Journal of Food Engineering 109 (2012) 49–61
Contents lists available at SciVerse ScienceDirect
Journal of Food Engineering
journal homepage: www.elsevier.com/locate/jfoodeng
A spinning disc study of fouling of cold heat transfer surfaces by gel formation from model food fat solutions
Jen-Yi Huang, Y.M. John Chew, D. Ian Wilson ⇑
Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA, UK Department of Chemical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK
a r t i c l e
i n f o
Received 10 August 2011
Received in revised form 19 September
Accepted 29 September 2011
Available online 8 October 2011
a b s t r a c t
The formation of immobile gels on heat transfer surfaces (‘coring’) caused by cooling fat solutions below their cloud point was studied using a novel spinning disc apparatus (SDA). The SDA features a cooled, removable heat transfer surface with well deﬁned heat and mass transfer characteristics. Measurements of heat ﬂux were combined with computational ﬂuid dynamics simulations to yield reliable estimates of the surface temperature and shear stress. Fouling studies were performed with model solutions of 5 wt.% tripalmitin in a parafﬁn oil operating in the ‘cold start’ mode, wherein the experiment starts with the surface colder than the steady state, simulating one mode of operating a standard ‘cold ﬁnger’ experiment. Local heat ﬂux measurements allowed the thermal fouling resistance to be monitored: deposit mass coverage and composition were also measured. The cold surface promotes the rapid formation of an initial gel layer, followed by a period of linear fouling, and ﬁnally falling rate fouling behaviour. The linear fouling rate was relatively insensitive to temperature and shear rate, while the fouling rate in the falling rate regime was found to depend on the temperature driving force for crystallisation kinetics. The solids fraction within the deposit layer increased over the duration of a 12 h fouling test, indicating rapid ageing. The rheological properties of the deposits were highly sensitive to solids fraction. Ó 2011 Elsevier Ltd. All rights reserved.
The accumulation of unwanted solids on process surfaces is a persistent problem. These materials usually have low thermal conductivity, creating signiﬁcant resistance to heat transfer. This fouling deposition can also cause partial or complete blockage of piping and process equipment, reducing ﬂow rate together with increasing pressure drop. The formation of deposits from liquid fats on cold surfaces can affect both heat exchangers and distribution lines in the food sector. This ‘coring’ of distribution lines can impair product quality by contamination and by harbouring micro-organisms, as well as reducing the performance of trace heating or cooling designed to maintain the fat in a particular state. Coring is an example of crystallisation fouling, which Epstein (1983) deﬁned as deposition resulting from solubility differences, such that solids are generated from solution at the heat transfer
Abbreviations: CFD, computational ﬂuid dynamics; DSC, differential scanning calorimeter; NTU, number of turbidity units; PPP, tripalmitin; SDA, scanning disc apparatus.
⇑ Corresponding author at: Department of Chemical Engineering and Biotech nology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA, UK. Tel.: +44 1223 334791; fax: +44 1223 334976.
E-mail addresses: firstname.lastname@example.org,email@example.com(D.IanWilson). 0260-8774/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2011.09.034
surface. The fouling layer can form via heterogeneous growth on the surface, as in water scaling, or by crystallisation of the higher melting point components in the solution at the cold...
References: Nigo et al. (2009). Loci indicate power law trend lines (Eq. (21)) ﬁtted to the data
sets: G’ = 9 Â 107/3.7; sEL = 2.9 Â 105/4.8 and sC = 2.4 Â 105/2.8.
Akbarzadeh, K., Zougari, M., 2008. Introduction to a novel approach for modeling
wax deposition in ﬂuid ﬂows
Bansal, B., Muller-Steinhagen, H., 1993. Crystallization Fouling in Plate Heat
Bidmus, H.O., Mehrotra, A.K., 2004. Heat-transfer analogy for wax deposition from
Borisov, V.T., Dukhin, A.I., Matveev, Y.E., Nikonova, V.V., Rakhmanova, E.P., 1968.
Crittenden, B.D., Khater, E.M.H., 1987. Fouling From Vaporizing Kerosine. Journal of
Heat Transfer 109 (3), 583–589.
