Measurement of a heated surface temperature using a high-speed infrared camera during critical heat flux enhancement by a honeycomb porous plate in a saturated pool boiling of a nanofluid

This article presents an experimental study to investigate the critical heat flux (CHF)enhancement mechanism using honeycomb porous plate (HPP). The CHF enhanced significantly with combination of the HPP and nanofluid, up to 3.2MW/m2 at maximum compared to a plain surface, 1.0MW/m2. The mechanism by which the CHF is improved in this system was elucidated by measuring the temperature of the heated surface using an indium tin oxide (ITO) heater and a high-speed infrared camera. The pool boiling experiment of water and nanofluid is performed under saturated temperature and atmospheric pressure conditions. The CHF values obtained using ITO heater is in good agreement with a conventional CHF pool boiling experiment with HPP attachment. High-speed infrared camera is analyzed to understand the behavior of local temperature at various locations over time. It is observed at the burnout condition, the highest average temperature is occurred at the intersection of HPP wall. Moreover, the reversible dry spots were initiated in the cell part of the HPP, and small dry spots coalesced into a growth of large irreversible dry out that leads to burnout. Further CHF enhancement could be realized if the initiation of the dryout region could be suppressed

Magnetic phase diagram of antiferroquadrupole ordering in HoB2C2

The magnetic phase diagram for antiferro-quadrupole (AFQ) ordering in tetragonal HoB$_2$C$_2$ has been investigated by measurements of elastic constants $C_{11}$, $C_{44}$ and $C_{66}$ in fields along the basal $x$-$y$ plane as well as the principal [001]-axis. The hybrid magnet (GAMA) in Tsukuba Magnetic Laboratory was employed for high field measurements up to 30 T. The AFQ phase is no longer observed above 26.3 T along the principal [001] axis in contrast to the relatively small critical field of 3.9 T in fields applied along the basal [110] axis. The quadrupolar intersite interaction of $O_{xy}$ and/or $O_2^2$ is consistent with the anisotropy in the magnetic phase diagram of the AFQ phase in HoB$_2$C$_2$.Comment: Phys. Rev. B. (2005) in press. approx 8 pages, 10 figure

Phase separation of a ternary lipid vesicle including n-alkane: Rugged vesicle and bilayer flakes formed by separation between highly rigid and flexible domains

We investigate the phase separation of a ternary lipid bilayer including n-alkane and construct the ternary phase diagram. When a certain proportion of a long n-alkane is mixed with a binary mixture of lipids, which exhibit the disordered liquid-crystalline phase and the ordered gel phase at room temperature, we observed the characteristic morphology of bilayers with phase separation. The ordered bilayer forms flat and rigid domains, which is connected or rimmed with flexible domains in the disordered phase. The asymmetric emergence of the phase separation region close to the ordered phase side is interpreted based on the almost equal distribution of the n-alkane to the ordered and disordered phase domains

Observations of schooling behaviour in the oval squid Sepioteuthis lessoniana in coastal waters of Okinawa Island

The schooling behaviour of the oval squid Sepioteuthis lessoniana was observed over 4 summers at 3 observation sites in the coastal waters of Okinawa Island, Ryukyu Archipelago, Japan. During this field study, 3 static appearances (belt, ball and sheet shape) and 2 transitional appearances (high and low density) were noted, recorded and described. In addition to formations, a member of S. lessoniana schools also displayed particular and repeated behavioural patterns such as vanguard and intimidating display. The 3 observation sites were tropical coral reefs near the coastline at a depth of 1 to 15 m on an average. All participating observers snorkelled and were equipped with various underwater digital video and photographic cameras. The schools observed consisted of 8 to over 100 members with a wide range of body sizes. Despite these biological and locational differences, both static and transitional appearances were consistently observed with equally consistent individual behavioural patterns. There have been studies on related species, Sepioteuthis sepioidea, at the San Blas Islands along the Caribbean coast of eastern Panama, and the same species, S. lessoniana, at a different geographical location, Casuarina Beach on Lizard Island, Australia. The findings of this study are consistent with those reported previously, with some notable differences

Critical heat flux enhancement in saturated pool boiling using water-based nanofluid with honeycomb porous plate

The critical heat flux (CHF) limit is a great concern by many in the field of heat removal technology through pool boiling system. External cooling of pressure reactor vessel by in-vessel retention (IVR) method will involve boiling process in order to remove decay heat from the molten core through the lower head of the vessel. Increasing CHF could give extra safety margin for nuclear power plant to operate. Many researchers have shown that CHF is significantly enhanced by nanofluids compared to pure water. Nanoparticle deposited on heated surface improves surface wettability in which sustain more liquid to heat transfer surface. Therefore, dry out regions is delayed and further CHF enhancement is observed. On the other hand, surface modification by attaching honeycomb porous plate on heated surface have shown CHF enhancement approximately twice in comparison with plain surface. This is due to automatic liquid supply by capillary action and separation of liquid and vapor path contributed by the honeycomb structure. In the present study, the effects of surface modification by water-based nanofluid concentrations and honeycomb porous plate were investigated experimentally in saturated pool boiling atatmospheric pressure. Experimental result for combination of honeycomb porous plate and water-based nanofluids concentration of 4.0 g/L (0.110% by volume) shows the most enhanced CHF compared to other surface modification