Precipitation Characteristics of Scaling on Copper and Brass from 0.5mmol/l CaCO₃ Solution at 60°C

Abstract:

Brass and cooper are widely used in heat pump water heater as heat exchanger between refrigerant and water, and the scaling is seriously at 60°C. Study the precipitation characteristics of CaCO₃ is the first step to research anti-fouling technology. CaCO₃ precipitated on brass and copper coupons from 0.5mmol/l CaCO₃ solution by static reaction at 60°C. By weighing the coupons before and after experiments to get the mass of scaling and use Scanning Electron Microscope (SEM) to get the morphology. The results show that at the same condition there is more scaling on copper than brass; high pH not only makes more new crystal nuclei but also promotes square aragonite and calcite and square aragonite gradually recrystallizes to calcite; high pH makes both homogeneous and heterogeneous nucleation rate increasing, but the former increases more, so the scaling mass is bigger at low pH than high pH; under high temperature and supersaturation degree, very small and many crystals are the main substances covered metal surface and not big when scaling layer has been formed, but part of small crystals grow big and all three polymorphs existed but size and proportion were effect by temperature, concentration, pH and so on.

• Periodical: Applied Mechanics and Materials (Volumes 229-231)
• Pages: 142-146
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.229-231.142
• Online since: November 2012
• Authors: Jian Sheng, Hua Zhang
• Keywords: CaCO₃ Crystallization Fouling, Coupon Test, Crystal Morphology

References

[1] GB/T23137-2008. Heat pump water heater for household and similar application [S].

[2] AS 1056. 1-1991. Storage Water Heaters General Requirements [S].

[3] AS/NZS 2712-2002. Solar and Heat Pump Water Heaters Design and Construction [S].

[4] David J. Kukulka, Rick Smith and Kevin G. Fuller. Development and evaluation of enhanced heat transfer tubes [J]. Applied Thermal Engineering, 2011, 31 (13): 2141-2145.

DOI: 10.1016/j.applthermaleng.2011.01.024

[5] Ralf Beck and Jens- Petter Andreassen. The onset of spherulitic growth in crystallization of calcium carbonate [J]. Journal of Crystal Growth, 2010, 312 (15): 2226-2238.

DOI: 10.1016/j.jcrysgro.2010.04.037

[6] Yida Liu, Yong Zou, Liang Zhao, etl. Investigation of adhesion of CaCO3 crystalline fouling on stainless steel surfaces with different roughness[J]. International Communications in Heat and Mass Transfer, 2011, 38(6): 730-733.

DOI: 10.1016/j.icheatmasstransfer.2011.04.003

[7] GB/T 15452-2009. Industrial circulating cooling water-Determination of calcium and magnesium-EDTA titration method [S].

[8] GB19281-2003. Analytic method for calcium carbonate [S].

[9] A. Herz, M. R. Malayeri, H. Müller-Steinhagen. Fouling of roughened stainless steel surfaces during convective heat transfer to aqueous solutions[J]. Energy Conversion and Management, 2008, 49(11): 3381-3386.

DOI: 10.1016/j.enconman.2007.09.034

[10] Wang J., Shen Z.W., Shen Z.Q. Process dynamics and fractal analysis of new phase formation in thermal processes[J]. Journal of Thermal Science, 2001, 10(2): 153-158.

DOI: 10.1007/s11630-001-0058-x

[11] Silvia Rosa, Hans E. Lundager Madsen. Kinetics of mass crystallization of calcium carbonate at 25, 30 and 37℃[J]. Journal of Crystal Growth, 2011, 318(1): 99-102.

DOI: 10.1016/j.jcrysgro.2010.11.005

[12] Basim O. Hasan, Graham J. Nathan and Peter J. Ashman. The effects of temperature and hydrodynamics on the crystallization fouling under cross flow conditions. Applied Thermal Engineering, 2012, 36: 210-218.

DOI: 10.1016/j.applthermaleng.2011.12.027