Absorption Heat Research Articles

Dipodal silane‐treated ramie woven matt reinforced polylactic acid biocomposites for improved mechanical and thermal properties

AbstractHot compression molding was used to produce biocomposites from ramie plain‐woven fabric‐reinforced polylactic acid (PLA). Prior to composite fabrication, alkali and dipodal silane (bis(3‐trimethoxysilylpropyl) amine) (BAS) were applied to improve fiber‐matrix adhesion. Mechanical tests revealed improvements in tensile and flexural strength due to interfacial adhesion. The flexural strength of ramie PLA composite samples treated only with silane (SR‐PLA) was the highest, at 136.35 MPa. Young's modulus was 7.51 GPa. BAS treatment was crucial for ensuring strong adhesion between the fabric and the PLA matrix. In combined alkali‐BAS‐treated composites (ASR‐PLA), the glass transition and crystallization temperatures disappeared completely, affecting PLA morphology. The maximum heat of absorption (373°C) was found in SR‐PLA composites, suggesting electrostatic interactions created a three‐dimensional network. In conclusion, the initial incorporation of dipodal silane resulted in the formation of six silanol linkages with ramie fabric, leading to enhancements in the mechanical and thermal characteristics of ramie–PLA composites.Highlights Alkali and BAS treated Fabrics ironed to remove treatment‐induced wrinkles. Carded PLA fiber with consistent density and weighted in four equal portions. Fabric and PLA lay alternatively in warp direction before compression molding. SR‐PLA composites exhibited improved thermal and mechanical properties.

Utilizing metal-organic framework porosity for efficient antibiotic separation and sustained release

Metal-organic frameworks (MOFs) have emerged as a revolutionary class of nanoporous materials due to their highly tunable porosity and functionality. With the vast number of MOFs being discovered, traditional experimental techniques to identify the best candidates for various applications, including water treatment and drug delivery become time-consuming and expensive. This is where computational screening offers a powerful solution. We present a computational screening strategy using Monte Carlo (MC) simulation to identify the promising MOFs among over 14,000 MOFs for efficient absorption, membrane separation, and sustained delivery of antibiotics (e.g., azithromycin, AZ). The MC simulation was used to calculate the loading capacity and isosteric heat of the AZ absorption. These absorption properties were correlated with several structural characteristics of the MOF, including the largest cavity diameter, pore limiting diameter, accessible volume, helium void fraction, etc. Critical evaluation of the correlation results identified the best MOFs for AZ absorption, separation, and delivery. The results recommended a total of 578 MOFs, with 126 identified as suitable for use as AZ adsorbents or drug carriers, and 452 for use as membranes to separate AZ from water. Furthermore, the adsorption mechanism of the top MOF was analyzed using molecular dynamics simulation and non-covalent interactions. The solvation-free energy of AZ was evaluated in various solvents to identify the most effective solvent for extracting AZ from MOFs, thereby facilitating the regeneration of the MOF.

Photothermal Induced Dual-Interface: Accelerating Sustainable Hydrogen Evolution from Formic Acid.

Formic acid (FA), a liquid hydrogen storage carrier, can release hydrogen via photothermal catalysis, providing a clean and sustainable solution toward a carbon-neutral energy cycle. Despite recent advances in the design of efficient catalysts, the development of advanced systems with high H2 yield, stability, and durability remains challenging due to the inefficient photothermal conversion and mass transfer in the traditional liquid-solid bulk system, as well as the trade-off between hydrogen storage density and dehydrogenation rate. Here, we address these challenges by creating a photothermal-induced dual-interface characterized by high spectral absorption and low heat loss, a facile supply of FA, and vaporization of FA to minimize the energy barrier of the reaction. As a result, a record hydrogen evolution rate (200.9 mmol g-1 h-1) is achieved in a high concentration (26 M) of FA, which is about 15 times higher than the liquid-solid bulk system. In addition, it can be operated continuously for more than 192 h without additive addition and energy consumption, providing a strategy for accelerating interfacial mass transfer to improve catalytic activity, and also presents a reference for sustainable hydrogen production.

