Condensation Process Research Articles

Experimental analysis and investigation of desiccant coated heat exchanger applications involving condensation and sorption mechanisms

This study focuses on the application of desiccant coated heat exchangers (DCHEs) in conditions where condensation occurs below the dew point temperature. Previous experimental studies on DCHEs and DCHPs have predominantly examined the sorption mechanism above the dew point, leaving a gap regarding material selection and system design in the presence of condensation. To address this, a guide is introduced that combines the understanding of condensation and sorption processes for desiccant applications. The guide is applied to evaluate the suitability of a superabsorbent-LiCl (SAP-LiCl) composite desiccant for desiccant coated heat pump (DCHP) applications. The stability of the desiccant in the presence of condensed water droplets is validated. Additionally, an experimental investigation explores the relationship between sorption and condensation mechanisms, identifying the transitional coolant temperature at which dehumidification shifts from condensation-dominant to sorption-dominant. By incrementally adjusting the coolant temperature in 5 °C steps, the transitional temperature of the SAP-LiCl based DCHE is determined to be approximately 15 °C under the target operation scenario, rendering its suitability for additional below-dew-point applications. The study reveals optimal operational parameters for DCHE, demonstrating a potential energy saving of 20 %. Based on these findings, a DCHP prototype is constructed to assess the feasibility of DCHE in real-world applications. The transient behaviors of this prototype are analyzed during each operating cycle, yielding a coefficient of performance of 4.97 and a cooling capacity of 1.5 kW under baseline operating conditions.

Numerical research on refrigerant injection for motor cooling of screw compressor for heat pump with large temperature lift

In the screw compressor for heat pump with large temperature lift, the large load on the motor makes the motor heat up severely. The stability and safety of the motor directly affects the operation of the compressor. High motor temperatures or strong impact on winding will destroy the insulating coating on the copper wires of the motor winding, which could cause the motor to burn out. Refrigerant injection for motor cooling is an effective way of motor cooling. There is a lack of research on this method. In this paper, a computational fluid dynamics model containing evaporation–condensation and conjugate heat transfer is developed. In order to reasonably simulate the evaporation–condensation process, the physical parameters varying with temperature of the refrigerant are taken into account. The temperature field of the screw compressor by refrigerant injection for motor cooling is predicted, and the accuracy of the model is verified through experiments of an R134a heat pump with large temperature lift. The maximum discrepancy between the simulation results and the experimental results under four working conditions does not exceed 3.0%. Next, the effects of the injection pressure and the injection position on motor cooling, impact caused by refrigerant injection and temperature uniformity are investigated. The results show that by adjusting the injection pressure to make the refrigerant two-phase mixture, the impact caused by refrigerant injection is reduced by 57.0%, while the cooling effect is reduced by only 9.0%. By choosing the injection position appropriately, the cooling effect is increased by 12.0% and the impact caused by refrigerant injection is reduced by 21.2%. In addition, the temperature in the middle of the motor is the highest before refrigerant injection, so the motor temperature sensor should be arranged in the middle of the motor winding.

Evaluating and optimizing of steam ejector performance considering heterogeneous condensation using machine learning framework

In the context of global warming and pollution concerns, refrigeration systems have become pivotal in energy conversion system. Within this realm, ejector types that harness renewable energy resources emerge as promising alternatives, offering a pathway towards environmentally conscious and resilient energy practices. Under specific conditions, condensation within the heat exchanger results in diverse droplet sizes at the ejector inlet, inducing homogeneous-heterogeneous condensation (HMTC) and heterogeneous condensation (HTC) phenomena. This study aims to evaluate and improve the performance of steam ejectors by investigating and optimizing the effects of homogeneous condensation (HMC), HTC, HMTC, and evaporation processes using a machine learning (ML) framework. The drone squadron optimization (DSO), Particle Swarm Optimization (PSO), and Genetic Algorithm (GA) are chosen and used in the ML framework to find the optimal droplet radius and number. Findings predict that the presence of 1018 1/kg droplets with a radius of 0.02 μm (Optimal mode) at the inlet results in a 2.6 % increase in the entrainment ratio (Er) and a 6.9 % reduction in the entropy generation compared to the baseline mode. Generally, the research reveals that HTC exhibits superior performance compared to prevailing theories, leading to enhanced ejector performance.

