Numerical investigation on pre-heating of coal water slurry in shell-and-tube heat exchangers with fold helical baffles. (November 2018)

• Record Type: Journal Article
• Authors: Wang, Simin; Xiao, Juan; Ye, Shupei; Song, Chen; Wen, Jian
• Is Part Of: International journal of heat and mass transfer. Volume 126(2018)Part B
• Page Start: 1347
• Page End: 1355
• Publication Date: 2018-11
• Subjects: Shell-and-tube heat exchanger -- Fold helical baffle -- Coal water slurry -- Non-Newtonian fluid -- Bingham model -- Pre-heating process; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2018.06.060
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Coal water slurry can be effectively preheated in a new type of heat exchanger. Coal water slurry is a shear-thinning fluid and simulated with Bingham model. The thermo-performance of non-Newtonian fluid is different from Newtonian fluid. Both Nu and f increase with the helical angle and reduce with the overlapped degree. Comprehensive performance of fold helical baffle is superior to segmental baffles. Abstract: Pre-heating process of coal water slurry (CWS) in Integrated Gasification Combined Cycle (IGCC) systems is beneficial to enhance the energy efficiency. In this paper, shell-and-tube heat exchangers with fold helical baffles (STHXsFHB) were firstly used as pre-heating exchanger. Using numerical simulation method, the flow and heat transfer performance of STHXsFHB with different helical angles and overlapped degrees was investigated. CWS with concentration of 62 wt% was shell-side fluid, which is characterized as non-Newtonian fluid and simulated with Bingham model. The numerical results show the temperature of CWS rises obviously, both Nusselt number and friction coefficient increase with helical angle at same shell-side mean velocity, Nu · f − 1/3 decreases when helical angle increases. Nusselt number and friction coefficient have a negative correlation with overlapped degree, and Nu · f −1/3 with 50% overlapped degree is 13.8–33.1% and 3.9–8.8% higher than that with 1% and 30% overlapped degree, respectively. The variation of Nusselt number and friction coefficient versus helical angle and overlapped degree of CWS differs from thermal-hydraulic performance of Newtonian fluid in STHXsFHB. It is also found that the comprehensive performance of STHXsFHB is superior to shell-and-tube heat exchangers with segmental baffles.