New insights into the functional group influence on CO2 absorption heat and CO2 equilibrium solubility by piperazine derivatives

Piperazine(PZ) derivatives which have been widely used in CO2 capture technology exhibit stable physicochemical properties, such as resistance to thermal degradation and low regeneration energy consumption. Both two parameters of CO2 absorbents, low CO2 absorption heat(ΔHabs) and large CO2 equilibrium solubility(αe), are important to CO2 capture performance. However, the influence of functional group types of PZ derivatives on their CO2 capture performance remained unclear. This research aimed to study the functional group influence on the ΔHabs and αe by PZ derivatives with two amines using experimental and quantum chemical methods. The results indicated that PZ derivatives with the ethyl side chain had larger ΔHabs and αe than those with the methyl side chain. The presence of the hydroxy group in PZ derivatives reduced the ΔHabs and the αe. The presence of cyclic methyl side chains on the N atom of PZ derivatives decreased the ΔHabs and increased αe at the same time. The findings show that PZ derivatives with cyclic methyl side chains, steric hindrance effect, and no hydroxy group are favorable for CO2 capture. Among the eight PZ derivatives, TEDA with lower ΔHabs(48.99 kJ/mol) and higher αe(0.917 mol CO2/mol amine) is an excellent absorbent. The results of this study are very important for screening efficient and low-energy consumption absorbents for CO2 capture.

Scaling of HeatLMD-simulated impurity outflux from COMPASS-U liquid metal divertor

Abstract The Liquid Metal Divertor (LMD) concept offers a promising solution to manage extreme heat loads in plasma devices. This study presents predictive simulations using the HeatLMD model for the COMPASS-U tokamak with a full toroidal liquid metal divertor, expected to achieve reactor-relevant divertor heat flux densities. We derive the scaling of the Li|Sn outflux over 7 assumed independent parameters, transferable to other tokamaks. Its transport to LCFS (via ERO2.0) and its radiation (via Aurora and FACIT) predict acceptably low lithium concentration and negligible plasma cooling. However, for tin, the medium power scenario requires backside cooling beyond the capability of ITER-like water-cooled divertor, though a temporary heat absorber can approximate this for a 1-second plasma pulse. For incident divertor power exceeding 2 MW and strike point Te<10 eV, HeatLMD predicts significant tin plasma radiative disruption.

Research on performance and potential of distributed heating system for peak shaving with multi-energy resource

Climate change and its negative effects are driving the global shift from fossil fuels to renewable energy sources. To tackle the dependency on traditional energy sources in harsh winter regions and improve heating quality during periods of thermal demand fluctuations, this paper proposes a new distributed heating peak shaving system (DHPS). The system combines municipal heat and clean energy within the secondary network while reducing the return water temperature in the primary network. It comprises solar collectors, electric thermal storage tanks (ETST), and absorption heat pump (AHP) units, integrated into conventional heat exchange stations. The system operates in two modes to manage peak and off-peak loads respectively, with TRNSYS simulation used to evaluate performance across a range of peak-shaving gradients. A multidimensional comprehensive assessment is conducted between the DHPS under optimal peak shaving coefficient (θ) conditions and conventional peak clipping boiler (PCB). Results indicate that DHPS achieves a high primary energy ratio (PER) of 1.251 at θ = 0.5, reducing combustion emissions by nearly 40%. The static payback period (PBP) of the system is 3.5 years. When the electricity price drops to 0.275 CNY, its operational costs are comparable to PCB. DHPS caters to the energy characteristics of cold regions where electricity supply exceeds demand. It enables flexible peak shaving while ensuring the complete utilization of clean energy and effectively utilizing waste heat from power plants.

