Differences In Water Temperature Research Articles

Numerical investigation of the deep borehole heat exchanger in medium-depth geothermal heat pump system for building space heating

The deep borehole heat exchanger (DBHE) is a vital part in medium-depth geothermal heat pump system (MD-GHPs). In comparison to other forms of heat exchangers, the DBHE has the following outstanding advantages: the small footprints, the little damage to rock as well as the high efficiency. However, numerous DBHE models were fixed variable values such as flow rate or inlet fluid temperature and there were few studies combining the user heating load variation with the temperature fluctuation on the DBHE side. In order to fill this gap, a DBHE heat transfer model with dynamic building heating load constraint is developed. In this heat transfer model, the load boundary condition is the hourly flow rate and the difference in inlet and outlet water temperature, and the outlet water temperature is obtained through iteration. In addition, this model is validated by a building space heating experiment data in Harbin and guaranteed its correctness. The average heat exchange per meter at the coldest heating moment also ensures the viability of MD-GHPs, which is 141.5 W/m. A series of typical coordinates are used to analyze the effect of DBHE on the surrounding rock, and the concept of DBHE recommended insulation length are proposed. One single DBHE with 2000 m burial depth possesses a temperature effect radius of 13.0 m for one heating period. Besides, some critical conclusions are as follows: For the structural parameter, the recommended insulation length is 178 m. For the operating parameter, there is a minimum value for the total power consumption and 18 m3·h−1 is the recommended optimal flow rate in this situation. For the geological parameter, raising the geothermal gradient can dramatically improve inlet fluid temperature (IFT) and outlet fluid temperature (OFT), and enhance the ability of DBHE to carry the building heating load. When maintaining the same IFT at the coldest moment, the geothermal gradient of 0.04℃·m−1 is 1.33 times more capable of carrying loads than the 0.03℃·m−1. This paper can provide basis for a series of DBHE thermal performance in practical space heating engineering applications of MD-GHPs.

Automated data mining framework for building energy conservation aided by generative pre-trained transformers (GPT)

Data mining technologies have showed promising capabilities in extracting building operation patterns from massive amounts of building operational data for energy conservation. However, the number of the extracted operation patterns is always large. It is time-consuming and tedious for users to find valuable operation patterns among them. To overcome this barrier, this study proposes an automated data mining framework based on maximal frequent itemset mining and generative pre-trained transformers (GPT). An improved maximal frequent itemset mining-based data mining method is developed to extract non-redundant operation patterns from numerous building operational data for reducing the number of the extracted operation patterns. A template-based prompt generation method is proposed to transform the extracted operation patterns into prompts. The prompts are inputted into GPT to determine whether there are energy waste patterns hidden in the extracted operation patterns. It liberates humans from the tedious work on analyzing the extracted operation patterns. The framework is applied to analyze the one-year operational data from a real-world building chiller plant system for verifying its performance. Most of the energy waste patterns in this system are detected successfully, such as valve faults, low chilled water outlet temperature, small chilled and cooling water temperature differences, and improper coordinated control among devices. The detection accuracy of GPT is 89.17 % for energy waste patterns and 99.48 % for normal operation patterns. The response time and cost of GPT are 6747.60 s and $17.68, respectively.

A trawl collected dataset of Johnius (Actinopterygii, Sciaenidae) species in central-western Taiwanese waters.

