Inlet Water Research Articles

Relationships between morphological factors and heat extraction from the upper arm using liquid cooling garment

Astronauts wear liquid perfused garments inside their outer spacesuits for regulating body temperature. The present study explored relationships between local heat production from the upper arm and body morphology while wearing liquid perfused sleeve. Heat extraction from the upper arm of 19 subjects (8 males and 11 females) during three different exercise modes (running at 6–8 km∙h−1, cycling at 40–55 W, and arm ergometer at 10–20 W) and rest has been investigated. The total body fat (27.5 ± 7.2%), body mass index (24.4 ± 2.7 kg·m−2), arm surface area (589 ± 90 cm2), and arm volume (1300 ± 300 mL) were considered as covariates. Subjects wore a liquid perfused sleeve over the upper arm (left) with the water inlet temperature of 24.0 ± 0.3 °C and the heat extraction was calculated using the water flow rate and temperature differences. Heat extraction from the upper arm showed no significant differences among the three exercises. During cycling, there was a negative relationship between heat extraction and total body fat (r = − 0.527, P < 0.05). Heat extraction was more related to the arm volume (P < 0.05) than the surface area of the upper arm, which was significant only for the male group in the cycling mode. For the female group, heat extraction was related to upper arm temperature in the cycling and arm exercise modes (for both exercises P < 0.05). These results can be applied to improve liquid cooling garments for astronauts, considering their body morphology and sex.

Dehydration of turbine engine lubricant oil using cellulose hydrogel

Contamination of oils by water is a recurring problem in the industry and can damage engines and equipment. Oil dehydration systems with hydrogels have shown promise for the removal of free, soluble, and emulsified water. This work evaluates, in an unprecedented way, the dehydration of turbine lubricating oil using a cellulose hydrogel. The synthesis of the hydrogel was confirmed by the formation of specific functional groups. The hydrogel was characterized through high-resolution SEM, EDS, FTIR, BET, TGA, DVS and swelling degree. The oil was evaluated regarding its composition and physicochemical properties. The performance of the hydrogel in the treatment of water-in-oil emulsion was analyzed in batch and continuous flow systems. A fixed bed apparatus was specially designed and sized according to the industry's specifications to simulate on-site application. The batch treatment was evaluated using orbital and full tumbling inversion mixing systems, both reaching removal efficiency of around 47 %. Mixing by full tumbling allowed greater stability of the emulsion and control of the water concentration, but it required a longer time to enable adequate water uptake by the hydrogel. The efficiency of the hydrogel in the continuous flow system was affected by retention time and inlet water concentration. With a retention time of 12 min, it was possible to treat 1 L of oil, reducing the water concentration from 412 ppm to 197 ppm and the turbidity from Haze 6 to Haze 1. Thus, the cellulose hydrogel was efficient in dehydrating turbine lubricating oil, opening up the possibility of expanding its use to industrial facilities.

Comparison and regional suitability evaluation of different backfill source heat pumps using TRNSYS

As global energy demand and carbon emissions continues to rise year by year, the use of renewable energy for heating becomes increasingly urgent. This study employs solar and geothermal energy to supply heat to mining facilities. Initially, three distinct heating systems for mining areas were modeled in TRNSYS: the Backfill Source Heat Pump (BSHP), the Solar Assisted Backfill Source Heat Pump (SABSHP), and the Solar Assisted Backfill Source Heat Pump with Seasonal Heat Storage (SABSHP-SHS). Following a decade of simulation, the optimal system was identified through a comparative analysis that encompassed backfill temperature equilibrium, the inlet and outlet water temperatures for buried pipes, Coefficient of Performance (COP), Partial Load Ratio (PLR), and economic factors. Over the 10-year simulation period, the COP and PLR of the SABSHP-SHS system outperformed both the BSHP and SABSHP systems, showing higher energy efficiency and better heat pump performance. To further assess the regional adaptability of the SABSHP-SHS system, simulations were conducted across four regions with diverse climatic profiles: Shijiazhuang, Yan’an, Xining, and Hegang. The analysis focused on heat collection, efficiency, backfill temperature variation, system energy consumption, and the energy efficiency ratio. The findings indicate that Hegang exhibits the highest solar heat collection efficiency at 89.9% during the non-heating season, while Xining achieves a significantly higher heat collection efficiency of 54.1% during the heating season. These results suggest that the SABSHP-SHS system is particularly effective in regions with pronounced seasonal variations, characterized by extended cold winters and brief, intense summers.

