Consider a vertical cylinder shaped refrigerator (L=90 cm, D=120 cm) where upper flat surface is at T= 5°C, and surrounding air is at 25°C. If the Raleigh Number is 188-10, What is the convective heat transfer coefficient (W/m¯.K)? k= 0.02476 W/m.K air
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A: For solution refer below images.
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Q: QUESTION 1 A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1…
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- ....A journal bearing is to be used for a centrifugal pump where the shaft diameter is 50 mm and the bearing length is 80 mm. The ambient and bearing surface temperatures are 20°C and 45°C, respectively. Which of the following is the heat dissipated by the bearing if the heat dissipation coefficient is 280 W/m2-°C? Group of answer choices 56 W 14 W 73 W 28 WA domestic refrigerator with inner dimensions of 0,7 m by 0,7 m at the base and height 1m was designed to maintain a set temperature of 6 degrees Celsius. The bodies consist of two 10 mm thick layers of Aluminum (k=225W/mK) separated by a 30 mm polyurethane insulation (k=0,028W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 116W/m²K and 14,5W/m²K respectively. Calculate : 1)The individual resistance (R) for each thermal layer, as well as for the refrigerator 2)The steady rate of heat transfer from the interior to maintain the specified temperature in the kitchen at 25 degrees Celsius 3)The outer surface temperature of the Aluminum 4)Sketch the sectional view of the refrigerator showing thermal circuit4.) A 15-cm-diameter steam line carries saturated steam at 6 MPa and is located in a tunnel with stagnant air with a temperature of 50oC. The outside unit convective coefficient is 8.5 W/m2-K. The steam line is covered with 3 cm of 85% magnesia insulation. It is decided to reduce the heat loss by one-half. How much 85% magnesia insulation is required? Neglect thermal resistance of pipe and inside surface.
- A transformer that is L=20cm long, 6.2 cm wide, and 5 cm high is to becooled by attaching a 10 cm × 6.2 cm wide polished aluminum heatsink (emissivity =0.03) to its top surface. The heat sink has seven fins,which are 5 mm high, 2 mm thick, and 10 cm long. A fan blows air at25°C parallel to the passages between the fins. The heat sink is todissipate 20 W of heat and the base temperature of the heat sink is notto exceed 60°C. Assuming the fins and the base plate to be nearlyisothermal and the radiation heat transfer to be negligible, determinethe minimum free-stream velocity the fan needs to supply to avoidoverheating. (k=0.02681W/m˚C, Pr=0.7248, V= 1.726×10-5 m2/s, )A solid sphere (ρ= 800 kg/m3, cp = 4000 J/kg-K, k = 0.4 W/m-K) of diameter 1 cm is taken out of the refrigerator when it is at 15˚C and placed in a water bath that is at 45°C. a)Calculate the convective heat transfer coefficient using an appropriate practical equation.A CPU heatsink (fan included) blows room temperature air with a total convective heat transfer coefficient of 28 2/m2K. The air travels over a heatsink comprised of 12 fins 40mm long x 18mm high. If the CPU (intel I7-9700K) has a thermal dissipation of 120W, what must the average surface temperature of the fins be?
- An industrial freezer is designed to operate with an internal air temperature of -20°C when the external air temperature is 27°C, and the internal and external heattransfer coefficients are 8 W/m2 -K and 12 W/m2 -K, respectively. The walls of thefreezer are composite construction, comprising an inner layer of plastic (k = 0.33 W/m-K, and thickness of 10 mm), and an outer layer of stainless steel (k = 15 W/m-K, and thickness of 3 mm). Sandwiched between these two layers is a layer of insulation material with k = 0.07 W/m-K. Find the width (mm) of the insulation thatis required to reduce the convective heat loss to 60 W/m2.Number 3A food product with 73% moisture content in a 7 cm diameter can wants to be frozen. The density of the product is 970 kg/m³, the thermal conductivity is 1.2W/(m K), and the initial freezing temperature is -2.5°C. After 11 hours in the freezing medium -40°C, the product temperature becomes -10°C. Estimate the convection heat transfer coefficient of the freezing medium. Assume the can as an infinite cylinder. h= answer in W/(m²K)A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 ˚C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mK) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m2K and 14.5 W/m2K respectively, calculate: the outer surface temperature of the Aluminum in 0C to 2 decimal places
- A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 ˚C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mK) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m2K and 14.5 W/m2K respectively, calculate: Total inner surace area in m2 to 2 decimal places.Consider the cooling system for the back of an integrated circuit. The chip has dimension 10 cmx 21 cm, and has 6 evenly spaced fins of length 2cm and thickness 1cm running along the long side of the chip. The base of the cooling back is 150o The fins are made of aluminum. It is exposed to ambient air at 20oC with a convective heat transfer coefficient 25W/m2K. Use the approximation to change a convective tip to an adiabatic tip. Heat transfer from the fin. Individual fin effectiveness. Overall fin effectiveness.You are asked to design a metal hot dog holder for roasting hot dogs over an opencampfire. The holder is to be designed such that while the end holding the hot dogbecomes cherry red (1400oF), the other end can still be held without using aninsulated handle or glove (~95oF). Design it such that it can be used even on awarm, still day, Tf = 90oF (Assume the convective heat transfer coefficient, h, fora horizontal cylinder is uniform over the whole cylinder and equal to 4.0Btu/hrft2oF)