Cooling Fluid Flow Research Articles

Thermal characteristics analysis and cooling model optimization of motorized spindle

Aiming at the influence of poor cooling conditions and traditional cooling control strategy on motorized spindle temperature and machining performance. Firstly, the heat transfer model of the motorized spindle cooling system is studied. Secondly, the influence of coolant inlet flow rate and temperature on the thermal characteristics of the motorized spindle is studied. Then, a thermal network model is established to solve the temperature of each temperature measuring point. Finally, the thermal characteristic experiment of the motorized spindle is carried out, and the cooling fluid flow optimization model is established based on the particle swarm optimization algorithm and simulated annealing algorithm. The results show that the temperature difference of the motorized spindle does not exceed 45 °C, the thermal deformation does not exceed 40.2 μm, and the thermal elongation is inhibited by 36 %. The maximum error of the Thermal Network Method and Finite Element Method（FEM）is 14.24 %. The utilization of the average logarithmic temperature difference for assessing the cooling effectiveness of optimal flow rates revealed that the particle swarm optimization algorithm demonstrates a comparatively lower average logarithmic temperature difference in comparison to the simulated annealing algorithm. The heat exchange efficiency of the motorized spindle is higher under the optimal flow rate obtained by the particle swarm algorithm.

The Characterization of A Thermoelectric Generator Type TEC1-12706 Hybridized On 50W Polycrystalline PV

The potential of solar energy is very large in generating electrical energy conversion using TEG and PV technology. Therefore, it is important to understand how the technology works. This study aims to characterize the electrical generation of 12 TEG modules type TEC1-12706 hybridized with 2 PV panels. One PV panel is left without a TEG module as a comparison. Meanwhile, on the cold side of the TEG attached to the PV, a heatsink with 3 fins is placed. The left and right fins are air allowed to flow naturally, while the middle fin is flowed with cold water fluid through a 0.01 m diameter water hose with 2 flow rates; 0.02 and 0.05 m / s. The results of the study showed that the fluid flow rate of 0.02 presented a better TEG performance effect than 0.05 m / s at an irradiance of 450 W/m2. Different things are shown by PV solar panels, where the power generation and efficiency are better in TEG at a flow rate of 0.05 m/s compared to 0.02 m/s for the same irradiance. Overall, the performance of PV-TEG is better at a TEG cooling fluid flow rate of 0.05 m/s.

Coupling of photovoltaic thermal with hybrid forward osmosis-membrane distillation: Energy and water production dynamic analysis

This study proposes a novel solar photovoltaic thermal (PVT)-driven forward osmosis (FO) and membrane distillation (MD) system for desalinating brackish water, addressing water scarcity issues by combining the advantages of FO's low operating cost with MD's ability to treat hypersaline water. A physics-based dynamic model was developed for the system, and the model equations were discretized and solved using an open-source algebraic modeling language. Model validation involved verifying the consistency of outputs between successive unit operations and conducting sensitivity analysis by varying one operating condition at a time. The analysis considered varying weather conditions while maintaining constant operating conditions. Increasing the flow rate of brackish water (cooling fluid) from 19.79 to 59.38 kg/h improved thermal efficiency by 28.7 %; however, FO and MD water fluxes decreased by 1.12 LMH and 7.77 kg/m2/h, respectively. Peak thermal efficiency (81.2 %) was achieved at the highest flow rate. Incorporating heat transfer analysis into FO models goes beyond the common focus on mass transfer, allowing for a more comprehensive understanding of energy dynamics within the system. Both FO and MD water fluxes improved with irradiance and ambient temperature but decreased with cooling fluid flow rate and wind velocity. Increasing feed concentration to 10,000 mg/l reduced water flux by 0.66 LMH, and for each 0.5 M increase in draw solution concentration, FO water flux increased by >10 LMH. Compared to MD water flux, FO water flux is more sensitive to changes in concentration than to changes in weather conditions.

