• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.16 no.1
• /
• pp.103-108
• /
• 1987

The heat transfer processes taking place in the side wall of a thermocline enclosure have been analyzed for idealized conditions based on the assumption that, at any instant time, side wall heat transfer processses are independent of the thermocline bulk motion. However, the axial tempera-ture distribution in the thermocline core provides the means for specifying the liquid medium-side boundary condition to the enclosure side wall. A picture is drawn which reflects the side wan response to thermocline bulk motion within the frame work of a quasi-steady analytic approach. For valves of the parameters typical of systems of engineering interest, the analysis shows that a significant amount of heat transfer short - circuiting can take place along the side wall enclosure. This phenomenon is favored by high values of $H_l$ and low values of P and $H_g$ respec-tively. The location of the point of zero normal heat flux on the side wan can be expected to mark, approximately, the region of confluence of two sidewall boundary flows respectively driven by the buoyant effects.

• Journal of the korean society of oceanography
• /
• v.38 no.1
• /
• pp.11-16
• /
• 2003

The three dimensional structure of thermohaline circulation in a D-plane is investigated using a conceptual two layer model and a scaling argument. In this simple model, the water mass formation region is excluded. The upper layer represents the oceans above the main thermocline. The lower layer represents the deep ocean below the thermocline and is much thicker than the upper layer. In each layer, geostrophy and the linear vorticity balance are assumed. The cross interfacial velocity that compensates for the deep water mass formation balances downward heat diffusion from the top. From the above relations, we can determine the thickness of the upper layer, which is the same as thermocline depth. The results we get is basically the same as that we get for an f-plane ocean or the classical thermocline theory. Mass budget using the velocity scales from the scaling argument shows that western boundary and interior transports are much larger than the net meridional transport. Therefore in the thermohaline circulation, horizontal circulation is much stronger than the vertical circulation occuring on a meridional plane.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.22 no.4
• /
• pp.21-31
• /
• 1986

The author investigated the relation between the catches of tuna species and the distribution of horizontal mean temperature at the Jepth of 10m and of vertical temperture sections in the different fishing grounds, using the date of catches in 1980, showing a relative good ones during six years from 1975 to 1980, and of oceanographic observations. Yellowfin and bigeye are mainly caught in South Equatorial Current regions including equatorial upwelling region in 5$^{\circ}$N to 5$^{\circ}$S, and albacore is mainly caught in Subtropical region in 20$^{\circ}$5 to 40$^{\circ}$5. The good fishing grounds of yellowfin and bigeye are made in the depth layer of 100 m to 250 m and temperature of 15$^{\circ}$C to 26$^{\circ}$C having a smooth gradient of thermocline in the Central Pacific between 180$^{\circ}$ and 1500W. But albacore is caught well in which the temperature of thermocline ranges from 100e to 25$^{\circ}$C and its gradient very smoothly. Approaching to the American Continent, the catches of yellowfin and big eye decrease because the thermocline becomes shallower and steeper at Eastern Pacific Region between 1500 and 800W.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.7
• /
• pp.468-473
• /
• 2010

This paper deals with approximate integral solutions to the one-dimensional model describing the charging process of stratified thermal storage tanks. Temperature is assumed to be the form of Fermi-Dirac distribution function, which can be separated to two sets of cubic polynomials for each hot and cold side of thermal boundary layers. Proposed approximate integral solutions are compared to the previous works of the approximate analytic solutions and show reasonable agreement. The approach, however, has benefits in mathematical difficulties, complicated solution form and unstable convergence of series solution founded in the previous analytic solutions. Solutions for a semi-infinite region, which have simple closed form solutions, give close agreement to those for a finite region. Thermocline thickness is obtained in closed form and shows proportional behavior to the square root of time and inverse proportional behavior to the square root of flow rate.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.7 no.2
• /
• pp.184-195
• /
• 1995

A theoretical one-dimensional model for the charging process in stratified thermal storage tanks is established presuming that the fluid ensuing from the tank inlet creates a perfectly mixed, layer above the thermocline. Both the generic and asymptotic closed-form solutions are obtained via the Laplace transformation. The asymptotic solution describes the nature of the charging pertaining to the case of no thermal diffusion, whereas the generic solution is of practical importance to understand the role of operating parameters on the stratification. The present model is validated through comparison with available experimental data, where they agree well with each other within a reasonable limit. An interpretation of the exact solution entails two important features associated with the charging process. The first is that an in-crease in the mixing depth $h_m$ causes a relatively slow temperature rise in the perfectly mixed region, but on the other hand it results in a faster decay of the overall temperature gradient across the thermocline. Next is the predominance of the mixing depth in the presence of the prefectly mixed region. In such a case the effect of the Peclet number is marginal and there-fore the thermal characteristics are solely dependent on the mixing depth paticularly for large $h_m$. The Peclet number affects significantly only for the case without mixing. Variation of the storage efficiency in response to the change in the mass flow rate agrees favorably with the published experimental results, which confirms the utility of the present study.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.21 no.1
• /
• pp.1-10
• /
• 1988

