Experimental investigation of CaSO4 crystallization on a flat plate

M.G. Mwaba, C.C.M. Rindt, A.A. Steenhoven, van, M.A.G. Vorstman

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Abstract

The scaling of calcium sulfate was studied by performing laboratory experiments under controlled conditions. The experiments were aimed at measuring the rate of deposition at different positions on a heated surface. The overall thermal resistance was determined from temperatures measured using thermocouples positioned in the bulk fluid and the wall of the heated plate. Calcium sulfate was used as the experimental fluid. It was observed that nucleates started forming on the downstream side. A nucleation front was formed, and it was seen to move from the downstream to the upstream side. The rate of growth as a function of position was observed to increase with the initial wall temperature distribution, resulting in a final thickness of the scale layer that increases accordingly. While the rate of growth was found to be independent of flow velocity for Reynolds numbers of 11,000 and 23,000, the results showed that the rate of growth decreased by about 20% for Re == 34,000. Further, the induction period is reduced by increasing the flow velocity. An increase in the degree of supersaturation also reduces the induction period. It is concluded that scaling due to CaSO4 results in a non-uniform porous scale layer with a profile that mimics the initial surface temperature.
Original languageEnglish
Pages (from-to)42-54
Number of pages13
JournalHeat Transfer Engineering
Volume27
Issue number3
DOIs
Publication statusPublished - 2006

Fingerprint

flat plates
Crystallization
Calcium Sulfate
crystallization
Flow velocity
Calcium
calcium
sulfates
induction
Fluids
flow velocity
Supersaturation
Thermocouples
scaling
Heat resistance
fluids
wall temperature
Temperature distribution
Reynolds number
Nucleation

Cite this

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title = "Experimental investigation of CaSO4 crystallization on a flat plate",
abstract = "The scaling of calcium sulfate was studied by performing laboratory experiments under controlled conditions. The experiments were aimed at measuring the rate of deposition at different positions on a heated surface. The overall thermal resistance was determined from temperatures measured using thermocouples positioned in the bulk fluid and the wall of the heated plate. Calcium sulfate was used as the experimental fluid. It was observed that nucleates started forming on the downstream side. A nucleation front was formed, and it was seen to move from the downstream to the upstream side. The rate of growth as a function of position was observed to increase with the initial wall temperature distribution, resulting in a final thickness of the scale layer that increases accordingly. While the rate of growth was found to be independent of flow velocity for Reynolds numbers of 11,000 and 23,000, the results showed that the rate of growth decreased by about 20{\%} for Re == 34,000. Further, the induction period is reduced by increasing the flow velocity. An increase in the degree of supersaturation also reduces the induction period. It is concluded that scaling due to CaSO4 results in a non-uniform porous scale layer with a profile that mimics the initial surface temperature.",
author = "M.G. Mwaba and C.C.M. Rindt and {Steenhoven, van}, A.A. and M.A.G. Vorstman",
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Experimental investigation of CaSO4 crystallization on a flat plate. / Mwaba, M.G.; Rindt, C.C.M.; Steenhoven, van, A.A.; Vorstman, M.A.G.

In: Heat Transfer Engineering, Vol. 27, No. 3, 2006, p. 42-54.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Experimental investigation of CaSO4 crystallization on a flat plate

AU - Mwaba, M.G.

AU - Rindt, C.C.M.

AU - Steenhoven, van, A.A.

AU - Vorstman, M.A.G.

PY - 2006

Y1 - 2006

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AB - The scaling of calcium sulfate was studied by performing laboratory experiments under controlled conditions. The experiments were aimed at measuring the rate of deposition at different positions on a heated surface. The overall thermal resistance was determined from temperatures measured using thermocouples positioned in the bulk fluid and the wall of the heated plate. Calcium sulfate was used as the experimental fluid. It was observed that nucleates started forming on the downstream side. A nucleation front was formed, and it was seen to move from the downstream to the upstream side. The rate of growth as a function of position was observed to increase with the initial wall temperature distribution, resulting in a final thickness of the scale layer that increases accordingly. While the rate of growth was found to be independent of flow velocity for Reynolds numbers of 11,000 and 23,000, the results showed that the rate of growth decreased by about 20% for Re == 34,000. Further, the induction period is reduced by increasing the flow velocity. An increase in the degree of supersaturation also reduces the induction period. It is concluded that scaling due to CaSO4 results in a non-uniform porous scale layer with a profile that mimics the initial surface temperature.

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