Sciaenidae is one of the most important coastal fisheries in Taiwan, both in production and economic value. It is also significant as the main targetted diet of Chinese white dolphins, Sousachinensis, especially for the genus Johnius, such as J.taiwanensis, J.belangerii and J.distinctus, which is primarily found in central-western Taiwan coastal waters. Despite an abundance of Johnius species occurrences reported in the Global Biodiversity Information Facility (GBIF) and the Taiwan Biodiversity Information Facility (TaiBIF) data portals (Mozambique, Australia, Taiwan, Korea, India, Indonesia, South Africa, Pakistan, Vietnam and China), there are no specific datasets that properly document the regional distribution of this genus, especially in Taiwanese waters. Thus, this paper describes a dataset of genus Johnius occurrences in waters on the central-western coast of Taiwan. The data collection for the present study was conducted from 2009 until 2020 and comprised 62 sampling events and 133 occurrence records. All fish specimens were collected by trawling in Miaoli, Changhwa and Yunlin Counties, Taiwan and brought back to the lab for identification, individual number count and body weight measurement. These processing data have been integrated and established in the Taiwan Fish Database and published in GBIF. This dataset contains six Johnius species and 2,566 specimens, making it comprehensive Johnius fish fauna and spatial distributional data on the coastal habitat in central-western Taiwanese waters. This dataset contains 133 occurrence records of Johnius species (Sciaenidae) with 2,566 specimens, making it the most extensive public dataset of Johnius distribution records in Taiwan. The publication of this dataset through the TaiBIF and GBIF dataset platforms demonstrated that the number of Johnius spatial and temporal records in Taiwan waters is influenced by the topographical structure of the Changyun Rise (CYR) in combination with the cold current of the China Coastal currents and bound with the warm currents of the Kuroshio and the South China Sea on the central-western coast of Taiwan. The data serve as the foundation for understanding the biogeography and Johnius species ecology in Taiwan's coastal waters, which present a 2°C water temperature difference split at the CYR.

Power Increase due to Marine Biofouling: a Grey-box Model Approach

This paper proposes a grey-box modelling approach to predict marine biofouling growth and its effects on ship performance. The approach combines empirical or experimental-based white-box models with data-driven black-box models. First, a white-box model is built to predict ship resistance considering a bare hull. This prediction is based on calm water resistance, wind, waves, and temperature differences. Subsequently, marine biofouling growth is predicted using an experimental model that estimates the level of roughness on the ship hull. Finally, a deep extreme learning machine is used as a black-box model, employing a feedforward neural network technique. To test the approach, a superyacht case study was selected as a category of vessel heavily exposed to fouling. The study used a 2-year dataset obtained through a collaboration with Feadship. Results showed that the black-box approach outperforms the white-box approach in predictive capabilities. However, when the knowledge encapsulated in the white-box model is included in the grey-box approach, the model shows the highest prediction accuracy achieved by leveraging less historical data. This study demonstrates the potential of the proposed grey-box approach to accurately predict marine biofouling growth and its effects on ship performance, which can benefit ship operators and designers in improving operational efficiency and reducing maintenance costs.

Shading Influenced Water Quality and Seed Production of Nile Tilapia (Oreochromis niloticus L.) in the Hapa-within-Pond System During Warm Months

This study evaluated the influence of shading designs on water quality and Nile tilapia seed production in hapa-within-pond system. Metal frames were installed in three 200 m2 ponds and covered with greenhouse nets. Treatments were: no shading (NoS); top portion of frame covered (TopS); half of top and side portions of frame covered (HalfS); and top and sides of frame covered (TotalS). Twenty-four conditioned breeders (6♂:18♀) were bred on each hapa (1 m x 2 m x 1 m) installed in the ponds. Seeds were collected after 14 days. In both trials, significant differences in water temperature at 1500 h were observed among all treatments, with the lowest recorded in the TopS. The spawning rates of NoS (18.1±10.5%; 2.8±5.6%) were significantly lower than those of TopS (72.2±12.0%; 65.3±10.5%), HalfS (56.9±22.4%; 58.3±13.2%) and TotalS (66.7±23.6%; 65.3±10.5%). TotalS (8,563+3769 fry) and TopS (7,305+2491 fry) had significantly higher total seed production (TSP) than that of NoS (1,219+1150 fry) during the first trial, while TSP of HalfS (5,200+3051 fry) was comparable to those of the other treatments. During the second trial, shaded treatments had comparable TSPs but were significantly higher than NoS. For economic reasons, maximum reduction of water temperature, and optimum seed production during summer, the TopS design is recommended.

Effect Mechanism of Ambient Air Parameters on the Thermal Performance for Cooling Towers

Abstract As the volume of natural draft wet cooling towers (NDWCTs) continues to increase, the influence of ambient air on the thermal performance of the NDWCT is not clear. Therefore, the main parameters such as gas–water ratio, circulating water temperature difference, and heat transfer in each zone were calculated, and the temperature field and humidity field were also investigated. The results showed that the ambient temperature had the greatest influence on the cooling capacity of the NDWCT and the increase of ambient temperature led the circulating water temperature difference decreases the most, which was 7.63 °C (74.15%). The increase of relative humidity and atmospheric pressure led to an increase in convective heat transfer and the decrease in evaporative mass transfer, while both the convective heat transfer and evaporative mass transfer reduced with the decreasing temperature. This study establishes a theoretical foundation for optimizing of the thermal performance and energy-saving design of NDWCTs.

