Effects of fluid flowrate on coconut milk fouling at pasteurization temperature (70ºC - 74.5ºC) Waraporn Pichitvittayakarn 1 , Phavanee Narataruksa 2 , Peter J. Heggs 3 and Suvit Tia 4 Abstract Pichitvittayakarn, W., Narataruksa, P., Heggs, P.J. and Tia, S. Effects of fluid flowrate on coconut milk fouling at pasteurization temperature (70ºC - 74.5ºC) Songklanakarin J. Sci. Technol., 2006, 28(6) : 1275-1288 Effects of fluid flowrate on coconut milk fouling at pasteurization temperature (heating from 70ºC to 74.5ºC) were investigated. A test section equipped with four flat plates forming one coconut milk channel and two hot water channels was constructed with the total heat transfer area of 0.051 m 2 . Three different flowrates of coconut milk (2, 4 and 6 litres per minute (LPM)) were studied. Monitoring of the overall heat transfer coefficient (U) with time (t) and the rate of increase of the fouling resistance (dRf/dt) was done for all experimental runs. The results illustrated that there were two fouling periods: a fouling period and a post-fouling period, where the rate of increase of the fouling resistance of the fouling period was found to be ORIGINAL ARTICLE 1 M.Sc. Student in Energy Technology, The Joint Graduate School of Energy and Environment, 4 Ph.D.(Chem- ical Engineering), Assoc. Prof., Department of Chemical Engineering, Faculty of Engineering, King Mongkut's University of Technology Thonburi, Bandmod, Tungkru, Bangkok 10140, Thailand. 2 Ph.D.(Chemical Engi- neering), Asst. Prof., Department of Chemical Engineering, Faculty of Engineering, King Mongkut's Institute of Technology North Bangkok, Bangsue, Bangkok, 10800 Thailand. 3 Ph.D.(Chemical Engineering), Prof., School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M60 1QD, United Kingdom Corresponding e-mail: waraporn_pc@yahoo.com Received, 23 January 2006 Accepted, 10 April 2006