Performance assessment of turbular heat exchanger tubes containing rectangular-cut twisted tapes with alternate axes

Esfahani

2020

Powder Technology

In this study, turbulent flow characteristics of CuO-water nanofluid through heat exchanger pipe enhanced with louvered strips are numerically investigated. Nanoparticles volume fraction    varied from 0 to 2% . The louvered strips are mounted in single and double geometries. The slant angle    and the Reynolds number (Re) are within 15 25    and between 5,000 and 14,000, respectively. (RNG) k   model is employed based on the finite volume technique. The results illustrated that strong flow disturbance between the wall and the louvered strip is the main reason for turbulent kinetic energy increment. Besides, the nanoparticles improve the thermophysical properties of the working fluid, which results in better heat transfer. The Nu number increases 15.6% by using nanofluid instead of water at Re 14000  . The highest thermal enhancement parameter of 1.99 is obtained at Re 14000  by using double perforated louvered strip with 25    . The recirculating flow inside the holes can significantly improve the thermal performance.

Section: Discussionmentioning

confidence: 64%

CFD approach for two-phase CuO nanofluid flow through heat exchangers enhanced by double perforated louvered strip insert

Esfahani

2020

Powder Technology

“…Present study, DCTT (b/c=0.9) Twin TT [32] Arc-TA [33] Cross hollow TT [12] Non-uniform TA [34] Jagged TT [23] TA [35] Peripherally cut 2000 4000 6000 8000 10000 12000 14000 16000…”

Section: Resultsmentioning

confidence: 87%

Experimental investigation of heat transfer enhancement of a heat exchanger tube equipped with double-cut twisted tapes

Applied Thermal Engineering

Hatami

Rahmati

2020

“…As a result, the friction factor decreases, and the thermohydraulic performance intensified. Non-uniform TA [42] Jagged TT [43] Twisted tape-Alternate [44] Peripherally-cut TT [45] Square-cut TT [46] Twin TT [47] Rectangular-cut Alternate [48] Double V-cut TT [5] Multiple TT [49] V-shaped winglet [40] V-shaped ring [50] TT and Wire coil insert [51] Fig. 13 Comparisons of thermohydraulic efficiency parameter with previous studies…”

Section: Code Validationmentioning

confidence: 81%

Turbulent Flows Inside Pipes Equipped With Novel Perforated V-Shaped Rectangular Winglet Turbulators: Numerical Simulations

Journal of Energy Resources Technology

Rahmati

2020

In this study, computational simulations have been performed to investigate the turbulent characteristics and energy consumption through heat exchanger tubes equipped by new perforated V-shaped rectangular winglet (PVRW) turbulators. The effects of the holes intensity on the velocity and temperature contours are additionally investigated. The Reynolds number, hole diameter ratio, and the number of holes selected are in the range of 5000 ≤ Re ≤ 18,000, 0 ≤ DR ≤ 0.40, and 0 ≤ N ≤ 14, respectively. Renormalization group (RNG) k–ε turbulent model which is a finite volume solver is utilized for the computational fluid dynamics (CFD) simulation. It was noticed that the proposed perforated turbulators could considerably intensify the thermal performance compared to typical VRW inserts. It is found that the recirculating flow generated by the PVRW augments the fluid mixing and transfers the heat from the pipe walls to the core of the tube. The simulations illustrate that the amount of heat transfer enhances 25.2% reducing the DR from 0.4 to 0.13 at Re = 18,000 and N = 14. Also, using PVRW turbulators with N = 7 and DR = 0.26 augments the average Nusselt number around 354.3% compared to the circular pipe without inserts. The highest thermal efficiency parameter of η = 2.25 could be obtained at Re = 5000 for the heat exchangers fitted by vortex generators with N = 14 and DR = 0.26.