Performance simulation of solar-driven absorption heat pump-membrane distillation system for combined desalination brine concentration with feed recirculation and cooling applications

Desalination is the primary choice for securing freshwater provision in water-stressed regions and reduces the gap between rising demand and dwindling natural freshwater resources. However, global desalination plants are dominated by fossil fuel-driven desalination technologies with a 40–50 % recovery ratio. Hence, it is critical to decarbonize desalination and address brine effluent ecological concerns. In this paper, a solar-powered absorption heat pump (AHP)-membrane distillation (MD) system concept was proposed and analysed for small-scale RO plant brine reject management and space cooling applications. The MD subsystem is based on commercial MD modules with batch feed recirculation to reach saturation (from 70 to 260 g/kg salinity). The MD system's heating and cooling consumptions are supplied by the AHP (6.54 MWh and 13.47 MWh, respectively, for a complete batch cycle). The AHP is designed to supply hot water at 85 °C with 701.63 kW heating capacity and co-produced chilled water at 16 °C with a cooling capacity of 857.86 kW, about 67 % is utilized to cool down the brine reject to feed temperature. The thermal and exergy COPs were 1.273 and 0.40 at a driving heat of 135 °C. The solar-powered AHP-MD system is useful for sustainable desalination deployment besides space cooling applications.

Potential for Utilizing Organic Waste as a Heat-Insulating Composite

The ever-increasing global population growth has a direct impact on residential building demand, which often does not keep pace with construction growth. This condition leads to an increase in housing density and a decrease in construction quality, which contributes to excessive heat inside homes. Therefore, this research explores the use of organic waste, specifically reeds and young coconut fiber, as environmentally friendly thermal materials to reduce dependence on artificial energy and its negative impacts. The high cellulose content in reeds and the fiber in young coconut fiber is a combination that has the potential to create an effective heat absorber. Product composition material testing was carried out using a thermogun, and the results were analyzed using the one-way Analysis of Variance (ANOVA) method. This research aims to utilize the potential of organic waste to produce insulation that can reduce heat temperatures in buildings, with the hope of finding alternative materials that are more sustainable and environmentally friendly.

Effect of Heatsink Material on the Efficiency of Solar Panel-Thermoelectric Hybrid Devices

Solar panels exposed to solar radiation will produce heat, affecting their efficiency. A solution to this problem is integrating solar panels with thermoelectric generators that can convert thermal energy into electrical energy. In general, thermoelectric generators are equipped with heatsinks as heat absorbers. Many studies only look at the addition of heatsinks without examining the effect of the type of heatsink material used. Based on this background, this study identifies the effect of heatsink materials on the efficiency produced by solar panel thermoelectric devices. The purpose of this study is to determine which heatsink material can produce high efficiency in solar panel-thermoelectric devices. This research is useful for improving the efficiency of solar-thermoelectric hybrid devices. The novelty of this study is the selection of various heatsink materials that are directly tested against the efficiency of hybrid devices. The heatsink materials tested in this study were aluminum and copper. The equipment was tested by measuring the current and voltage generated by the solar panel-thermoelectric using a multimeter which was then used to calculate its power. The results showed that the hybrid solar panel-thermoelectric device with a heatsink made of copper produced a higher output power of 1.882 mW compared to aluminum material which was only 0.513 mW.

Enhanced characteristic equation method for single-stage absorption heat pumps

The method of characteristic equations aims to describe the part-load behavior of sorption heat pumps and chillers as well as heat transformers as simply as possible but yet still accurately. Based on an approach by T. Furukawa for heat transformers, the method was further developed by F. Ziegler and others for absorption heat pumps and generalized for application in multistage processes. Clever simplifications were made, to represent the cooling capacity Q˙E of absorption chillers with a characteristic temperature difference ΔΔt as a simple linear equation Q˙E=sE·(ΔΔt−ΔΔtmin,E). In ΔΔt, the average hot, cooling, and chilled water temperatures are combined, and the slope and loss parameters, sE and ΔΔtmin,E are constant. However, in practical applications of this established method, inconsistencies arise. For example, the calculated slope parameter sE does not match the slope when plotting simulated or measured cooling capacities against ΔΔt. Furthermore, the loss parameter ΔΔtmin,E is actually not constant.In this work a more precise formulation of the characteristic equation is derived which takes into account that the solution entering the absorber and desorber is generally superheated or subcooled. By means of a domain-wise heat transfer calculation, these effects can be implemented into the method and explain the above mentioned inconsistencies. The new formulation allows for explicit consideration of different heat exchanger designs and cooling water configurations. No iterations or regression analyses are required. Thus, the calculation method can be easily implemented into industrial controllers e.g. for the model predictive control of absorption chillers and heat pumps.