In Situ Combustion Characteristics of Heavy Oil in the Liaohe Oilfield at Different Temperatures

This study conducted in situ combustion oxidation experiments on crude oil from Block D within the Liaohe Oilfield, utilizing a kettle furnace low-pressure oxidation reaction method at various temperatures. The molecular composition of oxidation products was analyzed using gas chromatography–mass spectrometry (GC–MS) and high-resolution mass spectrometry. The results reveal that the molecular composition of the products remains relatively stable up to 300 °C, exhibiting a slight increase in C13-C30 alkanes. The ratio of the peak area for C21 to bisnorhopane is 0.082. From 300 °C to 450 °C, compounds with long alkyl chains gradually undergo thermal cracking, resulting in a significant increase in the production of alkanes within the C10–C30 range. The concentration of saturated hydrocarbons produced through thermal cracking reaches its maximum at a temperature of 400 °C. The most abundant peak of n-alkane is observed at C21, with a quantified ratio of peak area for C21 to bisnorhopane at 6.5, indicating a two-order magnitude increase compared to crude oil. From 500 °C to 600 °C, compounds undergo more profound thermal cracking and condensation processes. The predominant hydrocarbons consist of aromatic molecules containing two to six rings substituted with short side chains. The double bond equivalent (DBE) values of carbazoles and carboxylic acids are determined as 30 and 25, respectively. At 600 °C, the peak area ratio of naphthalene to biodecane is 300, indicating a remarkable increase of five orders of magnitude compared to the crude oil. The present study elucidates the correlation between the characteristics of combustion components in crude oil and the corresponding combustion temperature. Primary cracking reactions within crude oil are promoted effectively when keeping the combustion zone at 350 °C and 450 °C. This process significantly reduces the viscosity of heavy oil and enhances its fluidity.

Efficient and stable CsPbBr3/Cs4PbBr6 composite powders passivated and encapsulated with a novel silicon-based ligand

The metal halide perovskite have garnered significant attention for their exceptional photoelectric properties. However, their inherent instability and the sharp decrease of photoluminescence quantum yield (PLQY) in the solid-state significantly limit their practical applications. Appropriate heterojunction structures or matrix encapsulation can efficiently improve the PLQY and stability of the metal halide perovskite. Herein, we report a new silicon-based ligand hydrolysis condensation encapsulation to synthesize CsPbBr3/Cs4PbBr6/BTESPA-x (CPB–Si-x) composite powders with improved luminescence properties and enhanced thermal stability. With the increase of BTESPA (from 0 to 150 μL), the efficient hydrolysis condensation process occurs on the surface of CsPbBr3/Cs4PbBr6. Finally, the abundant amino-silane groups in BTESPA bind to undercoordinated Pb2+, thereby suppressing the surface defect states and enhancing the PLQY from 34.3 % for CsPbBr3/Cs4PbBr6 (CPB) to 82.1 % for CPB-Si-5. Simultaneously, the thermal stability of CPB-Si-5 exhibits a 13 % improvement over that of CPB after undergoing thermal cycling. Furthermore, tricolor white light-emitting-diode (WLEDs) with high color rendering index were fabricated using on-chip blue LED with bright green-emissive CPB-Si-5 composite powder and red-emissive K2SiF6:Mn4+ phosphor, demonstrating the potential applicability of these powders in WLED backlight systems.

Innovative and efficient integrations of desalination plants coupled absorption, adsorption, and humidification-dehumidification desalination units employing external heat recovery techniques

