Development of circumference oscillation mechanism with adjustable amplitude
According to the situation of the currently developed circumference oscillation mechanism without adjustable amplitude generally. The circular oscillation mechanism with adjustable amplitude is designed. It mainly comprises an eccentric motion mechanism and adaptive dynamic balance mechanism. The dynamic simulation and analysis is carried out on eccentric motion mechanism. The experimental results show it can achieve 0-Φ50mm adjustable amplitude and 20-350RPM adjustable oscillation frequency in the meantime, and the latter can be realized by changing eccentricity adjusting pin manually. The unbalance quality of the table can be compensated by adaptive dynamic balance mechanism in order to increase the die life. Its amplitude can be changed simply, conveniently and fast, and has the characteristics of simple and compact mechanism, rigid connection, strong bearing capacity and maintenance easily. It will be widely used in the field of biological engineering.
Prediction and simulation on the shear stress and mass transfer in perfused bioreactors I: Circular bioreactors
Bioreactors have been widely used in tissue engineering because of their controllability in environments and operating conditions. But bioreactor design is very complex and still at an early stage of development. Computational fluid dynamics (CFD) is commonly used for the design and manufacture of devices with fluid flow as a powerful computer ldquoexperimentsrdquo modelling and simulation tool. In our work, by the CFD simulations of different circular bioreactors with various parameters, we obtained the concentration status of glucose and lactate in different time and shear stress. It was shown that the inlet or outlet position, and the feed flow rate have quadric relationship with the shear stress. In order to provide the cells with comfortable culture environment, bioreactors should have a lower outlet than inlet, the Hc/Ho should be between 0.2 and 0.4 and the fluid exchange ratio Rfe should be between 0.68 and 6.84 hours.
Experimental Study for a Double-Glazed Forced-Flow Solar Collector/Regenerator
Experimental study of a double-glazed forced-convection solar collector/regenerator for absorption solar cooling is presented. The south facing experimental solar collector/regenerator with 10 deg slope is located at Kaohsiung, Taiwan at 120{degree}19minutesE longitude and 22{degree}34minutesN latitude. The size of the collector is 1 m wide and 7 m long with an effective regeneration area of 0.9 m by 6 m. Previous study for single-glazed forced-convection solar collector/regenerator operated at the same location has shown to have a best day-average efficiency of 17%. In order to raise the system performance, a double-glazed collector/regenerator is constructed such that air can be preheated in the upper channel flow. The preheated air is then conducted into the lower channel where it contacts with the film flow of solar heated lithium-chloride solution and regenerates the solution by carrying out the evaporated water vapor. The preheated air has lower relative humidity but the same humidity ratio since it is sensibly heated. Therefore, the regeneration driving potential is increased. The present study shows that the best day-average efficiency can reach 20% which increases the feasibility of the open-cycle absorption solar cooling system. Effects of controlling parameters on the collector/regenerator performance are studied, and heat and mass transfer correlationsmore » are also presented for design purposes.« less