Exergy loss measures ineffectiveness of a heat exchanger. Hence, it was experimentally found in a three-channel 1-1 pass plate heat exchanger (PHE). Air was made to flow in the central channel to get heated by water in the outer channels under conditions of counter and parallel flows. The plates had sinusoidal wavy surfaces having corrugation angle of 30 degrees. Reynolds numbers were in the range of 650-2600 for air and 400-1650 for water. Bulk temperature of air was in the range from 46 degrees C to 63 degrees C and that of water in the range 70-75 degrees C. To avoid entropy generation paradox, two methods have been proposed. In the first method exergy loss is scaled on product of heat capacity rate of cold fluid and its inlet temperature, and in the other on maximum heat transfer rate. The second method helps in arriving at the conclusions more precisely. The experimental results have been compared with the results available in the literature for corrugated water-water PHE. The exergy loss in the sinusoidal PHE is found less than that in the rectangular wavy PHE for given flow conditions and may be attributed to less turbulence and better solid-fluid contact. (C) 2011 Elsevier Ltd. All rights reserved.