Techno-exergy-economic assessment of humidification-dehumidification/reverse osmosis hybrid desalination system integrated with concentrated photovoltaic/thermal

Desalination is a process used to generate water for human consumption, irrigation, or industrial purposes. Assessment of desalination plants is crucial for freshwater productivity, energy consumption, exergy destruction, and economic feasibility calculations. Therefore, the study aims to conduct a technical, exergy, and economic analysis of a concentrated photovoltaic/thermal hybrid humidification-dehumidification reverse osmosis desalination system. The photovoltaic/thermal provides the electrical and thermal requirements for the hybrid desalination unit. Theoretical models for each unit are developed and integrated using the Engineering Equation Solver software. The sensitivity of system performance parameters was investigated under different climatic and operation factors. The analysis shows that the system produces 860 L per hour at the lowest specific energy consumption and water cost (3.3 kW-hours per cubic meter and 0.916 United States dollars per cubic meter), respectively, with a cost payback period of only 12 years compared to other green-powered desalination systems. The highest destruction portion of 84.6 % is at photovoltaic/thermal, while the largest cost portion of 68 % is at reverse osmosis. Productivity, energy consumption, and water cost are influenced by feed salinity, while destruction is most affected by solar irradiance. Ambient temperature, wind speed, and cooling fluid flow rate slightly affect the techno-exergy-economics of the system.

Dynamic performance analysis of a photovoltaic thermal (PVT) collector with an extruded absorber using python optimization modeling object (Pyomo)

Solar photovoltaic thermal (PVT) integrates photovoltaic panels and solar thermal collectors in one system for simultaneous electricity and heat production in a reduced area. The absorber type used for heat extraction significantly affects PVT performance. This work examines the performance of an extruded absorber PVT under varying solar irradiance, ambient temperature, and wind speed. A detailed dynamic mathematical model is developed from energy balance equations and heat transfer correlations for each layer of the PVT collector. Using orthogonal collocation on the finite difference method, the system of differential equations is discretized and solved numerically with Pyomo, a Python optimization modeling tool. Following validation against literature data, the model is used to predict the temperature of each layer and the thermal and electrical output of the PVT collector. The effect of cooling fluid mass flow rate, solar irradiance intensity, ambient temperature, and wind speed on PVT performance is analyzed. This design provides a maximum electrical efficiency of 15.47 % at a wind velocity of 3 m/s, regardless of the cooling fluid flow rate. Peak electrical power of 212.26 W is achieved at the highest flow rate (14.14 kg/hr) and with the highest wind velocity (3 m/s), while the peak thermal power of 348.03 W occurs at a wind velocity of 1 m/s and a flow rate of 11.31 kg/hr. Compared to the conventional sheet-and-tube design at 1 m/s wind speed and 5.65 kg/hr cooling fluid flow rate, the extruded absorber PVT delivers 203.18 W electrical and 189.27 W thermal power, outperforming the 207.46 W electrical and 128.9 W thermal power of the conventional design, demonstrating the potential of the extruded absorber design for enhancing heat generation.

Optimization of Heat Transfer Performance Using Response Surface Methodology-Central Composite Design (RSM-CCD) for Nano-Coolant (Al2O3+EG/W) in Electric Vehicle Battery

The presence of electric vehicles (EVs) must be supported by batteries that have good-quality energy storage. Battery power is critical to the development of electric cars. Temperature affects battery strength, so operating within the optimum temperature range must be ensured. During the charge and discharge processes, the electrochemical reaction generates hot energy, causing an increase in battery temperature. In this research, the solution to the problem is to make a cooling system with a mini channel cold plate and Al2O3 1%vol+EG/W (50:50) nano coolant. Optimization of heat transfer enhancement using Response Surface Methodology-Central Composite Design (RSM-CCD) and experimental tests with various flow rate variations. The research findings revealed that the RSM-CCD results and the outcomes of studies employing test equipment agreed that the highest cooling fluid flow rate was the most optimal condition, the highest T2 temperature drop of 17.63% occurred at a flow rate of 1.7 LPM, and the lowest T2 temperature was 13.13% at a flow rate of 1 LPM.

