Evaporation Temperature Research Articles

Fabrication and evaluation of stable amorphous polymer-drug composite particles via a nozzle-free ultrasonic nebulizer

We present a promising method for producing amorphous drug particles using a nozzle-free ultrasonic nebulizer with polymers, specifically polyvinylpyrrolidone (PVP), poly(acrylic acid) (PAA), and Eudragit® S 100 (EUD). Model crystalline phase drugs–Empagliflozin, Furosemide, and Ilaprazole–are selected. This technique efficiently produces spherical polymer-drug composite particles and demonstrates enhanced stability against humidity and thermal conditions, compared to the drug-only amorphous particles. The composite particles exhibit improved water dissolution compared to the original crystalline drugs, indicating potential bioavailability enhancements. While there are challenges, including the need for continuous water supply for ultrasonic component cooling, dependency on the solubility of polymers and drugs in volatile organic solvents, and mildly elevated temperatures for solvent evaporation, our method offers significant advantages over traditional approaches. It provides a straightforward, flexible process adaptable to various drug-polymer combinations and consistently yields spherical amorphous solid dispersion (ASD) particles with a narrow size distribution. These attributes make our method a valuable advancement in pharmaceutical drug formulation and delivery.

Optimizing electricity generation through the utilization of wasted heat from process streams in a LURGI methanol plant

In the realm of petrochemical operations, persistent efforts have been made to curtail specific energy consumption; however, certain heat sources continue to be underutilized. This paper investigates the condition of a Lurgi methanol plant to identify process streams with enough wasted heat that have the potential to produce electricity. After a thorough analysis, one particular zone is identified where an air cooler package and seawater exchanger are used to decrease the temperature of crude methanol vapor. To harness this untapped heat for electricity generation, an organic Rankine cycle (ORC) is proposed. In the quest for efficient electricity production, three distinct working fluids-dry (R600a), wet (R134a), and isentropic (R11)- are scrutinized to compare their performance in generating electricity within the ORC system. In addition, the maximum amount of electricity that can be generated from this waste heat recovery (WHR) project is determined and optimized using a multi-objective optimization method. By leveraging genetic algorithms, the system's exergy is enhanced while minimizing costs. A comprehensive economic comparison is conducted using probability analysis to evaluate each system's financial viability. The results show that dry and isentropic working fluids yield the best results for electricity production, generating approximately 9–10 MW. The return on investment (ROI) for these working fluids is also nearly similar, at 16 %. Among the chosen working fluids, R600a is selected as the superior option due to its lower outlet temperature for crude methanol. Additionally, because the cooling water flow for the condenser of the ORC is identified as a limitation in the current petrochemical plant, a new optimization is conducted with a constraint on the flow of cooling water, aiming for approximately 3000 tons/h. The results show that the proposed WHR-ORC system can generate a maximum of approximately 7.5 MW net electricity in the studied petrochemical plant, while also reducing CO2 emissions by up to 40,000 tons per year. The innovative methodology showcased in this research underscores its economic viability, paving the way for heightened energy efficiency and environmentally conscious methanol production practices.

Zero-dimensional analysis of the effect of water vapor on reducing electrons in the plasma sheath

In this study, an air-water vapor ionization reaction model is developed within the quantum-kinetic (Q–K) model of the direct simulation Monte Carlo method to investigate the detailed mechanism of how water vapor reduces electrons. The zero-dimensional simulations of a typical non-equilibrium flow field downstream of a normal shock are designed, where the electron number density decreases by two orders of magnitude due to water vapor. We conclude that the introduction of water vapor reduces the mole fractions of oxygen atoms and nitrogen atoms through five pairs of reactions and enhances the reverse nitric oxide associative ionization reaction, leading to electron consumption. The phenomena and corresponding mechanisms under varying mole fractions of water vapor, air temperatures, and water vapor temperatures are investigated. Based on the mechanisms, we propose that the addition of hydrogen ions could improve the water's mitigation effect, which is then proven to be able to reduce the electron number density by another two orders of magnitude, not only at high air temperatures but also at lower air temperatures or lower mass injection rates.

