An office heater (often incorrectly called a radiator, since the heat transfer mode is convection) is...

 

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An office heater (often incorrectly called a radiator, since the heat transfer mode is convection) is composed of a central pipe containing heated water at constant temperature, as depicted in Figure P7.18. Several two-dimensional heat transfer fins are attached to the pipe as shown. The fins are equally spaced along the length of the pipe. Each fin has thickness of 0.125 in. and overall dimensions 4 in. x 4 in. Convection from the edges of the fins can be neglected. Consider the pipe as a point source Q* = 600 Btu/hr-ft² and determine the net heat transfer to the ambient air at 20°C, if the convection coefficient is h = 300 Btu/(hr-ft²-°F). Use four finite elements with linear interpolation functions (consider symmetry conditions here). ***** Figure P7.18 An office heater (often incorrectly called a radiator, since the heat transfer mode is convection) is composed of a central pipe containing heated water at constant temperature, as depicted in Figure P7.18. Several two-dimensional heat transfer fins are attached to the pipe as shown. The fins are equally spaced along the length of the pipe. Each fin has thickness of 0.125 in. and overall dimensions 4 in. x 4 in. Convection from the edges of the fins can be neglected. Consider the pipe as a point source Q* = 600 Btu/hr-ft² and determine the net heat transfer to the ambient air at 20°C, if the convection coefficient is h = 300 Btu/(hr-ft²-°F). Use four finite elements with linear interpolation functions (consider symmetry conditions here). ***** Figure P7.18