Q.32 Computer memory chips are mounted on a finned metallic mount to protect them from overheating. A 152 MB memory chip dissipates 5 W of heat to air at 25°C. If the temperature of this chip is to not exceed 60°C. The overall heat transfer coefficient-area product of the finned metal mount must be atleast W/°C.
Q: A pin fin of AISI 302 stainless steel (k = 15.1 W/m.K) is attached to a surface whose temperature is…
A: To find: The height of the fin if fin transfer 3 W. Given: The thermal conductivity of pin fin is…
Q: A short cylinder having an initial temperature of 40 C is suddenly exposed to a convection boundary…
A: Given : To find : Temperature at given points A,B,C,D
Q: A rectangular Aluminum fin (k=200W/m.C°) is extended from a hot body of 100 C° temperature. The fin…
A: Given : A rectangular fin of aluminum which temperature is, t°=100°C . Thermal conductivity of…
Q: A rectangular aliminium bar 0.06 m by 0.03 m [k=200 W/(mK), Cp=890 J/(kgK), g=2700…
A: L=.06 m and h=.03 m and lets assume width unity w=1 mK=200 WmK,cp=.890 kJkgKρ=2700 kgm3, α=8.4×10-5…
Q: Solve for this: Steam at 200°C flows in a stainless steel pipe (k = 15 W/m·K) whose inner and outer…
A:
Q: o that the heat transfer rate is maximum, what is the heat transfer rate from the heat sink?…
A: Now find the optimum fin spacing for a vertical heat sink as follows,
Q: Compute the rate of convective heat transfer, in kW, from an uninsulated steam pipe, that has an…
A: Given data: Pipe outer surface temperature = 200 oC Ambient Temperature = 20oC Heat Transfer…
Q: Example: a fin pin with diameter D 0.03m is fixed between two walls at temperature 100 °C. Assuming…
A: For solution refer below images.
Q: Given a plaster of paris (PoP) slab with L = 0.052 cm, W = 0.052 cm, and H = 0.0095 cm, what is the…
A:
Q: Example: Multilayer cylindrical thermal resistance network Steam at T m.°C] whose inner and outer…
A:
Q: If the average connective heat transfer coefficient on the outer surfaçe of a tube (inner diameter =…
A:
Q: Q5//answer one of the following branches c jäll al je al A) cast iron pipe (k=75w/m. °C) air flows…
A:
Q: Brass cube "p 8530 kg/m, c = 380 J/kg.°C, k 110 W/m.°C, a = 33.9E-6 W/m.°C", side length=9 mm, are…
A: Option B is correct.
Q: T. = 310 K The thickness of a wall is 0.07 m. right side of the wall air and T sur = 300 K exposed…
A: given data; ⇒thickness of wall (x)=0.07m⇒external surface temperature of wall right side…
Q: A spherical steel tank (k 15 W/m.°C, thickness=1.5 cm) tank of inner diameter 4.88 m contains ice @…
A:
Q: 8. A pièpe 20cm in diameter contain steam at 20°C. It is covered S by a layer of insulation 6cm…
A: given; diameter of pipe(d)=20cm =20*10-2minlet…
Q: Let's say a 3.0 gram copper wafer is dropped from a height of 50.0 meters. If 60% of the potential…
A:
Q: day you Reep front windshield surface temperature at +3 °C by blowing hot air on the inside surface.…
A:
Q: A square pin fin (w=0.6 mm, L-33 mm) is attached to hot surface, Ts-155°C with convection heat…
A: Given:Square pin fin, w=0.6mm=0.0006m…
Q: AS STOWIT IIT the ske Delow, steam pipe of ue ulanmeter is Insulate u with d layer oI lum sincate.…
A:
Q: A steel disc (k = 56.7 W/m.K, p = 7854 kg/m³, c = 487 J/kg. K) 30 cm in diameter and 10 cm thick,…
A:
Q: Steam in a heating system flows through tubes whose outer diameter is 3 cm and whose walls are…
A:
Q: 3.8 Determine (i) the pressure drop, and (ii) the convective heat transfer coefficient from hot air…
A: The convective hotness move coefficient is reliant upon the actual properties of the liquid and the…
