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a b s t r a c tThis paper analyzes a total of 1930 collaboration projects, including contract research, joint research, technology transfer, and incubation models, between National Cheng Kung University (NCKU) and firms during the period between 2001 and 2009. Effects of both firm size and geographical proximity on the frequency of different models of collaboration are addressed. Results show that large-sized enterprises prefer adopting the contract research model and implementing it in a more comprehensive cooperation mechanism or with long-term cooperation relationships. By contrast, small and medium-sized enterprises prefer to give equal prominence to both contract research for research subject dominance and joint research due to low investment requirements. Results also show that geographical proximity is an important factor during the interaction between enterprises and NCKU. However, the influence is quite different when the cooperation models are compared individually.

This paper investigates the production of CO2 snow by flash-atomization of liquid carbon dioxide for material cleaning process. The evolution of flash-atomization processes was recorded by means of high-speed shadowgraph. Results shows that the degree of superheat condition of liquid CO2 greatly influence the atomization modes, bobbles growth rate and concentration, and thus result in difference spray angle, spray pattern, and the structure of liquid jet which is suitable for different material cleaning applications. It is found that the spray angle first slowly increases with increase in the degree of superheat (ΔT) under external flash atomization processes. It is increased drastically as the spray transform from external-flashing to internal-flashing mode. Finally the spray angle is decreased again because of the decrease of mass flowrate due to the internal flashing processes . Moreover, the spray angle is increased as the length-to-diameter ratio (L/D) is increased. This is due to the higher bobble growth rate in terms of different pressure distribution and bobble growth time. It is also found that the external-flashing disappears at higher L/D because of the heat transfer to the liquid carbon dioxide. It is concluded that the superheated condition is useful in the control of the spray angle for material cleaning processes.

This paper describes the atomization performance of a newly designed atomizer with internal impinging mechanisms inside the atomizer. The spray drop size distribution was measured by a Malvern RT-Sizer. Results show that the Sauter mean diameter below 10 µm has been achieved with GLR of 0.14. The minimum mean drop size can be lowered to 4.0 µm under a test condition of the liquid pressure and gas pressure of 2.5 bar and 3.5 bar, respectively. This test suggests that extra fine atomization on the liquid phase can be achieved under low pressure conditions using this particular atomizer. Such performance cannot be easily achieved with the conventional nozzle design. Results also show that better atomization performance can be achieved by increasing the internal impinging angle and the orifice diameter. An empirical formula of SMD, in terms of operating conditions and nozzle length scale is also presented in this paper.

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