Reduce Heat Generation Research Articles

Investigations on the effect of nozzle angle and air flow rate during nanofluid Minimum Quantity Lubrication milling of Aerospace alloy Al7075-T6

Present day industries are focusing upon finding various methods and techniques to implement sustainable manufacturing, which is ‘the need of the hour’. With increase in global competition, industries are striving hard to reduce the machining costs, which is a major contributor for ‘manufacturing cost per part’, in an industry. Conventional method of using large quantity of coolant/cutting fluids in several liters per hour, to cool machining zone is causing enormous concern. Strict Government regulations are necessitating industries to replace flood-coolant assisted machining by new techniques like ‘Minimum Quantity lubrication’ (MQL) coolant supply technique. The present work deals with investigating the effect of varying nozzle angle and air-flow rate during MQL assisted surface milling of aerospace aluminum Al7075-T6 alloy, using uncoated carbide tool. Three methods of coolant supply namely Dry, MQL and nanofluid MQL (nano particles us pended oil with MQL) are experimented. Cutting speed [150m/min, 208m/min, 264 m/min], feed rate [95 mm/min, 110 mm/min, 125 mm/min] and depth of cut [0.5 mm, 1.3 mm, 2 mm] are chosen as process variables. Two nozzle angles 25°C and 500, with 1.5 kg/cm2 and 3 kg/cm2 air flow rates were investigated. Best results were obtained for air flow rate of 1.5kg/cm2. Optimumnozzleangle was found to be 25°C. To obtain lowest temperature and reduced heat generation, nanofluid MQL machining is a feasible option. With regards to MQL technique, for obtaining better surface finish with reduced surface roughness of the work piece (Al7075-T6), nanofluid MQL technique is best.

Analytical and experimental investigations of optimum thermomechanical conditions to use tools with non-circular pin in friction stir welding

Friction stir welding tools with non-circular pins exhibit comparatively superior weld quality than circular pins. Improper selection of process parameters directs towards excess or insufficient heat supply which deteriorates weld quality and tool life. This necessitates exact prediction of heat generation with respect to the chosen pin geometry that is required to optimise process parameters. In this paper, a novel analytical model is developed to quantify the percentage reduction in heat generation on the replacement of circular tool pin with non-circular. Experiments were conducted using tools with different pin geometries to validate the proposed model. Based on the obtained results, optimum process variable selection charts were prepared with respect to the reduction in heat supply to facilitate amiable environment to use non-circular tool pins. Weld quality on the suggested range in the charts was examined through macro structure, hardness and tensile analysis.

The use of reusable fuel injection with the aim of improving the economic and environmental performance of the diesel engine

The current trend in the development of motor-and-tractor diesel engines imposes tough requirements on fuel equipment and the fuel supply process. The implementation of it is difficult to combine with the requirements of reducing heat generation at the initial stage of combustion and the rate of pressure increment to reduce exhaust emissions and engine noise. A decrease in the duration of the injection process and an increase in the volumetric feed rate lead to a growth in the cycle dynamism factor and an increase in the operation noise. This scientific article discusses the use of multiple injection of fuel in a diesel engine to reduce the emission of nitrogen oxides, smoke and particulate matter by improving the heat transfer processes, the mixture formation and, as a result, heat generation. Low exhaust gases toxicity and smokiness values are achieved.

Performance Evaluation of Cryogenic Treated and Untreated Carbide Inserts during Machining of AISI 304 Steel

The cutting tool in the machining process plays an important role as it acts on the working material. There are a few methodologies have been persued to improve tool life, for example traditional cooling, single layer coating, multilayer coating, heat treatment process, nitrogen cooling and latest being the cryogenic treatment which reported a significant improvement in cutting tool life, chip morphology, reduction in heat generation. Hence, the cryogenic treatment is emerged as the sustainable machining process. This paper presents machining of AISI 304 steel using both cryogenic treated (CT) and untreated (UT) cutting tool insert. The commercially available uncoated carbide insert has been cryogenically treated at -196°C for 24 hours soaking period. The machining test has been conducted under four different cutting speeds. The material characterization of cutting insert is studied by using scanning electron microscopy (SEM), hardness test, and microscopic image analysis has been carried out before and after cryogenic treatment. The cutting tool performance is assessed in terms of of wear, cutting temperature, chip morphology, surface roughness under the influence of cryogenic machining and the results are contrast with UT one. The exploratory findings reveals that the deep cryogenic treatment (DCT) with 24 hours soaking period, performed better wear resistance and improved surface roughness of the cutting tool. Also considerable reduction in the flank wear, crater wear, cutting temperature is obtained and found improved chip morphology.

