Development of a new high performance heat exchanger using a surfactant water solution

通过实验研究了表面活性剂水溶液流动中的减阻和传热特性。结果表明，该方法的减阻率可达70%以上，同时传热系数也以相同的速率降低。为了促进表面活性剂水溶液流动的传热，提出了一种三角肋强化方法。与无肋情况相比，减阻和换热特性对Re和C的依赖性相似，但减阻达到最大的临界雷诺数较小。通过恒定泵功率下的性能评价，验证了表面活性剂与三角肋复合的方法对换热器性能的改善是有效的。为了研究汤姆效应对温度的依赖性，在二维通道中以入口速度、工质温度和壁面温度为参数进行了速度和温度分布的测量。与温度分布相比，速度分布随壁面温度变化明显。然而，汤姆效应并没有停止工作，当热边界层的温度为0时，它停止工作。汤姆效应对温度非常敏感，另一方面表明变化过程是复杂的。由于上述三角肋过于昂贵，无法应用于实际产品换热器，因此对表面粗糙的单管进行了减阻率的测量。研究发现，观察到的汤姆斯效应的出现与以前的结果相似。在换热器方面，对市场上采用粗糙管的散热器减阻率进行了测量。它是由散热器的头部部分减少，但粗糙度管仍然是有用的，以减少阻力。少

An experiment was conducted to investigate the drag-reduction and the heat transfer characteristics in a surfactant water solution flow. It was confirmed that the percentage of the drag-reduction was more than 70 % and simultaneously, the heat transfer coefficient was reduced at the same rate. In order to promote the heat transfer for the surfactant water solution flow, an enhancement method using a triangular rib was proposed. Comparing with the case without rib, it was found that the dependence of the drag-reduction and the heat transfer characteristics on Re and C was similar, but the critical Reynolds number at which the drag reduction reaches a maximum was smaller. Further, by the performance evaluation based on a constant pump power, it was verified that the compound method by the surfactant and the triangular rib is effective to improve the performance of heat exchangers.To investigate the temperature dependence of the Tom's effect, measurements of velocity and temperature profi … More les in a two-dimensional channel were done as parameters of inlet velocity, temperature of the working fluid and wall surface. It was found that the velocity profiles vary clearly with temperature of the wall surface as comparing with the temperature profiles. However, the Tom's effect does not stop working, when the temperature in the thermal boundary layer is that it stops working. The Tom's effect is very sensitive for the temperature, on the other hand it is suggested that the varying process is complex.The rate of drag reduction of a single pipe with, roughness surface using the air-conditioner was measured, because the triangle rib as mentioned above is too expensive to apply to a real-product heat exchanger. It was found that the appearance of the Toms effect is observed as similar with previous results. As concerning the heat exchanger, the rate of drag reduction of the radiator on the market with using roughness pipe is measured. It is decreased by the header part of the radiator, however the roughness pipe is still useful for the drag reduction. Less