Q: Hot Air blows over steel plate with dimension (5000mm * 7.5m)), the steel plate temperature is 22'C,…
A:
Q: Q5/ A cylindrical storage steel tank with inside and outside diameters of 550 mm and 535 mm,…
A: In general, there are three modes by which heat gets transferred from one place to another. The…
Q: You want to increase the heat flux dissipated by a tube, OD = 2.5 cm, by placing cooling fins…
A: Given : To find : Percentage increase in heat flux
Q: A circular fin of uniform cross section, with diameter of 10 mm and length of 50 mm, is attached to…
A: Given:- Steady one-dimensional heat transfer D=10 mm=0.01m L=50 mm=0.05m h=250 W/m2.K k=240 W/m2.K
Q: A freezer of dimensions 4 m wide, 6 m long and 3 m high is under construction. The walls and ceiling…
A: Given, Conductivity of stainless steel k1=15W/m°C Conductivity of foam insulation k2=0.036W/m°C…
Q: A pipe with 8 cm internal diameter, 9 cm outer diameter, 2 meter long, thermal conductivity 30W/mK…
A: Given Heat transfer coefficient, h = 25 W/m2K Temperature, T1 = 80oC…
Q: Q5/ Determine the overall heat transfer coefficient U based on the outer surface of a D=2.5cm, and D…
A:
Q: ture of 90 °C. The ambient temperature is 20°C and the heat transfer coefficient per convection is…
A:
Q: 2. Air at 20° blows over a hot plate 50X60 cm made of carbon steel maintained at 220°. The…
A: Given, Temperature of air = Atmospheric temperature = Ta = 20 oC Area of the plate = A = 50 cm x 60…
Q: To cool hot oil, an engineer has suggested that the oil be pumped through a pipe submerged in a…
A:
Q: Q2) Consider a copper pin fin 0.25 cm in diameter k = 396 W/m. K that protrudes from a wall a 95°C…
A: Given data as per question Diameter of fin =0.25 cmk=396 wmkT0=95+273=368 kT∞=25+273=298 kConvective…
Q: Q2/ An aluminum sphere weighting 7kg and initially at a temperature of 533K is suddenly immersed in…
A: Given data: - The mass of the sphere is m = 7 kg. The initial temperature is Ts = 533 K. The…
Q: A food product with 80% water content in a 10 cm diameter can be frozen. Mass of the product type is…
A: Given data, x = Moisture contains in the food product = 0.8 a = Diameter of the food product = 0.1 m…
Q: Water flows through a cast steel pipe (k = 50 W/m.K) with an outer diameter of 104 mm and 2 mm wall…
A:
Q: Q3 - The rear window of an automobile is defogged by passing warm air over its inner surface If the…
A:
Q: Hot water (cp=4.18 kJ/kg.K, m = 2.8 kg/min) flows inside a tube (inner diameter = 9 mm, Length = 93…
A: From the given data, heat flux on the tube outer surface is (q") = 204×103 W/m2. Touter = 93 oC and…
Q: Two flat infinite slabs, each 5 m thick, are each initially uniform in temperature, with one being…
A:
Q: A stab of thermal conductivity9.35 W/m.K and thickness 15 cm has two surface temperatures of 150…
A:
Q: 14- A south wall group D at (32 oN, Kw = 0.65). The room temperature is (24 oC). The maximum outside…
A:
Q: The flow of water entering a pipe is 0.25 kg / s and its temperature is 20 ° C. The diameter of the…
A:
Q: A plane wall is a composite of two materials, A and B. The wall of material A has uniform heat…
A:
Q: 14- A south wall group D at (32 oN, Kw = 0.65). The %3D room temperature is (24 oC). The maximum…
A: Given:Room temperature, Tr=24o COutside temperature, To=42o Ch=1.2 W/m2 C
Q: A freezer of dimensions 4 m wide, 6 m long and 3 m high is under construction. The walls and ceiling…
A:
Q: 10. The layout of a wall and the heat transfer parameters are shown in the figure below. Find the…
A:
Trending now
This is a popular solution!