A nanofluid-based hybrid photovoltaic-thermal -thermoelectric generator system for combined heat and power applications

This study investigates the use of nanofluid-cooled Thermoelectric Generators (TEGs) integrated with a Photovoltaic (PV) panel to enhance the overall energy efficiency of the system. Three cooling fluids — Water (W), CuO/W single Nanofluid (NF), and CuO-Fe/W hybrid NF — are examined at various flow rates for cooling the PV panel. The research studies the PVT-TEG-NF system considering both normal and concentrated solar irradiation in a 3D parallelly-cooled heat sink setup and comparing its electrical and thermal performance, which has not been previously addressed in the literature. The results demonstrate that by utilizing CuO-Fe/W, the PV temperature at irradiation of 935 W/m2 in the summer can be maintained at 31.7 °C, which is 8.8 % and 13 % lower than those achieved by using CuO/W and water, respectively. For 0.08 m/s of CuO-Fe/W inlet velocity, the total output power PV-TEG is about 9.5 W, with a heat removal rate of ∼37.2 W. Additionally, by utilizing the CuO-Fe/W compared to water, the combined efficiency of the system (the ratio of electrical and thermal power output to solar input) increases from 66.7 % to 76.7 %. In the second part, the study introduces a new approach to maintain a steady PV efficiency while increasing solar concentration by adjusting the cooling fluid flow rate. By increasing solar concentration from 1.5 suns to 2.5 suns, the PV temperatures could be maintained at 44.5 °C and 51.5 °C using CuO-Fe/W and water with 0.12 m/s of inlet velocity, respectively. This made it possible to enhance the power output of the PV and TEGs by 65.9 % and 187 %, respectively, by using CuO-Fe/W as coolant, while the temperature of the panel could be maintained at a safe level.

Invoking Pre-Rotation Induced Flow to Improve the Performance of Gas Turbine Film Cooling

The present study proposes a novel method to improve the performance of film cooling. In this type of cooling, due to the presence of counter-rotating vortex pairs downstream of the injection hole, the formed film on the surface tends to detach from the surface. A new geometry is proposed to overcome this vortex pair. In this geometry, the injection passage is equipped with one or more helical ribs. These ribs induce rotation in the injected cooling fluid flow which prevents the separation of the coolant film from the surface. Analysis and optimization of the effective parameters are done including the injection angle, the height, thickness, number, and pitch of the ribs. The results show that by exceeding the injection angle from an optimum value, the mixing tendency of the injected fluid and main flow increases, and the cold fluid film liftoff occurs faster. On the other hand, as this angle decreases, the pressure drop rises. Considering both the heat transfer and pressure drop effects, the best performance is observed at the injection angle of 20°. Moreover, the best performance is achieved for the ribbed passage (of D diameter) with two ribs of 0.025D ​​thickness, 0.1D height, and 0.33D rib pitch.

Numerical Simulation and Validation of Flow-Induced Vibration of the Specific Rod under Elastic Supports using One-Way Fluid-Solid Interaction

The vibration induced by the cooling fluid flow around the fuel rods in the fuel Assembly of nuclear reactors causes the rods to be destroyed and eventually leak due to the fretting wear in the place of contact with their supports for a long time. In this paper, the vibration caused by axial fluid flow around a specific fuel rod under elastic supports is numerically simulated. In this study, the fluid flow is modeled using the Large Eddy Simulation (LES) turbulence model in the FLUENT software. The fluid-structure interaction is also modeled using the ANSYS coupling system. To validate the implemented numerical model, the test results of the reported brass rod vibration similar to the studied problem in this research are used. Due to the long execution time of the two-way fluid-structure interaction simulations with a high grid number, the one-way fluid-structure interaction method is proposed. The results of simulations show that the one-way fluid-structure interaction method can be used in cases where the vibration amplitude of the structure is less than the height of the viscous sub-layer. Also, this method reduces the simulation time by 80%. Finally, the results of the flow-induced vibration simulation of the fuel rod show that the vibration range of the fuel rod will increase by 20 times if the contact of the elastic supports with the rod is lost, which will lead to the intensification of the wear caused by the rod oscillation. Also, the main natural frequency of the rod decreases when the rod loses contact with the supports and falls within the range of the reactor excitation frequency, i.e. 0 to 50 Hz, which should be avoided.