Running thermoregulation effects using bioceramics versus polyester fibres socks

The feet, covered by socks and shoes during running, undergo an increase of temperature. The aim of this study was to reduce heat generation in the feet of athletes during running by wearing novel thermoregulatory socks impregnated with bioceramic materials. Thirty male athletes ran a half-marathon (21.0975 km) wearing polyester based with bioceramic fibres (zirconium silicate and titanium oxide) and control socks (polyester). The average temperatures were measured with a thermographic camera (FLIR e60bx) before and after the run. Nine regions of interests were evaluated in the plantar surface and eight in the dorsum. Before running, the plantar region with the highest temperature was the inner midfoot (plantar arch) with 30.3 ± 2.1°C on the control sock and 30.2 ± 2.1°C on the bioceramic one. After running, smaller temperatures were found at the plantar surface of five regions of interests: heel, inner midfoot, first and fifth metatarsal heads and first toe and all the dorsal regions of the bioceramic socks. The amount of temperature reduction from the bioceramic sock was between –1.1 and –1.3°C in heel, inner midfoot, first MTH and first toe (plantar) and 1.3°C at the dorsum of first and fifth toes. Polyester-based socks with bioceramic fibre materials, due to far-infrared radiation, promote cooler temperatures on the sock surface after running. This effect is more effective in heel, the inner midfoot and the first MTH and could help improve the behaviour of the sock to make it denser in bioceramics and preventing running lesions, like blisters.

Experimental investigation on analysis of performance of vortex tube through implementation of sustainable manufacturing

Sustainable manufacturing is the process of creating manufactured product that reduce harmful environmental impact, conserve energy and resources. It brings eco-friendly environment and are safe for employee, communities and consumers. Awareness of sustainable manufacturing is increasing in competitive world. Many industries have taken steps for green growth ensuring that process is environmentally and economically sustainable. Importance of this study is to attain sustainable in milling. Cutting fluid is used in CNC machine to reduce heat generation in metal cutting process but usage of cutting fluid causes hazardness to environment and employee. To minimise the hazardness cooling air technique is used. Cooling air technique is achieved using vortex tube. Taguchi optimisation technique was used to find optimal cutting parameters. Analysis of variance (ANOVA) is also applied to analysis the data obtained. The process was optimised for minimal flank wear considering environmental concern as a prime importance.

Temperature Distribution Study of Friction Stir Welded Aluminum Alloy 7075-T6 joints Reinforced with SiC Powders

Abstract Friction Stir Welding (FSW) is a unique process of joining two similar or dissimilar materials by generation of heat between two surfaces (tool shoulder and plate). The bonding made between two materials was achieved by a tool pin profile which makes the material to flow from the advancing side to retreating side. The main advantage of FSW is that during the welding process, the materials are joined with less heat and increased bond strength, due to reduced heat generation it results in better material properties when compared with other conventional welding processes. The experiments were conducted with SiC powders by varying the process parameters by keeping axial load as similar for all the trials. The tool used in the experiments is a high carbon steel D3, with a straight flat cylindrical pin. In the present work, we made an attempt to predict the theoretical temperature distribution for the joints made with FSW process using ANSYS. The temperature profiles were measured across different zones of welded sample for better understanding of temperature flow during the joining process. Metallurgical study was also carried outacross different zones and it is correlated with the theoretical temperature values for better understanding of process parameters and the effect / influence of adding SiC powders in material. From the results it is inferred that both temperature distribution and metallurgical study showed a good agreement due to its refined / coarse grain boundary development. The generation of higher temperature profile proves better mixing of SiC powders during the joining process. However, this work revealed that the process parameters and addition of SiC powders leads a major role in deciding the temperature profile across various zones of the FSW process.

Experimental investigation on analysis of performance of vortex tube through implementation of sustainable manufacturing

Sustainable manufacturing is the process of creating manufactured product that reduce harmful environmental impact, conserve energy and resources. It brings eco-friendly environment and are safe for employee, communities and consumers. Awareness of sustainable manufacturing is increasing in competitive world. Many industries have taken steps for green growth ensuring that process is environmentally and economically sustainable. Importance of this study is to attain sustainable in milling. Cutting fluid is used in CNC machine to reduce heat generation in metal cutting process but usage of cutting fluid causes hazardness to environment and employee. To minimise the hazardness cooling air technique is used. Cooling air technique is achieved using vortex tube. Taguchi optimisation technique was used to find optimal cutting parameters. Analysis of variance (ANOVA) is also applied to analysis the data obtained. The process was optimised for minimal flank wear considering environmental concern as a prime importance.

