Cooling Water Flow Research Articles

Experimental investigations on the productivity increase of solar stills utilising hybrid nanomaterials and water-cooling techniques

Solar stills are simple devices that can be used to remove salts from water. However, it has a lower distillate yield; hence, it is not popular. Increasing the solar energy collection at the absorber may help to address these issues. This is feasible by adopting highly absorbent energy storage substances. Hybrid nanomaterials have significant potential for this purpose, and they can boost the absorptivity of the absorber plate of solar stills. Taking this into account, a hybrid nanomaterial was synthesized in a laboratory and applied to the surface of a solar still absorber to achieve higher performance. Iron oxide (Fe2O3) and copper oxide (Cu2O) nanoparticles were used in a 50:50 ratio. In addition, the current research employed a water sprinkler to enhance the condensation rate in the condensing region and consequently increase the distillation output of the solar still. A cooling water flow rate of 10 kg/h was used to sprinkle the condensing surface. According to the results, combining Fe2O3 and Cu2O with epoxy resin increased the efficiency of the solar still by 34% when using a glass cooling approach and by 28% when operating without a glass cover cooling technique.

A simulation-based optimization of heat pump air circulation evaporating separation system for saline wastewater treatment

A simulation-based optimization of heat pump air circulation evaporating separation system for saline wastewater treatment

Inversion Analysis for Thermal Parameters of Mass Concrete Based on the Sparrow Search Algorithm Improved by Mixed Strategies

In the traditional mass concrete temperature field calculation, the accuracy of the thermal parameters is extremely important. However, the actual thermal parameters of mass concrete may have some errors with the laboratory-measured values or specification values due to the site ambient temperature, concrete surface insulation measures, cooling water flow, etc. Therefore, it can be combined with the measured temperature of the field temperature sensors using the sparrow search algorithm (SSA) for the inverse analysis of thermal parameters. Firstly, to address the problem that SSA has low convergence accuracy and easily falls into local optimum, a mixed strategy was adopted to improve the algorithm, including Logistic Chaos mapping initialization of the population, the introduction of adaptive weighting factors, and the use of the Cauchy mutation strategy. Then, the performance test was carried out to compare the performance of the algorithm with three different intelligent algorithms and reflect the superiority of the SSA that was improved by mixed strategies (SSAIMSs). Finally, the proposed method was applied to the thermal parameter inversion of a mass concrete pile cap. The inversion results demonstrated that SSAIMSs can improve the accuracy and speed of thermal parameter inversion, and the calculated results of the thermal parameters and temperatures obtained using the SSAIMSs matched well with the measured results in the field, which can meet the accuracy requirements of the actual engineering.

Experimental and numerical study on transcritical CO2 air source heat pump water heater

Experimental and numerical study on transcritical CO2 air source heat pump water heater

Modeling and Visualization of Coolant Flow in a Fuel Rod Bundle of a Small Modular Reactor

This article presents the results of an experimental study of the coolant flow in a fuel rod bundle of a nuclear reactor fuel assembly of a small modular reactor for a small ground-based nuclear power plant. The aim of the work is to experimentally determine the hydrodynamic characteristics of the coolant flow in a fuel rod bundle of a fuel assembly. For this purpose, experimental studies were conducted in an aerodynamic model that included simulators of fuel elements, burnable absorber rods, spacer grids, a central displacer, and stiffening corners. During the experiments, the water coolant flow was modeled using airflow based on the theory of hydrodynamic similarity. The studies were conducted using the pneumometric method and the contrast agent injection method. The flow structure was visualized by contour plots of axial and tangential velocity, as well as the distribution of the contrast agent. During the experiments, the features of the axial flow were identified, and the structure of the cross-flows of the coolant was determined. The database obtained during the experiments can be used to validate CFD programs, refine the methods of thermal-hydraulic calculation of nuclear reactor cores, and also to justify the design of fuel assemblies.