Cooling enhancement of cubical shapes electronic components array including dummy elements inside a rectangular duct

In this work, numerical simulation has been done to study the cooling enhancement of electronic components of cubical shapes including dummy elements inside a rectangular duct. The 12 electronic chips (3 ? 4 array) of dimensions (50 mm ? 50 mm ? 10 mm) are tested in an air duct of dimensions (350 mm ? 3500 mm ? 60 mm). The aim of the simulation is to study the influence of changing positions of the hot components on the overall cooling performance at different Reynolds numbers. Moreover, the effect of spacing between electronic components is studied. This is achieved by changing the position of the heat sources while keeping other elements as dummies to keep the flow characteristics. The Reynolds number is in the range (500-19000). The standard k-?, model is used and validated with experimental work showing good agreement. The 37 cases per Reynolds are considered, resulting in an overall 259 studied cases. It is concluded in terms of the large resulting data from this study that, increasing the spacing between elements in the cooling fluid-flow direction influences the cooling rate. Moreover, designers should be interested to operate such systems at optimized higher Reynolds values.

Study of the performance of thermoelectric generator for waste heat recovery from chimney: impact of nanofluid-microchannel cooling system.

A huge number of chimneys all over the world utilized in many industrial applications and applications like restaurants, homes, etc. contribute badly on the global warming and climate change due to their waste heat. So, in this paper, the performance of thermoelectric generator (TEG) cooled by microchannel heat spreader having nanofluid and used for waste heat recovery from vertical chimney is investigated. Using heat spreader with microchannel cooling system increases the output TEG power compared to natural convection cooling system. In this paper, the impact of microchannel sizes, using nanofluid and heat spreader with different sizes on the TEG performance and cooling, is considered. Three-dimensional mathematical models including TEG, microchannel, nanofluid, and heat spreader are presented and solved by Ansys Fluent software utilizing user-defined memory, user-defined function, and user-defined scalar. All TEG effects (Joule, Seebeck, and Thomson) are considered in TEG model. Results indicate that TEG power rises with increasing the heat spreader and microchannel sizes together. Increasing microchannel and heat spreader sizes four times of TEG size raises the TEG output power by 10%. This also achieves the maximum cooling system efficiency of 88.9% and the maximum net output power. Microchannel heat spreader cooling system raises the system (TEG power-pumping power) net power by 125.2% compared to the normal channel and decreases the required cooling fluid flow rate. Utilizing copper-water and Al2O3-water nanofluids rises maximally the TEG output power by 14% and 4%, respectively; however, it increases the pumping power. Moreover, using nanofluids increases the net output power at low Reynolds number and decreases it at higher Reynolds number.

Thermo-Mechanical Distortion of Tungsten Coated Steel During High-Heat Flux Testing Using Plasma-Arc Lamps

An experimental setup and a test section were designed and fabricated for high heat flux testing (HHFT) of neutron-irradiated specimens using water-wall plasma-arc lamps. Because of the radiological considerations and limitations of reactor irradiation, the size of the test articles was limited to disks less than 10 mm in diameter. The specimen was clamped onto an actively cooled block, and clamping allowed the insertion of several thermocouples on the back surface of the specimen through a copper (Cu) block. Five vacuum plasma sprayed tungsten (W)–coated F82H steel specimens were subjected to HHFT. Surface profilometry measurements, which were conducted after HHFT, revealed central bowing of the top W surface. This type of residual distortion occurred for all of the specimens, and the larger the specimens were, the larger was the distortion. In an attempt to understand specimen distortion and address the science questions related to the testing of subsize specimens during HHFT, a simplified thermo-mechanical model was developed. By using a measured temperature in the Cu as an isothermal boundary condition, the model eliminated the need for coupling cooling fluid flow models with stress models, greatly simplifying the analysis. The main variable in the proposed model is hC, i.e., the thermal contact conductance between the F82H and the Cu washer. Inelastic properties, including hardening properties, were considered for F82H steel and Cu. Numerical simulation results demonstrated a buildup of residual deformation during HHFT and a very complex state of stress and deformation during typical heat flux (HF) cycling. Hoop stress evolution during a high heat flux cycle reveals that F82H at an interface with W would be mainly in compression during HF application and experienced a transition to a tension state during cooldown. Also, specimen distortion evolves during each HF cycle, as the specimen bows downward during HF application and upward during the cooldown period between HF cycles. The final specimen distortion, i.e., upward bowing of the specimen center, was qualitatively predicted for hC values of 4000 to 5000 W/(m2·K). This hC range of values, for which bulging is obtained, is at the lower spectrum of the range of values for hC, consistent with the low thermal contact conductance expected from the unpolished F82H surface.