Analysis of operation regulation on delay time in long-distance heating pipe systems for practical engineering

The distribution area of the district heating network (DHN) is extensive, and there are inherent time delays and thermal losses in the process of heat transfer through heating pipes. The delay in heat transfer within long-distance heating pipes may result in inadequate heat supply to end-users or excessive energy consumption at the heat source. Therefore, this paper presents a quasi-dynamic model for calculating the transmission delay time in the long-distance heating pipeline. And the model is validated through the measured values obtained from a heating pipeline. The influencing factors of delay time are further discussed, including operating parameters, pipe structure parameters and thermal insulator thickness. Additionally, the impact of pipe delay time in practical engineering is analyzed. In practical engineering, the transmission delay time varies when the pipe structural or operational parameters differ, even under the same outdoor temperature change. The change in inlet water temperature and mass flow rate can impact the change rate of outlet water temperature, thereby influencing the delay time. Furthermore, the delay time exhibited an increase with pipe length, diameter, and thermal insulator thickness; however, the effect of thermal insulator thickness on it was minimal. When the inlet water temperature rose or dropped by 5℃, the delay time grew by more 70 % per 1 km pipe length, about 40 % per 100 mm diameter and less 2 % per 100 mm thermal insulator thickness, respectively.

Off-design performance optimization for steam-water dual heat source ORC systems

High-pressure steam and hot water often coexist as industrial waste heat. In this study, dual loop and single loop ORC systems are designed for 700 kPa, 4.1 kg/s steam, and 90 ℃, 122.36 kg/s hot water conditions to study the off-design performance when steam or hot water conditions change. To maximize net output power, we employ a particle swarm optimization algorithm to optimize the evaporation and condensation temperatures. The results show that within the specified hot water conditions, the evaporation and condensation temperatures of D-ORC's low-pressure loop and S-ORC increase with rising hot water inlet temperature and flow rate. The S-ORC demonstrates a higher net output power growth rate as hot water flow rate and temperature rise. Under specific steam conditions, when the steam outlet is in a gas-liquid two-phase state, D-ORC's maximum net output power is 1.7 % higher than that of the S-ORC, with little variation in optimal evaporation and condensation temperatures with respect to steam inlet pressure. At a 3.5 kg/s steam flow rate, the D-ORC's high-pressure loop becomes ineffective, whereas S-ORC efficiently adjusts heat exchange capacity under diverse steam-water conditions, Consequently, the D-ORC's average net output power is 34.2 % lower than that of the S-ORC.

Experimental study of the optimal design and performance of a mixed-flow dew-point indirect evaporative cooler

Evaporative cooling technologies represent a promising alternative to face the emerging cooling energy poverty, owing to their low production and operative costs. High performance can be achieved through more complex designs, such as dew point indirect evaporative cooling (DIEC) systems. Recent literature explores improvements on these systems, like flow configuration, materials, and water distribution. This study proposes a compact mixed-flow DIEC system made of polycarbonate plates covered with two possible wicking materials. Three water distribution systems are also studied. The prototypes are experimentally characterised by varying the inlet air temperature, humidity, volume flow, and working-to-intake air ratio. The best performing design is evaluated in terms of temperature drop, dew-point effectiveness, wet-bulb effectiveness, and cooling capacity. Results are consistent with those in the literature for equivalent heat transfer areas. The use of a wicking material improves the cooling capacity by up to 1.45. The type of material is less relevant, which enables to select the most economic and accessible option. External nozzles for water distribution offers temperature drops of more than 1 °C and better cooling capacities of approximately 100 W than inlet water distributors.