Design of experimental section of a water tunnel for simulation of heat dissipation condition of seawater-activated battery

Abstract A water tunnel is a crucial experimental apparatus in hydrodynamic research, as the traditional water tunnel has drawbacks such as a small cross-sectional area of the test section and higher costs, which makes it difficult to meet the requirements of a water tunnel for simulating the heat dissipation conditions of the seawater-activated battery. This paper proposes a water tunnel specifically designed for simulating the heat dissipation conditions of seawater-activated batteries, and the water tunnel consists of an external cooling water circulation system and an internal electrolyte circulation system. The experimental section’s design determines the water tunnel’s size and key technical indexes. The temperature distribution contour maps of the experimental section were obtained using Ansys Fluent software simulation. The cooling effect was analyzed, and a cooling water flow rate of 10 m/s was selected. Pressure and velocity contour maps were obtained by simulating the experimental section of the water tunnel. The results show that when the cooling water velocity is 10 m/s, the pressure drop of the experimental section is approximately 1.76 atmospheres. The flow field is uniform and stable, and the heat dissipation power can reach 45.5 kW, meeting the technical requirements.

Energy Consumption Optimization for the Cold Source System of a Hospital in Shanghai-Part I: Analysis of Operating Characteristics and the Control Strategies of the Chillers

Background: Hospitals account for the most proportion of energy consumption in the public building sector. Chillers usually account for most of the overall energy consumption of the cold source system. Objective: To solve the problem of chillers' large energy consumption problem, novel technologies were developed, and achievements were patented. Methods: The operating characteristics influencing factors of the magnetic suspension centrifugal chiller (MSCC) and variable frequency screw chiller (VFSC) of a hospital in Shanghai were analyzed and discussed by actual measurements. Then, based on the operating characteristics of the chiller obtained from the analysis of the measured data, the cooling capacity was classified by the K-Means clustering method to obtain the startup strategy of the chillers. Results: The effects of the supply chilled water temperature, the supply cooling water temperature and variable cooling water flow rate on the maximum cooling capacity and coefficient of performance (COP) of both chillers were explored. The load distribution scheme was discussed based on the chillers' startup strategy. Conclusion: The average part load ratio operation scheme was the preferred chiller distribution scheme. A chiller's maximum allowable part load ratio should not exceed 80% during the low-load operation period and should not be less than 60% during the conventional operation period. It provided a reference for optimizing the chiller operation strategy to reduce system energy consumption.

Experimental study on the thermal performance of a novel vapor chamber manufactured by 3D-printing technology

Experimental study on the thermal performance of a novel vapor chamber manufactured by 3D-printing technology

Enhancement of heat dissipation efficiency in the CSNS target through the innovative design of a serial cooling water channel

This paper presents a coupling of the Monte Carlo method with computational fluid dynamics (CFD) to analyze the flow channel design of an irradiated target through numerical simulations. A novel series flow channel configuration is proposed, which effectively facilitates the removal of heat generated by high-power irradiation from the target without necessitating an increase in the cooling water flow rate. The research assesses the performance of both parallel and serial cooling channels within the target, revealing that, when subjected to equivalent cooling water flow rates, the maximum temperature observed in the target employing the serial channel configuration is lower. This reduction in temperature is ascribed to the accelerated flow of cooling water within the serial channel, which subsequently elevates both the Reynolds number and the Nusselt number, leading to enhanced heat transfer efficiency. Furthermore, the maximum temperature is observed to occur further downstream, thereby circumventing areas of peak heat generation. This phenomenon arises because the cooling water traverses the target plates with the highest internal heat generation at a lower temperature when the flow channels are arranged in series, optimizing the cooling effect on these targets. However, it is crucial to note that the pressure loss associated with the serial structure is two orders of magnitude greater than that of the parallel structure, necessitating increased pump power and imposing stricter requirements on the target container and cooling water pipeline. These findings can serve as a reference for the design of the cooling channels in the target station system, particularly in light of the anticipated increase in beam power during the second phase of the China Spallation Neutron Source (CSNS Ⅱ).