Transient Response Improvement and Reduced Heat Generation Control for Satellite Bus Voltage Controller

Transient Response Improvement and Reduced Heat Generation Control for Satellite Bus Voltage Controller

Lithium dendrite inhibition via 3D porous lithium metal anode accompanied by inherent SEI layer

Lithium (Li) metal anodes have been considered as the ultimate anode materials for the next-generation rechargeable batteries. However, uneven dendrite formation and anode volume expansion still can put a brake on the development of Li metal anode. Here, freestanding three-dimensional Li metal foam accompanied by inherent solid electrolyte interphase (SEI) capsulation formed by template-free chemical etching is constructed to promote the uniform lithium deposition and suppress dendritic Li growth. Contrary to planar Li metal foil, the 3D porous Li matrix can buffer the volume change and guide Li deposition inside its porous structure. Moreover, the encapsulated artificial SEI layer, which efficiently uniform the diffusion of Li ions on the interface, enables deeply deposited Li metal. Benefiting from the unique deposition kinetics, the Li plating/stripping process based on our strategy can be deeply cycled at various current densities with low overpotential between 1.0 and 20.0 mA cm−2 and achieve long lifetime up to 350 h. Moreover, Li metal batteries with LiNiCoMnO2 (Ni:Co:Mn=1:1:1) cathode exhibit excellent electrochemical performance at high current density and active material loading for more than 20.4 mg cm−2. In terms of both porous Li matrix and inherent dense SEI layer, our cell greatly suppresses the gassing process and reduces heat generation, further demonstrating the reliability and security of the batteries.

An Efficient Representation Using Harmony Search for Solving the Virtual Machine Consolidation

A data center with a large number of servers, large storage, and many network devices requires power for cooling to reduce heat generation, air conditioning, and emergency power generation facilities, in addition to power for operation internally consumed by infrastructure equipment. The power consumed by data centers worldwide makes up a large proportion. Although the size of data centers is expected to increase, we are already faced with power problems because stability is prioritized over efficiency when operating data centers in order to meet the Service Level Agreement (SLA) conditions. Most data centers are in a virtualization environment, and virtual machine consolidation using physical machine (PM) transitions to the idle mode through virtual machine (VM) migration has been suggested as one of the most effective ways to reduce the amount of power usage in a data center. This study takes into account the characteristics of virtualization environments and presents an algorithm that effectively solves VM consolidation (VMC) through operator design using a grouping representation method and a meta-heuristic method known as harmony search.

Evaluation of loss characteristics of superconducting magnetic bearings for LiteBIRD satellite by three-dimensional finite element method analysis

The polarization modulator of LiteBIRD satellite is required to be used by continuously rotating the half-wave retarder under a low temperature environment of about 10 K. Then, it becomes an important issue to reduce heat generation due to rotation loss. Therefore, a rotation mechanism in a cryogenic environment by a superconducting magnetic bearing (SMB) using the pinning effect of the bulk superconductor has been studied. In SMB, because of the pinning effect of superconductor, it is possible to rotate the half-wave retarder with stably floating, and it is possible to avoid frictional heat due to contact. The half-wave retarder is incorporated inside the rotating part of the superconducting magnetic bearing composed of the permanent magnet ring and the iron yoke. At this time, since the permanent magnet ring divides the parallel magnetized permanent magnets into pieces, a gap is formed at the joint of the permanent magnets. For this reason, the magnetic field distribution generated by the permanent magnet ring is not uniform. Although SMB can reduce friction as compared to mechanical bearings, the magnetic properties of the bulk superconductor change due to the magnetic field fluctuation caused by such ununiformity of the magnetic field, resulting in energy loss. In this study, heat generation in bulk superconductor in SMB is evaluated by three-dimensional finite element method. First, using JMAG Designer 17.0, the magnetic field distribution created by the rotor side is obtained by static magnetic field analysis. Next, using the COMSOL Multiphysics 5.3a, by applying the magnetic field distribution created by the rotor side obtained above and rotate the magnetic field, the loss generated in the bulk superconductor is investigated. The resulting loss value satisfied the required value.

Influence of Interfacial Traps on the Operating Temperature of Perovskite Solar Cells.

In this paper, by developing a mathematical model, the temperature of PSCs under different operating conditions has been calculated. It is found that by reducing the density of tail states at the interfaces through some passivation mechanisms, the operating temperature can be decreased significantly at higher applied voltages. The results show that if the density of tail states at the interfaces is reduced by three orders of magnitude through some passivation mechanisms, then the active layer may not undergo any phase change up to an ambient temperature 300 K and it may not degrade up to 320 K. The calculated heat generation at the interfaces at different applied voltages with and without passivation shows reduced heat generation after reducing the density of tail states at the interfaces. It is expected that this study provides a deeper understanding of the influence of interface passivation on the operating temperature of PSCs.

