Engineering, 14.09.2019 00:30 elisaalonso8805

Polymers can be natural or synthetic. a)-true b)- false?

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Engineering, 04.07.2019 18:20

A3-mm-thick panel of aluminum alloy (k 177 w/m-k, c 875 j/kg-k and ? = 2770 kg/m) is finished on both sides with an epoxy coating that must be cured at or above t,-150°c for at least 5 min. the production line for the curing operation involves two steps: (1) heating in a large oven with air at ts,0-175°c and a convection coefficient of h, 40 w/m2. k, and (2) cooling in a large chamber with air at 25°c and a con- vection coefficient of he 10 w/m2.k. the heating portion of the process is conducted over a time interval te which exceeds the ime required to reach 150°c by 5 min (h = r + 300 s). the coating has an emissivity of ? = 0.8, and the temperatures of the oven and chamber walls are 175 and 25°c, respectively. if the panel is placed in the oven at an initial temperature of 25°c and removed from the chamber at a safe-to-touch tempera ture of 37°c, what is the total elapsed time for the two-step curing operation?

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Engineering, 04.07.2019 19:10

In general, how do thermosetting plastics compare to thermoplastics in mechanical and physical properties?

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Engineering, 04.07.2019 19:10

An electric kettle is made out of stainless steel, weighs two pounds (when empty) and is equipped with a heating element that consumes 2 kw of electricity. assuming that the water and the kettle are at the same uniform temperature at any moment of time, calculate the shortest possible time to bring 2 quarts of water from room temperature to the onset of boiling

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Engineering, 06.07.2019 04:10

An array of m-50 thermoelectric modules is installed on the exhaust of a sports car. each module has an effective seebeck coefficient of sp of 0.143 5vk and an internal electrical resistance of r.-4 ? in addition, : (15 points each module is of width w 60mm and contains n=100 pairs of semiconducting pellets. each pellet hasan overall length of 2l-5mm and a cross-sectional area as 1.2 x 10'm and is characterized by a thermal conductivity of kpl2w rnk. the hot side of each module is exposed to exhaust gases at·p650c with hia4ow rrk while the osite side of each module is cooled by pressurized water at surface) and 156 °c (at the cool surface). 11s c with h: -500w/m'k. the modules are wired n series and the load resistance is r d=400ohm .the module surface temperatures, t, and ts are 183 "c (at the hot surface and 156c (at the cool surface) a)-draw a schematic of this scenario and label all parts. a. b. if the induced current, i, is 0.15 amps, what is the total power (pa) for one module? c. what is the total power harvest from the exhaust with all 50 modules?