Process Heat Research Articles

Feasibility of using nuclear microreactor process heat for bioconversion and agricultural processes

IntroductionThere is a global goal to reduce greenhouse gas emissions by 43% by 2023. Nuclear microreactors, a subset of small modular reactors, offer a potential solution due to their compact size, transportability, and carbon-neutral power generation capabilities.MethodsThis study explores the feasibility of using heat from nuclear microreactors for bioconversion and agricultural processes, including transforming biomass into energy carriers and products such as syngas, bio-oil, and pasteurized milk. Operating requirements for gasification, pyrolysis, hydrothermal carbonization, hydrothermal liquefaction, hydrothermal gasification, ethanol production, anaerobic digestion, and pasteurization were obtained through a literature review. A Brayton cycle model based on the eVinciTM microreactor was developed to assess the feasibility of powering these processes using nuclear microreactor heat.Results and DiscussionExergetic efficiency values for high-temperature processes ranged from 72% to 100%, whereas lower-temperature processes ranged from 2% to 53%. These efficiencies depend on the available source temperature for each microreactor design. There were trade-offs between producing net power and using process heat, particularly for high-temperature processes. Three heat exchanger locations were considered: before the turbine (600℃), between the turbine and regenerator (370℃), and after the regenerator (192℃). High-temperature processes like gasification require temperatures too high for feasibility. Middle temperature processes are better suited to a heat exchanger between the turbine and regenerator, while also operable before the turbine. Lower-temperature processes like pasteurization and anaerobic digestion can use waste heat after the regenerator and do not impact power production. These findings are valuable for optimizing nuclear microreactor heat use and aligning with global climate initiatives.

On the most probable energy release in structured media

The problem of energy release in hierarchically structured media that are “pieces” of matter of various sizes, contained large quantity of reacting particles, for example, molecules, is investigated. The extremes media here are single–molecular (non-clustered) gases of these substances on the one hand, and homogeneous condensed substances on the other. Under natural assumptions about the different quantity of a substance that can enter into an energy release reaction (combustion, explosion, etc.) due to their location on the surface / inside the structure, the dynamics of access to reacting molecules and the obvious probabilistic nature of the process, a combinatorial procedure is carried out to determine the most probable distribution of energy release. In some simple approximation, the energy release is determined by a single parameter of the combinatorial scheme. The most probable distribution is coincided with the distribution of the unconditionally minimum values of energy release. The result may be used for quantitative interpretation of the difference in the values of the heat of combustion, explosion and other processes under various conditions.

Preparation of Durable Polytetrafluoroethylene Superhydrophobic Surfaces by Hot Embossing Technique

ABSTRACTIn this paper, the surface microstructure of screen meshes with different mesh sizes is processed onto the polytetrafluoroethylene (PTFE) surface using a micro‐nano thermal imprinting technique. Simultaneously, silica microspheres are coated on the screen mesh. After hot embossing, these microspheres adhere to the PTFE surface, enhancing its superhydrophobicity and addressing issues such as shallow microstructure, poor abrasion resistance, and reduced hydrophobicity over prolonged use. Through several comparative experiments, the optimal processing conditions, including temperature, pressure, heating time, mesh aperture, and material thickness, were determined by measuring the contact angle and observing the microstructure. The experimental results indicate that the maximum hydrophobic angle of the PTFE surface is 154°, and the addition of silica microspheres significantly improves the superhydrophobicity and weatherability of the PTFE.

Heat transfer modeling and vacuum brazing of SiCp/ZL102 composites brazed with Al77Cu20Ti3 filler

55% SiCp/ZL102 composite was vacuum brazed utilizing Al77Cu20Ti3 filler. Shear testing was used to investigate the mechanical properties of the joints while SEM, EDS, and XRD were used to analyze the microstructure of the joints and the Al77Cu20Ti3 filler. ABAQUS software was used to examine the brazing process's heat transmission mechanism. Thermodynamics was used to describe how compounds develop at the junction. The findings indicate that the Al77Cu20Ti3 filler alloy's grain size was refined. The filler's solidus and liquidus dropped to 527.13 ℃ and 565.04 ℃, from 540.33 ℃ and 580.07 ℃, respectively. The joint's interface was dense, and its maximum shear strength of 75.38MPa was achieved when vacuum brazed at 590 °C for 30minutes. In the weld, ternary compounds of Ti, Al, and Si were mostly produced. The simulation indicated that throughout the heating process, heat was radiated to the workpiece's surface. First, SiC particles with better thermal conductivity saw a rise in temperature. Lastly, internal heat conduction kept the workpiece's total temperature constant. The base materials conducted heat to the filler, distributing the temperature differential in a circular pattern.