Temperature distribution modeling of PV and cooling water PV/T collectors through thin and thick cooling cross-fined channel box

Many aspects relating to thermal, economic, and reliability challenges are involved while designing a Photovoltaic/Thermal (PV/T) system under high performance. When compared to standard PV systems, PV/T systems are more effective in locations with high irradiance. To eliminate the excess heat from a PVT system, an optimal cooling system is necessary, resulting in improved the temperature of PV module which directly effect on the overall performance. The current study is focused on a new economic and essay construction thin and thick (3 mm and 15 mm) cooling cross-fined channel box that have covered modeled. In terms of cell temperature and output cooling water temperature, the effects of various irradiation levels and cooling water flow rates are examined. Software that is based on finite elements, the problem was solved numerically in a three-dimensional model using ANSYS (19.2). It has been discovered that when the cooling fluid flow rate increases, the average surface temperature distribution of PV/T system and outlet cooling water temperature are reduced for thin and thick box heat exchanger and ideal with a cooling fluid flow rate of 3 L/min. The average surface temperature and water-cooling temperature are 30.7 °C and 38.9 °C for thin box heat exchanger, respectively, whereas for thick box heat exchanger are 30.8 °C and 32.4 °C, respectively, under solar irradiance 1000 W/m2 and optimal flow rate.

Optimization of fins arrangements for the square light emitting diode (LED) cooling through nanofluid-filled microchannel

In current paper, a finned micro-channel is designed for the cooling application in Light Emitting Diode (LED), numerically using Galerkin weighted residual Finite Element Method (GFEM). Selected materials for LED-chip is GaN, Die from Si, Die-attach is made by Au-20Sn, substrate is copper and heat sink material is considered to be Al. To make a convection heat transfer for cooling process, Al2O3-water nanofluid is used as the cooling fluid flow through the micro-channel and tried to maximize the heat transfer efficiency by optimized geometry. For this aim, there geometry variables from the microchannel were selected and minimum possible geometry cases (11 cases) were proposed by Central composite design (CCD) and variables were optimized by the Response Surface Method (RSM). As a main result, parameter B, i.e. fin length had the most effect on the Nusselt number and Al2O3 nanoparticles with φ = 0.05 stated greatest heat transfer value. Also, different designs of fins arrangements, caused up to 6.5% increase in the nanofluid temperature which enhanced the LED cooling process.

Numerical Study of Shell and Tube Heat Exchanger Performance Enhancement Using Nanofluids and Baffling Technique

The aim of this work is to investigate the forced convective heat transfer phenomena and fluid flows of water-based Al2O3 nanofluids in the baffled shell and tubes heat exchanger (STHE). Water as a hot fluid flows in the side of the tubes, and Al2O3 nanofluids as cooling fluid flow in the shell side. Numerical investigations have been carried out based on the continuity, momentum, and energy equations which are solved by using the finite element method with the help of the COMSOL 5.4 CFD software. The obtained results were presented by average Nusselt number, streamlines, isotherms, and various physical parameters which are a volumetric fraction of nanoparticles (1%? Cv ?3%). The results are found that the heat transfer increases with the rise of inlet velocity and volume fraction. In addition, the presence of baffles inside tubular heat exchangers can create a better mixture of fluids which is augmenting heat transfer execution. The choice of these parameters is important to get the maximum improvement of heat transfer with minimum entropy consumption.

Experimental investigation of pressure drop and cooling performance of an automobile radiator using Al2O3-water + ethylene glycol nanofluid

In this study, the cooling capacity and the pressure drop variation in an automobile radiator using nanofluid instead of water with antifreeze that are investigated experimentally. The nanofluid consisted of 50% Ethylene Glycol–Water mixture including Al2O3 nanoparticles with 0.5% volumetric concentration was used as coolant. In all experiments, the inlet temperature of the cooling fluid into the radiator was held constant at 95 C. The tests were carried out at the air inlet temperature between 23.4–28.6 °C, the air velocity between 1.7–4.3 m/s, the cooling loads between 2.5–15 kW and the cooling fluid flow rates between 10 and 25 L/min. Results demonstrate that 50% Ethylene Glycol–Water based 0.5% vol. Al2O3 nanofluid increased the cooling capacity of the radiator up to 15% compared to the fluid with only 50% Ethylene Glycol–Water mixture. Instead of 15% increment, radiator can make with smaller surface area up to 15%, or the flow rate can be decreased for same heat transfer rate, so fluid pumping power consumption can be reduced in order to save fuel as much as pumping power economy. In addition, it has not been observed a remarkable increase in the pressure drop.

