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Abstract Thermal stress in IGBT power module can lead to sever thermal reliability problems such as module deformation, performance degradation and even permanent damage. So, it is important to develop innovative and efficient IGBT cooling technologies. In this paper, a novel thermal management system is developed for cooling IGBT power module. The module is integrated with a vapour chamber-based heat sink to reduce thermal resistance and improve temperature uniformity significantly. 3D FEM modelling is conducted to investigate the effect of vapour chamber on temperature distribution, thermal stress, energy strain dissipation density and lifetime under power cycle. The simulation results show that the proposed thermal management system is superior to traditional cooling solution regarding cooling capacity, thermal stress, creep and plastic strain energy dissipation and thermal fatigue life. The study of failure mechanism of solder layer under power cycling suggests that creep causes the main is damage in the power cycling and cracks induced by thermal loading can be expected to initiate at the edge.

Abstract In this work, a novel wickless heat pipe fabricated using the roll-bond process and called the roll-bond flat thermosyphon was proposed for electronic component cooling due to its slim and large-size configuration, low-cost, and mass-production capable. The thermal performance of roll-bond flat thermosyphon was investigated through the tests in terms of 3 typical structures (stagger, cross and align) and 4 filling ratios (5%, 10%, 20%, and 40%) under the increasing heat power, and evaluated with the effective thermal conductivity and the maximum heat transfer capacity. The phenomena of boiling regime evolution, geyser effect, liquid entrainment and dry-out, can be found through the temperature responses in the cases of progressive filling ratios and heating powers. The cross-structured sample was found to behave the worst among the three structures due to its blocked up-flowing inflated circuits. The highest effectivity thermal conductivity of 22404 (W/K·m) was found in the 5%-align sample, however, accompanied with early dry-out. The heat transfer capability is positive correlated to the filling ratio, and maximum heat transfer capacity of 100 W (heat flux of 14.9 (kW/m2)) was recorded in the stagger-40% sample. The 20%-stagger sample is recommended as the optimum design, due to its more stable and relative high thermal conductivity, which is peaked to 16019 (W/K·m), and averaged at 12616 (W/K·m) in the range of 0–90 W.

Abstract The performance of thermoelectric generation (TEG) systems is significantly dependent on the hot side temperature of thermoelectric legs and the temperature difference between the hot side and cold side of the legs. To keep the TEG module working at an optimal condition, a high heat flux over 10 W/cm2 through the TEG needs to be maintained. Due to the low heat transfer coefficient of the gas flow to the exhaust pipe wall surface, typically at a high temperature ranging from 400 °C to 800 °C, the actual heat flux into the TEG heat exchanger is limited significantly, resulting in relatively low efficiency of the TEG conversion. In the present study, an effective solution for enhancing the heat transfer of gas flow in the radial direction to the TEG is proposed by means of immersing high temperature heat pipes perpendicularly into the exhaust flow. Similarly, conventional heat pipes are radially inserted into a concentric coolant jacket in order to enhance heat transfer performance at the cold side of TEG modules. Overall, the TEG assembly is configured as a compact and scalable heat pipe heat exchanger. The simulation results show that the hot side temperature of the TEG can reach and be maintained as high as 300 °C while the cold side temperature of the TEG can be maintained at approximately 85 °C for a normal engine coolant loop. The results also show that the closer to the heat source in the pipeline the TEG system is located, the better the power generation that is expected. Moreover, better thermoelectric generation can be expected at a higher engine speed. By installing the TEG heat exchanger between catalytic converter and muffler, the best power output in the thermoelectric heat exchanger can be achieved at 450 W and 5000 rpm. If the TEG heat exchanger is adjacent to the outlet of a catalytic converter, the best-simulated performance at 6000 rpm is 705 W for a single sub pipeline. Therefore, a total power generation of 1410 W is achievable since the existing exhaust pipe is a dual pipeline system.