Davey, R., Garside, J., 2000. Phase equilibria and crystallization techniques. In:
Davey, R., Garside, J
De Graef, V., van Puyvelde, P., Goderis, B., Dewettinck, K., 2009. Inﬂuence of shear
ﬂow on polymorphic behavior and microstructural development during palm
Elphingstone, J.G.M., Greenhill, K.L., Hsu, J.J.C., 1999. Modeling of Multiphase Wax
Epstein, N., 1983. Thinking about heat transfer fouling: A 5 Â 5 matrix. Heat
Transfer Engineering 4 (1), 43–56.
J.-Y. Huang et al. / Journal of Food Engineering 109 (2012) 49–61
Fernandez-Torres, M.J., Fitzgerald, A.M., Paterson, W.R., Wilson, D.I., 2001
Fitzgerald, A.M., Barnes, J., Smart, I., Wilson, D.I., 2004. A model experimental study
of coring by palm oil fats in distribution lines
Gregory, D.P., Riddiford, A.C., 1956. Transport to the surface of a rotating disc.
Journal of the Chemical Society(OCT) 3756, 3764.
Hartel, R.W., 2001. Crystallization in Foods. Aspen Publication, Maryland, USA.
Hillig, W.B., 1966. A derivation of classical two-dimensional nucleation kinetics and
the associated crystal growth laws
Hillig, W.B., Turnbull, D., 1956. Theory of crystal growth in undercooled pure
Jackson, K.A., Chalmers, B., 1956. Kinetics of solidiﬁcation. Canadian Journal of
Physics 34 (5), 473–490.
Jennings, D.W., Weispfennig, K., 2005. Effects of shear and temperature on wax
deposition: Coldﬁnger investigation with a Gulf of Mexico crude oil
Fuels 19 (4), 1376–1386.
Kellens, M., Meeussen, W., Reynaers, H., 1990. Crystallization and phase-transition
studies of tripalmitin
Kern, D.Q., Seaton, R.E., 1959. A theoretical analysis of thermal surface fouling.
Marangoni, A.G., Rogers, M.A., 2003. Structural basis for the yield stress in plastic
Mullin, J.W., 1993. Crystallisation, third ed. Butterworth-Heinemann, London, UK.
Nazar, A.R.S., Dabir, B., Islam, M.R., 2005. Experimental and mathematical modeling
of wax deposition and propagation in pipes transporting crude oil
Nigo, R.Y., Chew, Y.M.J., Houghton, N.E., Paterson, W.R., Wilson, D.I., 2009.
Parthasarathi, P., Mehrotra, A.K., 2005. Solids deposition from multicomponent
wax-solvent mixtures in a benchscale ﬂow-loop apparatus with heat transfer.
Energy and Fuels 19 (4), 1387–1398.
Ramirez-Jaramillo, E., del Rio, J.M., Manero, O., Lira-Galeana, C., 2010. Effect of
deposition geometry on multiphase ﬂow of wells producing asphaltenic and
Ribeiro, F.S., Souza Mendes, P.R., Braga, S.L., 1997. Obstruction of pipelines due to
parafﬁn deposition during the ﬂow of crude oils
and Mass Transfer 40 (18), 4319–4328.
Saiban, S., Brown, T.C., 1997. Kinetic model for cloud-point blending of diesel fuels.
Fuel 76 (14–15), 1417–1423.
Sato, K., Kuroda, T., 1987. Kinetics of melt crystallization and transformation of
Shih, W.-H., Shih, W.Y., Kim, S.-I., Liu, J., Aksay, I.A., 1990. Scaling behavior of the
elastic properties of colloidal gels
Singh, P., Venkatesan, R., Fogler, H.S., Nagarajan, N., 2000. Formation and aging of
incipient thin ﬁlm wax-oil gels
Singh, P., Venkatesan, R., Fogler, H.S., Nagarajan, N.R., 2001a. Morphological
evolution of thick wax deposits during aging
Please join StudyMode to read the full document