Power generation Technology of condensed water Temperature Differences in central air conditioning

With the rapid development of modern society, the improvement of people’s requirements for living comfort makes the utilization rate of central air conditioning in civil buildings and industrial plants greatly improved. The research and development of energy-saving technology under “double carbon” has also been paid attention to. As a hot new energy technology in recent years, thermoelectric power generation technology can improve the efficiency of old energy and be used in acquiring renewable energy, which is widely a concern by researchers. And central air conditioning in the summer operation of the condensate water still has much cold capacity not used. Therefore, the purpose of this study is to use the temperature difference between the low-temperature condensed water of central air conditioning and the external high temperature of the environment to achieve the purpose of energy saving and emission reduction.

How to improve the energy performance of mid-deep geothermal heat pump systems: Optimization of heat pump, system configuration and control strategy

Mid-deep borehole heat exchangers (MDBHEs) extract heat from geothermal energy with depth of 2–3 km, and provide high-temperature heat source for heat pump heating system. To improve the energy performance, this paper conducted optimization analysis on heat pump, system configuration and control strategy. Firstly, the energy efficiency and regulation characteristic of magnetic bearing variable-speed centrifugal heat pump (MBC-HP) was examined through field tests and simulation analysis. Results showed that MBC-HP performed efficiently with wide-range variation of heating load and compression ratio. And average COP of MBC-HP reached 6.21 during heating season. Besides, as evaporator-side water temperature difference (dTe) reached about 10 °C, two-stage MBC-HPs connected in series was raised to fit the large dTe, and the average COP of heat pump was improved to 6.97. Furthermore, the evaporator-side water flow rate (Ge) affected the energy efficiency of heat pump system and heat transfer performance of MDBHEs significantly. Thus the water pumps were recommended to be connected in parallel and then connected with heat pumps. Then the numbers and frequency of water pumps should be regulated to maintain dTe about 9.0 °C. Compared with control strategy of constant Ge, the COPs of heat pump system increased to 5.28, showing 18.7 % improvement.

Thermal response of an asphalt solar collector: Numerical and experimental validation

This study conducts a numerical analysis and experimental validation of the thermal performance of an asphalt solar collector. Both parallel and serpentine copper tubes with a total length of 3000 mm were embedded in the middle of a 1000 × 600 × 80 mm hot mix asphalt model. The sides and bottom of the test sections were insulated to prevent heat loss to the surrounding environment. Using four values of water mass flow rate and three values of artificial solar radiation, the thermal performance of the system was examined. A mass flow inlet of 0.0038–0.035 kg/s is specified for the water inside the embedded tubes, while 600, 800, and 1000 W/m2 solar radiation is applied on the upper section of the asphalt mix during this study. The thermal response was simulated using the COMSOL Multiphysics 5.6.0.280 heat transfer module. Using a reference asphalt solar collector, the desired parameter effects were investigated independently. The experimental results showed that the efficiencies of the asphalt solar collector with serpentine bare tubes and parallel bare tubes are 53.56 % and 52.85 %, respectively. The numerical simulation reveals that there is no significant thermal effect in the area under the embedded tubes when compared to the area above the tubes that are exposed to solar radiation from above. The average error found between the numerical and experimental results for the water temperature difference inside the embedded tubes of the asphalt solar collector ranged between 6 % and 14 %. This good agreement indicated that the computational fluid dynamics model is reliable and capable of simulating the thermal response of an asphalt solar collector.

WITHDRAWN: Analysis on high-efficiency chiller plant's characteristics

Building's power consumption counts a large ratio of the social total energy cost and chiller plants cost a large amount of power for public buildings. With the globe's carbon neutralization desire becoming more important, high-efficiency chiller plant (HECP) is the first thing for the design and management of building's central air condition system. With this goal in sight, this study analyses the chiller plant's efficiency which is composed by single chiller based on the system's view and presents the relative importance of 8 variables on the chiller plant's efficiency. To simplify the analysis, the concept of pump's head in power is introduced. HECP's constrains on chiller's COP, chilled and cooling water temperature differences and pump's head in power are presented. The energy consumption ratio of HECP's every component is also studied. The theoretical study results were verified by the operation data of one hotel building's chiller plant located in Chongqing municipality. The research results by this paper are significant for the design and operation of HECP and are further beneficial for the global carbon neutralization.