Giant Seebeck coefficient in SnTe thin films grown by thermal evaporation using layered structure engineering

In this work, we have reported a giant Seebeck coefficient (8033 µV/K) in SnTe thin films by controlling the layered structure using post growth annealing technique. The samples used in the current study were synthesized using a vacuum tube furnace having an evaporation temperature 700 °C, base pressure 180 m Torr and source to substrate distance 7 cm. Sn and Te metal powders with an equal weight ratio were evaporated on the glass substrate to form SnTe composite. Post-growth annealing in vacuum environment was performed for different time’s duration of 1–4 h with a step of one hour. XRD analysis reveals six diffraction peaks for all samples, which correspond to different crystal planes of SnTe structure. Raman spectra exhibit the presence of specific vibrational modes associated with SnTe. Using the giant value of Seebeck coefficient and moderate electrical conductivity, a strong power factor value of 8.1 × 10−3 W m−1 K−2 was observed for optimized sample (annealed for 3 h). The strongest values of Seebeck coefficient and power factor are supposed to be the layered structure of SnTe thin films which was verified by the SEM images.

Comparative analysis of water cooler for different working fluids: Energy and exergy approach

Enhancing the performance of traditional vapor compression cooling cycles is an important aspect in the quest to minimize global energy consumption, to own sustainable energy systems soon, and to preserve the environment. This study performed a comparative analysis of the performance of a water cooler with different working fluids to replace R143a and improve system performance. A mathematical model derived from energy and exergy analysis is developed for the evaluation of the effect of operating conditions on the system COP, exergetic losses, and exergetic efficiency. The evaluation has been conducted for evaporation and condensation temperatures ranging between -30°C to 15°C and 25°C to 55°C, respectively. Results showed that the cycle with R510A has the maximum COP. The average system COP with R510A, RE170, and R152a are 19.54%, 13.53%, and 9.36 % higher than that with R134a, respectively. The highest value of exergy loss takes place in the compressor. At different working fluids, exergy losses decrease as evaporation temperatures increase and condensation temperatures decrease. The system with R510A has the minimum exergy losses. The average exergy losses for systems with R510A, RE170, and R152a are 34.62%, 28.33%, and 18.64% lower than that of R134a, respectively. The system with R510A has higher exergy efficiency and R134a has the minimum values of exergy efficiency. Generally, the water cooler provided better performance with R510A and RE170 than with R152a and R134a. Therefore, R510A can be considered as the best replacement for R134a and R152a.

Performance Enhancement Analysis of Environmentally Friendly Refrigerants

Due to the impact of global warming and climate change, more and more people are starting to have a clearer understanding and vigilance about greenhouse gases. To prevent further deterioration of the global environment, this study examines the coefficients of performance of 21 currently available refrigerants with very low global-warming potential and zero ozone-depleting potential under evaporation temperatures of 10, −20, −40, and −60 °C and condensation temperatures of 30, 40, and 50 °C, respectively. It is found that the use of pure refrigerant in a two-stage refrigeration system to replace the single-stage refrigeration system, in addition to mixing it into an appropriate mixture, can effectively improve the performance coefficient of the refrigeration system. For single-stage vapor compression refrigeration systems, R1234ze(Z), R601, and R1233zd(E) have the best refrigeration performances among the environmentally friendly refrigerants studied, while R441A performs the worst for Teva = 10 °C and −20 °C. Moreover, RE170 has the highest COP of the refrigeration system for Teva = −40 °C and −60 °C. However, R1234yf performs worse in COP when the evaporation temperature is lower, and it ranks last for Teva = −60 °C. When a double-stage vapor compression refrigeration system is employed instead, the percentage increase in the COP of the system using R1234yf becomes the largest for Teva = −40 °C and −60 °C. However, the growth rate of R717 ranks last for Teva = −60 °C. For an R717/R1234yf mixture at an optimum mass fraction of 0.25, the COP of the refrigeration system can be increased up to 25.8% despite an increase of 15.2% in operating pressure compared to R1234yf. The discharge temperature may rise; however, there will be no overheating problem for the compressor.

