INFLUENCE OF TEMPERATURE CONTROL CURTAIN ON WATER TEMPERATURE STRUCTURE AND FLOW PATTERN IN RESERVOIR

2019 ◽  
Author(s):  
YANJING YANG ◽  
DENG YUN ◽  
YOUCAI TUO ◽  
TIANFU HE
Keyword(s):  
Water Temperature ◽  
Flow Pattern ◽  
Temperature Control ◽  
Temperature Structure ◽  
Influence Of Temperature

scholarly journals Study of the thermal regime of a reservoir on the Qinghai-Tibetan Plateau, China

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243198
Author(s):  
Yanjing Yang ◽  
Yun Deng ◽  
Youcai Tuo ◽  
Jia Li ◽  
Tianfu He ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Diurnal Variation ◽  
Water Temperature ◽  
Water Column ◽  
Temperature Structure ◽  
Observation Data ◽  
The Mean ◽  
Low Altitude ◽  
Mean Variance ◽  
Whole Water

The Qinghai-Tibetan Plateau region has unique meteorological characteristics, with low air temperature, low air pressure, low humidity, little precipitation, and strong diurnal variation. A two-dimensional hydrodynamic CE-QUAL-W2 model was configured for the Pangduo Reservoir to better understand the thermal structure and diurnal variation inside the reservoir under the local climate and hydrological conditions on the Qinghai-Tibetan Plateau. Observation data were used to verify the model, and the results showed that the average error of the 6 profile measured monthly from August to December 2016 was 0.1°C, and the root-mean-square error (RMSE) was 0.173°C. The water temperature from August 2016 to September 2017 was simulated by inputting measured data as model inputs. The results revealed that the reservoir of the Qinghai-Tibetan Plateau was a typical dimictic reservoir and the water mixed vertically at the end of March and the end of October. During the heating period, thermal stratification occurred, with strong diurnal variation in the epilimnion. The mean variance of the diurnal water temperature was 0.10 within a 5 m water depth but 0.04 in the whole water column. The mixing mode of inflow changed from undercurrent, horizontal-invaded flow and surface layer flow in one day. In winter, the diurnal variation was weak due to the thermal protection of the ice cover, while the mean variance of diurnal water temperature was 0.00 within both 5 m and the whole water column. Compared to reservoirs in areas with low altitude but the same latitude, significant differences occurred between the temperature structure of the low-altitude reservoir and the Pangduo Reservoir (P<0.01). The Pangduo Reservoir presented a shorter stratification period and weaker stratification stability, and the annual average SI value was 26.4 kg/m2, which was only 7.5% that of the low-altitude reservoir. The seasonal changes in the net heat flux received by the surface layers determined the seasonal cycle of stratification and mixing in reservoirs. This study provided a scientific understanding of the thermal changes in stratified reservoirs under the special geographical and meteorological conditions on the Qinghai-Tibetan Plateau. Moreover, this model can serve as a reference for adaptive management of similar dimictic reservoirs in cold and high-altitude areas.

scholarly journals Influence of the Thermometer Inertia on the Quality of Temperature Control in a Hot Liquid Tank Heated with Electric Energy

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 4039
Author(s):  
Dawid Taler ◽  
Tomasz Sobota ◽  
Magdalena Jaremkiewicz ◽  
Jan Taler
Keyword(s):  
Water Temperature ◽  
Time Constant ◽  
Temperature Control ◽  
Complex Structure ◽  
Small Diameter ◽  
Hot Water ◽  
Temperature Control System ◽  
Water Tank ◽  
Water Storage Tank

This paper presents the medium temperature monitoring system based on digital proportional–integral–derivative (PID) control. For industrial thermometers with a complex structure used for measuring the temperature of the fluid under high pressure, the accuracy of the first-order model is inadequate. A second-order differential equation was applied to describe a dynamic response of a temperature sensor placed in a heavy thermowell (industrial thermometer). The quality of the water temperature control system in the tank was assessed when measuring the water temperature with a jacketed thermocouple and a thermometer in an industrial casing. A thermometer of a new design with a small time constant was also used to measure temperature. The quality of water temperature control in the hot water storage tank was evaluated using a classic industrial thermometer and a new design thermometer. In both cases, there was a K-type sheathed thermocouple inside the thermowell. Reductions in the time constant of the new thermometer are achieved by means of a steel casing with a small diameter hole inside which the thermocouple is precisely fitted. The time constants of the thermometers were determined experimentally with a jump in water temperature. A digital controller was designed to maintain the preset temperature in an electrically heated hot water tank. The function of the regulator was to adjust the power of the electrical heater to maintain a constant temperature of the liquid in the tank.

Cyclomorphosis in Daphnia magna and Ceriodaphnia reticulata (Cladocera) from northern Tunisian groundwater: influence of temperature and invertebrates?