Quench Protection of HTS Magnet Composed of Multiple Pancake-coils by Forming Auxiliary Dump Resistor Loop

The most probable cause of quench damage of HTS magnets is over-heating at the highest temperature spot (hot-spot) in the magnet wire during the quench protection sequence. Therefore, to avoid damage, it is necessary to reduce heat generation in the hot-spot. The authors propose a method to reduce the hot-spot temperature of a magnet composed of multiple sub-pancake-coils by reducing current in a quenching sub-coil. A quench occurs most often in a sub-coil that has critical current Ic lower than that of the other sub-coils. When a quench is detected in the lower Ic sub-coil, the current of the quenching sub-coil is transferred to the other coils with higher Ic ' s resistively shorting the other sub-coils by forming auxiliary dump resistor loop. In this paper, the effectiveness of the method is shown by a case study of a magnet composed of eight pancake sub-coils.

A Simplified Model of Coaxial, Multilayer High-Temperature Superconducting Power Cables with Cu Formers for Transient Studies

Bypassing transient current through copper (Cu) stabilizer layers reduces heat generation and temperature rise of high-temperature superconducting (HTS) conductors, which could protect HTS cables from burning out during transient conditions. The Cu layer connected in parallel with HTS tape layers impacts current distribution among layers and variations of phase resistance in either steady-state or transient conditions. Modeling the multilayer HTS power cable is important for transient studies. However, existing models of HTS power cables have only proposed HTS cables without the use of a Cu-former layer. To overcome this problem, the authors proposed a multilayer HTS power cable model that used a Cu-former layer in each phase for transient study. It was observed that resistance of the HTS conductor increased significantly in the transient state due to a quenching phenomenon, which made the transient current mainly flow into the Cu-former layers. Since resistance of the Cu-former layer has a significant impact on the transient current, detailed modeling of the Cu-former layer is described in this study. The feasibility of the developed HTS cable model is evaluated in the PSCAD/EMTDC program.

Reduced Heat Generation During Magnetic Stimulation of Rat Sciatic Nerve Using Current Waveform Truncation.

Current truncating circuit designs used in some controllable pulse width transcranial magnetic stimulation systems can be adapted for use with the peripheral nervous system. Such a scaled-down stimulator produces neuromuscular activation using less stimulus energy than described in previous reports of sciatic nerve stimulation. To evaluate the energy reductions possible with current truncation, we performed six in vivo experiments in rats where the magnetic stimulating coil abutted the sciatic nerve. We used electromyographic data to quantify neuromuscular response, with a criterion level of 20%-of-maximum to indicate a useful level of neuromuscular activation. The energy required to evoke this criterion response from muscles innervated by the sciatic nerve was reduced by approximately 34% from 10.7J with a stimulus waveform lasting 300 [Formula: see text] to 7.1J with a waveform lasting 50 [Formula: see text]. In water, the 300 [Formula: see text] pulse heated the coil by 0.30°C whereas the 50 [Formula: see text] pulse heated the coil by 0.15°C. Truncated-waveform magnetic stimulation systems can be used in basic research and clinical applications not requiring rapidly pulsed stimuli. An example of such a clinical application is left vagus nerve stimulation, a treatment that is reported to reduce epileptic partial-onset seizures.

Three-dimensional thermal-mechanical analysis of retractable pin tool friction stir welding process

The retractable pin tool friction stir welding (RPT-FSW) is a technology for eliminating the exit hole at the end of the weld via in-process pin retraction. During RPT-FSW, the influence of the pin-retraction-induced continuous changing tool/workpiece interface on thermal-mechanical processes, such as the heat generation, temperature, and material flow, is critical knowledge for the process development and optimization. In this study, three-dimensional thermal-mechanical analysis based on computational fluid dynamics (CFD) is applied to investigate the RPT-FSW process. Technically, the dynamic mesh approach is utilized to allow dynamic geometric model for implementing the continuous change of the tool/workpiece interface. The thermal-mechanical condition during the RPT-FSW in the vicinity of the welding tool is investigated and compared with the conventional FSW. It is shown that the volume of the deforming material (with low viscosity) decreases significantly because of the reduction of the total area of the tool/workpiece interface immersed in the workpiece due to the pin retraction. Generally, in spite of the shrinkage of deforming zone volume, the thermal-mechanical condition during RPT-FSW inside the deforming zone is quite similar to the conventional FSW. Comparing to the conventional FSW, the decrease in average deformation temperature during the RPT-FSW is about 10 °C due to the reduction in heat generation. The pin retraction causes slight fluctuation in the average strain rate in the deforming zone. Finally, the numerical simulation data is supported by the experimental measurements regarding the temperature history and deformation zone geometry.

