Comparison of bottom and surface cooling water withdrawals on the thermal regime of Hamilton Harbour

1992 ◽  
Vol 19 (2) ◽  
pp. 355-358 ◽  
Author(s):  
Daesoo Lee ◽  
P. F. Hamblin ◽  
A. A. Smith ◽  
W. J. Snodgrass
Keyword(s):  
Thermal Regime ◽  
Thermal Stratification ◽  
Current Practice ◽  
Cooling Water ◽  
Surface Cooling ◽  
Weak Response ◽  
One Dimensional ◽  
Hamilton Harbour ◽  
Harbour Water ◽  
Water Withdrawals

An analysis of the sensitivity of the annual thermal regime of Hamilton Harbour to the depth of intake of industrial cooling water was conducted using a one-dimensional thermodynamic model. The intake of approximately 20 m3/s of cooling water from the bottom of the harbour, as opposed to the current practice of surface withdrawal, was calculated; the result indicates marginally reduced thermal stratification and hypolimnetic volumes in summer. It was shown by a further sensitivity analysis that the reason for this relatively weak response to the withdrawal level was due to the overwhelming input of colder Lake Ontario water to the Harbour. Key words: harbour water quality, thermodynamic modelling.

Temperature Impact of the Industrial Cooling Water Discharges in a Long Boat Slip of Hamilton Harbour

2009 ◽  
Vol 44 (3) ◽  
pp. 221-231
Author(s):  
Cheng He
Keyword(s):  
Water Temperature ◽  
Thermal Structure ◽  
Water Discharge ◽  
Three Dimensional ◽  
Cooling Water ◽  
Summer Period ◽  
Transport Models ◽  
Hamilton Harbour ◽  
Harbour Water ◽  
Intake Water

Abstract The thermal structure of industrial cooling water discharged into a long, narrow and shallow, straight open boat slip (Ottawa Street Slip, [OSS]) was investigated by field measurements during the hottest summer month in 2006. Three-dimensional hydrodynamic and thermal transport models were established and verified with measurements. The main purposes of this study were to understand the mechanism of the thermal structure in the OSS during the hot summer season under the present cooling water discharge conditions, to investigate the influence of harbour water on the thermal structure in the slip, and to establish a means for scientific predictions of the impact of cooling water discharges in a future study. Toward this end, the water temperature at multiple locations along the OSS and meteorological data near the study site were collected during the summer period of 2006. The collected data reveal: (1) during the measured summer period, the water temperature in the slip can be higher than 30°C during a period of high air temperatures; (2) water temperature variations within short periods of 15, 30, 60, and 120 minutes were no more than 4°C during the entire measurement period; (3) water temperature in the slip is controlled by both air and cooling discharge temperatures, and the cooling water temperature's increase due to industrial cooling processing seems to be relatively independent of the intake water temperature; therefore, the water temperature in the slip varied mainly with the air temperature; (4) since water temperature in the slip seemed to closely follow the intake water temperature, the intake channel may need to be optimized to maximize the possibility of getting the coolest water available from Hamilton Harbour; and (5) the cooler harbour water could not penetrate deeply into the slip. The collected water temperature data were also used for verification of three-dimensional hydrodynamic and transport models. The simulation results showed that the established model could reasonably well reproduce general thermal structures in the entire slip. This achieved the ultimate goal of the study for establishing a model to assess the impacts of further increase of cooling water discharge into the OSS.

scholarly journals Analytical solution of one-dimensional Pennes’ bioheat equation

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 1084-1092
Author(s):  
Hongyun Wang ◽  
Wesley A. Burgei ◽  
Hong Zhou
Keyword(s):  
Analytical Solution ◽  
Radiofrequency Energy ◽  
Bioheat Equation ◽  
Surface Cooling ◽  
One Dimensional ◽  
The Fourier Transform ◽  
The One ◽  
Parameter Values ◽  
Mathematical Derivation ◽  
Effect Of Surface

Abstract Pennes’ bioheat equation is the most widely used thermal model for studying heat transfer in biological systems exposed to radiofrequency energy. In their article, “Effect of Surface Cooling and Blood Flow on the Microwave Heating of Tissue,” Foster et al. published an analytical solution to the one-dimensional (1-D) problem, obtained using the Fourier transform. However, their article did not offer any details of the derivation. In this work, we revisit the 1-D problem and provide a comprehensive mathematical derivation of an analytical solution. Our result corrects an error in Foster’s solution which might be a typo in their article. Unlike Foster et al., we integrate the partial differential equation directly. The expression of solution has several apparent singularities for certain parameter values where the physical problem is not expected to be singular. We show that all these singularities are removable, and we derive alternative non-singular formulas. Finally, we extend our analysis to write out an analytical solution of the 1-D bioheat equation for the case of multiple electromagnetic heating pulses.

