Investigation of turbulent heat transfer and nanofluid flow in a double pipe heat exchanger

• Published in: Advanced powder technology : the international journal of the Society of Powder Technology, Japan Japan, 2018-02, Vol.29 (2), p.273-282
• Main Authors: Bahmani, Mohammad Hussein, Sheikhzadeh, Ghanbarali, Zarringhalam, Majid, Akbari, Omid Ali, Alrashed, Abdullah A.A.A., Shabani, Gholamreza Ahmadi Sheikh, Goodarzi, Marjan
• Format: Article
• Language: English
• Subjects: Double pipe heat exchanger; Finite volume method; Thermal efficiency; Turbulent nanofluid flow
• ISSN: 0921-8831; 1568-5527
• DOI: 10.1016/j.apt.2017.11.013

Schematic of the problem. [Display omitted] •Forced convection of nanofluids through a double pipe heat exchanger was studied.•Effects of flow direction, nanoparticle concentration and Re were investigated.•More nanoparticles volume fraction, higher outlet or wall temperature.•Increasing Re, thermal efficiency gradually tends to a constant amount. In present study, heat transfer and turbulent flow of water/alumina nanofluid in a parallel as well as counter flow double pipe heat exchanger have been investigated. The governing equations have been solved using an in-house FORTRAN code, based on finite volume method. Single-phase and standard k-ε models have been used for nanofluid and turbulent modeling, respectively. The internal fluid has been considered as hot fluid (nanofluid) and the external fluid, cold fluid (base fluid). The effects of nanoparticles volume fraction, flow direction and Reynolds number on base fluid, nanofluid and wall temperatures, thermal efficiency, Nusselt number and convection heat transfer coefficient have been studied. The results indicated that increasing the nanoparticles volume fraction or Reynolds number causes enhancement of Nusselt number and convection heat transfer coefficient. Maximum rate of average Nusselt number and thermal efficiency enhancement are 32.7% and 30%, respectively. Also, by nanoparticles volume fraction increment, the outlet temperature of fluid and wall temperature increase. Study the minimum temperature in the solid wall of heat exchangers, it can be observed that the minimum temperature in counter flow has significantly reduced, compared to parallel flow. However, by increasing Reynolds number, the slope of thermal efficiency enhancement of heat exchanger gradually tends to a constant amount. This behavior is more obvious in parallel flow heat exchangers. Therefore, using of counter flow heat exchangers is recommended in higher Reynolds numbers.