In 2012, a new fiber-optic cable of handling 40,000 telephone calls simultaneously was laid under the Pacific Ocean from California to Japan, a distance of 13,300 km. The cable was unreeled from shipboard at a mean temperature of 22oC and dropped to the Ocean floor having a mean temperature of 5oC. The coefficient of linear expansion of the cable is 75×10-6 /degree celsius. Determine the length of cable that must be carried on the ship to span the 13,300 Km. Also, find the percent change in length

In 2012, a new fiber-optic cable of handling 40,000 telephone calls simultaneously was laid under the Pacific Ocean from California to Japan, a distance of 13,300 km. The cable was unreeled from shipboard at a mean temperature of 22oC and dropped to the Ocean floor having a mean temperature of 5oC. The coefficient of linear expansion of the cable is 75×10-6 /degree celsius. Determine the length of cable that must be carried on the ship to span the 13,300 Km. Also, find the percent change in length

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.

Chapter3: Transient Heat Conduction

Section: Chapter Questions

Problem 3.10P: 3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the...

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3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the atmosphere from outer space. If its original temperature is 38°C, the effective average temperature of the atmosphere is 1093°C, and the effective heat transfer coefficient is , estimate the temperature of the shell after reentry, assuming the time of reentry is 10 min and the interior of the shell is evacuated.
An electrical transmission line of 1.2-cm diameter carries a current of 200 amps and has a resistance of 310-4 ohm per meter of length. If the air around this line is at v, determine the surface temperature on a windy day, assuming a wind blows across the line at 33 km/h.
1. A steel sphere 3” in diameter heated to 600oF, is to be cooled by immersion in an oil bath at 100oF. Calculate the average temperature of the sphere a) 10 sec and b) 6 min after immersion. For steel, k = 26Btu/ft-h-oF;  = 486lb/ft3 ; Cp = 0.11Btu/lboF.
Water flows at 5m/s is passed through a tube of 2.5 cm diameter, it is found to be heated from 20 °C to 60 °C. The heating is achieved by condensing steam on the surface of the tube and subsequently the surface temperature of the tube is maintained at 90degC. Water properties are as follows: density=995kg/m3, kinematic viscosity=.657x10-6 m2/s, Pr=4.43, k=.628W/mK, cp=4178J/kgK. a) Determine the Reynolds number b) What is the thermal coefficient on question number c) what is the heat absorbed by the water?
A thermocouple junction is in the form of 8 mm diameter sphere. Properties of materialare: Cp = 420 J/kg-K; ρ = 8000 kg/m3 ; k = 40 W/m-K; h = 40 W/m2 -K. This junction isinitially at 40 oC and inserted in a stream of hot air at 300 oC. Find the following:a. Time constant of the thermocouple.b. The thermocouple is taken out from the hot air after 10 seconds and kept in still airat 30 oC. Assuming the heat transfer coefficient in air is 10 W/m2-oC, find thetemperature attained by the junction 20 seconds after removal from hot air.
The velocity of the mercury at T_∞=250 o C is U_∞=0.033m/sec, and it flows over the pipe bundle of D= 1.25 cm diameter and L=1.2m length. The ratio of the vertical and diagonal spacing distances for the pipes in the shifted plate arrangement is ST /D=SD /D= 1.405. It consists of a matrix with the number of pipe rows in the horizontal direction NL=60 and the number of pipe rows in the vertical direction NT=30. Pipe wall (surface) temperatures are kept at a uniform temperature of T_w=160 o C. Accordingly, find the average heat transfer coefficient, the total heat transfer coefficient from the mercury to the pipe bundle. (Variables: ST /D=SD /D= 0.75-1.975, U=0.02-0.07m/s, L=0.5-1.4m)
Water flows at 5m/s is passed through a tube of 2.5 cm diameter, it is found to be heated from 20degC to 60degC. The heating is achieved by condensing steam on the surface of the tube and subsequently the surface temperature of the tube is maintained at 90degC. Water properties are as follows: density=995kg/m3, kinematic viscosity=.657x10-6 m2/s, Pr=4.43, k=.628W/mK, cp=4178J/kgK. Determine the Reynolds number Round your answer to 2 decimal places. What is the thermal coefficient Round your answer to 2 decimal places. what is the heat absorbed by the water? Round your answer to 2 decimal places.
Water at 20 C flows in a smooth pipe 0.04 m indiameter at a Reynolds number of 50,000. Thewall temperature is maintained at 25C. The bulk temperature and film temperature are assumed to be at 20C. Using Colburn analogy find the value of heat transfer coefficient. The properties of water are: Density = 999 kg/m3; viscosity = 1 cp; Pr = 6.94; Specific heat 4182 K/kgK; k=0.603 W/mK
Air flows inside a tube 60 mm in diameter (d) and 2.1 m long (l) at a velocity w = 5 m/sec. Find the heat-transfer coefficient α if the mean air temperature tf = 100oC. Note: Write your answer in space provided without the unit (the answer is in kcal/m2-hr-oC, one decimal places)
A steam pipe carrying steam at 380 kPa pressure for a distance of 120 m in a chemical plant is not insulated. Estimate the Amount of heat saved if 16 cm steam line were covered with 85% magnesia pipe covering 5 cm thick. Take room temperature to be 36 ℃. Thermal conductivity of 85% magnesia is 0.0745 W/m−K , unit convective coefficient of room air, ho = 12 W m2−K .Take the steam temperature as 142℃. Use atleast 4 decimal places in every computation
4.) 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.
As part of an industrial pipe system a 6-meter-long by .5 meter inner diameter copper pipeweighing 200kg holds a lubricating oil in place while is heats from 20 deg C to 55 deg C. At thatpoint, the valve opens and allows to oil to flow through. What is the total heat transferrequired? And, what percentage of the heat transferred does the oil and copper each accountfor? (oil density = .9 kg/L , oil specific heat = 1800 J/kgC)