Crustaceana ◽  
2015 ◽  
Vol 88 (10-11) ◽  
pp. 1139-1148
Author(s):  
H. Toumi ◽  
M. Bejaoui ◽  
M. Boumaiza
Keyword(s):  
Water Temperature ◽  
Daphnia Magna ◽  
Seasonal Distribution ◽  
Spine Length ◽  
Influence Of Temperature ◽  
Ceriodaphnia Reticulata ◽  
Groundwater Wells

In the present study, we investigated cyclomorphosis in two cladocerans, Daphnia magna and Ceriodaphnia reticulata, sampled from northern Tunisian groundwater (wells) during two seasons (spring and summer). Seasonal distribution of the two species was apparent, with dominance of D. magna only in spring and C. reticulata during the whole study period. Our results showed correlations between caudal spine length of D. magna and water temperature (, ), and between caudal spine length and the density of coleopteran larvae (Stictonectes escheri, Graptodytes sp., Gyrinus urinator, and Haliplus lineaticollis) (, ). In C. reticulata, we registered a correlation (, ) only between its size and the density of larvae of Ephemeroptera (Cloeon cognatum) but no correlation with water temperature was found.

SCM Based High Precision Temperature Controller Design

2013 ◽  
Vol 313-314 ◽  
pp. 549-552 ◽  
Author(s):  
Zhen Hua Han ◽  
Ze Hu Feng
Keyword(s):  
Water Temperature ◽  
Real Time ◽  
Temperature Control ◽  
Control Method ◽  
Controller Design ◽  
Heating Time ◽  
Single Chip ◽  
The Real ◽  
Pid Algorithm ◽  
Analog Voltage

t is designed by adopting SUNPLUS SPCE061A version 16-bits Single Chip Microcomputer; it has realized functions as manual setting temperature, automatic temperature control, showing the real-time temperature of water. The testing mode of water temperature adopts AD590 version integrated analog temperature sensor to perceive the temperature of water in vessels and uses operational amplifier to amplify minute analog voltage signal outputted by sensor. It employs keyboard scan mode to set target temperature (40°C~90°C) and displays dynamically the real-time temperature of water with digestion. The system controls the guide circuit and closing of the heating device by using relay circuit, achieving the aim of keeping design temperature constant essentially. PID algorithm is adopted in water temperature control method. The proportion, integration and differential constant in PID algorithm are debugged with experiments in order to control the proportion of heating time and reduce the adjusting time of the system. The system boasts the advantages of high controlling precision, stability and reliability, flexible operation, strong currency.

scholarly journals Characteristics and driving factors of thermal stratification evolution in Daheiting Reservoir

2021 ◽  
Vol 261 ◽  
pp. 04010
Author(s):  
Chang Liu ◽  
Shiyan Wang ◽  
Liang Wang ◽  
Xiaobo Liu ◽  
Huaidong Zhou ◽  
...  
Keyword(s):  
Wind Speed ◽  
Water Temperature ◽  
Air Temperature ◽  
Thermal Stratification ◽  
Chemical Properties ◽  
Driving Factors ◽  
Temperature Structure ◽  
Water Temperature Data ◽  
Physical And Chemical ◽  
Hydrodynamic Factors

Thermal stratification which is common in water bodies is subject to such factors as the water depth of the water body (a lake or reservoir, for instance), the fluidity of the water and the local meteorological conditions. The stable thermal stratification in reservoirs will lead to changes in the physical and chemical properties of the water as well as distribution of aquatic creatures, hence leaving an impact on the water quality. The Daheiting Reservoir was taken as the research object in this study. Based on the continuous monitored water temperature data in the reservoir, the tempo-spatial change features of the water temperature structure in the reservoir were analyzed, and the driving factors of thermal stratification in the reservoir was studied. The research found that air temperature, wind speed, and hydrodynamic factors are the driving factors for the thermal stratification and corresponding water temperature change patterns in Daheiting Reservoir. Among these factors, air temperature is the fundamental precondition, the wind speed is the auxiliary precondition, and the hydrodynamic factors are the disturbance factors for thermal stratification in the Reservoir. All these factors act together to cause the thermal stratification pattern and evolution features in Daheiting Reservoir.

scholarly journals Experimental and Numerical Study on the Effect of the Temperature-Control Curtain in Thermal Stratified Reservoirs

2019 ◽  
Vol 9 (24) ◽  
pp. 5354 ◽  
Author(s):  
Jijian Lian ◽  
Peiyao Li ◽  
Ye Yao ◽  
Wei He ◽  
Nan Shao
Keyword(s):  
Water Temperature ◽  
Temperature Control ◽  
Numerical Study ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Engineering Practice ◽  
Maximum Increase ◽  
Study Results ◽  
New Facility ◽  
Temperature Water

The impoundment and power generation of dams cause the temperature of released water much lower than the original rivers in the thermal stratified reservoirs. In addition, the released low-temperature water would damage the downstream habitats of fish and other biological groups seriously. Available facilities, such as stop log gate intakes and multi-level intakes, are built to alleviate the problem. For overcoming the limitations of traditional facilities on construction conditions and the improved effect of water temperature, a new facility of the temperature control curtain (TCC), with the advantages of convenient regulation and no hydropower loss, has been proposed recently. However, to the author’s knowledge, the theory of TCC is not abundant, with incomplete experimental tests and few numerical simulations. In this paper, a rectangular tank is designed specifically to conduct experimental tests to verify the effects of TCC and explore its potential impacts on released water temperature (RWT) under four major influencing factors. The study results show that TCC has significant effects on improving RWT, with a maximum increase of 8.3 °C. In addition, a three-dimensional hydrodynamic model with the same size of experimental model is established for further research. The results show that RWT is mainly related to the temperature distribution of a reservoir and the water-retaining proportion of the curtain. Finally, a basic principle for TCC construction is proposed and all these laid an important theory foundation for its application in engineering practice.

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