Abstract
Performance assessments on heat transfer, pressure loss, and thermal enhancement factor in the circular tube heat exchanger inserted with the V-orifices are investigated numerically. The influences of the blockage ratio, gap spacing ratio, and orifice arrangement are reported for turbulent regime, Re=3000–10,000. The finite volume method and SIMPLE algorithm are selected to solve the present problem. The mechanisms on flow and heat transfer characteristics are described. The periodic concepts on flow and heat transfer are also studied. The numerical results show that the gap spacing ratio is main reason for the changes of the flow and heat transfer topologies. The gap distance helps to adjust the optimum point of the thermal performance, especially at high flow blockage ratio. In addition, the optimum thermal performance of the present system is around 2.25 at the lowest Reynolds number, Re=3000.
Highlights
The passive technique had been used to improve various types of the heat exchangers
The influences of the diameter ratios and pitch ratios (P/D) were examined for turbulent regime, Re = 4000–20,000. They reported that the heat transfer augmentation is around 57–195% when compared with the smooth circular tube without vortex generator
The numerical investigations on turbulent forced convection and heat transfer behavior in the circular tube heat exchanger inserted with the V-orifices are reported
Summary
The passive technique had been used to improve various types of the heat exchangers. The passive method does not require the additional power to enhance the heat transfer rate and thermal performance. The influences of the diameter ratios (diameter of the orifice to the diameter of the tube) and pitch ratios (P/D) were examined for turbulent regime, Re = 4000–20,000 They reported that the heat transfer augmentation is around 57–195% when compared with the smooth circular tube without vortex generator. The selection of the conical-ring to improve the heat exchanger was reported by many researchers [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15] They found that the conical-ring in the heat exchanger enhances heat transfer rate and thermal efficiency and increases very large pressure loss, especially at low diameter ratio (low flow area). They concluded that the twistedring provides higher heat transfer rate, pressure loss, and thermal performance than the typical conical-ring They stated that the maximum thermal enhancement is around 1.24 at Re = 6000.
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