1. Saturated steam at 500 K flows in a 0.20 m inside diameter, 0.21 m outside diameter pipe. The pipe is covered with 0.08 m of insulation with a thermal conductivity of 0.10 W/m-K. The pipe's conductivity is 52 W/m-K. The ambient temperature is 300 K. The unit convective coefficients are h₁ = 18,000 W/m²-K and ho = 12 W/m²-K. Determine the heat loss (kJ/min) from 4 m of pipe. • show conversions, units, and box in your final answers

A chip that is of length L = 5.5 mm on a side and thickness t = 2.0 mm is encased in a ceramic substrate, and its exposed surface is convectively cooled by a dielectric liquid for which h = 150 W/m² K and To = 20°C. . Th Chip, q, T₁, P, Cp The time is Substrate In the off-mode the chip is in thermal equilibrium with the coolant (T; = T). When the chip is energized, however, its temperature increases until a new steady state is established. For purposes of analysis, the energized chip is characterized by uniform volumetric heating with a = 9 x 106 W/m³. Assuming an infinite contact resistance between the chip and substrate and negligible conduction resistance within the chip, determine the steady-state chip temperature Tƒ. Following activation of the chip, how long does it take to come within 1°C of this temperature? The chip density and specific heat are p = 2000 kg/m³ and c = 700 J/kg-K, respectively. The steady-state chip temperature Tf is i S. °C.

To maximize production and minimize pumping costs, crude oil is heated to reduce its viscosity during transportation from a production field. (1) Consider a pipe-in-pipe configuration consisting of concentric steel tubes with an intervening insulating material. The inner tube is used to transport warm crude oil through cold ocean water. The inner steel pipe (k, = 45 W/m-K) has an inside diameter of D;, 1 = 150 mm and wall thickness t; = 20 mm while the outer steel pipe has an inside diameter of D;, 2 = 250 mm and wall thickness t, = t;. Determine the maximum allowable crude oil temperature to ensure the polyurethane foam insulation (kp = 0.03 W/m-K) between the two pipes does not exceed its maximum service temperature of T, max = 70°C. The ocean water is at T,o = -5°C and provides an external convection heat transfer coefficient of h, = 500 W/m²-K. The convection coefficient associated with the flowing crude oil is hị = 450 W/m²-K. (2) It is proposed to enhance the performance of the…

16-26 In a certain experiment, cylindrical samples of diameter 4 cm and length 7 cm are used (see Fig. 16–9). The two thermocouples in each sample are placed 3 cm apart. After initial transients, the electric heater is observed to draw 0.6 A at 110 V, and both differential thermometers read a temperature difference of 8°C. Determine the thermal con- ductivity of the sample. Answer: 98.5 W/m.K