Engineering, 09.07.2021 19:20 help4068

Adding fins to a surface can increase the surface area but may also serve to decrease the convective heat transfer coefficient by decreasing the velocity of the fluid. If an array of aluminum fins that are 50 mm long, 0.5 mm thick, and equally spaced 4mm apart (S=4mm) are added to a plane wall, determine the change in heat transfer if the convection coefficient associated with the bare wall is 40 W/m^2K is reduced to 30 W/m^2K when the fins are added. Report your results as a percentage change in heat transfer (q_withfins-q_withoutfins)/q_withou tfins. a. The percentage increase in heat transfer is approximately 1300%
b. The percentage increase in heat transfer is approximately 600%
c. The percentage increase in heat transfer is approximately 200%
d. The percentage decrease in heat transfer is approximately 600%

Answers: 1

Show answers

Another question on Engineering

Engineering, 04.07.2019 18:10

Ajournal bearing has a journal diameter of 3.250 in with a unilateral tolerance of 20.003 in. the bushing bore has a diameter of 3.256 in and a unilateral tolerance of 0.004 in. the bushing is 2.8 in long and supports a 700-lbf load. the journal speed is 900 rev/min. find the minimum oil film thickness and the maximum film pressure for both sae 20 and sae 20w-30 lubricants, for the tightest assembly if the operating film temperature is 160°f. a computer code is appropriate for solving this problem.

Answers: 3

Answer

Engineering, 04.07.2019 18:10

Hydraulic fluid with a sg. of 0.78 is flowing through a 1.5 in. i.d. pipe at 58 gal/min. the fluid has an absolute viscosity of 11.8 x 105 lbf-sec/ft2. is the flow laminar, turbulent or within the critical range? give both a numerical reynolds number and a term answer.

Answers: 3

Answer

Engineering, 04.07.2019 18:20

Describe one experiment in which the glass transition temperature and melting temperature of a totally amorphous thermoplastic material can be determined. show the relevant experimental results in a diagram which should be properly annotated with the two temperatures clearly marked. what is likely to happen to the curve in the diagram if the amorphous polymer is replaced by a thermosetting type?

Answers: 2

Answer

Engineering, 04.07.2019 18:20

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.

Answers: 1

Answer

You know the right answer?

Adding fins to a surface can increase the surface area but may also serve to decrease the convective...

Questions