Quality Assessment of Drinking Water from Vending Machines for a Healthier Life

Commercial water vending machines in urban communities are important for consumers because of their convenience and affordability. Therefore, this study investigated the environmental conditions, maintenance, and quality of drinking water distributed through vending machines in an urban community in Thailand. The research sampled 101 drinking water machines in Buriram Municipality, Buriram Province. These machines were assessed for physical characteristics and the surrounding environment and were conducted according to an evaluation form provided by the Ministry of Public Health, Thailand. The findings revealed that 93.07% of the machines had auto coin failures; did not record the date, month, and year of filter changes; and did not display the business license on the cabinet. Additionally, 89.1% of the cabinets had thick dust, 57.43% had damaged or rusted handles on the water inlet door, and 56.44% had algae or rust stains on the water dispenser head. A physiochemical analysis revealed that 83.2% of the machines did not detect the pH levels. Total coliform bacteria and E. coli were not detected in 39.6% and 12.9% of samples, respectively. This study was conducted to develop an application for monitoring the quality of drinking water from vending machines to ensure that standards are met and up-to-date information is provided to help consumers make informed decisions about using clean and safe drinking water from vending machines.

Influence of Water Concentration on the Water/Vapor/ Oil Separation Process in a Vacuum Oil Filter: Modelling and Simulation

The vacuum oil filter (VOF) is widely applied in the oil-water emulsion demulsification separation due to the phase separation by using vacuum evaporation; however, the micro-dynamic characteristics of oil, water and vapor three phases and the influencing factors of separation efficiency are rarely studied. Therefore, the fluid flow and phase separation characteristics of water-in-oil emulsions were numerically analysed by ANSYS software. The demulsification conditions of water/oil emulsion were simulated by using the two-fluid model and the water evaporation model, and the turbulence effect was considered by using the Reynolds stress model. The results show that the established model could provide a convenient way to study the effects of the different water concentrations in oil; the turbulence intensity in VOF increases with the increase of water concentration in oil; The separation efficiency has been influenced by the inlet water concentration reaching values between 20.65-22.62% in the center axis, while 33.18-42.24% in the plate column; the vapor concentration ranged from 0 - 23.64% in the center axis, while 0 - 41.02% in the plate column. The relative volume fraction of water concentration decay tending with the water concentration increases, and the water concentration has a great influence on the separation efficiency.

Preparation of dodecahydrate disodium hydrogen phosphate shape-stabilized composite phase change materials and their experimental investigation in solar thermal storage and exothermic systems

To alleviate the mismatch between energy supply and demand caused by the spatial and temporal distribution mismatch and weather uncertainty during solar energy utilization, solar energy is combined with phase change thermal storage technology to improve the performance of solar thermal storage systems. In this study, a shape-stabilized composite phase change material with a highly absorbent resin structure is proposed as thermal storage material. This material exhibits a latent heat of phase change of 246.5 J/g, a thermal conductivity of 1.968 W/(m·K), and maintains good stability after 200 thermal cycles. Subsequently, a detachable experimental setup integrating solar energy with a phase change thermal storage tank was designed and constructed. The effects of inlet and outlet hot water flow rates and heat source temperature on heat storage time and the amount of stored water were investigated separately. The experiments show that increasing the heat source temperature during storage effectively shortens the storage time, and that the largest effective amount of hot water is obtained when the exothermic flow rate is 300 L/h. The study's results are significant for broadening solar energy utilization, alleviating the mismatch between solar energy supply and demand, and evaluating the thermal performance of latent heat storage systems.

Productivity, energy, and exergy analyses of a water desalination system-based vortex tubes with different configurations: An experimental implementation

