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Li, Wenming

Publications and source records attributed to Li, Wenming.

3 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Wick assisted embedded evaporative cooling of motors

A cooling system for an electric motor that includes a stator having a plurality of slot windings and a rotor, coaxial with the stator, having a plurality of magnets, includes a coolant inlet to the motor and a coolant outlet from the motor. A coolant pathway is in fluid communication with the inlet and the outlet. Heat is transferable from the slot windings to the coolant pathway. A coolant flows through the coolant pathway and is in a liquid phase as it enters the coolant inlet, changing into a gaseous phase as heat is transferred to the coolant from the slot windings. A cooling loop is in fluid communication with the coolant inlet and the coolant outlet. The cooling loop cools the coolant so that substantially all of the coolant is in the liquid phase when it enters the coolant inlet.

Joshi, Yogendra K.↗
DOE OSTI2022

A remarkable CHF of 345W/cm 2 is achieved in a wicked-microchannel using HFE-7100

Boiling heat transfer of dielectric fluids is a promising cooling technique for thermal management of microelectronic systems. However, the critical heat flux achievable is generally low, because of the poor thermophysical properties of these fluids. Here, to address this dilemma, we propose a new cooling concept to substantially enhance global liquid supply during phase-change process using enhanced capillary-driven force. Additionally, dedicated vapor pathways are designed among a bank of micro-pillars to facilitate vapor removal. In this work, new wicks comprised of silicon micro-pinfin arrays are explored to significantly enhance the flow boiling heat transfer performance. To examine the functionalities of this wick, experiments on HFE-7100 were carried out with mass velocities varying from 247 to 3,465 kg/m 2 s. To explore the enhancement mechanisms and to analyze the capillary-assisted flow boiling process, visualization studies were conducted. The results indicate that sustainable evaporation induced by wick microstructures and efficient liquid supply are the enhancement mechanisms compared to parallel microchannels with solid walls. It is found that the overall heat transfer coefficient is substantially increased up to 75%. Remarkably, a high critical heat flux (CHF) of approximately 345 W/cm 2 is recorded at G = 3,465 kg/m 2 s at coolant inlet temperature of ~20 °C. Equally importantly, this noticeable enhancement of CHF value is associated with drastically decreased pressure drops compared to microchannels decorated with μ-pinfin fences.

36 MATERIALS SCIENCE↗