Engineering, 07.04.2020 04:26 Bassoonist

An electric resistance heater is embedded in a long cylinder of diameter 30 mm. When water with a temperature of 25 oC and velocity of 1 m/s flows crosswise over the cylinder, the power per unit length required to maintain the surface at a uniform temperature of 90 oC is 28 kW/m. When air, also at 25 oC, but with a velocity of 10 m/s is flowing, the power per unit length required to maintain the same surface temperature is 400 W/m.

Calculate and compare the convection coefficients for the flows of water and air.

Answers: 1

Show answers

Another question on Engineering

Engineering, 04.07.2019 18:10

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

Answers: 1

Answer

Engineering, 04.07.2019 18:10

Afluid flows with a velocity field given by v=(x/t)i.. determine the local and convective accelerations when x=3 and t=1.

Answers: 2

Answer

Engineering, 04.07.2019 19:20

Afan that can provide air speeds up to 60 m/s is to be used in a low-speed wind tunnel with atmospheric air at 35 c. if one wishes to use the wind tunnel to study flat-plate boundary layer behavior up to reynolds numbes of re 10, what is the minimum plate length that should be used? at what distance from the leading edge would transition occur if the critical reynolds nurnber were rer,e = 5 × 105?

Answers: 2

Answer

Engineering, 06.07.2019 03:10

Asolid steel sphere (k=63.9 w m-1 k-1 , ? =7832 kg m-3 , c=0.523 kj kg-1 k-1 ), 100 mm in diameter is initially at a uniform temperature of 500o c and is suddenly quenched in a large oil bath for which t? = 100o c and h = 3200 w m-2 k-1. estimate the time required for the sphere to cool to 200o c and to 110o c

Answers: 1

Answer

You know the right answer?

An electric resistance heater is embedded in a long cylinder of diameter 30 mm. When water with a te...

Questions