Types Of Heat Sources Research Articles

Electro-thermal co-simulation of high-frequency structure of staggered double-grating traveling wave tube based on finite difference time domain

The heat dissipation issue of a Traveling Wave Tube (TWT) affects its stability and reliability. In this paper, the particle-in-cell (PIC) code based on the finite difference time domain (FDTD) method and the thermal analysis program are closely combined to realize the electro-thermal co-simulation of the high-frequency circuit of the staggered double-grating TWT. Two types of heat sources, including the ohmic losses inside the high-frequency structure and the energy loss caused by electron collision, can be analyzed by the code providing significant guidance for the design of TWT.

Element-based finite volume method applied to autogenous bead-on-plate GTAW process using the enthalpy energy equation

The welding process is the most used technique for metal joining. Understanding the temperature variation along the welded part during the process can prevent the appearance of failures. The experimental investigation process is quite time-consuming and costly. Therefore, numerical simulation processes based on the finite difference method, finite element method, finite volume method, or meshless Element-Free Galerkin (EFG) methods are important tools to optimize the welding process. The main goal of the present study is to show the feasibility of the Element-based Finite-Volume Method (EbFVM) approach for actual engineering applications. To solve the unsteady 2D and 3D thermal energy equation using enthalpy as an independent variable, an in-house Fortran code has been developed based on the EbFVM approach in conjunction with unstructured and structured meshes. The numerical simulations, with four types of different heat sources, were performed for applications of real welding processes with variations in density and enthalpy as a function of temperature. The results are presented in terms of thermal cycles and temperature fields. Furthermore, the developed code was confronted against experimental works from the literature, simulated and lab-controlled experiments with AISI 409 ferritic workpieces, and exact analytical solutions with thermocouples fixed in different positions. In general, the numerical results from the current investigation are in close agreement with the results from the literature and the experimental results performed by the authors. The numerical results also highlighted the differences between the 2D and 3D models for thermal cycles near the bead weld.

Recommended operating conditions and performance evaluation of commonly used hydrofluoroolefin (HFO) and hydrochlorofluoroolefin (HCFO) refrigerants in organic Rankine cycle

The application of the first three generations of organic refrigerants, namely, CFCs, HCFCs, and HFCs, in an organic Rankine cycle has been widely investigated. As environmentally friendly successors to the above three generations of refrigerants, hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs) have also attracted increasing research interest for their application in the organic Rankine cycle (ORC). Based on molecular complexity, characteristic points on saturation liquid and vapor curve and area of characteristic regions in temperature-entropy (T-s) diagram, eight common hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs) are classified, analyzed, and evaluated. In addition, the type of heat source and specific operating conditions in which these eight hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs) are most effective are recommended. The results show that molecular complexity of hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs) mainly depends on the length of the C chain, and then on the number and location of Cl and F atoms. HFO-1243zf has the best comprehensive evaluation indicator, and it is noteworthy as a recommended working fluid for subcritical ORC systems. The result obtained in this paper may provide a reference for the design and actual operation of Organic Rankine Cycle system using HFO and HCFO as working fluids.

Multi-Indicator Assessment of a Thermal Insulation Investment, Taking into Account the Pre-Set Temperature

The article proposes indicators to evaluate a thermal insulation investment in a building, such as net present value (NPV), profitability index, discounted payback period, and ecological cost efficiency. Economic and ecological aspects were taken into account. Life Cycle Assessment (LCA) was used in the ecological analysis. The following heat sources in the building were considered: condensing gas boiler and heat pump. The developed indicators also depend on the pre-set temperature in residential premises. A methodology to determine the optimum thermal insulation thickness for both economic and ecological reasons was also proposed. A case study was analyzed, and a reference building, typical for Polish construction conditions, was used for research. Various solutions were suggested regarding the type of thermal insulation material and heat sources. The values of the indicators were determined for the proposed variants and for the economically and ecologically optimum thermal insulation thicknesses. Based on the conducted research, it was found that air temperatures maintained in the rooms of the building undergoing thermal modernization should be taken into account in the energy audit. The energy demand of the building for a room temperature of 26 °C is higher by 61% compared to the demand for the same building at the design temperature (20 °C). The innovation in the proposed approach to the economic and ecological assessment of a building is the combination of a wide range of temperatures potentially maintained in living spaces with ecological cost-effectiveness.

