A submarine power cable is a cable that is run underwater to carry electrical power across oceans and seas. PETROLEUM JELLY POLYCARBONATE STRANDED METAL (STEEL) WIRES 1-OPTICAL FIBERS -9-POLYETHYLENE 7-STRANDED METAL (STEEL) WIRES 8-"MYLAR" TAPE 5-ALUMINUM WATER BARRIER 2-COPPER OR ALUMINUM TUBE (Image: Wind Systems Magazine) (Image: US Patent #4278835) Usually these cables are very thick and surrounded by protective material but you work for a company whose R&D is focused on developing a new material for submarine cables that allows them to be both electrically conductive and durable enough to withstand the harsh conditions of the ocean. Assume the cable being analyzed is made up of one core material with uniform properties throughout. These cables have a radius of only 0.5mm and some unknown but very long length L (keep your analysis in terms of this unknown length - don't assume a value for it in your written work). The water through which this cable runs is flowing very fast and has a convection coefficient of 450W/m² K and temperature of 25° C. You can assume that this water is touching the entire length of the cable you are analyzing on its entire surface. The special cable material has a density of 7500kg/m³, specific heat capacity of 500J/kgK, and a thermal conductivity of 20W/mK. Electric current flows through the cable at 220A, and its electrical resistance per unit length is 0.01N/m.

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In 1 paragraph, make a narrative of what you have learned in Heat Transfer

You are designing a PCB laid horizontally on the ground.  The PCB surface temperature can’t exceed 85℃ and has a size of 96mm x 90mm. Tinfinity = 45oC.  "p" is the perimeter of the plate a) Calculate the Rayleigh number. b) If the PCB is laid hot-side UP, what is the Nusselt number and heat transfer coefficient? c) If the PCB is laid hot-side DOWN, what is the Nusselt number and heat transfer coefficient? d) Given your results from b and c, which one has better heat transfer?  In that case, what is the maximum power dissipation the board can put out? Properties of Air:k = 0.025 W/mkPr = 0.72v = 1.847 x 10−5u = 16.84 x10−6p = 1.2 kg/m3B =1/ Tf (idwal gass)