Coolant Channel Research Articles

Experimental and computational analysis of the coolant distribution considering the viscosity of the cutting fluid during machining with helical deep hole drills

An experimental analysis regarding the distribution of the cutting fluid is very difficult due to the inaccessibility of the contact zone within the bore hole. Therefore, suitable simulation models are necessary to evaluate new tool designs and optimize drilling processes. In this paper the coolant distribution during helical deep hole drilling is analyzed with high-speed microscopy. Micro particles are added to the cutting fluid circuit by a developed high-pressure mixing vessel. After the evaluation of suitable particle size, particle concentration and coolant pressure, a computational fluid dynamics (CFD) simulation is validated with the experimental results. The comparison shows a very good model quality with a marginal difference for the flow velocity of 1.57% between simulation and experiment. The simulation considers the kinematic viscosity of the fluid. The results show that the fluid velocity in the chip flutes is low compared to the fluid velocity at the exit of the coolant channels of the tool and drops even further between the guide chamfers. The flow velocity and the flow pressure directly at the cutting edge decrease to such an extent that the fluid cannot generate a sufficient cooling or lubrication. With the CFD simulation a deeper understanding of the behavior and interactions of the cutting fluid is achieved. Based on these results further research activities to improve the coolant supply can be carried out with great potential to evaluate new tool geometries and optimize the machining process.

Creation of Grooving and Parting Tools with Cooling Channels Manufactured Using Additive Technologies

In this paper, we propose designs of grooving and cutting cutters that have internal channels for supplying coolant under high pressure. Due to the fact that drilling of narrow channels in the cutter body is very problematic, the front part of the cutter, which holds the cutting interchangeable carbide plate, is manufactured by an additive method. The back of the cutter (holder) can be manufactured using traditional methods. The design assumes the use of conventional cutting interchangeable carbide plates (ICP), offered by many manufacturers.

Core physical conceptual design of small reactor for unmanned underwater vehicle

In order to improve the endurance of unmanned underwater vehicle (UUV) and meet the needs of long-term underwater mission, the conceptual design of the 3.68 MWt long-life small reactor JCZER-20 is carried out in an UUV application scenario with a propulsive power of 850 kW. According to the design content, the concept of active zone partition design is put forward, and a new circulating scheme of coolant in the reactor primary circuit is given. The layout of control body in the reactor and the design of control system are carried out. The control rod structure of JCZER-20 adopts special design to deal with special conditions such as shaking during operation. The reactivity distribution scheme is given, and the reactor physical characteristics are analyzed for the design scheme. This scheme can lengthen coolant channels, effectively improve the total temperature rise of the coolant, but not increase the extra heat load. MCNP-ORIGEN2 simulation results show that the JCZER-20 reactor can operate at full power for more than 30 years without refueling. The reactor core reactivity can be effectively controlled by the control system of reactor. The core design meets preset design requirements.

Heat transfer experiment with the prototypical Ra number of heavy metallic layer in IVR strategy

In-Vessel Retention (IVR) strategy is significant to limit molten corium in the Reactor Pressure Vessel (RPV) during severe accident scenarios. A heat transfer experiment has been established to study the thermal load on the cooled wall adjacent heavy metallic layer. The test section of the heavy metallic layer experiment is a hemisphere, and its diameter is 2.4 m; the height of simulant is set to 0.3 m. Heavy metallic layer experiment uses water as the simulant, and it uses the internal heating coils to represent the decay heat. Three independent sidewall coolant channels are used to cool the whole test section. The top boundary condition of the test section could be a cooling or insulated condition. The experimental results illustrate that the Mayinger heat transfer correlation could predict the heavy metallic layer experiment results, and it is recommended to predict the sideward heat flux. Applicating the heat transfer correlation and experimental qlocal/qmean distribution to the heavy metallic layer in core degradation situation, the heat transfer correlation calculated results demonstrate that it is unlikely for the local sideward heat flux to exceed the Critical Heat Flux (CHF). The possible top cooling boundary for the heavy metallic layer contributes to alleviating wall melting. Generally, it is unlikely that the vessel failure occurs at the cooled wall adjacent the heavy metallic layer.