Integrated approach to Wire Arc Additive Manufacturing (WAAM) optimization: Harnessing the synergy of process parameters and deposition strategies

The flexibility of Additive Manufacturing (AM) technologies in the metal 3D printing process has gained significant attention in research and industry, which allows for fabricating complicated and intricate Near-Net-Shape (NNS) geometry designs. The achievement of desired characteristics in Wire-Arc Additive Manufactured (WAAM) components is primarily contingent upon the careful selection and precise control of significant processing variables, including bead deposition strategy, wire materials, type of heat source, wire feed speed, and the application of shielding gas. As a result, optimizing these most significant process parameters has improved, producing higher-quality WAAM-manufactured components. Consequently, this has contributed to the overall rise in the method's popularity and many applications. This article aims to provide an overview of the wire deposition strategy and the optimization of process parameters in WAAM. The optimization of numerous wire deposition techniques and process parameters in the WAAM method, which is required to manufacture high-quality additively manufactured metal parts, is summarised. The WAAM optimization algorithm, in addition to anticipate technological developments, has been proposed. Subsequently, a discussion ensues regarding the potential for WAAM optimization within the swiftly growing domain of WAAM. In the end, conclusions have been derived from the reviewed research work.

Coupled influences of magnetic field and several thermal loads on vibration of thermoelastic nano-ceramic (Si3N4) beam

Our study investigates the vibration of a thermoelastic nano-ceramic (Si3N4) beam exposed to a magnetic field under the effect of a moving heat source and different types of thermal loads. These nanobeams are modeled as non-Fourier heat conduction. In our formulation, the equation of motion and the principle of energy conservation from two coupled partial differential equations have been driven. A direct approach has been used to find the solutions to the governing equations using the Laplace transform definition. Numerical Laplace transform inversion was calculated using Hoing's approximation approach. Solutions have been applied to silicon nitride (Si3N4) nanobeam ceramics. Figures show the distribution of temperature increment, lateral deflection, and stress with different values of magnetic field and several thermal load parameters. In all the studied nanobeam functions, the magnetic field and several thermal loads’s parameters have significant effects. They could be used as tuners to control the vibration and temperature increment. In the present study, a moving heat source, and different thermal loads have been applied to a non-Fourier nanobeam exposed to a magnetic field. The results have been compared with those obtained in the thermoelastic cases.

Recent Advancements in Developing Metal Matrix Composites with Arc-Assisted Cladding Techniques: A Review

Cladding is one of the flagship technologies of improving the surface dependent properties of metals. Heat-assisted technique of reinforcing foreign precursor material into substrate such as tungsten inert gas cladding, laser cladding and plasma transferred arc cladding are reviewed and presented in this paper. A comprehensive study of the research work of the present era in this particular field is also discussed here. Selection of different types of substrate material, reinforcing metal powder, type of heat source, the method of preparing coating powder (in paste form) and impurity-free substrate material respectively prior to cladding is also detailed after thorough investigation of different research papers. The type of tests which has to be done after cladding to evaluate the surface dependent properties are also discussed in this paper.