The present implementation explores the use of vortex tubes (VTs) as an alternative thermal technology for water desalination systems (WDSs). VTs are utilized to provide hot air for evaporating salt water in the evaporator, while simultaneously supplying cold air to condense the water vapor in the condenser. The study investigates the influence of a number of operating parameters, including inlet water temperature (Ti,w), cold mass ratio (CR), and vacuum pressure (pvac) on the performance of WDS-based VTs through experimental analysis. Different configurations of VTs are tested for WDS applications, including WDS-based single vortex tube (VT), WDS-based two series vortex tubes (2SVTs), and WDS-based two parallel vortex tubes (2PVTs). Performance metrics such as the evaporation heat (QEvap), desalinated water production (DWP), gain output ratio (GOR), and exergy performance are evaluated for each configuration. Results show that the WDS-based 2SVTs exhibits the highest QEvap; while the WDS-based 2PVTs demonstrates the lowest value. Correlations are proposed to predict DWP for different configurations of WDS based on pvac, Ti,w, and CR with a maximum deviation of ±12.2 %. Furthermore, the WDS-based 2SVTs achieves the best GOR of 2.5 at an inlet water temperature of 80 °C, representing a significant improvement compared to the WDS-based VT and 2PVTs. The exergy efficiency (ηex) increases with higher CR, and the WDS-based 2SVTs ensures the best exergy performance, and its maximum overall ηex equals 78.2 %.

Impact of newer climate data for technical analysis of residential building energy use in the United States

In this study, we describe an analysis indicating the relative importance of newer hourly weather files for simulation analysis of the energy use of residential buildings in North America.Results show that older TMY3 (ending 2005) data compared with newer TMY2021 (2007–2021) data are less appropriate for the best prediction of low-energy buildings. The balance of heating and cooling is significantly altered in the more recent TMY files with potential impacts on best performing energy efficiency measures. With 64 high profile North American locations evaluated, we found heating to be approximately 11% lower with the newer data, while cooling was increased by a similar amount percentage wise. However, the dominance of space heating in North America made decreases to heating considerably larger in an absolute sense so that overall space conditioning energy fell.Small changes in annual temperature can have large impacts. For all electric homes with air source heat pumps, we found that a change of 1 °C to outdoor temperature can produce about a 19 % change in space conditioning energy. The newer data also shows increased average solar electric output from simulated rooftop photovoltaic systems, likely due to more sophisticated solar irradiance data. Water heating was about 3 % lower given rising groundwater temperatures and inlet water temperatures to water heating systems. Results also showed that the newer data tended to increase savings from comprehensive building efficiency efforts in all electric buildings. This largely takes place because higher temperatures in winter allow air source heat pumps to meet heating needs more efficiently. Generally, the direction of these influences ease pathways to reach zero energy buildings in North America.

Thermal performance analysis and optimization of a heat pipe-based electronic thermal management system using experimental data-driven neuro-genetic technique

Heat pipes are highly efficient heat transfer devices and are used widely to dissipate heat generated by electronic components, thereby maintaining their operating temperatures and preventing overheating. The present study deals with the thermal performance prediction of a cylindrical heat pipe (length 380 mm) based electronic thermal management system using steady-state experimental investigation. The experiments are conducted under varying operational conditions, including heat inputs (10–50 W), condenser cooling water inlet temperatures (288.15, 293.15, and 298.15 K), and flow rates (10, 25, and 40 LPH). The study shows that the evaporator temperature of the heat pipe consistently rises with the increase in heat inputs for all tested conditions. The lowest evaporator temperature (311.42 K) is noticed for the cooling water inlet temperature of 288.15 K across all heat inputs. Notably, at 10 LPH, the heat pipe supplied with cooling water at 288.15 K exhibits reductions of up to 1.47 % and 2.29 % compared to 293.15 K and 298.15 K, respectively. Similar trends are also observed at 25 LPH and 40 LPH. The heat pipe’s thermal resistance is lowest (0.95 K/W) at a cooling water inlet temperature of 298.15 K. At 10 LPH, there are reductions of 10.19 % and 5.62 % compared to 288.15 K and 293.15 K, and at 40 LPH, reductions are 15.66 % and 7.89 %. The heat pipe’s evaporator heat transfer coefficient also plays a significant role and is maximum for the cooling water inlet temperature of 288.15 K at a flow rate of 10 LPH. To understand the complex behavior of the heat pipe and for better prediction of its thermal performance, a neuro-genetic (experimental data-driven artificial neural network and genetic algorithm) optimization technique is considered in the study. This predicts the optimal combination of operating parameters (heat input, cooling water inlet temperature, and flow rate) to minimize the heat pipe’s evaporator wall temperature which is found to be 312.54 K at a heat input of 10 W, flow rate of 10 LPH, and cooling water inlet temperature of 289.14 K. These input combinations are further validated through the experiments and the error in the heat pipe’s evaporator temperature is found to be 0.66 % only. Overall, this neuro-genetic technique underscores the importance of optimizing operational parameters for enhanced heat pipe performance and offers valuable insights for electronic cooling systems.