Development of a High Heat Flux Electric Joule Heating System for Testing a One-Side Heated Cooling Channel

Systems such as solar thermal systems, chip coolers, beam dumps of neutral beam injectors, and fusion reactor divertors and blankets are subjected to one-side high heat flux. Specifically, high heat flux (10 MW/m2) is applied on the fusion reactor divertor in steady state. The monoblock design in a divertor is limited by the thermal-hydraulic and mechanical stability, which thermal-hydraulic data are required for. The lack of thermal-hydraulic data for the cooling channel causes difficulties for the design of the monoblock and the determination of the thermal-hydraulic condition for the safety and conversion of energy efficiency. To analyze the mechanisms and thermal hydraulics, a high heat flux heating system is recommended for the purpose of testing one-side heated cooling channels. Comparing an e-beam system to a joule heating system, the e-beam system requires higher cost, expertise, sophisticated design, and more power consumption, which delays the development of heat transfer correlations and the mechanisms of fluid motion inside the cooling channel. The production of 10 MW/m2 heat flux using the joule heating method is challenging, since it is limited by the temperature of the heater. In this study, the limitation of the joule heating system was overcome by optimizing the material selection for the heater, the configuration of the system, and the bonding method of the components used in the system. High heat flux testing was conducted and the target heat flux of 10 MW/m2 was successfully implemented, and it showed good reproducibility of the heating system. The reliability of the newly developed heating system was validated by comparing the results of the experiments with correlation-based simulations. The comparison analysis showed that the experimental results from the new heating system are comparable to the single-phase and two-phase correlation-based simulation results within 5% and 1.5% error, respectively. Further, through the comparison of various correlation-based simulations with the experimental results, we conclude that one-side joule heating results are only describable using a one-side correlation, not using correlations developed from uniform heating systems. To optimize the design of the cooling channel in a one-side heating condition in a faster and easier manner, the newly advanced joule heating system will help contribute to the development of the thermal-hydraulic analysis of the cooling channel.

Simulation of cooling plate effect on a battery module with different channel arrangement

Lithium-ion battery pack is widely used in electric vehicles (EVs), for which reasonable heat dissipation measures must be taken to keep battery working in a suitable temperature range. Liquid cooling is popular for its efficient heat dissipation performance. In order to evaluate the effect of layout and channel design of cooling plates on the heat dissipation of a battery module, numerical modeling and analyses were carried out. Two arrangements of the cooling plates with different coolant channels (i.e., single channel, multiple small channels, and S-shaped channel) are discussed. The Z-score method is applied to evaluate the six cooling plate designs with various inlet flow rates. It is found that the design with two cooling plates sandwiching one battery module shows a better cooling performance. In terms of the channel structures, the comprehensive performance of the cooling plates with multiple small flow channels is optimal, when inlet flow rate is between 7.817 × 10−4 kg s−1 ∼ 0.0105 kg s−1 under the New European Driving Cycle (NEDC) condition.

Conceptual design and thermal-hydraulic analysis of a megawatt-level lead-bismuth cooling reactor for deep-sea exploration

