3606 (RP-560) -- An Experimental Study of Tube-Side Fouling Resistance in Water-Chiller-Flooded Evaporators PDF

An experimental study was conducted to measure the fouling thermal resistance in the tubes of water-chiller-flooded evaporators operating at approximately 45 deg F (7.2 deg C). The fouling resistance measurements were made in a specially designed 12.6-foot-long test evaporator containing 16 tubes that was connected in parallel with an existing 250-ton R11 chiller evaporator. The test evaporator used the same water that flowed through the tubes of the 250-ton evaporator. Refrigerant from the 250-ton evaporator was boiled on the outer surface of the test evaporator tubes. Two sets of fouling data were taken-one for the 1990 cooling season (May through October) and one for the 1991 cooling season. The data were taken for one internally plain and three internally enhanced tube geometries. The fouling resistance of each tube was compared with that of an identical tube, which was manually brushed twice weekly. During the first year, the data were taken with normal water quality at 3.5 fps (1.1 m/s) water velocity. During the second year, the data were taken with dirty water quality at 3.5 fps (1.1 m/s) and 7.0 fps (2.1 m/s) water velocities. Presents and discusses the two-year fouling data. The results for two cooling seasons show that negligible fouling will occur in the evaporator tubes.

KEYWORDS: experiment, measuring, fouling, friction loss, tubes, chillers, evaporators, R11, cooling season, testing, comparing