Enhancing thermal efficiency in flat plate solar collectors through internal barrier optimization

This study investigates the impact of introducing horizontal barriers within the internal cavity of flat plate solar collectors on their thermal efficiency. The primary objective is to enhance thermal performance by reducing convective heat loss. An experimental test bench was constructed to evaluate five solar collectors under controlled conditions. One collector was unmodified as a reference, while the other four had 1 to 4 horizontal barriers inserted between the absorber plate and glass cover. Each collector’s efficiency was assessed by measuring inlet and outlet water temperatures, incident solar radiation, ambient temperature, and water flow rate. Efficiency versus heat loss parameter curves were generated, and correction factors were applied to account for material and sensor differences. The collector with four barriers demonstrated the highest overall thermal efficiency, achieving an efficiency improvement of up to 12 % compared to the reference collector. Specifically, the efficiency of the reference collector was around 70 %, while the collector with four barriers reached an efficiency of approximately 82 %. Introducing two barriers resulted in a 9 % increase in efficiency, bringing it to about 79 %. Conversely, the collector with three barriers showed a slight decrease in efficiency to 68 %. The barriers effectively reduced internal convective heat loss, enhancing the collector’s ability to harness incident solar radiation. Inserting horizontal barriers within the internal cavity of flat plate solar collectors significantly improves thermal efficiency by reducing convective heat loss. The optimal configuration, based on this study, involves using four barriers. This method presents a straightforward yet effective approach to enhancing solar collector performance. Future research should focus on refining barrier design and placement for different collector sizes and geometries, potentially supporting broader adoption of solar thermal energy systems and contributing to sustainable energy solutions.

Optimizing efficiency of proton exchange membrane electrolyzer system based on multiphysics model and differential evolution strategy

This work focuses on a comprehensive performance enhancement considering hydrogen production, energy consumption of balance of plant (BOP), and thermal safety by optimizing the inlet water temperature and flow velocity. First, a multiphysics model is introduced to show that the inlet water temperature and flow velocity can affect the current density as well as the hydrogen production. An overall efficiency is defined to balance the hydrogen production and the energy consumption of BOP. After that, a surrogate model is established based on artificial neural network to replace the multiphysics model because of its huge computational effort. For the thermal safety and performance enhancement, an optimization problem with the maximum membrane temperature as a constraint and the overall efficiency as an objective function is proposed. The differential evolution (DE) strategy with the feasibility rule (FR) is adopted to solve this optimization problem. Finally, the DE-FR-based optimization algorithm is applied to three typical days in Chengdu of China representing summer, winter, and transitional seasons, respectively. Compared to the invariant inlet water flow velocity and temperature, the optimal and time-varying parameters improve their efficiency by relative percentages of 2.68%, 3.79%, and 3.29% for the three typical days, respectively.

Comparative Study on Heat Dissipation Performance of Pure Immersion and Immersion Jet Liquid Cooling System for Single Server

Heat dissipation has emerged as a critical challenge in server cooling due to the escalating number of servers within data centers. The potential of immersion jet technology to be applied in large-scale data center server operations remains unexplored. This paper introduces an innovative immersion jet liquid cooling system. The primary objective is to investigate the synergistic integration of immersion liquid cooling and jet cooling to enhance the heat dissipation capacity of server liquid cooling systems. By constructing a single-server liquid cooling test bench, this study compares the heat dissipation efficiencies of pure immersion and immersion jet liquid cooling systems and examines the impact of inlet water temperature, jet distance, and inlet water flow rate on system performance. The experimental outcomes show that the steady-state surface heat transfer coefficient of the immersion jet liquid cooling system is 2.6 times that of the pure immersion system, with increases of approximately 475.9 W/(m2·K) and 1745.0 W/(m2·K) upon adjustment of the jet distance and flow rate, respectively. Furthermore, the system model is streamlined through dimensional analysis, yielding a dimensionless relationship that encompasses parameters such as inlet water temperature, jet distance, and inlet water velocity. The correlation error is maintained below 18%, thereby enhancing the comprehension of the immersion jet cooling mechanism.