Variation and taphonomic implications of composition in modern and fossil malacostracan cuticles (Decapoda: Malacostraca)

Abstract The crustacean fossil record is dominated by mineralized forms. These fossils, in turn, are mainly decapod chelae or parts of chelae. Studies of the composition of modern crustacean cuticles have likewise been dominated by decapods. We summarize major element chemical analyses (Ca, Mg, Na, P) using SEM-EDS of modern crustacean exoskeletons from Bermuda, Georgia (USA), and Lake Tanganyika (Burundi). Although most specimens were brachyuran and anomuran crabs, material also included examples of stomatopods, isopods, caridean shrimps, and achelatans. Transects were made of sections of the carapace, palm of the propodus, and tips of either the dactyl or propodus. Multiple transects were made of the Bermudan land crab Gecarcinus lateralis. Additional studies were made of brachyuran fossil crabs from Texas and South Dakota and of brachyuran crabs having undergone ten months of burial in marine sediments. Overall, the tips of the chela were the thickest and most heavily mineralized regions and had the lowest phosphorus content. In nearly all cases, they also had the lowest ratios of Mg to Ca. One notable exception was Gecarcinus, where the denticles had elevated Mg:Ca values. Anomura and Brachyura had markedly different composition from Stomatopoda and possibly Isopoda, suggestive of independent evolutionary origins of biomineralization within the Crustacea. There were also significant differences in composition between brachyuran crabs from Georgia and Bermuda, perhaps due to differences in water temperature. The fossil crustaceans had much more phosphate in their cuticles, likely as a result of diagenetic processes. Composition should be a first order control on the fossil record of crustaceans. Future studies need to expand the taxonomic and geographic ranges of material examined, determine whether there are environmental controls on composition, and explore the relevant diagenetic processes.

Bacterial and archaeal community distributions and cosmopolitanism across physicochemically diverse hot springs

Terrestrial hot springs harbor diverse microbial communities whose compositions are shaped by the wide-ranging physico-chemistries of individual springs. The effect of enormous physico-chemical differences on bacterial and archaeal distributions and population structures is little understood. We therefore analysed the prevalence and relative abundance of bacteria and archaea in the sediments (n = 76) of hot spring features, in the Taupō Volcanic Zone (New Zealand), spanning large differences in major anion water chemistry, pH (2.0–7.5), and temperature (17.5–92.9 °C). Community composition, based on 16S rRNA amplicon sequence variants (ASVs) was strongly influenced by both temperature and pH. However, certain lineages characterized diverse hot springs. At the domain level, bacteria and archaea shared broadly equivalent community abundances across physico-chemically diverse springs, despite slightly lower bacteria-to-archaea ratios and microbial 16S rRNA gene concentrations at higher temperatures. Communities were almost exclusively dominated by Proteobacteria, Euryarchaeota or Crenarchaeota. Eight archaeal and bacterial ASVs from Thermoplasmatales, Desulfurellaceae, Mesoaciditogaceae and Acidithiobacillaceae were unusually prevalent (present in 57.9–84.2% of samples) and abundant (1.7–12.0% sample relative abundance), and together comprised 44% of overall community abundance. Metagenomic analyses generated multiple populations associated with dominant ASVs, and showed characteristic traits of each lineage for sulfur, nitrogen and hydrogen metabolism. Differences in metabolic gene composition and genome-specific metabolism delineated populations from relatives. Genome coverage calculations showed that populations associated with each lineage were distributed across a physicochemically broad range of hot springs. Results imply that certain bacterial and archaeal lineages harbor different population structures and metabolic potentials for colonizing diverse hot spring environments.

