Numerical Analysis On The Laminar Flow And Heat Transfer In The Micro-channels With Roughness

For micro-channel cooling system, how to further enhance the heat transfer performance while reducing pressure drop has been an active area of research. Micro-channels with different morphologies roughness is an effective way to enhance the heat transfer performance. As a passive scheme, the roughness can increase disturbance of the flow to improve heat transfer efficiency due to induced breaking and destabilizing in the thermal boundary layer, but also enlarge the pressure drop of the fluid. This paper investigates the property of micro-channels by heat transfer enhancement and pressure drop reduction.In this paper numerical study of laminar fluid flow and heat transfer characteristics in three different morphologies roughness micro-channels were performed by using Fluent software. The author’s major contributions are outlined as follows:1. Firstly, according to the characteristics of the roughness micro-channel structure, the three-dimensional models were established; Then the model was meshed based on the finite element method, we also verify the accuracy and reliability of the calculation method by solving the smooth rectangular micro-channel.2. This paper emphasizes the difference of speed, pressure and temperature fields between the three micro-channels, analyses the trend of average Nusselt number Nu, pressure drop Dp and overall heat transfer factor PF along with the change of structure parameters, including the roughness of the wave height h, pitch p, and the Reynolds number Re. In general, the simulation shows that both Nu and Dp increase with the increase of roughness height and the Reynolds number or the decrease of pitch, but the latter increases by a big magnitude.3. Under the same parameters, the micro-channel I has the largest Nu and Dp among the three different morphologies roughness micro-channels, and when we use the PF as evaluation criteria, the micro-channel I also has better comprehensive performance compared to micro-channel II and micro-channel III, indicate micro-channel I has better heat transfer performance.4. Through the use of Design-Expert 9.0 software as a tool we establish a regression model about the Nu, Dp and PF based on the response surface methodology. For microchannel I, the biggest affect factor on Nu is the inlet velocity, while the most influential factor on Dp is the wave height. So the combinations of a large inlet velocity and small wave height can achieve the channel optimization. Considering the three structural parameters and inlet velocity, the paper carries an optimization on channel I with response surface method, and the goal is to obtain the parameters of the optimized microchannel.