A new conceptual design of a mega-power nuclear reactor (MPNR) for applications in deep-sea exploration was developed. A solid core cooled by the natural circulation of a lead-bismuth eutectic (LBE) reactor was designed with a thermal power of 1 MW. It consists of 126 coolant channels, which are holes surrounded by highly enriched fuel of UO2 dispersed in titanium-zirconium-molybdenum (TZM) alloy. A control rod at the center of the fuel and six control drums around the block are made of boron carbide to control the reactivity of the reactor. The core and heat exchangers are arranged horizontally to reduce the volume of the entire system. Compared with traditional deep-submersible reactors used at sea, the MPNR is highly compact, has a high-power output and simple structure, and ensures safety under ocean conditions. The neutronic and thermal-hydraulic design characteristics of the MPNR were calculated and assessed. The temperature reactivity and void fraction reactivity coefficients of the MPNR are negative values to ensure that the reactor has negative feedback characteristics. The thermal-hydraulic analysis of the MPNR design was carried out using the computational fluid dynamics program STAR-CCM+, in which field functions were added to the program to realize the inclined, rolling, and heaving motions of the reactor. The numerical simulations showed that under stationary conditions, the MPNR could establish natural circulation with a mass flow rate of 93.32 kg/s. At an inclination angle of ±30°, the natural circulation mass flow rates are 88.6 kg/s and 87.5 kg/s, respectively. Under rolling and heaving conditions, the mass flow rate fluctuated periodically, and the maximum temperature of the core changed within 10 K.

Metal Additive Manufacturing of Plastic Injection Molds with Conformal Cooling Channels.

Conformal cooling channels (CCCs) are widely used in the plastic injection molding process to improve the product quality and operational performance. Tooling that incorporates CCCs can be fabricated through metal additive manufacturing (MAM). The present work focuses on the MAM of a plastic injection mold insert with different CCC types that are circular, serpentine, and tapered channels with/without body-centered cubic (BCC) lattices. The entire manufacturing process of the mold insert is explained from the design step to the final printing step including the computational thermal & mechanical simulations, performance assessments, and multiobjective optimization. Compared to the traditional channels, conformal cooling channels achieved up to 62.9% better cooling performance with a better thermal uniformity on the mold surface. The optimum mold geometry is decided using the multiobjective optimization procedure according to the multiple objectives of cooling time, temperature non-uniformity, and pressure drop in the channel. Direct Metal Laser Sintering (DMLS) method is used for manufacturing the molds and the quality of the printed molds are analyzed with the X-ray Computed Tomography (X-ray CT) technique. The errors between the design and the printed parameters are less than 5% for the circular and tapered channels while the maximum deviation of the strut diameters of the BCC is 0.06 mm.

Out-of-pile chemical compatibility of Pb–Bi eutectic alloy with Graphite

Abstract Lead Bismuth eutectic alloy (Pb: 55.5 wt.%, Bi: 44.5 wt.%) is a potential candidate coolant material for high-temperature reactors because of its low melting point (124 °C), high thermal conductivity, heat capacity, and better neutronic properties. Out-of-pile chemical compatibility studies of this coolant with graphite (coolant channel) have been carried out by isothermal annealing of the liquid alloy in a graphite crucible at 800, 900, 1000, and 1100 °C for times ranging from 100 h to 1000 h. Formation of a reaction layer is observed. The growth rate of the reaction layer follows a parabolic law. Reaction layer thicknesses of 61.3 μm and 121 μm are estimated from the growth rate vs. time relation after 1 year and 5 years respectively. The growth of the reaction layer is diffusion-controlled and the activation energy of the reaction is estimated to be 100 KJ/mol.

Active cooling of photovoltaic (PV) cell by acoustic excitation in single-dimpled internal channel

Solar energy is widely advocated by many countries which is the most popular renewable energy. To get the higher efficiency of the photovoltaic (PV) cell, enhancing cooling performance of the coolant channel is important. In this study, the effect of acoustic excitation was analyzed to enhance the cooling performance of internal channel imprinted with single-dimple for solar PV cell system. Various acoustic-excitation frequencies were compared for the optimized cooling performance of dimple-imprint channel. All experiments were conducted under laminar-flow conditions. The experiments indicated that a Strouhal number of 1.1 corresponding to a similar frequency of the vortex shedding within the dimple cavity was most-effective to enhance cooling performance. By analyzing the local heat/mass transfer distributions, the effect of acoustic excitation can be clearly noticed within the dimple cavity where vorticities formed. In the aft-plateau region, heat/mass transfer gradually decreased and the effect of acoustic excitation was minimal. Overall, the area-averaged heat/mass transfer was enhanced by 68% at St = 1.1. Furthermore, when the acoustic excitation was adopted, the area-averaged heat/mass transfer was enhanced by 26–35% in other frequency cases. It was concluded that an appropriate acoustic-excitation frequency could effectively improve the cooling performance of a single-dimple imprinted channel. In the end, the efficiency of PV cell will be enhanced by adopting the acoustic-excitation with dimple imprint cooling channel.