Study on the Performance of a Novel Double-Section Full-Open Absorption Heat Pump for Flue Gas Waste Heat Recovery

Open absorption heat pumps are considered one of the most promising methods for efficiently utilizing low-grade waste heat, reducing energy consumption, and lowering greenhouse gas emissions. However, traditional heat pumps have significant limitations in the range of flue gas temperatures they can recover, and their relatively low system performance further restricts practical applications. In this study, we propose a novel double-section full-open absorption heat pump driven by flue gas from the desulfurization tower. By designing the absorber with a double-layer structure, the system can recover more latent and sensible heat from the flue gas, significantly enhancing its thermal recovery capability. Additionally, replacing the traditional LiBr/H2O working pair with LiCl/H2O significantly reduces the risks of solution crystallization and equipment corrosion. Through comprehensive research, the strengths and weaknesses of the system were explored. The results indicate that this system effectively recovers flue gas waste heat within the temperature range of 30–70 °C. Specifically, at a flue gas temperature of 70 °C and a flow rate of 3 kg/s, the system achieves a COP of 1.838, along with a heating capacity of 158.83 kW and a ROI of 34.1%. These metrics demonstrate that the system not only delivers high performance but also exhibits excellent economic viability. Additionally, when the solution temperature is lowered to 10 °C, the system’s maximum COP reaches 1.96, reflecting a significant 30.67% improvement over traditional heat pumps. These findings highlight the system’s potential for application in coal-fired power plants, where varying levels of power output can benefit from enhanced thermal recovery and efficiency.

Scenario-based stochastic optimization on the variability of solar and wind for component sizing of integrated energy systems

The inherent intermittency and variability of renewable energy sources present significant challenges to the optimal design and implementation of integrated energy systems (IES). This paper introduces a novel stochastic optimization model that integrates advanced scenario generation and clustering algorithm for renewable energy sources within a multi-objective, bi-level optimization framework. Specifically, the clearness index is employed to represent the stochastic distribution of solar radiation intensity by beta distribution, while wind speed uncertainty is modeled seasonally using the Weibull distribution. Monte Carlo sampling with synchronous back substitution is applied for scenario generation and reduction of solar radiation and wind speed. To address the multi-objective evaluation, the analytic hierarchy process is utilized, and the joint optimization is achieved by combining a region contraction algorithm with stochastic programming. The proposed methodology is validated on an IES featuring various heating devices, incorporating uncertainties in both wind and solar energy. The results indicate that the absorption heat pump-based scheme achieves superior energy-saving performance, achieving an energy rate of 0.4724. Additionally, the compression heat pump-based scheme exhibits excellent economic efficiency and environmental sustainability, with a cost of energy of 0.3639 and a renewable fraction of 0.5536.

Self-exothermic reaction behavior and pore structures of Ni-Al intermetallics with more than 70% porosity

Abstract In this study, high-porosity Ni-Al alloys with complete shape and controllable pore structures were prepared by combining the self-exothermic reaction with the space holder method. The observations show that porous Ni-Al sintered discs appeared to melt and deform after a violent reaction without adding space holder particles. The link between the volume content of urea particles and macroscopic morphology, combustion behavior, phase composition and pore structures of porous Ni-Al compounds were studied. The space holder pores acts as a heat absorber, greatly increasing the open porosity to 76.0% when adding 50 vol% urea particles. This leachable space holder method can be an effective strategy to regulate the sample shape and pore characteristics of porous Al-containing intermetallics.

A mass-coupled hybrid absorption-compression heat pump with output temperature of 200 °C

Heat pump technology is a promising solution for energy saving and emission reduction in industry. However, current technologies with limited temperature lift are not sufficient to meet the industrial heat demands. Aiming at efficient heat supply over 200 °C, this work proposes a hybrid absorption-compression heat pump cycle with mass coupling between LiBr-water type II absorption heat pump and water vapor compression heat pump, which could reduce the working pressure of compressor. Water injection is applied in the compressor for performance improvement. Detailed performance analysis is carried out for the hybrid heat pump cycle, showing an optimized COP of 3.01 under the temperature lift from 150 °C to 200 °C. Besides, the proposed system is capable of achieving temperature lift of 50 °C for heat source between 100 °C and 164 °C. Greater application superiority occurs at higher temperature output. The proposed cycle broadens the working domain of heat pump.