Thermal desalination technologies have been developed recently to solve some pressing problems, such as high energy expenditure, increasing fuel costs, and environmental problems related to conventional plants. However, these technologies still need to be enhanced in terms of water production and gain output ratio (GOR). This paper presents innovative and efficient combined thermal desalination plants consisting of absorption (ABDS), adsorption (ADDS), and humidification-dehumidification (HDH) desalination units to enhance energy utilization, water production, and overall system performance. Four innovative combined desalination plants employing different external heat recovery scenarios are presented and compared. The result from each scenario is evaluated and compared with those of the standalone ABDS and with other studies found in the literature at the same heat source temperatures. The heat source is mainly utilized to drive the ABDS plant. The ADDS and HDH are driven by the heat rejection from the ABDS components with different external heat recovery scenarios. Results illustrated that the maximum freshwater production generated from the proposed scenarios ranges between 1.57 and 2.94 m3.day−1 with a GOR of between 1.38 and 1.75 at 120 °C. Raising heat source temperatures from 55 to 120 °C decreased the improvement in the water productivity from 618.5 to 224 % and decreased the enhancement in the GOR from 222.8 to 99 %. In scenarios where the ADDS and HDH are driven by the heat rejection from the absorption and condensation process of the ABDS, the maximum freshwater production results from the ABDS unit. On the other hand, in scenarios where the ADDS and HDH are driven by the outlet hot water from the ABDS-generator, the maximum freshwater production is obtained from the HDH unit. The finding provided that the proposed innovative scenarios have an effective improvement in overall system performance indicators.

Ionic Organic Network-based C3-symmetric@Triazine core as a selective Hg+2 sensor

ABSTRACT The C3-symmetry ionic polymer PPyTri has been designed with multi-walled carbon nanotubes (MWCNTs) or graphene nanoplatelets (GNPs) and studied as an ultrasensitive electrochemical sensor for trace Hg(II) detection. The synthesis approach incorporated attaching three pyridinium cationic components with chloride anions to the triazine core. The precursors, BPy, were synthesized using a condensation process involving 4-pyridine carboxaldehyde and focused nicotinic hydrazide. The polymer PPyTri was further modified with either MWCNTs or GNPs. The resulting ionic polymer PPyTri and its fabricated nanocomposites were characterized using infrared (IR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and powder X-ray diffraction (XRD). The analysis revealed that both the polymer and its nanocomposites have semi-crystalline structures. The electroactivity of the designed nanocomposites toward Hg + 2 ions revealed that among the nanocomposites and bare copolymer, the glassy carbon electrode (GCE) adapted with the PPyTri GNPs-5% exhibited the greatest current response over a wide range of Hg + 2 concentrations. The nanocomposite-modified electrode presented an excellent sensitivity of 83.33 µAµM − 1 cm − 2, a low detection limit of 0.033 nM, and a linear dynamic range of 0.1 nM to 0.01 mM (R2 = 0.9945).

A numerical study on the effect of particle surface wettability on homogeneous and heterogeneous condensation processes in supersonic flows

Supersonic separators are an emerging device for processing natural gas impurities. Natural gas contains solid particulate impurities in addition to gaseous impurities, which can trigger heterogeneous condensation within the supersonic separator. There is a lack of research on the effect of particle wettability on supersonic condensation flow, although there have been studies on the effect of particle surface wettability on heterogeneous condensation in this area. Therefore, in this paper, the supersonic condensation flow is modeled considering the contact angle, and the effects of particle contact angle on heterogeneous condensation and homogeneous condensation are investigated separately. The results show that homogeneous condensation is inhibited and heterogeneous condensation is promoted by decreasing the particle contact angle. The reason is the smaller contact angle leads to the reduction of the free energy barrier for heterogeneous nucleation, which makes the conditions for heterogeneous nucleation lower and condensation more likely to occur.

Numerical study of uranium hexafluoride desublimation process based on Eulerian two-phase model

This paper presents a numerical study on the condensation process of uranium hexafluoride (UF6) in the supply and extraction system of a uranium enrichment plant. The numerical study was conducted using a standard UF6 receiving container with a nominal diameter of 127 mm and a volume of 8L under constant temperature boundary conditions. A phase change heat and mass transfer model for the desublimation process of uranium hexafluoride gas was established, and this model was combined with the Euler two fluid model to predict the distribution of key parameters such as temperature, pressure, and volume fraction of each phase during the UF6 cooling process, as well as the gas flow characteristics inside the container. In addition, this study also investigated the influence of various factors on the cooling rate. The research results indicated that UF6 gas initially condensed on the container wall and gradually diffused inward, with the highest solid density observed on the wall. Furthermore, increasing the inlet gas temperature, inlet mass flow rate, and reducing the cooling temperature, initial pressure inside the container could all enhance the desublimation rate to various degrees. The optimization plan proposed based on the above influencing factors could increase the yield of UF6 solid by 64.20% in 2 h, compared to the basic operating conditions.