A new method for characterizing the heat transfer capacity of the divertor and high heat flux components

The divertor is usually exposed to extreme incident heat flux conditions in nuclear fusion engineering and its ability to remove the heat is extremely crucial for the safe operation of magnetic confinement nuclear fusion device. The evaluation of the heat removal capacity of the divertor has been always based on high heat flux (HHF) tests. Yet such methods are only available for the small size of experimental components, it is more difficult to compare under different loading and cooling conditions. In order to assess the heat removal capacity in real time and accurately, a new method was developed to characterize the heat removal capacity of the divertor and other high heat load components based on the cooling water thermal decay time constant, the time constants model has also been established. The thermal decay time constant was obtained by fitting the characteristic curves of the water temperature differences with time during the cooling phase of different components under HHF tests. This index is used to quantitatively analyze, characterize and evaluate the heat transfer capacity of the system of the divertor.

Improved Performance of Heat Source Free Water‐Floating Carbon Nanotube Thermoelectric Generators Controlling Wettability Using Atmospheric‐Pressure Plasma Jet and Waterproof Spray

AbstractWater‐floating carbon nanotube thermoelectric generators (CNT‐TEGs) can effectively power Internet of Things (IoT) applications. CNT‐TEGs produce electricity by floating on water to generate a temperature gradient in the CNT films, where water pumping via capillary action causes evaporation‐induced cooling in selected areas. However, the amount of electricity required for target applications needs to be increased. Therefore, the wettability of CNT films is controlled via various treatments to increase water evaporation and temperature difference in the films. The contact angle of the water droplet on the film surface related to the wettability decreases upon atmospheric‐pressure plasma jet irradiation and increases upon waterproof spray treatment. Intermediate wettability is obtained by combining the two aforementioned treatments. Under the environmental conditions of light irradiation (1 kW m−2) and wind (3 m s−1) at a water temperature of 20 °C, the CNT‐TEGs with the combined treatment exhibit a highest output voltage of 3.9 mV, which is 30% larger than that of the pristine CNT‐TEG. At a water temperature of 60 °C, a highest output voltage of 13.1 mV is achieved in the pristine CNT‐TEG. The performance enhancement of CNT‐TEGs by controlling the wettability of CNT films under various environmental conditions can facilitate advancements in IoT technology.

Decline of young-of-year walleye (Sander vitreus) growth due to Bythotrephes impacts predicted from bioenergetic principles

Invasive species are a major threat to ecosystem structure and function. For example, Bythotrephes cederströmii (Bythotrephes hereafter) invasions have significantly reduced native zooplankton density and biomass, resulting in competitive interactions with zooplanktivorous fishes. Young of year (YOY) walleye (Sander vitreus) are initially zooplanktivorous and have recently been shown to display reduced growth in Bythotrephes-invaded lakes. Here, we combined a bioenergetics model for larval walleye with changes in the zooplankton community following Bythotrephes invasion and predicted reduced larval walleye growth in the presence of Bythotrephes, supporting field observations. The model predicted greater negative impacts on larval walleye growth in oligotrophic compared with mesotrophic lakes, though reduced growth was only significant under oligotrophic conditions. Under Bythotrephes invasion, net energy available to growth over the simulated period was often observed to be negative (indicating mass loss). These combined results from the model suggest that Bythotrephes invasion could potentially lead to walleye recruitment failure, especially in low nutrient environments. This result was insensitive to differences in annual mean water temperatures ranging from 18.5 to 23.5 °C. As YOY growth, survival, and recruitment are ultimately linked to adult abundance and sustainability of managed stocks, our results highlight the potential impacts of Bythotrephes on the sustainability of walleye populations in boreal lakes.

Experimental investigation on thermal stratification characteristic of steam condensation through multi-hole sparger

Thermal stratification induced by steam direct contact condensation is experimentally investigated through a multi-hole sparger of horizontal injection with different steam mass flux, initial water temperature, and submergence depth. The exitance of chugging regime and oscillatory bubble regime causes the differences in flow patterns of pool water through multi-hole sparger. The four stages of temperature evolution, complete mixing, gradual stratification, stable stratification, and downward extension of the heated region stage, are found. Thermal stratification vanishes at water subcooling lower than 3℃. The influence of key factors on the thermal stratification and thermocline dynamic characteristic is discussed and analyzed. With steam mass flux increasing, the maximum temperature difference of pool water increases first and then decreases, and the inflection point of temperature growth increases. Besides, thermocline downward velocity increases with steam mass flux increasing resulting from the enhanced turbulence effect. Larger initial water temperature and smaller distance from sparger to pool bottom help to reduce the maximum temperature difference. The thermocline velocity increases with the initial water temperature rising due to the reduced density difference. Lower sparger position can effectively move down the thermocline position, and the thermocline velocity decreases resulting from the weakened turbulence motion. The initial water level has a limited effect on thermal stratification and thermocline velocity. In addition, the Richardson number, used to judge whether thermal stratification occurs, reaches the maximum at water temperature 65℃. The results are helpful to understand the mechanism of thermal stratification and provide an effective reference for the design of the suppression system.

