Thermohydraulic analysis of covalent and noncovalent functionalized graphene nanoplatelets in circular tube fitted with turbulators

© The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Covalent and non-covalent nanofluids were tested inside a circular tube fitted with twisted tape inserts with 45° and 90° helix angles. Reynolds number was 7000 ≤ Re ≤ 17,000, and thermophysical properties were assessed at 308 K. The physical model was solved numerically via a two-equation eddy-viscosity model (SST k-omega turbulence). GNPs-SDBS@DW and GNPs-COOH@DW nanofluids with concentrations (0.025 wt.%, 0.05 wt.% and 0.1 wt.%) were considered in this study. The twisted pipes' walls were heated under a constant temperature of 330 K. The current study considered six parameters: outlet temperature, heat transfer coefficient, average Nusselt number, friction factor, pressure loss, and performance evaluation criterion. In both cases (45° and 90° helix angles), GNPs-SDBS@DW nanofluids presented higher thermohydraulic performance than GNPs-COOH@DW and increased by increasing the mass fractions such as 1.17 for 0.025 wt.%, 1.19 for 0.05 wt.% and 1.26 for 0.1 wt.%. Meanwhile, in both cases (45° and 90° helix angles), the value of thermohydraulic performance using GNPs-COOH@DW was 1.02 for 0.025 wt.%, 1.05 for 0.05 wt.% and 1.02 for 0.1 wt.%.Peer reviewe

The influence of the Mosul Dam on the bed sediments and morphology of the River Tigris

Abstract The Mosul dam and its flow regulating scheme have been constructed 60 km north of Mosul city. A minimum discharge of 330 m 3 s"' is usually released from the dam. The reach of the River Tigris below the dam (about 8.3 km long) investigated in this study serves as a small reservoir for the regulating scheme. The effects of high velocity discharges from the bottom outlet and spillway structures on channel morphology were monitored for two periods using fixed cross-sections. The characteristics of the bed sediments were studied using 32 samples. The results showed that large amounts of sediment (average 0.5 m) were eroded from the bed of the river during a 10 month period. The bed sediments were characterized by a sand:silt:clay ratio of 42.4:50.2:7.4 respectively and it is believed that lining of the bed of the river downstream of the bottom outlet and spillway would reduce the scour downstream

Assessment of Climate Change Impacts on Water Resources of Al-Adhaim, Iraq Using SWAT Model

SWAT model (Sediment and Water Assessment Tool) was used to evaluate the impacts of climate change on water resources in Al-Adhaim Basin which is located in north east of Iraq. Al-Adhaim River is the main source of fresh water to Kirkuk City, one of the largest cities of Iraq. Recent studies have shown that blue and green waters of the basin have been manifesting increasing variability contributing to more severe droughts and floods apparently due to climate change. In order to gain greater appreciation of the impacts of climate change on water resources in the study area in near and distant future, SWAT (Soil and Water Assessment Tool) has been used. The model is first tested for its suitability in capturing the basin characteristics, and then, forecasts from six GCMs with about half-a-century lead time to 2046-2064 and one-century lead time to 2080-2100 are incorporated to evaluate the impacts of climate change on water resources under three emission scenarios: A2, A1B and B1. The results showed worsening water resources regime into the future.Validerad; 2016; Nivå 1; 2016-11-29 (inah)</p

Model-Based Assessment of Climate Change Impact on Isaac River Catchment, Queensland

Isaac River catchment, which is located within Fitzroy basin in Central Queensland, Australia is mostly a semi-arid region, sparsely populated, but rife with economic activities such as mining, grazing, cropping and production forestry. Hydro-meteorological data over the past several decades reveal that the catchment is experiencing increasing variability in precipitation and streamflow contributing to more severe droughts and floods supposedly due to climate change. The exposure of the economic activities in the catchment to the vagaries of nature and the possible impacts of climate change on the stream flow regime are to be analyzed. For the purpose, SWAT model was adopted to capture the dynamics of the catchment. During calibration of the model 12parameters were found to be significant which yielded a R2 value of 0.73 for calibration and 0.66 for validation. In the next stage, six GCMs from CMIP3 namely, CGCM3.1/T47, CNRM-CM3, GFDLCM2.1, IPSLCM4, MIROC3.2 (medres) and MRI CGCM2.3.2 were selected for climate change projections in the Fitzroy basin under a very high emissions scenario (A2), a medium emissions scenario(A1B) and a low emissions scenario (B1) for two future periods (2046-2064) and (2080-2100). All GCMs showed consistent increases in temperature, and as expected, highest rate for A2 and lowest rate for B1. Precipitation predictions were mixed-reductions in A2 and increases in A1B and B1, and more variations in distant future compared to near future. When the projected temperaturesand precipitation were inputted into the SWAT model, and the model outputs were compared with the baseline period (1980-2010), the picture that emerged depicted worsening water resources variability.Validerad; 2016; Nivå 1; 20160729 (nadhir

Assessment of climate change impacts on water resources of Khabour in Kurdistan , Iraq using SWAT model