Separation of arsenic and antimony: A comprehensive theoretical and experimental study

Arsenic is commonly used in alloy materials and the semiconductor industry, and has promising applications. Arsenic and antimony have similar physicochemical properties, and their binding and separation mechanisms are unknown, thereby limiting the purification and preparation of arsenic. This study, from a microscopic perspective, reveals that arsenic and antimony covalently interact in alloys through a combination of thermodynamic analysis and molecular dynamics simulations. In addition, antimony as arsenic-antimony clusters enters the gas phase, and the diffusion coefficients of the clusters are in the order of As4>As3Sb > As2Sb2>AsSb3. A green and efficient vacuum sublimation-graded condensation process for arsenic purification is proposed based on the different diffusion coefficients to obtain the optimal process parameters. The coalescence of arsenic on a condenser was normally distributed. The removal rate of antimony in the most concentrated area of the condensate was 91.37% under the optimal conditions of 748 K, 60 min, and 10 Pa. Thus, the proposed method effectively solves the challenging problem of separating arsenic and antimony, and the study results provide theoretical support for purifying arsenic via vacuum sublimation.

Highly acid-stable polyvinyl alcohol/chitosan/phytic acid aerogel for selective separation of uranium from actual wastewater

Conventional adsorption materials encounter difficulties in achieving optimal selectivity in uranium-containing wastewater (UCW) because of the low uranium concentration and the presence of diverse coexisting ions. Aerogel, renowned for its abundance of adsorption sites and remarkable structural flexibility, is widely regarded as an innovative material. Nonetheless, its stability in solution hinders its utility in the separation of uranium during wastewater treatment. To counter this limitation, a polyvinyl alcohol/chitosan/phytic acid aerogel (PCPA) was synthesized by employing several polymerization agents. An exceptional degree of selectivity, speed, and stability was achieved in the separation of low concentration uranium from UCW. The results indicated that polyvinyl alcohol (PVA) proved to be the most effective in generating stable aerogels, even when immersed in 0.1 M HCl or acidic UCW. PCPA displayed the highest efficacy in isolating U(VI) in UCW at a pH of 6.0. The novel aerogel exhibited remarkable resistance to ion interference during adsorption, leading to an impressive 96.3 % efficiency in the separation of U(VI) from actual low-concentration UCW. Even after five desorption, PCAC could still achieve U(VI) separation efficiencies of more than 80 %. The adsorption of U(VI) in this aerogel is characterized by chemisorption. PVA plays a crucial role in the condensation process of the aerogel, resulting in an increase in the presence of easily dissociable -OH groups. This, in turn, effectively improves the selectivity of the aerogel. PCPA has demonstrated successful capability in the efficient recovery of uranium from UCW.

Optimization of Membrane Condenser Process with PTFE Hollow Fiber Membrane.

A membrane condenser (MC) is a novel membrane separation technology that utilizes the hydrophobic nature of porous membranes to capture water vapor from humid gas. Factors such as temperature, pressure, flow rate, and gas composition entering the membrane condenser play a crucial role in water recovery efficiency. This study utilized hydrophobic polytetrafluoroethylene (PTFE) hollow fiber membranes to create multiple identical membrane modules. This research investigated the impact of temperature, flow rate, pressure on the intake side, gas flow on the cooling side, membrane area, and other variables on the performance of the membrane condenser process. This study compared water extraction efficiency under different conditions, focusing on feed flow temperature and sweeping flow. Results showed that at a temperature of 60 °C, the water recovery rate was 24.7%, while a sweep gas flow rate of 4 L/min resulted in a recovery rate of 22.7%. The efficiency of the membrane condenser decreased with higher feed flow rates but increased with larger membrane areas. A proportional relationship between inlet flow and membrane area was observed, suggesting an optimal range of 0.51-0.67 cm/s for both parameters. These findings offer valuable insights for the practical implementation of hydrophobic membrane-based membrane condenser technology.

