A resistor, part of a circuit, is dissipating at 0.1 W. It is shaped like a cylinder with a radius of 1.8 mm and a length of 1 cm. If the air in the cabinet is at 308 K and the resistor has a heat transfer coefficient of h = 13 W/m2K for natural convection and hrad of 6.5 W/m2K, what is the resistor’s temperature? Assume heat is lost by only convection and radiation in a parallel circuit. Now if the power to the resistor is turned off, how long will take it to cool? The resistor has a thermal conductivity of 10 W/m.K, density of 2000 kg/m3 and specific heat of 700 J/kg.k. (no figure)
A resistor, part of a circuit, is dissipating at 0.1 W. It is shaped like a...
A long cylinder of diameter D 0.012 m, thermal conductivity k 358 W/(mK), density p - 7614 kg/m3, specific heat c 418 J/(kgK) is initially at a uniform temperature of Ti-74°C. The cylinder is suddenly exposed to a gas at T,-18 ℃ The convection coefficient is h -17 W/(m2K). Verify that a lumped capacitance analysis can be used for the transient response of the cylinder temperature. What is the time t in seconds for the cylinder temperature to become Tf-32...
A bare copper cable 2.5 cm in diameter is situated in still air at 15°C. A current of 800 Amps is passed along the cable. Heat is transferred from the cable to its surroundings by natural convection for which the heat transfer coefficient may be expressed as 2.95025 W/m2 K. Determine whether or not it may be assumed that the temperature across the copper cross section is uniform and what the equilibrium temperature of the cable surface will be. If...
summatize the following info and break them into differeng key points. write them in yojr own words apartus 6.1 Introduction—The design of a successful hot box appa- ratus is influenced by many factors. Before beginning the design of an apparatus meeting this standard, the designer shall review the discussion on the limitations and accuracy, Section 13, discussions of the energy flows in a hot box, Annex A2, the metering box wall loss flow, Annex A3, and flanking loss, Annex...
summarizr the followung info and write them in your own words and break them into different key points. 6.5 Metering Chamber: 6.5.1 The minimum size of the metering box is governed by the metering area required to obtain a representative test area for the specimen (see 7.2) and for maintenance of reasonable test accuracy. For example, for specimens incorporating air spaces or stud spaces, the metering area shall span an integral number of spaces (see 5.5). The depth of...