface should be kept below 180°C. It has been determined that the 5- mm-thick insulation layer is…
A very thick slab with thermal diffusivity 5.6x10-6 m2/s and thermal conductivity 20 W/m.K js initially at a uniform temperature of 325 oC. Suddenly, the surface is exposed to a coolant at 15 oC for which the convection heat transfer coefficient is 100 W/m2 .K. --> Determine temperatures at the surface and at a depth of 45 mm after 3 min have elapsed.
Question 6 1 pts A composite wall constructed of 2.5cm of steel (k-60.5 W/m-K) and 5.0 cm of aluminum (k177W/m-K) separates two liquids. The liquid on the steel side has a film coefficient of 15W/m²-K and a temperature of 400degC. The liquid on the steel side has a film coefficient of 30W/m² and a temperature of 100degC. Assume steady state conditions, what is the temperature at the steel-aluminum interface in deg C
Two water columns are at different temperatures, one being at 35°C and the other being at 18oC. The water columns are separated by a glass wall of area Im by 2m and a thickness of 0.005m. Calculate the amount of heat transfer. (Thermal Conductivity of glass is 1.6 W/mK) TABLE 13-13 Typical values of resistance for common building materials R, m K/W R for thickness shown, m K/W Building material Building board Eypsum, 9.5 mm particle board Building membrane 2 layers, 0.73 kg/ns³ felt 0.056 7.35 0.21 Glass single glazing. 3 mm double glazing. 6 mm air space triple glazing, 6 mm air space 0.16 0.32 0.47 Insulating material Blanket and batt mineral fiber from glass, approx. 90 mm approx. 150 mm approx. 230 mm approx. 275 mm glass fiber, organic bonded loose fill milled paper spray applied polyurethane foam Roofing 2.29 3.32 5.34 6.77 27.7 23 40 asphalt shingles buil-up, 10 mm 0.077 0.058 Masonry brick 1.15 concrete 0.6 Siding materials hardboard, 1l mm 0.12 plywood, 9.5 mm Aluminum or…
(a) If the cost of producing the hot water is $0.10 per kWh, what is the representative daily costof heat loss from an uninsulated pipe to the air per meter of pipe length? The convectionresistance associated with water flow in the pipe may be neglected.(b) Determine the savings associated with application of a 10-mm-thick coating of urethaneinsulation (k = 0.026 W/m-K) to the outer surface of the pipe.
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Calculate the tons of refrigeration required to freeze in 4 hrs 3 mm of 10 deg C water on askating rink 61 m x 30 m if the ground temperature is 10 deg C and the air temperatureabove the rink is 16 deg C .The heat transfer coefficient from the air to O deg C is 6.8 W/m2.Cand the heat transfer from the ground to ice is 0.3402 W/m2.C
- Ground cherry seeds need to be planted at a depth of 1-cm below the surface and will only germinate if their surrounding soil is at a temperature of 24-30°C. Farmer Joe wants to know whether adding straw mulch (Amulch = 0.05 W/m K, Lmulch = 10 cm) on top of his soil will increase the odds of germination. The topsoil in Deleware is sandy loam (soil = 0.5 W/m K), with a thickness of 1 m. Immediately beneath the topsoil is the subsoil, which is at a constant temperature of Tsubsoil = 10°C. You can assume that the air in Deleware is fairly calm, with a heat transfer coefficient of h = 10 W/m².K. deleware (a) Sketch the system (with and without mulch), labeling all temperatures, dimensions, and proportionality constants. You may assume that the subsoil, topsoil, mulch, and air are at steady state. You should have two sketches.
16-67E A 2-in-diameter spherical ball whose surface is maintained at a temperature of 170°F is suspended in the middle of a room at 70°F. If the convection heat transfer coefficient is 15 Btu/h-ft².°F and the emissivity of the surface is 0.8, deter- mine the total rate of heat transfer from the ball. 16-68 An 800-W iron is left on the iron board with its base exposed to the air at 20°C. The convection heat trans- fer coefficient between the base surface and the surround- ing air is 35 W/m².K. If the base has an emissivity of 0.6 and a surface area of 0.02 m², determine the temperature of the base of the iron. Answer: 601°C Iron 800 W FIGURE P16-68 20°C
An ordinary egg can be approximated as a 5.5-cm-diameter sphere whose thermal conductivity of roughly k = 0.6- W mk overall density of p = 1000; and heat capacity of C₂ = 3000- kg m² The egg is initially at a uniform temperature of T₂ = 10°C and is dropped into boiling water at T.. = 90°C W - determine how long it will take for the egg to m²K Taking the convective heat transfer coefficient to be h reach T = 70°C. In solving the problem, please follow the steps below. For the Lump Model In solving this problem, please use the lump model method (ignoring the requirement of small Biot number and discuss the outcomes, 1. 2. Compute the characteristic length Lc Compute the volume and surface area of the sphere (as the egg model) Vol As 3. Compute the diffusivity α = = 10- k p Cp = J kgk Compute non-dimensional excessive temperature 0 = h Lc k 4. Compute the Biot number using the characteristic length found above Bi = T-Too 5. Ti-Too 6. Calculate the Fourier number from the equation =…