An experimental study on cooling performance of a car radiator using Al2O3 - ethylene glycol/water nanofluid

Nanofluids have high thermal conductivity and can be used as vehicle engine coolant. In this article, the effects of Al2O3 nanoparticles to an engine coolant were experimentally investigated and the results were compared with the results of the original coolant including 50% ethylene glycol and 50% water mixture. The nanofluid was prepared by adding 0.5% Al2O3 nanoparticles by volume. The inlet temperature of the coolant was held constant at 95?C. The tests were carried out at the air inlet temperatures between 23.4-28.6?C, the air velocity be-tween 1.7-4.3 m/s, the cooling power between 2.5-15 kW and the cooling fluid flow rates between 10-25 Lpm. The results show that nanoparticles increase the cooling performance of the engine radiator. By using Al2O3 nanoparticles, cooling power of the radiator has increased up to 17.46% compared to original case.

Experimental analysis of fluids discharge in cooling tower condenser distillation model

The application of traditional cooling distillation devices is carried out naturally where hot steam is left in the condenser tube. The heat transfer occurs depends on outdoor temperatures (20-25 degree C). The heat transfer is also felt to be ineffective because the time needed is quite long (2-3 hours). Based on these problems, we design a heat exchanger by applying cooling tower model to distillation condenser. Tests are carried out by experimental methods on devices designed to obtain the required temperature data. It is expected to obtain an effective heat transfer rate in terms of the amount of cooling fluid flow. Good difference from average heat transfer rate of 153.276 W/m degree C at discharge 2 l/min to an average of 168.758 W/m degree C at discharge 4 l/min. Increased heat transfer rate is 10.1 percent when fluid discharge is added 2 l/min. The increase in heat transfer rate is 13.7 percent when the fluid discharge is added to 4 l/min from the initial discharge of 2 l/min. The test results show that cooling water fluid discharge influences the rate of heat transfer that occurs because the cooling fluid can be more in contact with cooling area.

Effect of Aspect Ratio and Installation Direction on Channel Flow Heat Transfer Performance under a Wide Range of Reynolds Number

In recent years, in the cooling technology for high-power electronic devices such as power transistors used for drive motor control of electric vehicles and hybrid vehicles, a method of flowing a cooling fluid to a cooling substrate having a fin structure has become the main technology. The structure of the cooling fluid flow path is a channel flow through multiple narrow plate gaps to secure a heat transfer area. In this study, the heat transfer characteristics when the aspect ratio of the channel having a flat rectangular cross-section was changed were investigated in detail by experiments. Moreover, the difference in the heat transfer characteristic at the time of making a rectangular flow path into vertical installation and horizontal installation was also investigated.

A three‐dimensional heat transfer model for thermal performance evaluation of ZrCo‐based hydride bed with embedded circular‐shaped cooling tubes

Nowadays, metal hydrides are generally deemed as one of the most potential materials that are in favor of compact hydrogen storage for industrial applications. This work was committed to evaluate the thermal performance of a circular-shaped-tube thin double-layered hydrogen storage reactor using a three-dimensional model. Finite element simulations were conducted to systematically study the influences of structural geometries, cooling patterns, and material thermophysical properties on the heat diffusion behavior under the framework of convection heat transfer. The results indicate that the proposed model effectively characterizes temperature evolutions during hydrogen absorption process. Moreover, a statistical analysis was performed to reveal the sensitivity sequence of these factors on the total thermal performance, suggesting that decreasing the hydride layer thickness, increasing the number of U-shaped cooling tubes, accelerating the cooling fluid flow rate, and enhancing the thermal conductivity are more beneficial to the thermal performance improvement. Detailed analysis confirms the possibility of developing the present hydrogen storage tank utilizing metal hydrides for engineering practice.