Experimental Study on the Performance and Internal Flow Characteristics of Liquid–Gas Jet Pump with Square Nozzle

In order to ascertain the impact of working water flow rate and inlet pressure on the performance of the liquid–gas jet pump with square nozzle, the pumping volume ratio and efficiency of the liquid–gas jet pump with square nozzle were experimentally investigated at different inlet pressures and working water flow rates. Furthermore, the internal flow characteristics of the liquid–gas jet pump with square nozzle were explored through the utilization of visualization technology in the self-designed square-nozzle liquid–gas jet pump experimental setup. The findings indicate that the pumping ratio of the liquid–gas jet pump increases in conjunction with an elevation in the inlet pressure. Liquid–gas jet pump efficiency is higher at lower inlet pressures, up to 42.48%, and drops rapidly as inlet pressure increases. The pumping volume ratio of the liquid–gas jet pump increases significantly as the working water flow rate increases, and the working water flow rate exerts a minimal effect on the working efficiency of the liquid–gas jet pump. In the context of extreme vacuum conditions, a considerable number of droplets undergo substantial reflux in the posterior section of the throat, with a notable absence of bubbles in the diffusion tube. The size and number of bubbles diminish gradually along the axial direction. The objective of this paper is to provide a reference point for determining the optimal operational parameters for a square-nozzle liquid–gas jet pump in a practical context.

Dynamic heat transfer characteristics of printed circuit precooler in supercritical CO2 Brayton cycle

The dynamic characteristics of heat exchangers are critical in supercritical CO2 Brayton cycle, especially in the precooler where significant thermophysical property variations occur. However, few studies have comprehensively analyzed the dynamic heat transfer characteristics in precooler, particularly with respect to the detailed flow and thermal field evolution. A three-dimensional numerical model was developed to study the dynamic performance of a printed circuit precooler, with an emphasis on the impact of thermophysical properties. The study examines responses to abrupt changes in CO2 and water inlet temperature, as well as mass flux variations. Results show that the precooler exhibits rapid response characteristics with mild fluctuations in heat transfer parameters and flow structure. Notably, the large specific heat near the critical point results in minimal variation in CO2 outlet temperature despite abrupt increases in CO2 inlet temperature, thereby enhancing system stability. Conversely, a decrease in CO2 mass flux causes a transition from forced convection to mixed flow, with strengthened buoyancy effects and decreased entropy production. These variations lead to significant changes in CO2 outlet temperature, posing potential challenges to system stability under CO2 mass flux step change conditions. The heat transfer shows a relatively lower response rate to parameter changes of water compared to CO2. Although variations in water parameters have a negligible effect on CO2 heat transfer, they influence the overall heat transfer coefficient. The dynamic heat transfer characteristics of the precooler presented in this paper address research gaps left by 1D numerical and experimental studies, which have provided limited information on flow and thermal fields during dynamic processes. These insights are essential for understanding the dynamic behavior of the entire system.

Carbon dioxide stripping from acidic wastewater through a vortex venturi tubular microbubble generator