Step by step
Solved in 2 steps with 2 images
- 2.30 An electrical heater capable of generating 10,000 W is to be designed. The heating element is to be a stainless steel wire having an electrical resistivity of ohm-centimeter. The operating temperature of the stainless steel is to be no more than 1260°C. The heat transfer coefficient at the outer surface is expected to be no less than in a medium whose maximum temperature is 93°C. A transformer capable of delivering current at 9 and 12 V is available. Determine a suitable size for the wire, the current required, and discuss what effect a reduction in the heat transfer coefficient would have. (Hint: Demonstrate first that the temperature drop between the center and the surface of the wire is independent of the wire diameter, and determine its value.)One end of a 0.3-m-long steel rod is connected to a wall at 204C. The other end is connected to a wall that is maintained at 93C. Air is blown across the rod so that a heat transfer coefficient of 17W/m2 K is maintained over the entire surface. If the diameter of the rod is 5 cm and the temperature of the air is 38C, what is the net rate of heat loss to the air?1.10 A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss through a wall of 10-cm thickness is . If a thermocouple at the inner surface of the wall indicates a temperature of 22°C while another at the outer surface shows 6°C, calculate the thermal conductivity of the concrete and compare your result with the value in Appendix 2, Table 11.
- An electronic device that internally generates 600 mW of heat has a maximum permissible operating temperature of 70C. It is to be cooled in 25C air by attaching aluminum fins with a total surface area of 12cm2. The convection heat transfer coefficient between the fins and the air is 20W/m2K. Estimate the operating temperature when the fins are attached in such a way that (a) there is a contact resistance of approximately 50 K/W between the surface of the device and the fin array and (b) there is no contact resistance (in this case, the construction of the device is more expensive). Comment on the design options.2.15 Suppose that a pipe carrying a hot fluid with an external temperature of and outer radius is to be insulated with an insulation material of thermal conductivity k and outer radius . Show that if the convection heat transfer coefficient on the outside of the insulation is and the environmental temperature is , the addition of insulation actually increases the rate of heat loss if , and the maximum heat loss occurs when . This radius, is often called the critical radius.1.63 Liquid oxygen (LOX) for the space shuttle is stored at 90 K prior to launch in a spherical container 4 m in diameter. To reduce the loss of oxygen, the sphere is insulated with superinsulation developed at the U.S. National Institute of Standards and Technology's Cryogenic Division; the superinsulation has an effective thermal conductivity of 0.00012 W/m K. If the outside temperature is on the average and the LOX has a heat of vaporization of 213 J/g, calculate the thickness of insulation required to keep the LOX evaporation rate below 200 g/h.
- The interior wall of a large, commercial walk-in type meat freezer is covered under normal operating conditions with a 2-cm thick layer of ice. One day, a power outage cuts electricity to the refrigeration system of the freezer. Estimate the time required to melt this layer of ice if it has a mass density of 700kg/m3 and a latent heat of fusion of 334 kJ/kg. Consider the air temperature inside the freezer to be 20C with a heat transfer coefficient of 2W/m2K for convection from the freezer surface to air, and clearly state the assumptions made in your calculations.1.4 To measure thermal conductivity, two similar 1-cm-thick specimens are placed in the apparatus shown in the accompanying sketch. Electric current is supplied to the guard heater, and a wattmeter shows that the power dissipation is 10 W. Thermocouples attached to the warmer and to the cooler surfaces show temperatures of 322 and 300 K, respectively. Calculate the thermal conductivity of the material at the mean temperature in W/m K. Problem 1.41.37 Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5-cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5% of the wall area, determine the unit thermal conductance of the composite wall and the percent of the total heat flow that passes through the nails when the temperature difference across the wall is 25°C. Neglect contact resistance between the wood layers.
- 2.7 A very thin silicon chip is bonded to a 6-mm thick aluminum substrate by a 0.02-mm thick epoxy glue. Both surfaces of this chip-aluminum system are cooled by air at , where the convective heat transfer coefficient of air flow is . If the heat dissipation per unit area from the chip is under steady-state conditions, draw the thermal circuit for the system and determine the operating temperature of the chip.3.17 A 1.4-kg aluminum household iron has a 500-W heating element. The surface area is . The ambient temperature is 21°C, and the surface heat transfer coefficient is . How long after the iron is plugged in does its temperature reach 104°C?A high-speed computer is located in a temperature-controlled room at 26C. When the machine is operating, its internal heat generation rate is estimated to be 800 W. The external surface temperature of the computer is to be maintained below 85C. The heat transfer coefficient for the surface of the computer is estimated to be 10W/m2K. What surface area would be necessary to assure safe operation of this machine? Comment on ways to reduce this area.