The Thermal Regime of South Bay, Manitoulin Island

1967 ◽  
Vol 24 (1) ◽  
pp. 101-125 ◽  
Author(s):  
A. M. McCombie
Keyword(s):  
Thermal Regime ◽  
Thermal Stratification ◽  
Yellow Perch ◽  
Lake Trout ◽  
Smallmouth Bass ◽  
Lake Huron ◽  
Vertical Temperature ◽  
Class Strength ◽  
Influence Of Temperature On ◽  
History Of

The thermal regime of South Bay is described from records collected from 1953 to 1962 with thermometers, thermographs, and bathythermographs, the last being cast at 11 stations along the bay and one in Lake Huron. Warming begins in April and thermal stratification is established in June. Shallow areas warm more rapidly than deep in the spring and cool more quickly in autumn. The boundary between the epilimnion and the thermocline becomes sharper as summer advances but the transition from thermocline to hypolimnion remains gradual. The average seasonal trend of surface temperatures is a sine function with a maximum of 66 F in mid August and a minimum of 34 F in late March, though values outside this range occur frequently. At 180 ft the maximum of 47 F is attained in November. At the lake and outermost bay stations there is a temperature slump in June and July which may be due to an upwelling in the lake. Evidence of an exchange of water between the lake and bay is seen in vertical temperature sections and water movements Variations in epilimnial temperatures are correlated with those of the air temperature, but variations in epilimnial and hypolimnial temperatures appear to be unrelated. Finally, literature describing the influence of temperature on the year class strength of smallmouth bass, the distribution of lake trout, the growth of yellow perch, and the life history of Pontoporeia in South Bay is reviewed.

A New Thermal Categorization of Ice-covered Lakes

2021 ◽  
Author(s):  
Bernard Yang ◽  
Mathew Wells ◽  
Bailey McMeans ◽  
Hilary Dugan ◽  
James Rusak ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Water Column ◽  
Wind Stress ◽  
Thermal Regime ◽  
Thermal Stratification ◽  
Trophic Status ◽  
Cold Water ◽  
Entire Water Column ◽  
Lake Type

<p>Lakes are traditionally classified based on their thermal regime and trophic status. While this classification adequately captures many lakes, it is not sufficient to understand seasonally ice-covered lakes, the most common lake type on Earth. We describe the inverse thermal stratification in 19 highly varying lakes and derive a model that predicts the temperature profile as a function of wind stress, area, and depth. The results suggest an additional subdivision of seasonally ice-covered lakes to differentiate under-ice stratification. When ice forms in smaller and deeper lakes, inverse stratification will form with a thin buoyant layer of cold water (near 0<sup>o</sup>C) below the ice, which remains above a deeper 4<sup>o</sup>C layer. In contrast, the entire water column can cool to ~0<sup>o</sup>C in larger and shallower lakes. We suggest these alternative conditions for dimictic lakes be termed “cryostratified” and “cryomictic.”</p>

Analysis of Thermal Stratification and Fatigue Stress for Pressurizer Surge Line

2010 ◽  
Author(s):  
Xiaofei Yu ◽  
Yixiong Zhang
Keyword(s):  
Cross Section ◽  
Thermal Stratification ◽  
Thermal Stresses ◽  
Structural Integrity ◽  
Bending Moments ◽  
One Dimensional ◽  
Pipe System ◽  
Pipe Cross Section ◽  
Fatigue Stress ◽  
Surge Line

