A 5-cm-diameter steel pipe is covered with a l-cm layer of insulating material hav- ing k=0.22 W/m-°C followed by a 3-cm-thick layer of another insulating material having k =0.06 W/m-°C. The entire assembly is exposed to a convection surround- ing condition of h =60 W/m2.°C and T-15°C. The outside surface temperature of the steel pipe is 400°C. Calculate the heat lost by the pipe-insulation assembly for a pipe length of 20 m. Express in Watts.

A 5-cm-diameter steel pipe is covered with a l-cm layer of insulating material hav- ing k=0.22 W/m-°C followed by a 3-cm-thick layer of another insulating material having k =0.06 W/m-°C. The entire assembly is exposed to a convection surround- ing condition of h =60 W/m2.°C and T-15°C. The outside surface temperature of the steel pipe is 400°C. Calculate the heat lost by the pipe-insulation assembly for a pipe length of 20 m. Express in Watts.

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

See similar textbooks

Similar questions

A thin insulator rod of mass m and length L=40 cm, as shown. thresholdon the surface of the plane and in an outer bend from the rails placed on the edges. It slides frictionlessly with a constant velocity of V=0,8 m/s. Itrails at the lower edge of the inclined plane. to each other with a rail parallel to the bar connected so that the bars and rails are closed, a rectangular frame they form. Rail plane is Ɵ=50° angle with horizontal plane (xz plane) is doing. Before the rod begins to weld, it must be tilted above the inclined plane. It stood above the lower edge of the plane at a distance of S=4m. Inclined plane and the rod shows a magnetic field of uniform B=0,5i+0,8j+0,20k(T) is under the influence. When the bar starts to slide, at t=3s moments the bar, the edge magnetic passing through the frame surface formed by the rails and the rails at the bottom edgewhat is flux?
In a three layered, cylindrical electrode system, 100 kV is applied to the inner conductorwhile the outer conductor is grounded. Radii of cylinders in this system are: r1 =1 cm, r2 =1.5cm, r3 =3 cm, and R =5 cm. Relative dielectric constants of layers are r1 = 5, r2 = 3 and r3 =2.5 respectively;a) Calculate maximum and minimum field strengths across each layer.b) If R=5 cm and r3 =4.5 cm, for uniformly stress condition find the new values of r1 and r2and the thickness of each layer.
Find the capacitance in picofarad between inner and outer curved conductor surfaces shown in the figure containing two dielectrics, εr1 = 4.9 and εr2 = 3.5. Here r1 = 39.4 mm, r2 = 64.4 mm, α1 = 19.7 degrees, α2 = 41.2 degrees and L = 158.6 mm.
A solid cylindrical aluminum conductor 25 km long has an area of 336,400 circular mils. Obtain the conductor resistance at 20C and 50C. Find the AC resistance per Km of the cable at 50C. Assume a skin-effect correction factor of 1.02 at 50 Hz. The resistivity of aluminum at 20C is 2.8x10-8 Ωm
In free space, q1= 3nC and q2= -4nC are located in the form of load axes, as well as at the base y=1 and y=6 on the y-new. Accordingly, how many volts is the electric potential value at the origin?
9-- A loop of wire in the shape of a rectangle of width b=5 cm and length L and a long, straight wire carrying a current I lie on a tabletop as shown in Figure 1. Suppose the current is changing with time according to I =10 e-wt A, where w is constants. Determine the direction and magnitude of the emf that is induced in the loop in 2 sec, if w= 0.2 s-1, a = 10 mm, and L = 10cm. Show step by step solution.
High Voltage Technique For the most puncture-related arrangement of a concentric spherical electrode system with a voltage of 100 kV to be applied between the electrodes and with Ed=80 kV/cm (insulator puncture strength), Emax = 0.6. Ed a) Inner and outer sphere radii, b) Maximum and minimum field strengths, c) Equivalent electrode opening and utilization factor, d) Its capacity (Ɛ0=8,854x10-12 F/m, Ɛr=1) and insulator volume, e) By keeping the outer sphere radius constant, calculate the inner sphere radius value range that can be used in the system without discharge. ANSWERS: a) r1=4.16 cm, r2=8.32 cm b) Emax=48 kV/cm, Emin=12 kV/cm c) α=2.08 cm, η=0.5 d) C=9.257 pF, Vinsulator=2110 cm3 e)1.53<r1<6.8 cm
A 0.1-W small cylindrical resistor mounted ona lower part of a vertical circuit board is 0.3 in long andhas a diameter of 0.2 in. The view of the resistor is largelyblocked by another circuit board facing it, and the heat transferthrough the connecting wires is negligible. The air is free to flow through the large parallel flow passages between theboards as a result of natural convection currents. If the airtemperature at the vicinity of the resistor is 120°F, determinethe approximate surface temperature of the resistor. Evaluateair properties at a film temperature of 170°F and 1 atm pressure.Is this a good assumption?
The relative dielectric coefficient of the planar electrode system given in the figure is Er = Er0 - n. It changes linearly according to the x relation. Er0 = 7.2 for this electrode system; n = 1.8 cm ^ -1 and the gap between electrodes is given as a = 3 cm. 26 kV direct voltage is applied to this planar electrode system, so find the amplitude of the electric field strength at point A (2.7cm, 3cm). (Edge effects will be neglected, electrode length b <15 cm) y 4 a (cm) -> electrode electrode
The inner conductor of a long coaxial cable has radius a. The inner radius of the outer conductor is b. Inner conductor V0, outer conductor at 0 potential. Determine the electric potential and electric field strength in the insulating material.
a long straight cylindrical wire of radius r meter, in a medium of permittivity e is parallel to a horizontal plane conducting sheet. The axis of the wire is it expr metres above the sheet (a) Derive an expression of the capacitance per unit length between the wire and the sheet (b) If r = 0.3 x 10-2 m, h.= 0.12 m find the capacitance per metre length (c) If the potential difference betweenthe wire and sheet is 5 kV, find the magnitude and direction of electric stress in the medium at theupper surface of the sheet at a distance 20 cm from the axis of the wire. Take e = 1/36π x 10-9 F/m [(a) C = 2πe/ln 2h - r/r F/m (b) 0.0127 x 10-9 F/rn (c) 6.85 kV/m acting vertically downward]
A copper wire at 20 degrees C, and 164 cmil, has a K value of 10.4 ohms per mi-foot. If the distance to the load is 600 feet (183 m) calculate the resistance of the loop.