A novel permanent magnet synchronous motor with heat pipe for electric vehicle is designed with the aim to reduce the end winding temperature. Software FLUENT is used to simulate the temperature fields. The temperature distribution profile of the winding of the permanent magnet synchronous motor with heat pipe is similar to that of the traditional permanent magnet synchronous motor. But the temperature values of the winding of the permanent magnet synchronous motor with heat pipe are lower than those of the traditional permanent magnet synchronous motor. The area of the region with relative low temperature at permanent magnet synchronous motor with heat pipe is also larger than at traditional permanent magnet synchronous motor. The highest temperature of the winding of the permanent magnet synchronous motor with heat pipe is 16.4°C lower than that of the traditional permanent magnet synchronous motor. The highest temperature and the lowest temperature of the lamination of the permanent magnet synchronous motor with heat pipe are all lower than those of the traditional permanent magnet synchronous motor. The temperatures of the two end caps of the permanent magnet synchronous motor with heat pipe are apparently higher than those of the traditional permanent magnet synchronous motor since some heat generated at the end winding is transferred to the end cap by the heat pipe. The low temperature area at the middle housing of the permanent magnet synchronous motor with heat pipe is larger than that of the traditional permanent magnet synchronous motor. The temperature discrepancy between the evaporator of the heat pipe and the end winding is about 60°C.

Hybrid photovoltaic and thermal (PVT) collectors with sheet-and-tube water-based flat-plate structure (simplified as STWF-PVT) are very popular because of their simple structure and ease of manufacture. Generally, their performance is closely related to their structure, especially the location arrangement of photovoltaic (PV) cells. In this work, the authors present three kinds of PVT collectors with different PV cell locations, denoted as PVT-1, PVT-2, and PVT-3, representing a conventional air-gap STWF-PVT collector whose PV cells are stuck on its solar absorber, a new air-gap STWF-PVT collector whose PV cells are fixed on the bottom of its glass cover, and a zero-air-gap STWF-PVT collector, respectively. Experiments and computational fluid dynamics (CFD) analyses were carried out to investigate the performance of these STWF-PVT collectors, by means of various comparisons with a pure thermal collector. The effects of the PVT configuration and the covering factor of the PV cells on the collector performance were discussed. Among these PVTs, the PVT-1 behaves with the greatest overall efficiency, followed by PVT-3 and PVT-2 in turn, whereas PVT-3 is proven to have the highest photoelectric conversion efficiency of PV cells, followed by PVT-2 and PVT-1. In summary, PVT-3 is much preferred by the customers who want more electricity than thermal energy, and PVT-1 is the first choice for a comprehensive evaluation of electrical and thermal energy. The authors hope this work is useful for STWF-PVT collector design, especially for the location design of PV cells and air gap.

A miniature loop heat pipe (mLHP) is a promising device for heat dissipation of electronic products. Experimental study of heat transfer performance of an mLHP employing Cu-water nanofluid as working fluid was conducted. It is found that, when input power is above 25 W, the temperature differences between the evaporator wall and vapor of nanofluid, T_e − T_v, and the total heat resistance of mLHP using nanofluid are always lower than those of mLHP using de-ionized water. The values of T_e − T_v and total heat resistance of mLHP using nanofluid with concentration 1.5 wt. % are the lowest, while when the input power is 25 W, the values of T_e − T_v and total heat resistance of mLHP using de-ionized water are even lower than those of mLHP using nanofluid with concentration 2.0 wt. %. At larger input power, the dominant interaction is collision between small bubbles and nanoparticles which can facilitate heat transfer. While at lower input power, nanoparticles adhere to the surface of large bubble. This does not benefit boiling heat transfer. For mLHP using nanofluid with larger concentration, for example 2.0%, the heat transfer may even be worse compared with using de-ionized water at lower input power. The special structure of the mLHP in this study, two separated chambers in the evaporator, produces an extra pressure difference and contributes to the heat transfer performance of the mLHP.