Dynamic modelling of supplemental cooling systems with vapor compression refrigeration units in civil aircrafts

Newly developed airliners have adopted supplemental cooling systems (SCS) to provide for non-cabin cooling requirements. In the present study, dynamic component models for compressor and phase change heat exchangers were developed with dynamic decoupling and explicit solution methods, and pressure zone separation and solution methods are developed based to obtain dynamic pressures as key values. A dynamic VCRU subsystem model is established, and the result under single-unit startup condition shows pressure deviations less than 0.16 %, with a simulation time ratio of 5.65 %, exhibiting good overall performance at both precision and speed. A dynamic SCS system model is developed, and the simulation of a 9000 s flight took 1973.3 s to complete. Result in the cruise phase shows the condensation and evaporation temperatures are in the ranges of 28.39–31.33 °C and −17.93 to −10.71 °C, respectively, meeting their respective designed ranges of 30 ± 5 °C and −15 ± 5 °C. These results reflects good consistency of the model with actual system characteristics. Control optimization is conducted based on the developed model to eliminate temperature fluctuation. The optimization reduced the maximum temperature deviation from 0.4004 K to 0.0019 K after system starting process, proving the feasibility of control method optimization based on the developed dynamic simulation model.

Net Radiation Drives Evapotranspiration Dynamics in a Bottomland Hardwood Forest in the Southeastern United States: Insights from Multi-Modeling Approaches

Evapotranspiration (ET) is a major component of the water budget in Bottomland Hardwood Forests (BHFs) and is driven by a complex intertwined suite of meteorological variables. The understanding of these interdependencies leading to seasonal variations in ET is crucial in better informing water resource management in the region. We used structural equation modeling and AIC modeling to analyze drivers of ET using Eddy covariance water flux data collected from a BHF located in the Russel Sage Wildlife Management Area (RSWMA). It consists of mature closed-canopy deciduous hardwood trees with an average canopy height of 27 m. A factor analysis was used to characterize the shared variance among drivers, and a path analysis was used to quantify the independent contributions of individual drivers. In our results, ET and net radiation (Rn) showed similar variability patterns with Vapor Pressure Deficit (VPD) and temperature in the spring, summer, and autumn seasons, while they differed in the winter season. The path analysis showed that Rn has the strongest influence on ET variations via direct and indirect pathways. In deciduous forests like BHFs, our results suggest that ET is more energy dependent during the growing season (spring and summer) and early non-growing season (autumn) and more temperature dependent during the winter season.

Heat transfer enhancement for flow boiling of zeotropic mixtures with regulating liquid mass transfer resistance

The mass transfer resistance is a significant element leading to heat transfer degradation of zeotropic mixtures in the flow boiling. In this paper, the heat transfer enhancement of zeotropic mixtures in the flow boiling was investigated through regulating the mass transfer resistance by constructing reasonable surface structure. The heat and mass transfer, pressure drop characteristics of stratified bubble flow for R134a/R245fa zeotropic mixtures in a rectangular channel with multi-cone staggered spoiler porous structure were studied experimentally. The bottom of channel was sintered with multi-cone staggered porous layer with thickness/height/diameter of 1/3/2 mm, respectively. The experiments were carried out under an inlet evaporation temperature of 20 ℃, and the ranges for heat and mass fluxes were 10–150 kW/m2 and 100–150 kg/(m2·s), individually. Compared to the rectangular channel with smooth porous structure, liquid mass transfer resistance of zeotropic mixtures in the rectangular channel with multi-cone staggered porous structure was decreased obviously. The decrease degree for Mixture 2 was largest, while the maximum average decrease was 89.61 % at G = 100 kg/(m2·s). The heat transfer coefficients were obviously improved and heat transfer enhancement increased gradually especially under conditions of high heat flux. The enhancement degree for Mixture 2 was the largest, while the maximum average increase was 26.05 % at G = 100 kg/(m2·s). The pressure drop increased significantly, and the increasing degree for Mixture 2 was smallest, while the minimum average increase was 38.18 % at G = 150 kg/(m2·s). Multi-cone staggered structure was helpful to reduce liquid mass transfer resistance and improve heat transfer performance for zeotropic mixture. The zeotropic mixture with higher liquid mass transfer resistance would have better heat transfer intensify and smaller increase of pressure drop with the help of multi-cone staggered structure.