Study of the heat and mass transfer characteristics of the main cable dehumidification process under internal and external environments

Study of the heat and mass transfer characteristics of the main cable dehumidification process under internal and external environments

Diffusion-thermo and thermo-diffusion of gravity-driven chemical reactive magneto-Casson fluid in vertical oscillatory porous media with inclined magnetic field: Finite Element Solution

An interest in enhancing heat transfer and industrial materials performance has propelled studies of diverse viscoelastic fluids with various conditions and geometries. Thus, this research examines the combined influences of diffusion-thermo and thermo-diffusion on the flow and thermal distribution characteristics of a gravity-driven chemically reacting magneto-Casson fluid in vertical oscillatory permeable media with an inclined magnetic field effect. The Casson liquid formulation is adopted for the liquid viscous behaviour, which is essential in different engineering and industrial usages. The formulated partial derivative model for the flow velocity, thermal, and reacting species is transformed via similarity variables into an invariant model and solved computationally via the Galerkin finite element method (GFEM). The results indicate that the inclined magnetic field impacts the fluid flow and heat distribution characteristics. The Soret and Dufour influences are critical in modifying the heat and species boundary layers, particularly in chemical reactions. Hence, the study offers perceptions into augmenting non-Newtonian fluids industrial processes with heat and mass transfer for chemical reactors, polymer processing, and oil recovery. Therefore, an inclusive study clarifies the interplay complexity between different physical phenomena governing the behaviour of hydromagnetic Casson fluids in porous oscillatory media is considered for dynamical heat transfer in engineered systems.

Thermal and economic performance assessment of different high temperature heat pump layouts for upgrading district heating to process heating of steam production at 160°C

Thermal and economic performance assessment of different high temperature heat pump layouts for upgrading district heating to process heating of steam production at 160°C

Thermodynamic Analysis of the Concentration Process of Solar Radiation

Extremely rarefied but high-temperature solar radiation energy is nowadays commonly concentrated to produce a high-temperature heat source. The article is a contribution to theoretical considerations on the process of concentration of solar radiation. The process of concentration of extraterrestrial solar radiation was subjected to thermodynamic analysis and the energetic, entropic and exergetic points of view were taken into account. An imaginary model of concentration was defined, which allowed the development of thermodynamic analyses of the concentration process. In the model, concentrated solar radiation irradiates the absorbing surface, the temperature of which is controlled by the intensity of cooling. The newly revealed values of temperature (7134 K) of the Sun's surface and its energetic and exergetic emissivity (0.431 and 0426, respectively) were used in the analyses. With the use of model equations, the relationship between the ratio of radiation concentration, temperature and emissivity of the absorption surface, cooling intensity, absorbed heat, ambient temperature, and energy and exergetic efficiency of the concentration process was determined. Entropy analysis confirmed that the concentration limit temperature is equal to the temperature of the Sun's surface. Examples of energy and exergetic balances of the concentration process, illustrated by band diagrams, showed the percentage share of energy and exergy fluxes. In contrast to the energy balance showing no energy loss, the exergy balance showed a significantly large loss of exergy due to the irreversibility of the process. The components of this irreversibility have been identified, which are the absorption of solar radiation and the much lower irreversibility of the emission of the heated surface.