The vertical temperature profiles of the Yellow Sea in summer are investigated by means of the nine air temperature (AT) patterns which are classified with the AT of winter and summer. The sea surface temperature (SST) is high when the AT of summer is high, and vice versa. The gradient of thermocline in the offshore region is higher than that in the coastal region and is not always favorable with the AT patterns. The relation between sea bottom temperature (SBT) and the AT of winter is favorable when the SBT is averaged in the coastal and offshore stations. In addition, the SST of coastal stations is higher than that of offshore stations because of the strong mixing by the tidal current in the coastal region. The correlation between the AT and the SST of August is favorable (r=0.44-0.69), while the correlation between the AT of February and the SBT of August is not favorable except the stations, A2 (r=0.57) and B2 (r=0.61).

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.36 no.2
• /
• pp.170-177
• /
• 2003

This study is to analyze the influence of the Tsushima Warm Current (TWC) on the variation of sound speed in the southern part of the East Sea. Sound speed is calculated by method of Chen and Millero (1977:, based on the CTD data measured in June of 1996. Sound speed in the central part of the TWC is about $45ms^{-1}$ more fast than that in the other regions without the TWC. Sound speed minimum layer (SML) in the TWC region exists between loom and 341 m, while it exists between 260m and 290m in the non-TWC region. SML distributes along the path of TWC over continental shelf in the coastal waters of Japan.

• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2004.05a
• /
• pp.27-27
• /
• 2004

We studied algal growth-related water quality of the Sangsa lake which is the drinking water reservoir for the south-eastern region of Jeonnam province. Peridinium cinctum and several diatomic algal species frequently caused water bloom throughout the lake from early spring to late autumn. With the heaviest predominance of Peridinium cintum in May 2003, COD was 22.7 mg/l in the surface layer. Highly turbid surface water of 15 NTU was also caused by Perdinium bloom. Cyanobacterial growth was effectively prohibited by dominant growth of Peridinium in the Sangsa lake, otherwise confronted with cyanobacterial bloom. Dense algal layer was confined in the upper several meters of the water column above the thermocline, which gives relatively algae-free water in deeper layer suitable for drinking source water supply. Upon collapse of thermocline, water quality of the surface layer was improved while deeper layer was deteriorated. This paper deals with some details of water quality changes with algal growth in the Sangsa lake past two years.

• Journal of the Korean Society of Visualization
• /
• v.19 no.3
• /
• pp.99-105
• /
• 2021

In this study, the thermal stratification in solar seasonal thermal storage tanks was numerically simulated. The effects of the aspect ratio (AR) and inlet velocity on the thermal stratification in the diffuser type heat storage tank were investigated. The temperature distributions inside the tank were similar with velocity fields. Jet flows from opposite diffusers encountered each other at the tank center region. Thereafter, the downward flows occurred, and this flows strongly affected the thermal stratification. When AR was smaller than 2, these downward flows influenced a further distance and enhanced mixing inside the tank. Thermal stratification was evaluated by thermocline thickness and degree of stratification, and AR of 3 had the highest degree of stratification. The inlet velocity effect was expressed with the ratio (Re/Ri) of Reynolds and Richardson numbers. The second-order approximation was found for the relationship between the thermocline thickness and log Re/Ri.

• Korean Journal of Ecology and Environment
• /
• v.41 no.2
• /
• pp.247-263
• /
• 2008

A two-dimensional (2D) reservoir hydrodynamics and water quality model, CE-QUAL-W2, is employed to simulate the hydrothermal behavior and density current regime in Andong Reservoir. Observed data used for model forcing and calibration includes: surface water level, water temperature, dissolved oxygen and suspended solids concentration. The model was calibrated to the year of 2003 and verified with continuous run from 2000 till 2004. Without major adjustments, the model accurately simulated surface water levels including the events of large storm. Deep-water reservoirs, like Andong Reservoir, located in the Asian Monsoon region begin to stratify in summer and overturn in fall. This mixing pattern as well as the descending thermocline, onset and duration of stratification and timing of turnover phenomenon were well reproduced by the Andong Model. The temperature field and distinct thermocline are simulated to within $2^{\circ}C$ of observed data. The model performed well in simulating not only the dissolved oxygen profiles but also the metalimnetic dissolved minima phenomenon, a common1y occurring phenomenon in deep reservoirs of temperate regions. The Root Mean Square Error (RMSE) values of model calibration for surface water elevation, temperature and dissolved oxygen were 0.0095 m, $1.82^{\circ}C$, and $1.13\;mg\;L^{-1}$, respectively. The turbid storm runoff, during the summer monsoon, formed an intermediate layer of about 15 m thickness, moved along the metalimnion until being finally discharged from the dam. This mode of transport of density current, a common characteristic of various other large reservoirs in the Asian summer monsoon region, was well tracked by the model.