Hybrid sol-gel silane composite coating reinforced with a hybrid organic/inorganic inhibitive pigment: Synthesis, characterization, and electrochemical properties

This work aims to develop environmentally friendly silane coating reinforced with a hybrid pigment to protect mild steel against corrosion in a saline environment. Fourier-transform infrared (FT-IR) spectroscopy, contact angle (CA) measurement, field emission scanning electron microscopy (FE-SEM), and energy dispersive spectroscopy (EDS) were used to study the coating structure and its protective mechanisms. The presence of hybrid pigment led to the conversion of more Si–OH groups into Si–O–Si groups during condensation process increasing the cross-linking density of silane; the enhanced cross-linking yields the coating with lower defects and stronger adhesion to substrate and so improved barrier and anti-corrosion properties. The EIS test showed that the charge transfer resistance (Rct) for the sample coated with hybrid sol-gel silane increases up to 40 % for all immersion times after the incorporation of the hybrid pigment into the coating matrix. The polarization test showed that the corrosion current density (icorr) value decreases from 1.40 to 0.56 μA/cm2 after 120 h of exposure to the saline solution when the hybrid pigment is added to the coating matrix. These results demonstrate the inhibitive action of the hybrid pigment enhancing the protective performance of the sol-gel silane coating.

Quantitative morphological analysis of Deinococcus radiodurans elucidates complex dose-dependent nucleoid condensation during recovery from ionizing radiation.

The extremophile Deinococcus radiodurans maintains a highly organized and condensed nucleoid as its default state, possibly contributing to its high tolerance to ionizing radiation (IR). Previous studies of the D. radiodurans nucleoid were limited by reliance on manual image annotation and qualitative metrics. Here, we introduce a high-throughput approach to quantify the geometric properties of cells and nucleoids using confocal microscopy, digital reconstructions of cells, and computational modeling. We utilize this novel approach to investigate the dynamic process of nucleoid condensation in response to IR stress. Our quantitative analysis reveals that at the population level, exposure to IR induced nucleoid compaction and decreased the size of D. radiodurans cells. Morphological analysis and clustering identified six distinct sub-populations across all tested experimental conditions. Results indicate that exposure to IR induced fractional redistributions of cells across sub-populations to exhibit morphologies associated with greater nucleoid condensation and decreased the abundance of sub-populations associated with cell division. Nucleoid-associated proteins (NAPs) may link nucleoid compaction and stress tolerance, but their roles in regulating compaction in D. radiodurans are unknown. Imaging of genomic mutants of known and suspected NAPs that contribute to nucleoid condensation found that deletion of nucleic acid-binding proteins, not previously described as NAPs, can remodel the nucleoid by driving condensation or decondensation in the absence of stress and that IR increased the abundance of these morphological states. Thus, our integrated analysis introduces a new methodology for studying environmental influences on bacterial nucleoids and provides an opportunity to further investigate potential regulators of nucleoid condensation.IMPORTANCEDeinococcus radiodurans, an extremophile known for its stress tolerance, constitutively maintains a highly condensed nucleoid. Qualitative studies have described nucleoid behavior under a variety of conditions. However, a lack of quantitative data regarding nucleoid organization and dynamics has limited our understanding of the regulatory mechanisms controlling nucleoid organization in D. radiodurans. Here, we introduce a quantitative approach that enables high-throughput quantitative measurements of subcellular spatial characteristics in bacterial cells. Applying this to wild-type or single-protein-deficient populations of D. radiodurans subjected to ionizing radiation, we identified significant stress-responsive changes in cell shape, nucleoid organization, and morphology. These findings highlight this methodology's adaptability and capacity for quantitatively analyzing the cellular response to stressors for screening cellular proteins involved in bacterial nucleoid organization.

