Influence of thermal shock on the mitigation of calcium sulfate crystallization fouling under subcooled flow boiling condition

• Published in: Applied thermal engineering 2020-01, Vol.164, p.114434, Article 114434
• Main Authors: Vosough, A., Peyghambarzadeh, S.M., Assari, M.R.
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Boiling; Calcium; Calcium sulfate; Chemical compounds; Chen model; Cooling; Crystallization; Flow velocity; Fouling; Heat flux; Heat transfer; Subcooled flow boiling; Temperature effects; Thermal shock
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2019.114434

•Effects of thermal shock on the fouling mitigation under subcooled flow boiling.•Thermal shock cracked and removed fouling layer while the system is in operation.•Thermal shock was successful when fouling resistance is above 0.1 m2 K/kW. Fouling is a common and high cost problem in various heat transfer equipment. Different on-line and off-line solutions were recommended for fouling mitigation in the recent years. Thermal shock technique which is performed by sudden decrease or increase in heated surface temperature is known as one of the on-line ways to mitigate fouling. In this research, several experiments performed in order to investigate the effects of thermal shock on the fouling mitigation in a vertical upward annulus under subcooled flow boiling conditions for calcium sulfate (CaSO4) aqueous solution. The experiments conducted at different levels of operating conditions such as fluid bulk temperatures (55–75 °C), volume flow rates (2.5–5.5 l/min), heat fluxes (8–95 kW/m2), and calcium sulfate aqueous solution concentrations (1.75–2.2 g/l). The results revealed that at higher fouling resistance approximately above 0.1 m2 K/kW, thermal shock could successfully disintegrate and deteriorate the fouling layer, and return the heat transfer surface to its initial condition.