Abstract
This paper presents a new statistical, nondestructive method for determination of the experimental channels clogging rate in a mini- or microchannel heat exchanger. Channels clogging may be caused by inaccurate fabrication of the heat exchanger or by fouling of microchannels during exploitation. The theoretical model, used in this method, predicts a significant increase of the pressure drop as the number of clogged microchannels increases. However, the exchanger’s heat transfer rate decreases moderately. It may partly be caused by the additional heat transfer in metal walls, bypassing the inactive, clogged microchannels. The presented method was tested on the prototype of a microchannel heat exchanger. The experimental values of the pressure drop of the hot and cold water flows are 2–5 times higher than the values predicted for clean microchannels. The experimental values for the pressure drop and heat transfer are in good agreement with the values calculated by the use of the theoretical model. The presented statistical method gives two channels clogging rates (for the “hot” and “cold” channels) obtained during normal exploitation without cutting (destroying) the heat exchanger.
Statistical Determination of Rainfall-Runoff Erosivity Indices for Single Storms in the Chinese Loess Plateau