Shape Optimization of Pin Fin Array in a Cooling Channel Using Genetic Algorithm and Machine Learning

Shape Optimization of Pin Fin Array in a Cooling Channel Using Genetic Algorithm and Machine Learning

Enhancement of Heat Transfer Capability between the Cylindrical Cells and Coolant Channels for Battery Thermal Management System

Enhancement of Heat Transfer Capability between the Cylindrical Cells and Coolant Channels for Battery Thermal Management System

Film Cooling Effectiveness and Surface Coverage Under the Effects of Varying the Coolant Channel Wall-Roughness

Film Cooling Effectiveness and Surface Coverage Under the Effects of Varying the Coolant Channel Wall-Roughness

Shape-Stabilized Phase Change Material with Internal Coolant Channel Coupled with Phase Change Emulsion for Power Battery Thermal Management

Shape-Stabilized Phase Change Material with Internal Coolant Channel Coupled with Phase Change Emulsion for Power Battery Thermal Management

Heat Transfer and Pressure Loss Simulations of Matrix Cooling Channels for Gas Turbine Airfoils

The paper selected 10 geometrical parameter combinations to numerically investigate the dependencies of heat transfer enhancement, flow resistances and overall thermal performance on three geometrical factors including rib inclination angle, channel blockage ratio and subchannel number. The investigated Reynolds number starts at 5,000 and can be as high as 90,000. The turbulence model selected was Transition SST model. The results show that the matrix cooling channels of 30deg rib angle have greater heat transfer enhancement and much higher pressure loss than that of 60deg rib angle. Moreover, matrix cooling channels of higher channel blockage ratio have greater heat transfer enhancement and higher flow friction, while the relationship between the overall thermal performance and the channel blockage ratio depends on the Reynolds number. It was also concluded that the heat transfer performance factor of matrix cooling channel does not change linearly with the subchannel number and the effect of subchannel number on heat transfer performance is less significant than the other two factors. Besides, matrix cooling channels of higher subchannel number have higher pressure loss and poorer overall thermal performance.

Topology Optimization of Cooling Channel in 3d Chip Considering Through-Silicon Vias

Topology Optimization of Cooling Channel in 3d Chip Considering Through-Silicon Vias

Enhanced Thermal Performance of a Pin-Fin Cooling Channel for Gas Turbine Blade by Density-Based Topology Optimization

Enhanced Thermal Performance of a Pin-Fin Cooling Channel for Gas Turbine Blade by Density-Based Topology Optimization

Thermal Boundary Effect on the Heat Transfer Performance of a Ribbed Cooling Channel with Intersecting Ribs

Thermal Boundary Effect on the Heat Transfer Performance of a Ribbed Cooling Channel with Intersecting Ribs

Thermal Behavior of Supercritical Co 2 Inside Scramjet Cooling Channels with Different Structural Parameters

Thermal Behavior of Supercritical Co 2 Inside Scramjet Cooling Channels with Different Structural Parameters

Numerical Investigation of Heat Transfer Characteristics of Pin-Fins with Roughed Endwalls in Gas Turbine Blade Internal Cooling Channels

Numerical Investigation of Heat Transfer Characteristics of Pin-Fins with Roughed Endwalls in Gas Turbine Blade Internal Cooling Channels