Unsteady heat transfer in porous fiber composite cylinders with compressible fluid

The study of heat transfer behavior in porous fiber composite cylinders is vital for optimizing efficient thermal management, insulation materials, and heating equipment design, with applications spanning fields like materials drying, atomization equipment, and aerospace. However, the existing research in this area faces challenges including inadequate experimental data and a lack of clarity regarding fluid-porous material interactions, particularly under the influence of compressible fluids, which demand a more nuanced investigation. This study has developed a model to depict the unsteady heat transfer behavior of porous fiber composite cylinders containing compressible fluid. Consequently, a momentum equation describing the gradual diffusion of compressible fluid within the porous medium is established based on the Darcy-Brinkman-Forchheimer equation. For the purposes of this investigation, the air is treated as a compressible fluid. Concurrently, the corresponding energy equation is formulated, assuming Local Thermal Equilibrium. Ultimately, the devised model is solved by employing the finite volume method. Additionally, a temperature measurement experiment is designed to furnish boundary conditions and verify the model's reliability. The findings indicate that omitting the influence of compressible fluid yields a maximum predicted temperature deviation of approximately 5.6 K at a heating temperature of 420 K. The temperature deviation gradually expands as the heating temperature rises. Furthermore, the parametric analysis is conducted to investigate the impact of porosity, thermal conductivity, geometric size, and the type of heat source on the non-steady heat transfer behavior of composite cylinders. This novel model contributes to a more accurate prediction of the unsteady temperature distribution within porous fiber composite structure cylinders.

Informing directed energy deposition strategies through understanding the evolution of residual stress

Residual stress is a critical concern in directed energy deposition (DED) as it impacts the functional performance of components, in terms of load-bearing capacity and corrosion behavior. In this paper, an analytical model is developed to characterize the temperature distribution, residual stress profiles, and geometric distortions in DED-built components, which enables efficient planning of the DED strategies. The model combines a finite difference method to predict the temperature history, modified Green's functions to quantify thermal stress, and a radial return method to update plastic stress, which features the deposition of materials with heat source movement. The predictions are validated against the temperature, residual stress, and distortion profiles reported in the literature. In the fabrication of multiple-layer thin-wall structures, the model demonstrates a maximum prediction error of 18.2% for the peak temperature at the middle of the deposit-substrate interface and 17.7% for the vertical distortion of the deposit-substrate system. Simulation results from the model provide insights into understanding stress evolution in the deposition and offer guidance in the selection of linear energy density parameters (heat source power and traverse speed) and process planning parameters (idle time and deposition patterns) when designing DED strategies for thin-wall structures. This approach can be implemented in an efficient workflow to optimize the DED technologies for specified residual stress profiles within a component geometry regardless of heat source or material type.

On the Feasibility of Building Mini-Thermal Power Plant Using Local Fuels in the Conditions of the Republic of Belarus. Part 2. Role of Mini-Thermal Power Plant in Heat Supply Systems of Cities and Settlements in Belarus

. Within the framework of ensuring the country's energy security and pursuing a policy of decarbonization of the economy in the Republic of Belarus, it is assumed to maximize the use of its own fuel and energy resources (TER). However, the question of choosing the type of heat source in centralized heat supply systems when using local fuels (LF) remains open. The commissioning of the Belarusian Nuclear Power Plant and the relatively high unit cost of power generation capacities running on LF inclines the scales to use boiler houses as heat sources. Based on the world experience in the development and application of heating as the most energy-efficient solution in the field of heat supply, this problem has been studied in the conditions of Belarus. It is shown that the electric capacity of mini-thermal power plants using traditional LF connected to the unified system of the country is less than 100 MW, and the main technologies implemented at mini-thermal power plants using LF in the Republic of Belarus are traditional steam power plants with water steam as the working fluid (11 power plants) and steam power plant with organic Rankine cycle (ORC) (3 power plants). Geographically, mini- thermal power plants operating on LF are located evenly throughout the entire territory of the Republic of Belarus. The number of hours of use of the installed capacity of renewable energy sources (RES) of the Republic of Belarus has been determined. Energy sources based on organic waste and biomass (over 4,000 hours per year) and on hydro resources (about 3,500 hours per year) have a clear advantage, for which indicator of the number of hours of installed capacity use is much higher than for solar and wind power installations. In addition, biomass generating capacities have the lowest coefficient of electricity supply to the combined energy system. Based on the analysis of modern trends in the development of energy, technical and economic “attractiveness factors” for the construction of heating systems for heat supply on LF in the conditions of Belarus have been formulated, which, in addition to traditional factors (substitution of imported fuel – natural gas and oil), include improvement of the quality and reliability of energy supply to consumers in remote locations, development of polygeneration, reduction of losses of electric energy for its transport, participation in covering the electric load schedule of the unified power system, and also indicated the possibility of creating an energy hub on the basis of a mini-thermal power plant, structured for the integration of energy sub-sectors, distributed generation sources and the option of generating “green” energy carriers.