A downscaling framework with WRF-UCM and LES/RANS models for urban microclimate simulation strategy: Validation through both measurement and mechanism model

Microscale numerical simulation models are widely applied to explore potential factors and adaptive strategies for localized high temperatures in urban surface or near-surface environments. However, few studies address the limited availability of meteorological input data and the use of multiple meteorological outputs to investigate the mechanisms between factors as a theoretical verification for simulation. This study used the WRF-UCM model outputs in Tianjin, China, as the basic background meteorological field for microclimate simulation and compared the improvement in simulation accuracy of LES-based scheme (PALM-4U) and RANS-based software (ENVI-met) in predicting pedestrian-level air temperature and relative humidity during the downscaling simulation. Subsequently, attribution analysis of land surface temperature imbalance is performed using the two-resistance model (TRM) based on surface and atmospheric simulation outputs which also aids in verifying the applicability of the one-way downscaling simulation framework. It is found that the WRF-UCM-RANS framework exhibits superior overall performance, reducing the error in 2-m height relative humidity by approximately 50 % at the same location compared to mesoscale results. The attribution results indicate that localized high temperature on impervious surfaces within urban neighborhood are primarily driven by surface resistance (rs) during the daytime heating process and ground heat storage (G) during nighttime cooling. However, surface resistance (rs) remains the dominant driving factor influencing land surface temperature throughout both daytime and nighttime. The framework reduces the challenge of obtaining initial meteorological data and provides technical support for expanding microclimate research to multi-site simulations and future scenario predictions in complex urban environment.

Power Transfer Station for Process Heat

The challenges of integrating solar heat into industrial processes are discussed using the example of two plants. To this objective, the standardisation concept for a power transfer station developed in the Modulus project is explained using the example of the solar plant in Turnhout, Belgium. Test plans were defined for a standardised qualification during the production and installation of the power transfer station on site. The in-situ test plans were categorised according to characteristics that have a significant influence on the test procedure. In a next step, the developed test plans were transferred to the commissioning of the plant in Belgium. The findings and results of the commissioning are described in detail and possible problems that arose are analysed. Attention is then focussed on the largest solar thermal process heat plant in Seville, Spain and its design and technical features are discussed. To conclude, the results of the 2023 global market analysis for concentrating solar collectors are presented.

Thermodynamic analysis of a solar-fed heat upgrade system using the reverse air brayton cycle

This analysis focuses on exploiting solar energy to meet industrial energy needs. It is based on upgrading solar heat production using surplus electricity from renewables to generate high-temperature industrial process heat. The approach involves the use of efficient evacuated flat plate solar thermal collectors coupled with a thermal storage tank to power a reverse air Brayton heat pump for high-temperature heat production. A Matlab algorithm has been developed to dynamically analyse energy balances across the system. The analysis is conducted for the location of Komotini, Greece and the results regard the operation of a system for a typical summer week. For the baseline design point with a 1000 m2 collecting area and 50 m3 thermal tank volume, the average daily process heat production for the industry is 8.63 MWh, while the average daily coefficient of performance (COP) for the heat pump is 1.478. Moreover, the present work includes results regarding the parametric performance of the system for different combinations of collecting area and thermal tank volume. It was demonstrated that with the optimization of the solar thermal collector area and thermal tank volume, the daily average COP can be increased up to 23.1 %. Finally, the influence of the units of transfer area of the heat exchangers on the coefficient of performance has been investigated.

Correction: Hasanbeigi, A.; Zuberi, M.J.S. Electrified Process Heating in Textile Wet-Processing Industry: A Techno-Economic Analysis for China, Japan, and Taiwan. Energies 2022, 15, 8939

There was an error in the original publication [...]

Optimizing energy consumption in post-combustion CO2 capture at an NGCC power plant: a simulation-based approach

Abstract This study aims to optimize energy consumption in post-combustion carbon capture processes at a Natural Gas Combined Cycle (NGCC) power plant. It further addresses challenges associated with steam extraction from NGCC power plants and explores non-condensable steam turbines to boost process efficiency. Various scenarios are explored to minimize energy requirements by leveraging heat integration and alternative solvent compositions. The research uses simulations with commercially available software and literature-derived data to address the challenges of high energy consumption in such processes. Emphasis is placed on optimizing solvent composition and implementing advanced heat optimization strategies to reduce energy consumption. Four scenarios with different solvent compositions are investigated, utilizing Monoethanolamine and aqueous piperazine. The results show that process parameter optimization and heat optimization strategies can result in significant energy savings. To attain a carbon-neutral energy landscape, this research helps develop more sustainable and effective carbon capture methods.