Effect of Cs and Sr separation on occupied area reduction in current nuclear energy system and its evaluation by CAERA index

ABSTRACTSeparation of Cs and Sr from high-level liquid waste (HLLW) contributes to reducing heat generation and correspondingly to minimizing the required use of space in geological disposal repositories for high-level radioactive waste. To maximize the impact of Cs and Sr separation on reducing the occupied area of a repository, it is necessary to consider both the front-end and back-end stages of the nuclear energy system. Therefore, we quantitatively surveyed factors that potentially affect the reduction in the occupied area – that is, the area required for disposal of one waste package – when introducing Cs and Sr separation. From an evaluation using the Comprehensive Analysis of Effects on Reduction of Disposal Area (CAERA) index, we found that in case of a 15-year cooling period of spent nuclear fuel (SNF) after discharge, which is the current operational condition at the Rokkasho Reprocessing Plant, a maximum reduction of 30% in occupied area was achieved for 25 and 30 wt% waste-loaded vitrified waste with Cs and Sr separation. In that case, separation of more than 70% of Cs and Sr was required based on the current reference case for the Japanese geological disposal concept (the so-called H12 Report). In addition, the effectiveness of Cs and Sr separation for reducing the occupied area was drastically decreased if the cooling period after discharge was extended beyond 15 years; for instance, vitrified waste with a more than 40-year cooling period showed almost no reduction in occupied area. This was because the amount of 241Am, which is generated from the beta decay of 241Pu, and the contribution of 241Am to heat generation in vitrified waste increased as the cooling period became longer. The results suggested that the cooling period of the SNF, the waste loading of the vitrified waste, the Cs and Sr separation ratio and the occupied area of the waste were key factors governing the effectiveness of Cs and Sr separation for geological disposal area reductions.

A novel phacoemulsification needle with scissor-like motion end effector for reducing heat generation at cornea incision

In this paper, we designed a novel scissor-like phacoemulsification needle for efficiently disrupting cataract with low risk of corneal burns. The proposed phaco needle consists of a needle shaft and an end effector with two slight beams connected at the shaft tip by an inverse symmetrical groove structure. The longitudinal driving force transmits through the needle shaft and converts into opposite transversal forces at the groove structure based on elastic wave reflection. These opposite transversal forces excite efficient scissor-like vibration at slight beams, as well as restrict the shaft deflection to reduce the frictional heat generation between the needle sleeve and shaft at the cornea incision. In the paper, the design principle was presented firstly. Next, a scissor-like needle was designed, simulated, fabricated and experimentally characterized. In the performance test, the scissor-like needle showed high efficiency to disrupt tissue. Moreover, under the same conditions, the proposed needle generated obviously lower frictional heat than the conventional longitudinal needle at the needle shaft, thus making it a successful design for reducing the risk of burns thoroughly in cataract removal application.

A novel, new generation drill coating for osteotomy site preparation.

Implant success and survival rate ranges from 93% to 97%; however, failures are not very uncommon. These failures can be caused due to a variety of reasons out of which increased heat during drilling of osteotomies is a major contributor. The aim of this study was to develop a new generation diamond-coated drill and compare the thermal changes between commercially available drills and the experimental diamond coated drill during implant site preparation in artificial bone. Three types of drills were selected for the study; Group A (Carbide), Group B (Stainless Steel), and Group C (Experimental). A total of 60 implant site preparations were performed with all the drills in artificial bone using a surgical unit linked to a testing device, in order to standardize implant drilling procedures. Bone temperature variations were recorded when drilling at a depth of 10 mm. A constant irrigation of 50 ml/minute and drilling speed of 800 r.p.m. was maintained. The mean temperature of Group A, Group B, and Group C was 35.57°C, 36.83°C and 34.23°C, respectively. The results were assessed and statistically analyzed using ANOVA test and post hoc Bonferroni test. Statistically significant higher temperatures were obtained with stainless steel drill and carbide drill when compared with the experimental diamond coated drill. (P = 0.000). Diamond coated osteotomy drills have shown promising results in reducing heat generation at the osteotomy. Further studies need to be conducted to maximize the potential use of diamond as components of drills in implant dentistry.