Effects of heat source type and FE time discretization strategy on predicting temperature histories during laser direct energy deposition process of Fe-based alloys

Effects of heat source type and FE time discretization strategy on predicting temperature histories during laser direct energy deposition process of Fe-based alloys

Effect of heat source and Zn-coating type on the geometry and morphology of laser-brazed thin-gauge steels

Laser brazing (LB) offers significant advantages over other types of traditional seam joining methods: the ability to join dissimilar materials without significant melting of the substrates, reduced Zn burn-off in Zn-coated steels, and minimal heat-affected zone (HAZ) formation. However, the edge (or the tip) of laser-brazed beads can be one of the potential cracks initiations sites which results in catastrophic failure of the parts. The existing literature on LB offers no insights into the geometry and elemental segregation at the edge of the brazing bead as a result of the interaction between the laser beam and the substrate. To bridge this gap in knowledge, LB was conducted in the bead-on-plate configuration on two different types of Zn-coated hot-dip galvanized (GI) and galvannealed (GA) advanced high-strength steels (AHSS) using a Si-Bronze filler wire. LB provided an improved wettability because of the formation of a tail-like geometry at the bead edge of both coatings showing a high Zn concentration, which is opposed to what has been observed in similar studies on gas metal arc brazing (GMAB). LB had a significant effect on modifying the surface morphology of the GA-coating, which has previously not been reported in the literature. Similar Zn distribution of LB samples at the bead edge of both coatings clearly showed that the wettability of molten filler material in LB is improved relative to GMAB.

Progress in Active Infrared Imaging for Defect Detection in the Renewable and Electronic Industries.

In recent years, infrared thermographic (IRT) technology has experienced notable advancements and found widespread applications in various fields, such as renewable industry, electronic industry, construction, aviation, and healthcare. IRT technology is used for defect detection due to its non-contact, efficient, and high-resolution methods, which enhance product quality and reliability. This review offers an overview of active IRT principles. It comprehensively examines four categories based on the type of heat sources employed: pulsed thermography (PT), lock-in thermography (LT), ultrasonically stimulated vibration thermography (UVT), and eddy current thermography (ECT). Furthermore, the review explores the application of IRT imaging in the renewable energy sector, with a specific focus on the photovoltaic (PV) industry. The integration of IRT imaging and deep learning techniques presents an efficient and highly accurate solution for detecting defects in PV panels, playing a critical role in monitoring and maintaining PV energy systems. In addition, the application of infrared thermal imaging technology in electronic industry is reviewed. In the development and manufacturing of electronic products, IRT imaging is used to assess the performance and thermal characteristics of circuit boards. It aids in detecting potential material and manufacturing defects, ensuring product quality. Furthermore, the research discusses algorithmic detection for PV panels, the excitation sources used in electronic industry inspections, and infrared wavelengths. Finally, the review analyzes the advantages and challenges of IRT imaging concerning excitation sources, the PV industry, the electronics industry, and artificial intelligence (AI). It provides insights into critical issues requiring attention in future research endeavors.