Novel highly performing tandem selective solar absorber for industrial heat applications

The needed decarbonisation of the industrial sector for an efficient transition to a Net Zero future, alongside the lack of commercially competitive solar absorbers for industrial heat applications using small non-evacuated receiver tubes, has motivated the design of a new highly stable material suitable for the open-air conditions. This work demonstrates that the potential candidate is the CuCoMnOx/SiO2 tandem selective absorber, designed to coat line-focussed receiver tubes to supply thermal energy up to 450 °C for industrial process heat applications. Remarkably, with only two layers deposited on stainless-steel (SS) under optimised conditions, the material exhibits excellent optical performance, achieving a αs > 0.95 and a ε350°C = 0.16. The absorber design prioritises cost-effective industrialisation by optimising thermal treatment to lower both temperature and duration time, while fine-tuning layer thicknesses to locate optical interferences at the required wavelengths. This approach ensures outstanding reproducibility, uniformity, and efficiency, marking the first successful deposition of coatings on tubular forms. The coatings composing the absorber are characterised optically, by X-ray diffraction, scanning electron microscope, and thermogravimetric and differential scanning calorimeter techniques. In terms of durability, the absorber shows extraordinary resilience, maintaining thermal stability for 27 months at 400–450 °C in open air, and exhibiting good resistance to condensation (PC = 0.03 in the most drastic situation). Therefore, the SS-substrate/CuCoMnOx/SiO2 absorber emerges as a promising commercial material for both evacuated and non-evacuated receiver tubes, promoting the integration of concentrating solar power (CSP) technology with solar heat for industrial processes (SHIP).

Comprehensive study on statistical methods for optimization of process parameters and material properties of AlSi10Mg in laser powder bed fusion

This study provides a systematic investigation of the effects of process parameters and heat treatments on the material properties of AlSi10Mg, produced by laser powder bed fusion (L-PBF). Using a central composite design (CCD) with 106 test specimens (49 cubes, 57 tensile), the samples were studied for key properties: density (up to 99.96%), hardness (up to 154.6 HV1), surface roughness (as low as 1.9 Ra), tensile strength (up to 487.5 MPa), and elongation at break (up to 16.6%). Statistical analysis (ANOVA) identified laser power and scanning speed as the most influential parameters on these properties. Additionally, heat treatment was shown to reduce hardness and tensile strength but increase elongation at break, demonstrating the ability to modify mechanical properties based on the desired outcome. Process parameter optimization yielded properties comparable to some of the highest reported values for AlSi10Mg in the literature. The study also discusses the transferability and reproducibility of L-PBF results across different machines, highlighting challenges related to machine-to-machine variations, lack of calibration and standardization and parameter consistency. The results demonstrate the potential of L-PBF to produce AlSi10Mg parts with tailored properties for industrial applications.

Inactivation of foodborne pathogens on fruit juice with different solid contents by using pilot-scale 915 MHz microwave heating system

Fruit juices are often distributed in the form of concentrate for the sake of quality conservation and cost-reduction during distribution. The objective of this study is to investigate the effect of solid content on heating rate, dielectric properties, and foodborne pathogen inactivation in fruit juices when subjected to 915 MHz microwave heating. 50 mL of fruit juice with different solid contents were exposed to 915 MHz microwave at 3.0 kW for up to 60 s. Solid content was found to be an important factor for heating rate. The fastest heating rate was observed when concentrates were diluted by 50% (36 ° Brix apple and 30 °Brix orange juice). Though dielectric constant decreased along with increase in solid contents, different trends were observed for the dielectric loss factor. Especially, the fruit juices with higher magnitudes of the dielectric loss factor presented faster heating rate. Inactivation of the pathogens inoculated in the fruit juices was investigated by using E.coli O157:H7 and L.monocytogenes. In case of apple juice, 915 MHz microwave heating was most effective for 72 °Brix as 20 s operation resulted in over 5-log reduction for both pathogens. However, in orange juice, 30 °Brix was found to be most effective for 915 MHz microwave heating. In the inactivation mechanism analysis, cell membrane damage was observed when cells were exposed to higher solid contents due to low water activity. 915 MHz microwave heating did not include significant quality changes in terms color and total phenolic contents, except for 60 ° Brix of orange juice. The obtained results highlight the potential application of 915 MHz microwave heating for fruit juice processing