Carbon nanotube heat absorber for efficient direct-heating of liquid tin in a solar receiver

A new approach that use vertically-aligned carbon nanotubes (VACNT) as heat absorbers is proposed for efficient direct solar heating of liquid tin in a solar receiver integrated with beam-down optics. Plate-type CNT heat absorbers were prepared by adjusting the concentration of CNTs in the processing solvent m-cresol. The prepared CNT absorber exhibited an increase in bulk density and the formation of a densely packed nanotubes skeleton with a higher CNT concentration in m-cresol. Thermal conductivity, a key design factor for solar absorbers, showed a stronger correlation with skeletal density than with bulk density. Heat absorption characteristics of the solar liquid tin receiver (50 mm-i.d., 60 mm-high) with the CNT absorbers integrated with a Fresnel lens (0.98 m i.d.) were determined. The tin temperature in the receiver with the CNT absorber reached a maximum of 728 °C. Bare tin exhibited system efficiency of 27.7 % and receiver efficiency of 38.3 %, but tin heating through the CNT plates exhibited system efficiency of up to 48.4 % and receiver efficiency of 64.3 %, showing a system heat absorption rate 1.75 times higher. The thermal absorption efficiency was proportional to the skeletal density of the plates, and the thermal absorption of the system was dominated by the efficient transfer of absorbed heat in the energy absorption region. The energy flow and heat loss in the receiver system were analyzed. Although the bare tin receiver exhibited a high heat loss of 27.1 % owing to the low emissivity or high reflectivity of the tin surface, the heat loss in the CNT absorber plates with high absorptivity was only 0.9 %. The flat plate-shaped transmission window in the receiver caused significant reflective heat loss and convective heat loss owing to head-on wind. Based on the energy flow analysis, improvement approaches for enhancing the thermal efficiency of the proposed receiver system are suggested.

Heating Induced Nanoparticle Migration and Enhanced Delivery in Tumor Treatment Using Nanotechnology.

Nanoparticles have been developed as imaging contrast agents, heat absorbers to confine energy into targeted tumors, and drug carriers in advanced cancer treatment. It is crucial to achieve a minimal concentration of drug-carrying nanostructures or to induce an optimized nanoparticle distribution in tumors. This review is focused on understanding how local or whole-body heating alters transport properties in tumors, therefore leading to enhanced nanoparticle delivery or optimized nanoparticle distributions in tumors. First, an overview of cancer treatment and the development of nanotechnology in cancer therapy is introduced. Second, the importance of particle distribution in one of the hyperthermia approaches using nanoparticles in damaging tumors is discussed. How intensive heating during nanoparticle hyperthermia alters interstitial space structure to induce nanoparticle migration in tumors is evaluated. The next section reviews major obstacles in the systemic delivery of therapeutic agents to targeted tumors due to unique features of tumor microenvironments. Experimental observations on how mild local or whole-body heating boosts systemic nanoparticle delivery to tumors are presented, and possible physiological mechanisms are explored. The end of this review provides the current challenges facing clinicians and researchers in designing effective and safe heating strategies to maximize the delivery of therapeutic agents to tumors.

Synthesis of Ti3C2Tx MXene@Carbon-Enhanced cellulose fiber composite-based photothermal absorber for sustainable water desalination

Desalination is a process that extracts salt and minerals from seawater to produce fresh water. It is critical, particularly for those who live on islands or coastal areas. Solar thermal desalination harnesses solar energy to address some of the challenges of traditional desalination methods. It uses solar power to heat seawater directly, initiating evaporation and leaving the salt behind, and further the vapor is condensed to produce fresh water. This method reduces reliance on fossil fuels, minimizing environmental impact and energy costs. This research unveils the synthesis of a solar evaporator consisting of Ti3C2Tx MXene coated over the carbon-enhanced cellulose fibers (CCF) (hereby termed the Ti3C2Tx MXene@CCF composite), which is the first-time report in the field of solar water desalination in using sustainable solar heat absorber. The Ti3C2Tx MXene@CCF composite achieves an impressive evaporation rate of 3.8 kg m−2 h−1 under 1 sun exposure. The hydrophilic Ti3C2Tx MXene coating on the porous CCF promotes rapid water evaporation. Ti3C2Tx MXene@CCF composite maximizes evaporation rates while maintaining water purity, which is in accordance with the World Health OrganizationFF (WHO) standards.