On the Feasibility of Building Mini-Thermal Power Plant Using Local Fuels in the Conditions of the Republic of Belarus. Part 1. State of Use of Local Fuels in Heat Supply Systems

As part of ensuring the country's energy security and pursuing a policy of decarbonization of the economy in the Republic of Belarus, the maximum use of its own fuel and energy resources (FER) is expected. However, the question of choosing the type of heat source in centralized heat supply systems when using local fuels (LF) remains open. The commissioning of the Belarusian Nuclear Power Plant and the relatively high specific cost of electricity generating capacities using local fuels tip the scales to the use of boiler houses as heat sources. However, world experience in the development and application of heating, as the most energy-efficient solution in the field of heat supply, requires a more thorough study of this problem. The paper presents an overview of the use of local fuels in Belarus and a number of European countries with developed centralized heat supply. Based on the analysis of open source data, the paper provides information on the state of use of local fuels in district heating systems of the Republic of Belarus and a number of European countries that have experience in the widespread use of solid biomass and where it constitutes a significant share in the structure of thermal and electrical energy production in relation to other fuel and energy resources. The main aspects of the energy programs of a number of European countries with the largest share of thermal and electrical energy generation using local fuels are presented. It has been revealed that the energy program of Finland is of the greatest interest for Belarus, where the share of nuclear energy in the structure of electrical energy production, just like in the Republic of Belarus, is approaching to 40 % and the energy strategy assumes an increase in the share of thermal power plants using local fuels in the structure of heat and electricity generation.

Unveiling an underground climate change in the Chicago Loop with a district-wide sensing network

Unveiling an underground climate change in the Chicago Loop with a district-wide sensing network

Thermal and economical performances analyses of a desiccant wheels-assisted atmospheric water harvesting system used in humid climate regions

The thermal and economic performance of an atmospheric water harvesting system that uses four-stage desiccant wheels to pre-humidify processed air was analyzed. A vapor-compression refrigerator was used as the cold source. Two types of heat sources, i.e., heat pump and solar water heater, were considered, and their performance was evaluated. First, thermal performance of the system using different heat sources was analyzed under humid ambient conditions (relative humidity was 40–90 %, dry bulb temperature was 15–35 °C). The results showed that the water harvesting rate was 25.1–94.1 kg/h under these ambient conditions. When a heat pump was used, the water harvesting efficiency with heat recovery was 0.97–2.48 kg/kWh, and 2.41–4.59 kg/kWh when the solar water heater was used. The economic performance of the system was investigated by using diesel generators as the power source. To provide drinking water for 100 people, who consume 3–8 kg/day/person, as compared with bottled water sold in the market, the recovery period of the systems with heat recovery were 0.97–2.58 years and 0.34–0.91 years when the heat pump and solar water heater were used, respectively.

Loop-mediated isothermal amplification assay for screening congenital cytomegalovirus infection in newborns

Congenital cytomegalovirus (CMV) infection is a common cause of sensorineural hearing loss and neurodevelopmental impairment in newborns. However, congenital CMV infection cannot be diagnosed using samples collected more than 3 weeks after birth because testing after this time cannot distinguish between congenital infection and postnatal infection. Herein, we developed a robust loop-mediated isothermal amplification (LAMP) assay for the large-scale screening of newborns for congenital CMV infection. In contrast to conventional quantitative polymerase chain reaction (qPCR), which detects CMV within a dynamic range of 1.0 × 106 to 1.0 × 102 copies/μL, our quantitative LAMP assay (qLAMP) detects CMV within a dynamic range of 1.1 × 108 to 1.1 × 103 copies/μL. Moreover, the turnaround time for obtaining results following DNA extraction is 90 min in qPCR but only 15 min in qLamp. The colorimetric LAMP assay can also detect CMV down to 1.1 × 103 copies/μL within 30 min, irrespective of the type of heat source. Our LAMP assay can be utilized in central laboratories as an alternative to conventional qPCR for quantitative CMV detection, or for point-of-care testing in low-resource environments, such as developing countries, via colorimetric naked-eye detection.Key points• LAMP assay enables large-scale screening of newborns for congenital CMV infection.• LAMP allows colorimetric or quantitative detection of congenital CMV infection.• LAMP assay can be used as a point-of-care testing tool in low-resource environments.

