WDetermine the heat-transfer rate from an electronic chip whose surface temperature is 31ºC and has an exposed surface area of 2 cm². The temperature of the surrounding air is 22°C. The heat-transfer coefficient for this situation is h = 25W) and U.S. Customary units (in Btu/h).m². Krate in W(No Response) Wrate in Btu/h(No Response) Btu/hWhat is the R-factor (film resistance, in Km²/W) for this situation?(No Response) K. m²/wExpress your answer in both SI units (in

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Determine the heat-transfer rate from an electronic chip whose surface temperature is 31ºC and has an exposed surface area of 2 cm². The temperature of the surrounding air is 22°C. The heat-transfer coefficient for this situation is h - 25 m². K Express your answer in both SI units (in W) and U.S. Customary units (in Btu/h). rate in W (No Response) W rate in Btu/h (No Response) Btu/h What is the R-factor (film resistance, in Km²/W) for this situation? (No Response) K-m²/w

Determine the heat-transfer rate from an electronic chip whose surface temperature is 31ºC and has an exposed surface area of 2 cm². The temperature of the surrounding air is 22°C. The heat-transfer coefficient for this situation is h - 25 m². K Express your answer in both SI units (in W) and U.S. Customary units (in Btu/h). rate in W (No Response) W rate in Btu/h (No Response) Btu/h What is the R-factor (film resistance, in Km²/W) for this situation? (No Response) K-m²/w

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.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.74P: A manufacturer in the United States wants to sell a refrigeration system to a customer in Germany....

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1.77 Explain each in your own words. (a) What is the mode of heat transfer through a large steel plate that has its surfaces at specified temperatures? (b) What are the modes when the temperature on one surface of the steel plate is not specified, but the surface is exposed to a fluid at a specified temperature?
A manufacturer in the United States wants to sell a refrigeration system to a customer in Germany. The standard measure of refrigeration capacity used in the United States is the ton (T); a 1 T capacity means that the unit is capable of making about 1 T of ice per day or has a heat removal rate of 12,00 Btu/h. The capacity of the American system is to be guaranteed at 3 T. What is this guarantee in SI units?
1.22 In order to prevent frostbite to skiers on chair lifts, the weather report at most ski areas gives both an air temperature and the wind-chill temperature. The air temperature is measured with a thermometer that is not affected by the wind. However, the rate of heat loss from the skier increases with wind velocity, and the wind-chill temperature is the temperature that would result in the same rate of heat loss in still air as occurs at the measured air temperature with the existing wind. Suppose that the inner temperature of a 3-mm-thick layer of skin with a thermal conductivity of 0.35 W/m K is and the air temperature is . Under calm ambient conditions the heat transfer coefficient at the outer skin surface is about (see Table 1.4), but in a 40-mph wind it increases to . (a) If frostbite occurs when the skin temperature drops to about , do you advise the skier to wear a face mask? (b) What is the skin temperature drop due to the wind?
The thermal conductivity of fibreglass insulation at 67F is 0.02 Btu/h ft F. What is its value in SI units?
V:01 Expert Q&A Done Question 1: In your own words, write down the differences between thermodynamic and heat transfer. (3 Marks) Question 2: Estimate the heat loss per square metre of surface through a brick wall 0.5 m thick when the inner surface is at 400 K and the outside surface is at 300 K. The thermal conductivity of the brick may be taken as 0.7 W/mK. (2 Marks) Question 3: A furnace is constructed with 0.20 m of firebrick, 0.10 m of insulating brick, and 0.20 m of building brick. The inside temperature is 1200 K and the outside temperature is 330 K. If the thermal conductivities are as shown in the figure below, estimate the heat loss per unit area. (5 Marks) 1200 K 330 K Insulating brick X-0.10m k= 0.21 Ordinary brick X=0.20 m Fire brick X= 0.20 m k= 1.4 k= 0.7 (W/mK)
Conduction Heat Transfer X material (a) material (b) . both (a) and (b) have the same thermal conductivity the temperature distribution is independent of thermal conductivity it's not that simple 9. Fin efficiency is defined as: • tanh (mL) (hP/k Ac)1/2 (heat transfer with fin) / (heat transfer without fin) (actual heat transfer through fin) / (heat transfer assuming all fin is at T = Tb) (Tx=L-Tf)/(Tb-Tf) 10. For an infinite fin, the temperature distribution is given by: (T-Tf)/(Tb-Tf)= e-mx. The heat flow through the fin is therefore given by: k (Tb-Tf)/L ● zero, because the fin is infinite ● infinite because the fin is infinite ● (Tb-Tf) (hP/k Ac)1/2 ● (Tb – Tf) (h P / k Ac)1/2 tanh (mL) 11. The Biot number, Bi, is defined as: • Bi=hk/L • Bi=hL/k • Bi= k/LH • Bi=qL/k • Bi=p UL/k 12. For a plate of length L, thickness, t, and width, W, subjected to convection on the two faces of area L x W. What is the correct length scale for use in the Biot number? . L ● W ● t • t/2 • L/2 13. If Bi…
The following unit conversions are illustrations of the SI system of units. Show cancellation of units. Convert:a. A thermal conductivity value of 0.3 BTU/h ft oF) to W/m-Kb. A surface heat transfer coefficient value of 105 Btu/h ft2 oF to W/m2-Kc. A latent heat of fusion value of 121 Btu/lbm to J/kg.
A liquid reactant solution is pumped through a pre-heater before entering a reaction vessel. The solution enters the pre-heater at 25 °C and must enter the reactor at 45 °C. The flow of the reactant solution is 1500 mL per minute. The density of the reactant solution is 0.91 g-cm3 and the heat capacity is 1.75 Jg1.K1. ASsume there is no heat loss in the pre-heater or between the pre-heater and the reactor. a. Draw a schematic of the pre-heater, detailing all mass and energy flows. b. Clearly define a system boundary. c. Write the general energy balance, and a simplified energy balance stating all assumptions that apply to this problem. d. What is the minimum power rating required for the pre-heater?
The rate of heat lost through insulation varies inversely as the thickness of the insulation. The rate of heat lost through a 3.5-inch thickness of insulation is 2200 Btu per hour. What is the rate of heat lost through a 5-inch thickness of the same insulation?
The following unit conversions are illustrations of the SI system of units. Convert:a. A thermal conductivity value of 0.3 BTU/h ft oF) to W/m-Kb. A surface heat transfer coefficient value of 105 Btu/h ft2 oF to W/m2-Kc. A latent heat of fusion value of 121 Btu/lbm to J/kg.
Q1. A 50 meter long cast iron pipe with outer diameter of 10 cm passes in an open space of 288 K temperature. The outer surface of the pipe temperature is 423 K and the combined heat transfer coefficient on the outer surface of the pipe is 25 W/m? K. Considering and stating the necessary assumptions determine, (a) The rate of heat loss from the pipe (b) The energy lost per year if the cost of the fuel is 0.52 $/therm ( 1 therm = 105,500 kJ) (c) The thickness of the insulation if 98% of the energy loss is planned to be saved. Consider the conduction coefficient of the insulation is 0.035 W/mK. Tair = 288 K 423 K Steam 50 m Fiberglass insulation Figure Q1.
The presence of thermal reservoir of a Geothermal Power Plant, supplements the generation of power and energy. What is then the thermal energy at the reservoir if the temperatures of the reservoir and a reference point are 315 C and 295 C respectively with volumetric specific heat and the value at the reservoir are 78 KJ/KG and 155 cu.meter. 241.800 KJ 352.500 K) 421.850 KJ 541, 820 KJ