Power factor enhancement in benzodithiophene-based conjugated polymers through controlling solution-state aggregation

Controlling solution-state aggregation of conjugated polymers is crucial for tuning solid-state morphology as well as electrical properties. However, the effect of solution-state aggregation on their thermoelectric performance is rarely reported. Using a series of poly(benzodithiophene-alt-thiophene) conjugated polymers (PBDT-Fm, m is the content of semi-fluorinated groups in polymer chain), the polymer solution aggregations were tuned by the evaporation temperature, which has achieved optimized P(BDT-Fm) films with high degree of molecular order, homogeneous polymer aggregates and small crystalline domains, leading to dramatic enhancement in thermoelectric performance. Compared with the naturally dried polymer films, the heated evaporating process led to at least 49-fold and 15-fold enhancement in the conductivity and power factor, respectively. Optical spectroscopy and microcosmic morphology have shown that the strong molecular motion of polymer chains at high evaporation temperature would disaggregate the polymer pre-aggregations in solution and assist the formation of orderly packed microstructures in solid state, leading to a significant increase in the power factor. Through controlling solution-state polymer aggregations, PBDT-F15 achieved the power factors up to 7.74 ± 0.01 µW m−1 K−2, which is among the highest values in the reported benzodithiophene-based conjugated polymers, highlighting the importance of controlling polymer solution aggregation in optimizing thermoelectric performance.

Energetic Potential of Parallel Operation of Two Heat Sources in a Dual-Source Heat Pump

Dual-source heat pumps can mitigate disadvantages of single source heat pumps: They have fewer geological requirements compared to ground-source heat pumps while having higher efficiencies compared to air-source heat pumps. Parallel operation of two heat sources can also make electric heaters for peak loads obsolete, leading to economic benefits in the operational costs. Parallel operation has not been analysed thoroughly at different evaporation temperature gradients. To address this gap in research, four possible interconnections of two heat sources were analysed using a refrigerant cycle simulation, two with similar and two with separate evaporation pressures. The energetic potential of each interconnection is evaluated and compared to single source operation with an air-source and a ground-source heat pump. The results showed that only the interconnections with separate evaporation pressure allowed significant reduction in evaporation power from the ground source. As expected, the efficiency – compared to single air-source operation – increased for all parallel interconnections but decreased compared to ground-source operation. Efficient peak load coverage with small ground-source collectors therefore requires a more complex interconnection of completely split evaporator branches at different evaporation pressures. While the efficiency and heating power compared to single ground-source operation decreased slightly (by 4% and 6%, respectively), the power load on the GSHX and ASHX reduced to about 54% and 66% compared to the corresponding single-source operation, respectively. This allows high efficiency at reduced GSHX size and ASHX noise emission. Additionally, this interconnection also allows increased flexibility for improved heat source management.