Response reconstruction based on substructural condensation and modal-group superposition

Abstract Increasingly complex civil structures result in an enormous consumption of computational resources in response reconstruction. Moreover, common closely spaced modes (CSMs) also impair reconstruction performance. This study proposed an improved approach that incorporated substructural condensation and modal-group superposition. This method efficiently extrapolated the desired response by dividing the entire finite element model into multiple manageable substructures, which were then condensed and assembled into a super-element model with fewer degrees of freedom (DOFs). The reconstruction response was directly performed on the condensed model by selectively retaining the physically measured DOFs during the condensation process. To address the challenges posed by CSMs, defined modal group responses (MGRs) were extracted from dynamic measurements using empirical mode decomposition. Based on these results, the corresponding MGRs at inaccessible locations were extrapolated using a condensed model. Finally, all the MGRs are superposed to form the desired response. Numerical and experimental tests were conducted to demonstrate the efficiency and accuracy of the proposed approach. The effects of substructural division, measurement noise, and measurement locations on the reconstruction were studied in detail.

Understanding the role of the structure of single-stimuli hybrid systems on their behaviour as platforms for colonic delivery.

The success of colon-targeted oral hybrid systems relies in the proper control over the release of the entrapped nanostructures at the colon. This work describes the design of hybrid systems for their colonic enzyme-triggered release. The hybrid systems were constituted by nanoemulsions, with adequate characteristics for the treatment of ulcerative colitis, included in a pectin hydrogel-like matrix. For that purpose, pectins with similar degrees of methylation (< 50%) and increasing degree of amidation, i.e. 0, 13 and 20%, were selected. Hybrid systems were formulated by a novel aggregation induced gelation method, using Ca2+, Ba2+ or Zn2+ as aggregating agents, as well as by a polyelectrolyte condensation approach, obtaining structures in the micrometric range (< 10μm). Despite the resistance of pectins to the upper gastrointestinal tract stimuli, the analysis of the behaviour of the different prototypes showed that the non-covalent crosslinks that allow the formation of the hybrid structure may play a relevant role on the performance of the formulation.Our results indicated that the partial disassembling of the hybrid system's microstructure due to the intestinal conditions may facilitate the stimuli-triggered release of the nanoemulsions at the colon. More interestingly, the particle tracking experiments showed that the condensation process that occurs during the formation of the system may affect to the enzymatic degradation of pectin. In this sense, the effect of the high degree of amidation of pectin may be more prevalent as structural feature rather than as a promoter of the enzyme-triggered release.

Power-to-ammonia synthesis process with membrane reactors: Techno- economic study

This work aims at investigating the potential of catalytic membrane reactors (CMRs) for ammonia production from renewable hydrogen. To achieve this objective, computer-aided process simulation is deployed using Aspen plus v14 simulation tool. A 1D model is developed to describe the integration of a ruthenium catalyst into a CMR equipped with inorganic membranes that are selective to NH3 over N2 and H2. First, the CMR performance is studied across a broad spectrum of membrane properties and operating conditions. Subsequently, the CMR model is integrated into several Power-to-Ammonia (PtA) process layouts, which are optimized and techno-economically compared against a traditional PEM-based PtA production process, employing condensation for the purification stage. Key findings at the reactor level confirmed that beyond a selectivity threshold towards hydrogen of 10–20, both the degree of conversion and recovery tend to be generally independent of the membrane's selectivity. However, for producing pure ammonia permeate, highly selective membranes (>1000 towards H2) depending on the pressure drop are found essential making this alternative elusive based on existing membranes. At the PtA level, results in terms of efficiency indicates that the use of membrane reactor increases the system efficiency by around ∼8% with respect to reference case while ∼15% enhancement is achieved with this process when using SOEC technology. When examining the final Levelized Cost of Ammonia (LCOA), incorporating a membrane reactor in conjunction with condensation separation results in a cost that nearly matches the reference case. Future research should focus on replacing the condensation process with a method of purification at lower pressures. This could potentially further improve efficiency and reduce the cost of the membrane reactor compared to the traditional one.

