A second law assessment is conducted to study irreversibility values for the stream of a hybrid water-based nanofluid within a microchannel heat sink fitted with secondary channels and rectangular ribs. The hybrid nanofluid has been synthesized from the graphene nanoplatelets on which the silver nanoparticles have been decorated. In the fluid part, entropy generations caused by heat transfer and friction are intense in the interfaces of solid-fluid, whereas lower thermal entropy generation occurs in the dead zones. In the solid part, thermal entropy generation in corners of the solid-fluid interface is higher than other regions. The lowest thermal entropy generation happens at the front of ribs, whereas the frictional entropy generation demonstrates lowest values at the heat sink central part. With the elevation of either Reynolds number (Re) or weight fraction, the entropy produced by heat exchange reduces. A 7 % decline in the total entropy generation happens by adding the nanoparticles with concentration of 0.1 % at Re = 300, while a 17 % reduction in this parameter happens with elevating the Re from 100 to 500 at concentration of 0.06 %. Furthermore, with the growth of concentration and decrement of Re, the contribution of solid to thermal entropy generation intensifies compared with the fluid.

进行第二定律评估，以研究装有次级通道和矩形肋的微通道散热器中混合水基纳米流体流的不可逆性值。杂化纳米流体是由已在其上装饰了银纳米颗粒的石墨烯纳米片合成的。在流体部分，由热传递和摩擦引起的熵产生在固体-流体的界面中很强烈，而在死区中发生的热熵较低。在固体部分，固体-流体界面角落的热熵产生高于其他区域。最低的热熵产生发生在肋骨的前部，而摩擦熵的产生则在散热片的中央部位表现出最低的值。随着雷诺数（Re）或重量分数的升高，由热交换产生的熵减小。通过添加Re = 300时浓度为0.1％的纳米颗粒，总熵产生降低了7％，而当Re浓度从0.06％提高到100时，该参数降低了17％。此外，随着Re浓度的增加和Re的减少，与流体相比，固体对热熵产生的贡献增加。