Delivering holistic energy-saving operation for heterogeneous all-parallel chiller plant systems through two-stage optimization assisted by input convex neural networks

Delivering holistic energy-saving operation for heterogeneous all-parallel chiller plant systems through two-stage optimization assisted by input convex neural networks

Experimental analysis on the thermoelectric effect of various solid-state devices used for direct conversion of thermal energy into electrical energy

Experimental analysis on the thermoelectric effect of various solid-state devices used for direct conversion of thermal energy into electrical energy

Experimental investigation on performance of heat pump air circulation evaporating separation system for saline wastewater treatment

Experimental investigation on performance of heat pump air circulation evaporating separation system for saline wastewater treatment

Experimental investigation of humidified air condensation in different rows of serpantine heat exchanger – Cooling water flow rate effect

Experimental investigation of humidified air condensation in different rows of serpantine heat exchanger – Cooling water flow rate effect

An Experimental Investigation Of Local Thermo-Fluidic Heat Transfer In A U-Shaped Mini-Channel Sink

This study investigates experimentally a heated U-shaped mini-channel heat sink using Infrared Thermography and Particle Image Velocimetry for a water coolant flow of Reynolds numbers of 280, 650, and 1350 (based on the hydraulic channel diameter). The choice of this cell geometry is based on its role as a simplified unit of a serpentine heat exchanger, which is proved to be one of the most promising for cooling processes. The use of the infrared camera allows the detection of temperature fields on top of the external surface of the cell. Therefore, aiming to derive the temperature distribution on the channel roof, a dedicated transfer function is implemented. Moreover, we employed the lumped capacitance model for thermal analysis on both infrared measurements and thermocouple data. The latter are recorded to capture the cooling process of the aluminium base and water temperature at the end of the outlet tube. As a result, thermal transient rate, cooling magnitude and equilibrium temperature are obtained. These parameters indicate that higher Reynolds numbers correspond to increased thermal transient rates, enhanced cooling effects, and lower equilibrium temperatures. A non-uniform distribution of heat transfer along the channel is reported, with the most efficient cooling area localized close to the first 90-degree corner. These findings are consistent with numerical simulations and previous experimental observations. PIV results reveal the presence of two fluid acceleration zones following both 90-degree corners, which contribute to improve the water cooling ability in their respective regions. Additionally, the formation of two recirculating bubbles is reported at the inner wall from corners vertices, whose intensity is dependent on Reynolds number, pushing the main flow towards the outer channel wall and reducing the local heat transfer. Turbulent kinetic energy distributions are also investigated, pointing out the presence of intense areas that better match with regions of minimum equilibrium temperature than maximum velocity zones. This suggests the presence of local turbulent unsteadiness and three-dimensional phenomena, which contributes significantly to cooling enhancement.

A numerical study on summer operation performance of PCM wallboard cooling tower coupling system in hot-summer and cold-winter regions of China

A numerical study on summer operation performance of PCM wallboard cooling tower coupling system in hot-summer and cold-winter regions of China

Thermal-flow-force-electrical coupling characteristics of microchannel cooling systems in high heat flux chips

To address the challenges faced by designers of multi-field coupled cooling systems for high heat flux chips, this paper proposes a “near-source” microchannel cooling strategy and establishes a thermal–flow-force electrically coupled model for chips. The effects of chip Joule heat and cooling water flow rate on the cooling performance with respect to multi-field coupling effects were studied. The impact of multi-field coupling effects was revealed, and a method for enhancing microchannel cooling performance in light of multi-field coupling effects is proposed. The results indicated that considering multi-field coupling effects in the microchannel cooling process leads to a deterioration in the thermal performance of chips, accompanied by a significant increase in electrical fluctuations and thermal deformation amplitude. Compared to chips upstream of the cooling water, chips downstream subjected to thermal cascade effects were more sensitive to multi-field coupling effects. Moreover, the temperature variance index, output current, and strain energy density of high heat flux chips were positively correlated with Joule heat but inversely proportional to the Reynolds number of the cooling water for cases in respect of multi-field coupling effects. Additionally, serpentine microchannels maximized the operational performance of high heat flux chips by reducing temperature of chip by up to 55.1%, decreasing strain energy density by 96.7%, and increasing input potential by 120%.