High-pressure liquid refrigerant injection for reciprocating compressors

Isentropic (adiabatic) compression of superheated vapor in vapor compression refrigeration cycles usually results in some discharge superheat, i.e. the discharge temperature exceeding the condensing temperature. Large discharge superheat reduces both operating range and compression efficiency. Sub-isentropic compression with heat rejection to the heat sink is therefore superior to adiabatic compression, as it results in lower discharge superheat and improved efficiency. However, significant temperature reduction by heat transfer through the working chamber walls is difficult to facilitate in common refrigeration compressors, particularly reciprocating compressors. Refrigerant and oil injection is a well-established method for reducing temperatures and increasing efficiency in screw and scroll compressors, as well as multi-stage systems. In comparison, effective methods for temperature reduction in single-stage reciprocating compressors are fairly limited. Therefore, a concept for high-pressure liquid injection is proposed. By means of a pump and injection valve, high-pressure liquid refrigerant is injected into the working chamber and atomized. The compressed gas is cooled through the evaporation of the injected liquid. The injection valve allows for control over the injection timing and quantity, enabling adjustment of the temperature profile, which is a major distinction from existing refrigerant injection methods. The coupled compression-injection process is evaluated for various refrigerants using an energetic chamber model. The injection is found to be particularly suitable for refrigerants with a large evaporation heat and a shallow dew line slope. For the example of ammonia, a theoretical reduction in compression work of 8.9% at an evaporation temperature of −10 °C and a condensing temperature of 45 °C is found.

Optimization of operating conditions for lampante olive oil deacidification by short path molecular distillation: Waste valorization approach

Short path molecular distillation (SPMD) is an advanced distillation eco-friendly technique performed under high vacuum with vast applications in food processing, including vegetable oils physical refining. In this research, lampante olive oil, as a low-grade byproduct of olive oil producing companies, with high free fatty acids (FFA) content of 10.11 (wt % as oleic acid) was deacidified using SPMD. Optimization of SPMD was carried out using Box-Behnken response surface methodology (RSM-BB). Three important operating factors including evaporation temperature (150–200 °C), feed flow rate (0.50–3.00 mL/min), and feed temperature (50–100 °C) were selected to evaluate the SPMD process. At the best separation conditions of 195 °C, 0.5 mL/min, and 50 °C, the FFA content, deacidification efficiency (DE) and polar compounds (PC) were determined as 1.42 wt %, 85.95 % and 8.2 wt % respectively. Furthermore, SPMD efficiency was compared to some conventional methods including fractional distillation (FD), steam stripping distillation (SSD) and alkali neutralization (AN). In addition, the impact of FFA content on SPMD process was examined. It was concluded that SPMD could effectively and sustainably deacidify lampante olive oil to a reasonable extent and could facilitate the physical refining as a valorization process.

A COMPARATIVE ANALYSIS OF HYPOTHESIS IN THE MODELING OF A HYBRID COMPRESSION REFRIGERATION CYCLE

This paper presents a comprehensive thermodynamic analysis of a hybrid refrigeration system that integrates an evacuated tube solar thermal collector into a vapor compression refrigeration cycle. The proposed analysis comprises two distinct approaches: an isovolumetric model and a compressible flow model. The former assumes a constant specific volume within the solar heat exchanger, while the latter applies principles of compressible fluid dynamics. The study compares these models with a reference work, emphasizing similarities and disparities. The investigation systematically varies key parameters, including evaporator and condenser temperatures, inlet and outlet temperatures of the heat exchanger, and heat load. By varying these parameters, the coefficient of performance (COP) and compressor work are evaluated, elucidating the impact of heat addition on the system's performance. Additionally, the influence of different working refrigerant fluids, such as R22 and R410A, is examined under various design point conditions. The results demonstrate the potential energy savings achievable by the hybrid system, with reductions in electrical power compared to the conventional compressor, as solar heat is introduced. While the isovolumetric analysis closely aligns with the reference work, the compressible flow modeling highlights sensitivity to inlet conditions. Although not directly comparable, the latter approach presents promising trends within specific design point ranges. Comparisons of performance curves for different refrigerant fluids further validate the models and assist in potential fluid selection. Overall, the outcomes indicate a promising avenue for energy-efficient refrigeration systems and provide valuable insights for engineering design and optimization.

