No abstract

Existing databases and correlations in literature on the microchannel pressure drop and heat transfer are reviewed in this paper. From this review, it is found that none of the existing correlations can cover the wide ranges of working fluids, operational conditions, and different microchannel dimensions. In addition, the importance of the Bond number, which relates the nominal bubble dimension or capillary parameter with the channel size, is revealed in this paper. Using the Bond number, improved correlations of pressure drop and heat transfer are established, which predict the existing data well over a wide range of channel sizes, fluids, and operational conditions.

The surface temperature and equivalent heat conductivity of Flat Plate Heat Pipe (FPHP) under different heat flux, liquid filling and tilt angles are investigated experimentally. Electrical discharge machining (EDM) micro-channels wick are select as the wick inside FPHP. A set of experimental facility to measure the temperatures of FPHP is build up. The surface temperature along channels under different tilt angles, liquid filling and heat flux are measured by thermal couples. The results indicate that the temperatures are independent to the tilt angles and liquid filling. The equivalent thermal conductivity increases with the increasing of heat flux, and is 1.36 to 1.44 times to that of brass.

The Heat transfer characteristics of water and ethanol flow boiling in micro-channel are studied. Flow boiling of different mass and heat flux is carried out in 61 parallel microchannel with hydro diameter of 0.293mm, and the local heat transfer coefficient (HTC) of is calculated. The results indicate that the HTC decreases with the increasing of vapor quality, and depends on heat flux. Two latest correlations are used to predict the experiment, and the results indicate that the Bond number plays an important role in the correlation.

With the increasing of market demand for finned tube and fin tube processing equipment in China continued to deepen, the problems of the inefficient study design a new type of finned tube winding machine in order to solve the traditional winding machine problem such as low efficiency and the unstable quality. Using a design method for assembly , complete design parameters to calculate the main structure of the feeding and winding device and implementing the device on three dimensional Assembly based on CATIA modeling process. Finally, to verify the overall structural design rationality, we have created a virtual prototype of finned tubes and motion simulation and the collision detection also be done.