Experiments were carried out to measure the heat transfer from the surface fitted with short rectangular fin of different arrangement (co angular, zigzag, co rotating and co-counter rotating) in a rectangular duct. Thermal images were taken by an infrared camera and then analyzed the local heat transfer coefficients. Among different pattern of fin arrays co rotating is found to be most effective for heat transfer enhancement for smaller pitch ratio. Flow pattern was clarified by flow visualization in a water table and longitudinal vortices with others are observed.
The time and spatial temperature variations and smoke flow behaviors were simultaneously measured by using an infrared radiometer and a video camera in order to obtain the information about heat transfer characteristics downstream of vortex generator. The vortex generator, a thin rectangular plate, was set in the bottom of the two dimensional duct with 20 degrees inclined oncoming flow. It was found that the vortices were periodically generated downstream from the vortex generator and the temperature field well corresponds to the location of the vortices. Moreover this method will be useful for understanding the heat transport phenomenon.
The influence of photosynthesis on the growth of red algae Agardhiella subulata was investigated. First, changes in photosynthetic activity due to the amount of light irradiated on algae and changes in photosynthetic activity due to addition of CO2 were tested under a total of 6 conditions including a seawater temperature of 25 °C, light intensity of 75, 150, 250 μmol/(m2·s) and CO2 addition amount of 0, 15 mg/L. Next, the change in photosynthetic activity by seawater temperature was tested in total 3 conditions including CO2 not added, light intensity of 150 μmol/(m2·s), seawater temperature of 20, 25, 30 °C. Measurement of the maximum quantum yield Fv/Fm, which is an indicator of photosynthetic activity, uses chlorophyll fluorescence measurement PAM. Fv/Fm with the continuous light period L24 h, CO2 not added, the light intensity of 75 μmol/(m2·s) was the highest, and Fv/Fm decreased in a short time as the photon quantity increased. The maximum slope was 0.55 at sea water temperature of 25 °C and 30 °C, but the maximum value was 0.44 at 20 °C. In the continuous dark period D 24 h, Fv/Fm increased by about 0.10 at D 9 h regardless of the number of photons when CO2 was not added and increased by about 0.10 at D 3 h at a CO2 addition amount of 15 mg/L. Fv/Fm is an indicator of photosynthetic activity. It is thought that maintaining this high will lead to the growth of algae. Experimental results show that Fv/Fm is maintained high by setting the light period to 12 h and the dark period to 3 to 6 h. It was also shown that Fv/Fm is also affected by the photon quantity and CO2. From the above it is considered that growth of seaweed can be expected by balancing the light period and the dark period.