This study proposes three composite wick structures (copper power or mesh sintered on grooved tube), namely, single arch-shaped sintered–grooved wick (SSGW), bilateral arch-shaped sintered–grooved wick (BSGW), and mesh–grooved wick (MGW), to improve the thermal performance of ultra-thin heat pipes (UTHPs). Phase-change flattening technology is employed to fabricate UTHPs. The morphologies of the wick structures after flattening are observed. An experimental apparatus is setup to investigate the thermal performance of UTHP samples under incremental heat loads. The heat transfer limits of UTHP are theoretically and experimentally analyzed. Capillary limit is found to be the main heat transfer limit, and the theoretical values of the samples with SSGW and BSGW are in good agreement with the experimental results. Results indicate that the maximum heat transport capacities are 12 W, 13 W and 14 W, under the corresponding optimum filling ratios of 70%, 70%, and 80%, for the SSGW, BSGW and MGW UTHPs, respectively. Evaporation and condensation thermal resistances of UTHP samples increase with the increase in the filling ratio before the occurrence of dry-out. UTHPs with SSGW have the least evaporation thermal resistance whereas UTHPs with MGW have the least condensation thermal resistance.

Abstract Cylindrical heat pipes with sintered-grooved composite wicks are manufactured by more than 20 processes. Essential to their thermal performances are the working fluid filling and vacuuming processes. In this work, the effects of various process parameters on the thermal performance of a composite heat pipe were examined experimentally by conducting transient and steady-state tests. Under the conditions of the first vacuuming process, the effective working length showed a more remarkable effect on the start-up performance of the heat pipes than the first vacuuming time and filling ratio. The isothermal performance demonstrated sensitivity to the filling ratio. Under the conditions of the second vacuuming process, the second vacuuming temperature showed a remarkable effect on the isothermal performance. The thermal resistances were less than 0.02 K/W at the evaporator and less than 0.09 K/W at the condenser with respect to those less than 0.16 K/W after the first vacuuming process.

Enhancing battery safety and thermal behaviour are critical for electric vehicles (EVs) because they affect the durability, energy storage, lifecycle, and efficiency of the battery. Prior studies of using air, liquid or phase change materials (PCM) to manage the battery thermal environment have been investigated over the last few years, but only a few take heat pipes into account. This paper aims to provide a full experimental characterisation of heat pipe battery cooling and heating covering a range of battery ‘off-normal’ conditions. Two representative battery cells and a substitute heat source ranging from 2.5 to 40 W/cell have been constructed. Results show that the proposed method is able to keep the battery surface temperature below 40 °C if the battery generates less than 10 W/cell, and helps reduce the battery temperature down to 70 °C under uncommon thermal abuse conditions (e.g. 20–40 W/cell). Additionally, the feasibility of using sintered copper-water heat pipes under sub-zero temperatures has been assessed experimentally by exposing the test rig to −15 °C/−20 °C for more than 14 h. Data indicates that the heat pipe was able to function immediately after long hours of cold exposure and that sub-zero temperature conditions had little impact on heat pipe performance. We therefore conclude that the proposed method of battery cooling and heating via heat pipes is a viable solution for EVs.

Thermoelectric generator (TEG) system as a burgeoning method for light-duty automotive waste heat recovery has drawn the researcher’s attention for the last decade with the advantages of no moving parts and high reliability [1]. However, the low heat to electricity conversion efficiency is the key drawback that prevents the TEG from wildly using in practice. Furthermore, the efficiency of heat to electricity conversion for thermoelectric (TE) material is in the sharp of parabola, which means TE materials have a peak point of conversion efficiency and a best range for working temperatures. As a result, during most of the time in vehicle driving, the TEMs will not perform at their best range for working temperature and affect the efficiency of TEG system subsequently. Although there are plenty of researches focusing on the improvement of efficiency for the (TE) material, there are rare researches regarding the heat transfer enhancement on the system level, especially for the transient performance improvement for TEG.