Temperature field simulation and asymmetric heat transfer distribution of dissimilar steel welded with external transverse magnetic field

During the welding process of Q235 mild steel to 304 L stainless steel, the difference in their thermal properties and magnetic permeability deflects the arc to the mild steel side, resulting in unstable welding process, poor weld formation, and reduced penetration depth. In this paper, a method of applying an external transverse magnetic field acting on the welding arc is proposed to overcome the adverse effects of arc deflection. The experimental results show that the welding depth of Q235/304 L can be significantly improved by magnetically controlled arc welding process. In order to understand the asymmetric heat transfer distribution of dissimilar steel under the action of external transverse magnetic field, a new type of deflection heat source was constructed. The influence of transverse magnetic field deflection arc on heat source parameters was considered, and the welding temperature field of Q235/304 L was simulated to study the welding temperature field of dissimilar steel under the action of magnetic field. In the error analysis, the maximum error of the deflected heat source model is less than 16 %, and the average error is less than 7 %. Compared with the asymmetric heat source model, the constructed heat source model is more accurate in calculation. The depth of melt and temperature variation around the weld under different excitation currents were studied. The weld forming and welding heat transfer law of dissimilar steel with external transverse magnetic field are obtained, which could be used to further improve the welding quality of dissimilar steel.

The Effect of Lowering Indoor Air Temperature on the Reduction in Energy Consumption and CO2 Emission in Multifamily Buildings in Poland

This article analyzes the possibility of reducing the energy consumption from building heating as a result of lowering the indoor air temperature, which is recommended as a response to the energy crisis. Various values of the set-point temperature (16–22 °C), as well as different scenarios for their changes, were assumed for analysis. Changes in clothing that were determined to maintain the same level of thermal comfort after a temperature change were determined. The associated reduction in CO2 emissions emitted into the atmosphere was determined. The effect of reducing CO2 emissions was studied depending on the type of heating source. Simulation calculations were carried out for an exemplary multifamily building. The effect of different building insulations required in Poland over the years 1964–2022 was considered. Analyses were performed for the climatic conditions of cities located in different climatic zones of Poland: Koszalin, Wroclaw, Warsaw, Bialystok, Suwalki. Depending on the scenario, the insulation standard of the building, and the variant of location, the energy reduction achieved ranges from 6.6%/K to 13.2%/K. Taking into account the type of heating source, the reduction in CO2 emissions is from 0.7 to 7.5 kgCO2/(K·m2). The reduction in temperature by 1 or 2 K can be compensated for by wearing an additional sleeveless vest (0.12 clo) or sweater (0.28 clo).

Synthesis of Rankine cycle systems with cascade and separate configurations utilising multiple heat sources at different temperature levels

The optimisation of Rankine cycle systems is mainly influenced by the type of heat source, working fluid selection, process components, control strategy, component layout and sizing, and has been recognised as a promising way to contribute to the development of renewable and sustainable energy systems. In this study, a combined steam-organic Rankine system is proposed to recover waste heat from aluminium production at various temperature levels and heat from solar, geothermal and biomass renewable sources. Based on a case study in a Slovenian city, the operating conditions of two different configurations are optimised for individually positioned cycles and for a cascade design of these cycles. The process design and its characteristics are captured in a flowsheet structure formulated with a non-linear programming model and solved in GAMS. The comparison of the optimal performance of the studied systems shows the better performance of the separate design, generating a total power of more than 1.6 MW, while in cascade design 11.4% less power is produced. The flexibility and adaptability of the system to different energy sources are investigated and the trade-offs associated with different system configurations are discussed.