Investigation on the Influence of the Condenser Length and Its Coupling Effect With Elevation on the Performance of Loop Heat Pipe

Abstract The effects of condenser length and evaporator/condenser elevation on the performance of a loop heat pipe (LHP) in a gravity field were investigated, respectively, as well as their coupling effect. The refrigerant R40 was selected, and the condenser length was altered by changing the number of fins connected to the water-cooled plates. The experiments were conducted at three evaporator/condenser elevations: zero elevation, favorable elevation, and adverse elevation. The experimental results indicated that the evaporator temperatures of LHP with three different condenser lengths are very close when the LHP operates in variable conductance mode (VCM). However, an excessively long condenser will increase the LHP thermal resistance in VCM. In constant conductance mode (CCM), the longer the condenser, the lower the evaporator temperature. As the heat load increases, the LHP first exhibits gravity-driven mode and then capillarity-gravity-driven mode at a favorable elevation. The positive coupling effect on reducing the evaporator temperature by extending the condenser length and running at a favorable elevation manifests that the influence of condenser length is very small in gravity-driven mode, while in capillarity-gravity-driven mode, the effect of operating at a favorable elevation gets weakened, and the positive effects of the two factors cannot be simply calculated by the linear superposition principle. Additionally, reverse flow and flash evaporation were also observed and analyzed in depth. These results and conclusions can be used to guide the design of the condenser and the installation of LHP for ground applications.

Refrigerants for eutectic refrigerating systems–Experimental results and future consideration

The new European F-Gas and PFAS Directives threaten to dramatically reduce quotas or even outright ban synthetic refrigerants, and transition to natural refrigerants in the near future seems inevitable. This article examines eutectic refrigerating systems used in low-temperature transport refrigerators for retail distribution considering transition to natural refrigerants. The main limitation for the operation of eutectic systems is the low evaporation pressure, and various designs addressing this limitation were already tried in the last few years during transition from R507A to R452A and other alternatives. In this article 5 systems with R452A, two with R290 and two with R1270 are compared. The greatest effect was demonstrated by addition of roll-bond plates – it reduced the difference between the inside air and evaporation temperatures by about 3 K. However, this solution is not promising with hydrocarbons due to the higher refrigerant charge. All other solutions together give no more effect than roll-bond plates in terms of evaporation temperature at the end of pull-down. Based on experimental results, the prospects of eutectic refrigeration system with natural refrigerants are reviewed. R290 is not suitable for such systems, but R1270 could be used in systems where eutectic plates just need to be crystallized. However, in weight-optimized systems used in refrigerated vans, the evaporation pressure of R1270 would be lower than atmospheric, which is considered unacceptable due to safety requirements. If this provision remains, the eutectic refrigerators with a single-stage vapour compression refrigerating system become impossible, and more complicated cascade system has to be developed.

Experimental investigation of multi-ejector CO2 heat pump system with and without IHX

Environmental degradation due to the use of synthetic refrigerants should motivate end users to request natural refrigerants to secure their businesses from unforeseen negative ecological impacts. Further, using natural refrigerants as working fluids for HVAC requirements helps achieve zero CO2 emissions from this sector. The CO2 heat pumps are energy efficient units providing simultaneous heating and cooling. Implementing performance enhancing components like ejectors and/or internal heat exchangers (IHX) is sometimes beneficial. This study experimentally evaluates the ejector performance in a multi-ejector CO2 system of 33 kW cooling capacity, with and without an IHX, at different gas cooler exit temperatures. Evaporator and gas cooler exit temperatures are varied from 4 to 10 °C and 34 to 46 °C, respectively. These temperature ranges suit the simultaneous cooling (AC) and heating demands in various buildings and food- and beverage industries. At the gas cooler exit temperature of 42 °C, the system COP is improved by 12 % with an IHX, whereas the ejector efficiency increased from 14 to 18 % without the IHX. The ejector efficiency and entrainment ratio also increased at elevated heat rejection temperatures. However, as expected, the system COP decreased. Therefore, the heating system must be adapted to avoid high gas cooler exit temperatures.