Multi-Physical Field Analysis and Optimization Design of the High-Speed Motor of an Air Compressor for Hydrogen Oxygen Fuel Cells

The hydrogen oxygen fuel cell is a power source with significant potential for development. The air compressor provides ample oxygen for the fuel cell, and as a key component of the air compressor, the performance of the motor greatly impacts the efficiency of the fuel cell. In order to enhance the system performance of high-speed permanent magnet motors, optimization was conducted on the motor’s geometric dimensions to minimize rotor loss and maximize power density, taking into account the comprehensive constraints of electromagnetic and mechanical properties. The finite-element method was employed to analyze the motor’s performance, conducting a multi-physical field analysis that included electromagnetic field, rotor loss, and mechanical strength analysis, as well as temperature field analysis. Aiming at the problem of high temperature rise in high-speed motor winding, the influence of the cooling water flow rate on the winding temperature rise was analyzed and simulated. Based on the analysis results, the minimum cooling water flow rate was obtained. According to the optimized design results, a prototype of an 18 kW, 100,000 rpm motor was manufactured, and the efficiency and temperature rise were tested. The experimental results verify the correctness and effectiveness of the optimal design.

Solar regenerated carbon-based composite desiccant coated heat exchangers for air dehumidification

Solar regenerated carbon-based composite desiccant coated heat exchangers for air dehumidification

Optimizing electricity generation through the utilization of wasted heat from process streams in a LURGI methanol plant

In the realm of petrochemical operations, persistent efforts have been made to curtail specific energy consumption; however, certain heat sources continue to be underutilized. This paper investigates the condition of a Lurgi methanol plant to identify process streams with enough wasted heat that have the potential to produce electricity. After a thorough analysis, one particular zone is identified where an air cooler package and seawater exchanger are used to decrease the temperature of crude methanol vapor. To harness this untapped heat for electricity generation, an organic Rankine cycle (ORC) is proposed. In the quest for efficient electricity production, three distinct working fluids-dry (R600a), wet (R134a), and isentropic (R11)- are scrutinized to compare their performance in generating electricity within the ORC system. In addition, the maximum amount of electricity that can be generated from this waste heat recovery (WHR) project is determined and optimized using a multi-objective optimization method. By leveraging genetic algorithms, the system's exergy is enhanced while minimizing costs. A comprehensive economic comparison is conducted using probability analysis to evaluate each system's financial viability. The results show that dry and isentropic working fluids yield the best results for electricity production, generating approximately 9-10MW. The return on investment (ROI) for these working fluids is also nearly similar, at 16%. Among the chosen working fluids, R600a is selected as the superior option due to its lower outlet temperature for crude methanol. Additionally, because the cooling water flow for the condenser of the ORC is identified as a limitation in the current petrochemical plant, a new optimization is conducted with a constraint on the flow of cooling water, aiming for approximately 3000 tons/h. The results show that the proposed WHR-ORC system can generate a maximum of approximately 7.5MW net electricity in the studied petrochemical plant, while also reducing CO2 emissions by up to 40,000 tons per year. The innovative methodology showcased in this research underscores its economic viability, paving the way for heightened energy efficiency and environmentally conscious methanol production practices.

A multi-objective optimization of a single-phase immersion cooling system at cabinet level

A multi-objective optimization of a single-phase immersion cooling system at cabinet level