Forced Convection over a Cylindrical Heating Element: Air Flow along the Surface of a Solid Cylinder

A convection heat transfer experiment was conducted in which a ball valve attached to an air compressor was used to vary the air velocity through a rectangular pipe. Within the pipe was a cylindrical heating element oriented with its axis parallel to the air flow through the pipe. PID's were used to measure the pipe's inlet and outlet temperature and the temperature of the heating element. After the air exited the rectangular pipe, it passed through a cylindrical pipe with a pitot tube. The pitot tube was connected to a hose which acted as a U-tube manometer. This manometer measured the difference in the air flow's stagnation pressure with the atmospheric air pressure through the pipe. The air then exited the pipe into the atmosphere. Increasing the air velocity resulted in an increasing mass flow rate, which in turn increased the Reynolds number of the air flow. Increasing the mass flow rate also resulted in increasing heat transferred to the air as seen below. This is most likely a result of the air flow not being fully developed in the heated section as suggested by the calculated Graetz number.