Thermal stratification of pressurizer surge line induced by the inside fluid brings on global bending moments, local thermal stresses, unexpected displacements and support loadings of the pipe system. In order to confirm the structural integrity of pressurizer surge line affected by thermal stratification, this paper theoretically establishes thermal stratified transient and studies the calculation method of thermal stratified stress. A costly three-dimensional computation is simplified into a combined 1D/2D technique. This technique uses a pipe cross-section for computation of local thermal stresses and represents the whole surge line with one-dimensional pipe elements. The 2D pipe cross-section model is used to compute elastic thermal stresses in plane strain condition. Symmetry allows half the cross-section to be considered. The one-dimensional pipe elements model gives the global bending moments including effects of usual thermal expansion and thermal stratification of each model nodes. This combined 1D/2D technique has been developed and implemented to analyze the thermal stratification and fatigue stress of pressurize surge line in this paper, using computer codes SYSTUS and ROCOCO. According to the mechanical analysis results of stratification, the maximum stress and cumulative usage factor are obtained. The stress and fatigue intensity of the surge line tallies with the correlative criterion.

Modeling of eutrophication and strategies for improvement of water quality in reservoirs

2016 ◽  
Vol 74 (6) ◽  
pp. 1376-1385 ◽  
Author(s):  
Mojtaba Shourian ◽  
Ali Moridi ◽  
Mohammad Kaveh
Keyword(s):  
Water Quality ◽  
Thermal Regime ◽  
Thermal Stratification ◽  
Present Situation ◽  
The State ◽  
Nitrogen Loads ◽  
Quality Of Water ◽  
Pollution Loads

The purpose of this study is to survey the thermal regime and eutrophication states in Ilam reservoir in Iran as the case study. For this purpose and to find solutions for improving the water's quality in the reservoir, two general strategies for reducing the entering pollution loads and water depletions from the reservoir's outlets were analyzed by use of the CE-QUAL-W2 model. Results of the simulation of the present situation show the existence of thermal stratification during summer, which results in the qualitative stratification in the reservoir. According to the qualitative criteria, the Ilam reservoir's state is between mesotrophic and eutrophic. Results of the scenarios of reduction of the nutrients show that in the scenario of 50% reduction of the phosphorus and nitrogen loads into the reservoir, the state of the reservoir would recover from eutrophic to semi-eutrophic. Also, release of water from the reservoir during September, October and November would cause the restoration of the quality of water in the reservoir. To avoid the occurrence of critical eutrophication in the reservoir, reducing the ponding time in the reservoir by fast depletion, preventing entrance of the upstream villages' sewage and agricultural drained waters, which are sources of nitrate and phosphate contamination into the rivers, and also management of the usage of agricultural fertilizers have been suggested.

scholarly journals One-dimensional Droplet Model for Prediction of Jet-tip Height of Subcooling Mixing Jet for Cryogenic Propellant Storage Tank

2021 ◽  
Author(s):  
Osamu Kawanami ◽  
Kentaro Takeda ◽  
Ryoki Matsushima ◽  
Ryoji Imai ◽  
Yutaka Umemura ◽  
...  
Keyword(s):  
Experimental Data ◽  
Storage Tank ◽  
Thermal Stratification ◽  
Droplet Model ◽  
Spherical Droplet ◽  
One Dimensional ◽  
Long Term Storage ◽  
Proposed Model ◽  
Term Storage

Abstract This study proposes a one-dimensional droplet model to predict the jet-tip height of a subcooling mixing jet issuing from the bottom of a cryogenic propellant storage tank. Cryogenic liquids, such as liquid hydrogen and liquid oxygen, are used as propellants and oxidants in spacecraft propulsion systems that require long-term storage in a closed tank. However, thermal stratification forms near the gas-liquid interface during long-term storage of cryogens due to heat flowing into the tank from the surrounding environment. In addition, boil-off gas (BOG) is generated from the interface, which causes increased pressure in the tank. To reduce the BOG, it is effective to destroy the thermal stratification by mixing in the cold jet issuing from the bottom of the tank. Ground experiments using FC-72 and water as test fluids are conducted to investigate the behavior of the jet using the proposed one-dimensional spherical droplet model as the tip of the jet. The jet behavior is visualized using the Shadowgraph system and the height of the jet-tip is investigated under various experimental conditions. The proposed model is also verified by comparison with experimental data available in the literature. The results show that the proposed model aligns well with the experimental data.

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