## 1 Introduction
[13] experimentally and numerically investigated the thermal performance of plate fin heat sink subjected to impinging air flow with variable Reynolds numbers, the impinging distance, and the fin constructions. [PERSON] and [PERSON] [14] made a critical review to summarize the development of air-cooled heat sink with forced flow arrangement. [PERSON] et al. [15] investigated the air cooling module of electronic equipment and found the influences of heat load of heater and input current to cooler by experiments. [PERSON] et al. [16] investigated the performance of a thermoelectric generator which has air cooling system and made two-stage optimized design. [PERSON] [17] made the three-dimensional computational fluid dynamics (CFD) simulation of fluid flow and heat transfer capabilities for the plate fin and pin fin heat sinks with different inlet velocities. [PERSON] et al. [18] developed a CFD model to compare the flow and thermal characteristics for the plate fin heat sink of fillet profiles in parallel flow arrangement with that of a rectangular channel without fillet profiles in impinging flow. [PERSON] et al. [19] made numerical simulations to investigate the thermal and flow performance of heat sinks which possess finned metal foam subjected to impinging air flow with different configuration parameters. [PERSON] et al. [20] developed a V-groove cool-plate to investigate its pressure drop and thermal performance and made a structural optimization. They studied the effect of tilt angle on flow and thermal performance simultaneously. [PERSON] et al. [21] used the standard k-\(\varepsilon\) model to make numerical simulations and found the conjugate heat transfer effects in a computer chassis. Fully and partially shrouded heat sinks with forced convection flow were used by [PERSON] et al. [22] to numerically and experimentally study the influence on thermal performance, and they found that the pressure drop with partially shrouded heat sinks decreased 50% compared with fully shrouded heat sinks. [PERSON] et al. [23] experimentally and numerically studied the hydrodynamic and heat transfer characteristics for a plate fin heat sink with a variable rectangular impinging jet. [PERSON] et al. [24] made numerical simulations to investigate the performance of the thermoelectric generator system and optimized the operation by Taguchi method. [PERSON] and [PERSON] [25] compared the cooling performance of micro-structured flat-plate heat sinks with that of cross-cut heat sinks in thermoelectric generation application. [PERSON] et al. [26] developed a three-dimensional solid-fluid model to complete the optimization of thermal performance and bottom wall temperature uniformity for double-layeredheat sink with the method of simplified conjugate gradient. [PERSON] et al. [27] investigated the flow performance of micro-channel heat sink with impinging nanofluids flow employing experiments and numerical simulations. [PERSON] and [PERSON] [28] made numerical simulations on account of optimal design problems for non-uniform fin heights and widths applied in the impinging heat sink module. [PERSON] et al. [29] made numerical simulations to investigate the flow and thermal performance for the impingement/effusion double-wall heat exchanger with different cooling crossflow arrangements including zero, maximum, blocked maximum crossflow. They found that the blocked maximum crossflow displays relatively better cooling performance for the Reynolds numbers of 1000 compared to zero crossflow. [PERSON] et al. [30] carried out a novel optimal design of an air-to-air heat exchanger with cross-corrugated triangular ducts employing particle swarm optimization algorithm, considering the Colburn factor, friction factor, and comprehensive thermal hydraulic performance index as the objective functions. [PERSON] et al. [31] investigated the flow characteristics of non-Newtonian nanofluids flow in shell side of helical baffled heat transfer combined with elliptic tubes. They pointed out that a remarkable heat transfer enhancement can be obtained.