Principle
The temperature response of the unsteady inlet temperature varying with time is an essential parameter in the thermal design of the heat exchanger and other heat transport equipment. The temperature amplitude variation along the general passage decays exponentially and can usually be determined by experiment. This variation will affect the entire heat transport process within the heat exchanger and other heat-transport equipment.
Objective
The objective of this experiment is to determine the decay of the temperature oscillation along the channel for a timewise oscillation of inlet temperature. In practical applications, the heat transfer within the channel may be exposed to some planned or unplanned transients or start-ups and shutdowns during the operation. Thus, such a knowledge is critically necessary for those devices which never attain steady-state operation because of their nature of periodical operation in time.
Apparatus
The experimental apparatus consists of a rectangular duct with different sections of filter, calming, inlet, test, and convergence. The geometry of the test section is a rectangular duct with a cross section of 254 × 25.4 mm2 (10 × 1 in.2). The instrumentation includes a wave generator, a power supply, a heater, an inclined manometer, voltmeters, thermocouples, an orifice plate, and a fan, as shown in Fig. 14.1.
Air flows from the calming section to the inlet section (2770 mm in length) wherein the velocity becomes fully developed.