Study on liquid-jet cooling and heating of the moving SMA actuator

At present, internal combustion engines (ICE) are still the main power source for cars, and about 60% of the fuel energy is wasted through exhaust gas and cooling system of ICE. One of the methods for energy recovery of ICE is to use thermoelectric generator (TEG). To improve the energy recovery efficiency of TEG, the temperature distribution over the cooling system should be known. For this purpose, the temperature filed of a TEG is analyzed using ANSYS software. In this paper, some inner structures of TEG are designed and their temperature fields are simulated. Through comparing the simulation with experimental results, the design with inclined symmetrical baffles can generate the most uniform temperature distribution. Then, this design is used to further simulate the cooling capacity of the TEG. The results show that the impact of thermal radiation should be considered in the TEG simulation; otherwise large errors will be generated. It also can be seen that the cooling method using solid plate connecting with a solid column has limitation because most of the heat is concentrated in the solid plate, and it should be optimized in further research.

Temperature Field Analysis of Engine’s Energy Recovery System using Fluid–Structure Coupling

Transient thermal response of shape memory alloy actuator under gas-jet impingement has been investigated numerically and experimentally. Two-dimensional incompressible and unsteady flow (both hydrodynamically and thermally) is solved using the standard k–ɛ turbulence model and energy conservation equation. The solid region is simulated by coupling the fluid with moving and static boundary condition at the fluid–solid interface, respectively. Much attention was focused on the effects of jet velocity and periods on temperature fields and shape deformation of the SMA actuator. Results show that the temperature of the actuator for static boundary condition is slightly higher than for moving boundary condition and the difference increases along the flow direction. The difference of temperature and the shape deformation on the surface of SMA increase with the increasing of exit velocity and jet periods. The numerical simulation and the experiment have been performed with the following parameters: 16 ≤  v in  ≤ 40 m/s, L/D = 5, 2≤ T ≤12 s. An experimental apparatus about periodic jet impingement is set up to study the transient thermal response and heat transfer between the jet gas and the SMA actuator. The effect of the jet period and velocity on the transient thermal response was investigated in detail. The results of the numerical simulation are shown in good agreement with the experimental data.

Transient thermal response of SMA actuator under gas-jet impingement

The temperature and flow fields of CPU heat sink Cooled by vertical jet are investigated based on numerical method. Furthermore, the recirculating flow is found under the low part of the fin, and it would deteriorate the heat dissipation at a certain degree. The heat dissipation performance of CPU heat sink cooled by vertical uniform jet is analyzed by numerical simulation under different conditions. These results are useful for the design of the heat sink with efficient performance and the further research.

Sun Xiao

Papers

The numerical analysis on the heat transfer performance of cpu heat sink cooled by vertical uniform jet