Numerical simulation of electrically-pumped overgrown III-V microwire lasers on silicon

Electrically-pumped III-V lasers on Si by aspect ratio trapping (ART) techniques have been a promising candidate for Si-based light sources. Although the lasers based on the ART approach enable large-scale integration and are compatible with complementary metal-oxide semiconductor processes, the sub-micron size laser structure suffers from severe metal absorption loss and heat accumulation. In this paper, we propose a novel Si-based III-V multi-quantum well laser by ART methods. The overgrowth of III-V microwires is adopted, with additional {110} quantum wells (QWs) generated during epitaxy. Through numerical simulation, the mode loss of the overgrowth structure is reduced from 3.59 dB/cm to 0.96 dB/cm, the threshold current is decreased by 42.5% and the output power is increased by 91.7% under pulsed conditions. Due to the growth of QWs on {110} planes, the injection efficiency of the device increases, leading to an improvement of performance. The effects of temperature and cavity length on the lasing characteristics of the device under continuous wave (CW) conditions are also analyzed that the proposed structure can realize CW lasing at room temperature. Moreover, the device deterioration caused by growth defects is discussed, which can be improved by high reflection coating. The suggested Si-based overgrowth III-V microwire laser has great potential to integrate high-density electrically-pumped light sources for silicon photonics.

Optimized energy efficient reactive distillation for octane upgrading with economic and environmental considerations

Advancing fuel efficiency and production technologies can significantly reduce “Well to Wheels” and “Octane on Demand” emissions. This has been accomplished by integrating intensified technologies in fuel refineries. However, maintaining low energy consumption and high octane number while considering the impact of operating conditions under uncertainty on the process feasibility remains a challenge. Therefore, this article proposes a novel absorption heat pump reactive distillation (AHPRD). Aiming to maximize the economic potential of the AHPRD, an optimization framework that considers operating conditions under uncertainty (i.e. temperature (T), pressure (P), reflux ratio (RR), and feed stage (FS)) is developed. The optimization framework synchronizes Monte Carlo simulation and particle swarm optimization (PSO) to maximize the net present value (NPV). The framework used a hybrid Python-DWSim interface platform. The AHPRD was further investigated and compared against existing processes, namely, a conventional process refinery (CP) and reactive distillation (RD), to improve energy saving, increase financial return, and cut CO2 emissions. Attractively, the AHPRD outperforms existing processes, both economically and environmentally, doubling profit values and avoiding 52.2% − 77.4% of CO2 emissions. This study believes that the future direction will be to build an artificial intelligence model for process optimization and economic prediction.

Investigating the effect of absorbent material and heat flux in natural gas sweetening process using molecular dynamics simulation

This study investigated the efficiency of various absorbents in the gas-sweetening process for removing corrosive acidic gases, specifically hydrogen sulfide (H₂S) and carbon dioxide (CO₂), from natural gas. The study used molecular dynamics simulations to investigate how well MEA, DEA, MDEA, and PC work as absorbents in various heat flux (HF) situations. The simulations demonstrated that all absorbents reached equilibrium within 10 ns, with potential and total energies stabilizing at 10.45 and 11.50 kcal/mol, respectively. The absorption efficiencies were 88.28 % for MEA, 81.06 % for DEA, 73.25 % for MDEA, and 64.11 % for PC, highlighting MEA as the most effective and PC as the least. MEA had an interaction energy of −131.58 kcal/mol, DEA had an interaction energy of −115.63 kcal/mol, MDEA had an interaction energy of −121.38 kcal/mol, and PC had an interaction energy of −73.09 kcal/mol. Increasing the external HF from 0.001 to 0.005 W/m2 enhanced the absorption rate of H₂S and CO₂ from 89.26 % to 95.18 % and increased interaction energy from −146.31 to −159.38 kcal/mol. These findings provided insights into optimizing gas-sweetening processes and selecting effective absorbents.