Assessment of booster refrigeration system with eco-friendly working fluid CO2/halogenated alkene (HA) mixture for supermarket application around the world: Energy conservation, cost saving, and emissions reduction potential

For the scope of commercial supermarkets, the demand for energy efficiency improvement and environmentally-friendly working fluid of the refrigeration system is necessary. In this study, supermarket booster refrigeration system by using eco-friendly working fluid CO2/halogenated alkene (HA) mixture is proposed, and the mixture used in systems with two evaporation temperatures and operating modes affected by ambient temperature are studied. The energy efficiency, economic performance and emission reduction potential of the whole life cycle are conducted to compare with the pure CO2 booster refrigeration system. Furthermore, the influence of climate condition is discussed when used in 40 typical cities around the world. The results show the coefficient of performance (COP) of booster refrigeration system can be significantly improved by using CO2/HA mixtures. As the ambient temperature is 33 °C, the CO2/R1234yf (93/7) operates with the maximum COP of 1.367, which is 11.59 % higher than that of pure CO2. Using CO2/HA mixtures in the booster refrigeration system can significantly improve the exergy efficiency of system. Moreover, the system using CO2/HA mixtures has higher annual performance factor and lower life cycle cost (LCC) than pure CO2. LCC of the system using CO2/R1234yf (94/6) is the lowest, and the reduction rate is 3.06–5.59 %. Meanwhile, the life cycle carbon emissions of systems in different climatic regions using CO2/R1234yf can be reduced by 2.39–5.21 %. The booster refrigeration system adopting CO2/HA mixtures is a promising alternative solution for commercial supermarket refrigeration and energy-saving.

Vacuum Evaporation Plating Enabling ≤ 10µm Ultrathin Lithium Foils for Lithium Metal Batteries.

Lithium (Li) metal is widely recognized as a viable candidate for anode material in future battery technologies due to its exceptional energy density. Nevertheless, the commercial Li foils in common use are too thick (≈100µm), resulting in a waste of Li resources. Herein, by applying the vacuum evaporation plating technology, the ultra-thin Li foils (VELi) with high purity, strong adhesion, and thickness of less than 10µm are successfully prepared. The manipulation of evaporation temperature allows for convenient regulation of the thickness of the fabricated Li film. This physical thinning method allows for fast, continuous, and highly accurate mass production. With a current density of 0.5mAcm-2 for a plating amount of 0.5mAhcm-2, VELi||VELi cells can stably cycle for 200h. The maximum utilization of Li is already more than 25%. Furthermore, LiFePO4||VELi full cells present excellent cycling performance at 1C (1C = 155mAhg-1) with a capacity retention rate of 90.56% after 240 cycles. VELi increases the utilization of active Li and significantly reduces the cost of Li usage while ensuring anode cycling and multiplication performance. Vacuum evaporation plating technology provides a feasible strategy for the practical application of ultra-thin Li anodes.

Investigation of environmentally friendly new generation refrigerant R471A instead of R404A in low and medium temperature commercial refrigeration system

Hydrofluorocarbon (HFC) refrigerants (such as R134a and R404A), which are widely used in commercial refrigeration systems, contribute greatly to global warming. Because the global warming potential (GWP) values of HFC refrigerants are high. With increasing concerns about the environment (global warming, climate change, etc.) various legal regulations have been made to limit or phase out the use of refrigerants with high GWP values. To use the R471A refrigerant developed by Honeywell in 2022 as an environmentally friendly new-generation refrigerant in the commercial refrigeration system, the performance of the R471A refrigerant should be comprehensively evaluated. In this study, energy, exergy, and environmental analyses of using R471A refrigerant instead of R404A in low and medium-temperature commercial refrigeration systems were carried out and presented. Evaporator temperatures of − 30 °C, − 25 °C, − 20 °C, − 15 °C and − 10 °C and condenser temperatures of 30 °C, 40 °C, and 50 °C were selected to represent low and medium cooling temperatures and hot and cold country seasons. It was seen that R471A presents a lower mass flow rate (between 67 and 71%) and cooling capacity (between 61 and 68%) than R404A however has higher COP (between 6% and 14%) and R404A has exergy efficiency value of 6–14% lower than R471A. Also, from an environmental point of view, R471A has better environmental results than R404A.