Fall distribution and diversity of cetaceans along the southern and eastern coasts of Hokkaido, Japan

The southern and eastern coasts of Hokkaido, part of the western North Pacific and the southern Sea of Okhotsk, are productive regions with a high degree of biodiversity and human activity. This area is an important habitat for cetaceans. However, only a few studies have been conducted on comprehensive species co-inhabiting the study area at the same time. Information regarding cetacean distribution patterns is necessary for ecosystem management and marine conservation. The objective of this study was to investigate the distribution patterns and environmental variables affecting the distribution of cetaceans in coastal Hokkaido using sighting surveys. Five baleen and seven toothed whale species were observed during the study period. The maximum entropy model used to map the distribution of 11 selected cetacean species showed a heterogeneous distribution, which may reflect a potentially suitable habitat for each species. In the North Pacific region, there are differences in water temperature between east and west of Cape Erimo, which is possibly the reason why some species are only distributed in the eastern side. In the Nemuro Strait, the distribution differs from north to south, likely influenced by seafloor topography. Our results will help to clarify the habitat of various cetacean species in coastal Hokkaido and provide essential information for their conservation.

Experimental assessment and modeling of radiant cooling technology using constant and variable water flow rate

The goal of this study is to perform an analysis of the performance of radiant cooling panels using experimental testing and transient system simulation software. The effect of design parameters such as water supply temperature and water flow rate on thermal comfort and energy efficiency is studied. Two control schemes are used in the study in which either the water flow rate or the water temperature difference between the inlet and outlet of radiant panels is held constant. This paper demonstrates the modeling and validation of a radiant cooling system in TRNSYS and uses this model to study the performance of the system during the cooling season in Egypt. It was found that the lower water temperature of 16 °C was found to be suitable for achieving thermal comfort. The constant water flow rate control scheme showed a 5% less unmet hours percentage than the constant water temperature difference, but the latter used 38% less electrical energy. A constant water temperature difference control scheme can achieve better thermal comfort with an unmet hours percentage down to 12.5% by coupling the system with a dehumidification device.

Diversity and distribution pattern of copepods in Palk Bay coastal waters of India

The aim of this study was to find the species abundance and composition of copepod zooplankton in four selected sites such as Karangadur, Thevipattinam, Athangarai and Mandapam in Palk Bay region during February 2022 to January 2023. There is no significant difference (P<0.05) in water temperature, salinity, DO and pH values between the sites during this study period. In this study, we have observed 46 species of copepods belongs to 30 genus, 20 families and four orders. The overall percentage of copepod species composition in the four collection sites was: Calanoida (58.7%), Poecilostomatoida (17.4%), Harpacticoida (15.2%) and Cyclopoida (8.7%). In Athangarai site, a maximum of 40 copepod species were recorded. In Karangadu site, 34 species, in Devipattinam site, 28 species and in Mandapam site only 25 species were observed. In calanoid copepods, Acartia, Calanopia and Temora was the dominant genus which representing three species. In Poecilostomatoida order, four families, seven genus and eight species were observed. Out of the seven genus, Corycaeus was the dominant genus which comprises two species such as Corycaeus crassiusculus and C. speciosus. In Harpacticoida order, six families, six genus and seven species were recorded. Among the six genus, Longipedia represents two species (Longipedia coronata and L. weberi). The order Cyclopoida, has only one family, two genus and four species. Among the genus, Oithona was the dominant genus which contains three species. Among the 20 families, Pontellidae was the dominant one includes six species.

Coastal water temperature difference, a potential predictor of glass eel recruitment in Anguilla japonica during non-meander periods of the Kuroshio

Coastal water temperature difference, a potential predictor of glass eel recruitment in Anguilla japonica during non-meander periods of the Kuroshio