Experimentation and thermo-enviro-economic analysis of solar still coupled with large-capacity heating and cooling units

Solar still is a water desalination method that works by the principle of evaporation and condensation, which has been adopted earlier as a simple and low energy consumption method. However, it suffers from low reliability and poor performance. Hence, the current study provides a developed solar still combined with a heat pump and an evacuated tube water heater to augment the thermal processes. The heat pump was attached to advance the condensation process. Besides, the heater was combined with the system to afford a storage medium and boost the evaporation process. Firstly, a parametric analysis was performed in order to select a suitable water recirculation rate and operating temperature. The productivity increased linearly with the temperature by a rate of about 0.035 L/h/m2 for a 1 ℃ temperature rise until below 68 ℃; then, the relation becomes exponential where the productivity increased by 0.16 L/h/m2 after a 1.5 ℃ temperature rise. Daily, the modified design exhibited productivity, energetic efficiency, and exergetic efficiency of 13.38 L/m2, 44.12 %, and 4.17 %, respectively. Furthermore, including cover cooling boosted these findings to 14.22 L/m2, 47.79 %, and 4.69 %, which were higher than that of a basic distiller by 291.73, 16.05, and 30.28 %, respectively. From the cost perspective, the minimum distilled water price was obtained at a 20-year lifetime span and a 5 % interest rate of 0.0121 $/L.

Study of Condensation during Direct Contact between Steam and Water in Pressure-Relief Tank

Direct contact condensation (DCC) is a phenomenon observed when steam interacts with subcooled water, exhibiting higher heat and mass transfer rates compared to wall condensation. It has garnered significant interest across industries such as nuclear, chemical, and power due to its advantageous characteristics. In the context of pressure-relief tanks, understanding and optimizing the DCC process are critical for safety and efficiency. The efficiency of pressure-relief tanks depends on the amount of steam condensed per unit of time, which directly affects their operational parameters and design. This study focuses on investigating the direct gas–liquid contact condensation process in pressure-relief tanks using computational fluid dynamics (CFD). Through experimental validation and a sensitivity analysis, the study provides insights into the influence of inlet steam parameters and basin temperature on the steam plume characteristics. Furthermore, steady-state and transient calculation models are developed to simulate the behaviour of the pressure-relief tank, providing valuable data for safety analysis and design optimization. There is a relatively high-pressure area in the upper part of the bubble hole of the pressure-relief tube, and the value increases as it is closer to the holes. The steam velocity in the bubbling hole near the 90° elbow position is higher. This study contributes to the understanding of steam condensation dynamics in pressure-relief tanks. When the steam emission and pressure are fixed, the equilibrium temperature increases linearly as the initial temperature increases (where a = 1, b = 20 in y = a x+ b correlation), the equilibrium pressure increases nearly exponentially, and the equilibrium gas volume decreases. When the steam emission and initial temperature are fixed, the equilibrium temperature does not change as the steam discharge pressure increases. The correlations between the predicted equilibrium parameters and the inlet steam parameters and tank temperature provide valuable insights for optimizing a pressure-relief tank design and improving the operational safety in diverse industrial contexts.

Investigation of the Photothermal Performance of the Composite Scaffold Containing Light-Heat-Sensitive Nanomaterial SiO2@Fe3O4

The objective of this investigation was to fabricate a photothermally responsive composite bone scaffold aimed at facilitating bone tissue regeneration and remedying bone defects via mild thermal stimulation. The photothermal-sensitive nanomaterial SiO2 coated Fe3O4 (SiO2@Fe3O4), synthesized through the hydrolysis–condensation process of tetraethyl orthosilicate (TEOS), displayed a uniform distribution of SiO2 coating, effectively preventing the aggregation of Fe3O4 particles within the scaffold matrix. The composite scaffold containing 5% mass fraction of photothermal-sensitive nanoparticles exhibited evenly dispersed microstructural porosity, a compressive strength of 5.722 MPa, and a water contact angle of 58.3°, satisfying the mechanical property requisites of cancellous bone while demonstrating notable hydrophilic characteristics. Upon exposure to near-infrared light at ambient temperature, the 5% composite scaffold underwent a temperature elevation of 3–6 °C within 40–45 s, attaining a temperature range (40–43 °C) conducive to fostering osteogenic differentiation. Experimental findings validated that the SiO2@Fe3O4/polyvinyl alcohol (PVA)/hydroxyapatite (HA)/polycaprolactone (PCL)/β-tricalcium phosphate (β-TCP) bone scaffold showcased outstanding mechanical and photothermal attributes, thereby presenting a pioneering avenue for advancing bone tissue cell proliferation and addressing bone defect rehabilitation.