چکیده:
In this study, laminar flow is considered, and the heat transfer oil is investigated numerically in horizontal, smooth and micro-fin tubes at different fin heights and spiral angles with boundary conditions of constant wall temperature. The variables considered in the micro-fin tubes are the number of fins that varies from 40 to 60, the micro-fin’s height that varies is from 0.2 to 0.5 mm, and the micro-pin spiral angle that varies between 5 and 47 degrees. This study was conducted for Reynolds number ranging from 500 to 100, inner tube diameter of 8.62 and outer diameter of 9.52 mm. The numerical resolution was done using ANSYS fluent v.15 commercial software.
The numerical method was validated by comparing the results of simulating laminar flow of oil through a smooth and micro-fin tube with experimental results and previous observations. The simulation results are then used in the genetic algorithm for optimizing the micro-fin geometry. The results showed that increasing Reynolds number and micro-fin height increases the optimum surface. However, a different trend is observed for the desired spiral angle.
خلاصه ماشینی:
com Received: March 2018 Accepted: April 2018 Abstract In this study, laminar flow is considered, and the heat transfer oil is investigated numerically in horizontal, smooth and micro-fin tubes at different fin heights and spiral angles with boundary conditions of constant wall temperature.
s/m2 ṁ mass flow rate, kg/s θ dimensional coordinates Nu Nusselt number density, kg/m3 p pressure, Pa, and fin pitch, m Subscripts Re Reynolds number f fluid t fin width, m i inlet r, z dimensional coordinates, m o outlet T temperature, K w wall A number of recent experimental studies have been conducted on single-phase fluid flow through micro-fin tubes.
In another experimental study, Han and Lee [2] investigated the characteristics of single-phase heat transfer and the characteristics of fluid flow in micro-fin tubes.
Their results showed that larger angle and fin height caused pressure drop in inside the angularly-shaped micro-fin tubes and, furthermore, the pressure drop in the spiral tube was significantly higher than that in the smooth tubes, which works depending on the geometric parameters of the sheet and the velocity of the mass fluid.
4. Numerical Pattern The governing equations for laminar non-isothermal flow of the heat transfer oil through smooth and micro-fin tubes for constant wall temperature boundary conditions are applied numerically using ANSYS CFX v.
Additionally, the Reynolds number is estimated based on the integrated inlet fluid velocity, thermo-physical properties at the inlet temperature of the fluid hydraulic diameter for determining the optimal conditions related to pressure drop and heat transfer for the micro-fin tubes.