Microbubble generation technology can improve CO2 stripping efficiency while consuming less sweeping gas. In this paper, a vortex venturi tubular microbubble generator is developed based on the concept of “Initial bubble generation with a thin plate type static mixing element” and “Bubble collapse with a venturi channel”. Microbubble characteristics were tested, followed by post-processing of the focused beam reflectance measurement (FBRM) to obtain a multidimensional dataset. The test results indicated that the microbubble quality generated by the vortex venturi tubular microbubble generator was higher than that of the SV-type static mixer. When the gas-liquid volume ratio was 1, the average bubble diameter was 107.05 μm, and microbubbles accounted for 93.29 %. The average bubble diameter of the SV-type static mixer was 473.55 μm, and the proportion of microbubbles was 23.81 % under identical conditions. Furthermore, the CO2 removal efficiency and pH enhancement rate were greatly affected by the gas-liquid volume ratio and the inlet water flow rate, and both fitted an exponential equation correlation. Accordingly, when the gas-liquid volume ratio increased, the quantity of bubbles generated significantly influenced the CO2 stripping efficiency. The stripping efficiency based on the tubular microbubble generator is significantly higher than that of the SV-type static mixer. When the gas-liquid volume ratio was 1, the CO2 removal efficiency was equivalent to that of the SV-type static mixer at a gas-liquid volume ratio of 3.5. When achieving equal CO2 removal efficiency, the gaseous nitrogen consumption of the tubular microbubble generator was 48.61 %-63.30 % lower than that of the SV-type static mixer, and the corresponding energy consumption of the gas compressor was reduced by 38.24 %-55.83 %. The CO2 stripping process based on the vortex venturi tubular microbubble generator offers an environmentally and economically viable treatment option for acid wastewater.

A numerical investigation on the dynamics of particle deposition and fouling on a vertical falling film pipe

The zero liquid discharge process is designed to eliminate the discharge of industrial wastewater into the environment, addressing significant environmental concerns that have emerged in recent decades. Falling film evaporator is one of the primary technologies employed in these systems. As observed, there is a noticeable lack of research numerically simulating these phenomena in a vertical pipe including falling film flow. In the present study, an effort has been made to address the existing research gap by conducting numerical simulation of particles deposition and fouling phenomena in a falling film flow in a three-dimensional vertical pipe using computational fluid dynamics. Continuous phases which contain two non-penetrating fluids, i.e., air and water, are simulated using volume of fluid multiphase model and the large eddy simulation turbulence model. Meanwhile, particles motion has been tracked utilizing discrete phase model. Water film enters the pipe with a thickness of 3.7 mm and an inlet velocity of 1 m/s, and particles with a density of 3110 kg/m3 are injected through the water inlet surface in various cases, each with different diameters. As observed, with an increase in particles diameter from 5 to 15 μm, the asymptotic total fouling mass has increased over 14 times, reaching from 0.016 to 0.18 kg/m2, and the total number of deposited particles has also increased. By increasing the fluids inlet velocity from 1 to 1.5 m/s, the total number of deposited particles has decreased throughout the pipe wall, and the total fouling mass has experienced a reduction of 55.8 %.

Evaluation of return cooling water reuse in the wet cooled power plant to minimise the impact of water intake and drainage

The treatment and reuse of industrial water is a matter of great interest, given the severe shortage of water resources. It is widely acknowledged that power plants, particularly wet-cooled power plants, consume a significant amount of water. Therefore, research on the circulating cooling system (CCS) and the treatment of the return cooling water is of utmost importance. This study examined data on CCS inlet (water body), make up, and cooling water parameters, calculated a water balance, and predicted the hydrochemical quality of cooling tower blowdown water (CTBD). The study was conducted for an operating power plant to propose an effective treatment scheme for the return of CTBD to the process cycle. Additionally, it evaluated the possibility of recycling CTBD in the clarifier through laboratory modeling. Therefore, based on the results of this study, an effective treatment scheme is proposed to return CTBD to the technological cycle to ensure environmental sustainability. Recycled water was used as the water supply for the cooling tower, and a lime softening treatment was applied to clean the CTBD. According to the results, it is possible to recover quality indicators from a portion of the return cooling water after lime softening treatment. The novelty of this study lies in the successful demonstration of a lime softening regime that enables the blending of up to 25 % CTBD with make up water, without necessitating an increased CaO dose. This regime maintains TH levels at 2.2 mg-eq/dm³ and ensures that the discharge velocity of 0.7 m/s remains within regulatory standards. Additionally, it maintains standard concentrations of chloride (Cl⁻) and sulfate (SO₄²⁻) in CTBD at 200 mg/dm³ and 250 mg/dm³, respectively.