In many manufacturing plants, individuals are often working around high-temperature surfaces. Exposed hot surfaces that can cause thermal burns on human skin are considered hazards in the workplace. Metallic surfaces above 70°C can instantly damage skin that touches them. Consider an AISI 1010 carbon steel strip (? = 7832 kg/m3) 2 mm thick and 3 cm wide that is conveyed into a chamber to be cooled at a constant speed of 1?m/s. The steel strip enters the cooling chamber at 597°C. Determine the rate at which heat needs to be removed so that the steel strip exits the chamber at 47°C. Discuss how the conveyance speed can affect the required rate of heat removal.
A 2 mm thick by 3 cm wide AISI 1010 carbon steel strip is cooled in a chamber from 597 to 47°C to avoid instantaneous thermal burn upon contact with skin tissue. The amount of heat rate to be removed from the steel strip is to be determined.
Assumptions 1 Steady operating conditions exist. 2 The stainless steel sheet has constant specific heat and density. 3 Changes in potential and kinetic energy are negligible.
Properties For AISI 1010 carbon steel, the specific heat of AISI 1010 steel at (597 + 47)°C / 2 = 322°C = 595 K is 682 J/kg?K (by interpolation from Table A-3), and the density is given as 7832 kg/m3.
Discussion By slowing down the conveyance speed of the steel strip would reduce the amount of heat rate needed to be removed from the steel strip in the cooling chamber. Since slowing the conveyance speed allows more time for the steel strip to cool.
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