The Khabour River is one of five tributaries of Tigris River and the first river flows into Tigris River contributing to Tigris Flow by about 2 BCM at Zakho Station. The area of this catchment is 6,143 km2, of which 57% are located in Turkey and 43% in Iraq with a total length of 181 km. Khabour River is the main source of fresh water to Duhok City, one of the major cities of Kurdistan Region. Hydrometeorological data over the past several decades reveal that the catchment is experiencing increasing variability in precipitation and stream flow contributing to more severe droughts and floods presumably due to climate change. SWAT model was applied to capture the dynamics of the basin. The model was calibrated at Zakho station. The performance of the model was rather satisfactory; R2 and ENC were 0.5 and 0.51, respectively in calibration period. In validation process R2 and ENC were nearly consistent. In the next stage, six GCMs from CMIP3 namely, CGCM3.1/T47, CNRM-CM3, GFDL-CM2.1, IPSLCM4, MIROC3.2 (medres) and MRI CGCM2.3.2 were selected for climate change projections in the basin under a very high emissions scenario (A2), a medium emissions scenario (A1B) and a low emissions scenario (B1) for two future periods (2046-2064) and (2080-2100). All GCMs showed consistent increases in temperature and decreases in precipitation, and as expected, highest rate for A2 and lowest rate for B1. The projected temperatures and precipitation were input to the SWAT model to project water resources, and the model outputs were compared with the baseline period (1980-2010), the picture that emerged depicted deteriorating water resources variability.Validerad; 2016; Nivå 1; 2016-11-30 (inah)</p

Impacts of Climate Change on Water Resources in Diyala River Basin, Iraq

Diyala River is the third largest tributary of the Tigris River running 445 km length and draining an area of 32,600 km2. The river is the major source of water supply for Diyala City for municipal, domestic, agriculture and other purposes. Diyala River Basin currently is suffering from water scarcity and contamination problems. Up-to-date studies have shown that blue and green waters of a basin have been demonstrating increasing variability contributing to more severe droughts and floods seemingly due to climate change. To obtain better understanding of the impacts of climate change on water resources in Diyala River Basin in near 2046~2064 and distant future 2080~2100, SWAT (soil and water assessment tool) was used. The model is first examined for its capability of capturing the basin characteristics, and then, projections from six GCMs (general circulation models) are incorporated  to assess the impacts of climate change on water resources under three emission scenarios: A2, A1B and B1. The results showed deteriorating water resources regime into the future.Validerad; 2016; Nivå 1; 2016-11-29 (kribac)</p

Climate Change Impacts on Water Resources of Greater Zab River, Iraq

Greater Zab is the largest tributary of the Tigris River in Iraq where the catchment area is currently being plagued by water scarcity and pollution problems. Contemporary studies have revealed that blue and green waters of the basin have been manifesting increasing variability contributing to more severe droughts and floods apparently due to climate change. In order to gain greater appreciation of the impacts of climate change on water resources in the study area in near and distant future, SWAT (Soil and Water Assessment Tool) has been used. The model is first tested for its suitability in capturing the basin characteristics, and then, orecasts from six GCMs (general circulation models) with about half-a-century lead time to 2046~2064 and one-century lead time to 2080~2100 are incorporated to evaluate the impacts of climate change on water resources under three emission scenarios: A1B, A2 and B1. The results showed worsening water resources regime into the future.Validerad; 2017; Nivå 1; 2017-02-16 (andbra)</p

Groundwater Hydrology in Iraq

In the current work, the spatial distribution of the precipitation in Iraq were reviewed, as it is considered as one of the most important parameters that controls groundwater recharging. In addition, the physiographical divisions of Iraq had been assessed as it is contributing in determining the groundwater aquifers, as well as a review of the division of the main groundwater aquifers. Subsequently, a review of the level and depths of groundwater, the regional trends of its flow, the variation of its specific quality (especially salinity), and its suitability for multipurpose, throughout of the Iraqi territory had been conducted. The characteristics of each region were highlighted separately, including the detailed aspects that relate to the groundwater recharge, quality flow of groundwater, the hydraulic characteristics of the groundwater aquifers, the problems facing the groundwater sector, and the development of recommendation in terms of the optimal investment and development of groundwater resources in each region.Validerad;2020;Nivå 1;2020-01-09 (johcin)</p

Impacts of Climate Change on Water Resources of Greater Zab and Lesser Zab Basins, Iraq, Using Soil and Water Assessment Tool Model

The Greater Zab and Lesser Zab are the major tributaries of Tigris River contributing the largest flow volumes into the river. The impacts of climate change on water resources in these basins have not been well addressed. To gain a better understanding of the effects of climate change on water resources of the study area in near future (2049-2069) as well as in distant future (2080-2099), Soil and Water Assessment Tool (SWAT) was applied. The model was first calibrated for the period from 1979 to 2004 to test its suitability in describing the hydrological processes in the basins. The SWAT model showed a good performance in simulating streamflow. The calibrated model was then used to evaluate the impacts of climate change on water resources. Six general circulation models (GCMs) from phase five of the Coupled Model Intercomparison Project (CMIP5) under three Representative Concentration Pathways (RCPs) RCP 2.6, RCP 4.5, and RCP 8.5 for periods of 2049-2069 and 2080-2099 were used to project the climate change impacts on these basins. The results demonstrated a significant decline in water resources availability in the future

Assessment of Climate Change Impact on Water Resources of Lesser Zab, Kurdistan, Iraq Using SWAT Model

Kurdistan in northern Iraq, a semi-arid region, predominantly a pastureland, is nourished by Lesser Zab, which is the second major tributary of Tigris River. The discharge in the tributary, in recent times, has been experiencing increasing variability contributing to more severe droughts and floods supposedly due to climate change. For a proper appreciation, SWAT model has been used to assess the impact of climate change on its hydrological components for a half-centennial lead time to 2046-2064 and a centennial lead time to 2080-2100. The suitability of the model was first evaluated, and then, outputs from six GCMs were incorporated to evaluate the impacts of climate change on water resources under three emission scenarios: A1B, A2 and B1. The results showed worsening water resources regime.Validerad; 2016; Nivå 1; 2016-11-29 (inah)</p