Preparation and Performance Study of Thermally Conductive Silicone Adhesive Applying in Flip Chip Ball Grid Array

A thermally conductive silicone adhesive UB-5715 was prepared using vinyl silicone oil of medium viscosity, hydrogen-containing silicone oil and micron alumina powder. The results revealed that UB-5715 demonstrated superior thermal and mechanical properties. Specifically, its thermal decomposition temperature exceeded 400 °C, the thermal conductivity coefficient surpassed 1.80 W/m·K, the thermal resistance was under 12.0 °C·cm2/W, the shear strength reached achieved was over 5.00 MPa. Meanwhile, after being subjected to uHAST for 384 hours, thermal cycle for 1000 times and heat aging for 1000 hours respectively, UB-5715 still maintained its high thermal conductivity coefficient and mechanical properties. The thermal conductivity coefficient still exceeded 1.70 W/m·K, shear strength still surpassed 5.00 MPa, the tensile modulus remained below 100 MPa, the linear expansion coefficient was less than 160 ppm/°C, and its comprehensive performance met the reliability requirements for advanced packaging process substrates and heat dissipation cover assemblies.

Multiphysics fields simulation of photothermal catalytic degradation of R134a in a flat plate reactor

Photothermal catalytic degradation is an environment-friendly way to dispose high-global-warming-potential hydrofluorocarbon refrigerants (HFCs). There are challenges in understanding the heat and mass transfer mechanism of this multi-physicochemical process. This study focuses on photothermal catalytic degradation of R134a, one of the hydrofluorocarbon refrigerant, in a flat plate reactor. A numerical model was developed to couple laminar flow, conjugate heat transfer, dilute species transport, surface radiation and chemical reaction. Meanwhile, experiments were conducted to measure the R134a degradation across various temperatures. The parameters of thermal boundary conditions and the kinetics were calibrated by combining the experimental data and the numerical model. The preexponential factor of 0.1146 m/s and activation energy of 21129.1 J/mol were yielded, achieving less than 10 % relative error of the R134a concentration. The average degradation rate was intensified by around one magnitude from 100 °C to 400 °C. Across various temperatures, molecular diffusion always dominated the mass transport process. However, the governing mechanism limiting the photothermal catalytic process was the degradation kinetics, as evidenced by the uniform concentration distribution and the Damköehler number significantly below 1. Several methods were also proposed to enhance the photothermal catalytic degradation rate.

Electrification of Heating—Requirements for Successful Wide‐Scale Deployment

ABSTRACTElectrification is potentially the most efficient method of decarbonization of space, water, and in certain instances, process heating through the deployment of electrically driven heat pumps. However, challenges are noted in terms of electricity network capacity that ultimately must influence a holistic approach to building/process heating demand reductions which in turn must influence heat pump development, heat pump operations, heat pump capital cost, and the role of thermal storage. Approaches to these challenges are presented from a global and, a UK and Ireland perspective, as for the UK and Ireland, it is often muted that the electricity network is less well suited to addressing the electrification of heating. Thus, this work will consider the likely cost‐effective heat demand reductions in buildings and processes, how might heat pumps operate in future electricity markets and systems, how can we make heat pumps cheaper to purchase and cheaper to operate and what is the role and type of energy storage in terms of demand side management. Thermal energy storage will be considered for space heating (30°C–80°C), water heating (60°C+ to negate legionella), and lower temperature industrial process (up to e.g., 300°C). Furthermore, an analysis of a UK housing development is presented as a retrofit case study for social housing, illustrating the impacts of the electricity network, and approaches that can be taken, for example, thermal storage, to minimize such impacts. Higher temperature systems will be considered for process applications.

Fabrication of 17-4PH stainless steel by metal material extrusion: Effects of process parameters and heat treatment on physical properties

Fabrication of 17-4PH stainless steel by metal material extrusion: Effects of process parameters and heat treatment on physical properties