The Chinese Journal of Process Engineering

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The Chinese Journal of Process Engineering. 2021, 21(11): 0.

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Peptide-drug conjugates improve the efficacy and safety of anticancer medicines

Xue LIU Jing ZHANG Bo LIANG Yao ZHANG Weiying WANG Chun ZHANG Yongdong LIU

The Chinese Journal of Process Engineering. 2021, 21(11): 1245-1258. DOI: 10.12034/j.issn.1009-606X.220303

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Cancer has become the biggest threat to human health in the world. Small-molecule chemotherapeutic drugs are widely used in clinical practice in cancer treatment, but systemic toxicity and drug resistance are common due to the lack of tumor targeting. One of the main challenges for the chemotherapeutic drug is how to directly transport sufficient drugs to tumor but not normal tissues. To solve this problem, antibody-drug conjugate (ADC) was proposed and has been the hot spot in tumor drug research for decades. Guided by the specific monoclonal antibodies, ADC can selectively deliver highly cytotoxic drugs to tumor sites therefore overcome the above shortcomings of small molecules. However, the molecule weight of antibodies is generally large that makes ADC low permeability in the tumor and seriously limits its therapeutic effect. In recent years, peptide-drug conjugate (PDC), using peptides with tumor targeting ability to replace antibodies, is emerging as another novel targeted delivery route of tumor drugs. A great number of tumor targeting penetration peptides have been investigated in PDC design and shown great potential in cancer treatment. Peptides could be easily prepared through chemical synthesis or expressed by prokaryotic systems. Therefore, compared with ADC, PDC has the advantages of higher drug loading, enhanced penetration capacity in solid tumors, easier multifunctional modification through chemical or genetic techniques, and lower production cost. With the deep study of intracellular transport pathway and drug release mechanism, PDC will be expected to be put into clinical application as soon as possible. In this review, the latest advances of PDC are summarized. Types and characteristics of different targeting peptides, cytotoxic molecules and linkers in PDC and their applications in cancer treatment are discussed. The advantages and disadvantages of current researches on PDC are reviewed, and future development prospected.

Progress in boron recovery from salt lake brines by solvent extraction

Zhenya XU Hui SU Jian ZHANG Wensen LIU Zhaowu ZHU Jinggang WANG

The Chinese Journal of Process Engineering. 2021, 21(11): 1259-1268. DOI: 10.12034/j.issn.1009-606X.220366

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In this work, four types of solvent systems for boron recovery from salt lake brines including aliphatic alcohol (monohydric alcohol, diol, mixed alcohol), aromatic polyhydroxy compound, amine compound containing hydroxyl group and ionic liquid were systematically reviewed, focusing on the recent research and application progress. The extraction mechanism of boron by various extractant systems were highly summarized to clearly explain the effect of extractant structures on the extraction performance. The extraction performance of different extractants and the influence of coexisting ions on the extraction process were analyzed, and the future research and development direction of boron extraction from salt lake brines were discussed. The monohydric alcohol was suitable for extracting boric acid under the conditions of high salting-out and acidity. But it also had serious disadvantages including low extraction rate, and severe equipment corrosion. Diol had higher extraction efficiency than monohydric alcohol, but it was difficult to realize large-scale industrial production due to high viscosity, high solution loss and difficult stripping from the loaded organic phase. Therefore, the recycling performance of diol extractant was relatively poor. The mixed alcohol system was suitable for industrial application of boron extraction from acid salt lake brines because of its synergistic extraction effect and low cost, and can also reduce viscosity and solution loss. Other systems, such as hydroxyl-containing aromatic and amine compounds, had good extraction effects on boron from alkaline salt lake brines, but they were generally expensive and difficult for industrial application. Ionic liquid can be used for boron extraction and diluent because of its advantages such as low volatility, good chemical stability and designable structure, which had a certain application prospect.

Comparative study of fluid residence time distribution and flow pattern in baffle equipment

Zhangfan GAO Muyi FAN Shaobei LIU Xiong ZOU Weixing HUANG

The Chinese Journal of Process Engineering. 2021, 21(11): 1269-1276. DOI: 10.12034/j.issn.1009-606X.220363

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The flow pattern in the equipment can be the main performance index for its internal structure. Innovation of process equipment is to optimize its internal structure for desired flow pattern. Numerical simulation, as a primary research approach of fluid flow pattern, is not easy and economical to perform in large-scale or complex equipment, but the residence time distribution (RTD) experiment has the advantages of simplicity and convenience. In order to estimate the flow pattern with RTD experiments, taking the typical baffle structure as an example, several groups of structures were designed to compare and analyze the residence time distribution and the flow patterns corresponding to the structures, which can provide clues for short circuits judgement and determination of reasonable structures. The results showed that the short circuit and dead zone in the equipment were relativistic. The peak time and tailing of the RTD density function curve can be used to judge the short circuit and dead zone in the equipment. This conclusion can provide a theoretical basis for equipment design. The number of tanks in the multi-tank series model and the peak time and variance of the RTD curve were used to analyze the influence of flow rate, baffle gap area and plate spacing on the fluid flow pattern in the equipment. With the study of the pressure drop and the comprehensive consideration of the energy consumption and performance of the equipment, the most suitable tanks number, peak time and variance were put forward based on RTD experiments to determine the reasonable structure of the equipment, which provided a reference for the structural design of industrial baffle equipment.

Numerical study on performances of a super vortex quick separation system at riser outlet under oil steam conditions

Zhiliang ZHANG Haijun CHEN Tao CHEN Pei MOU Anjun LI Wenjun LI

The Chinese Journal of Process Engineering. 2021, 21(11): 1277-1286. DOI: 10.12034/j.issn.1009-606X.220408

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In recent years, there are many reports on super vortex quick separation (SVQS) system using air instead of oil steam, but the performance parameters such as separation efficiency are not very accurate, moreover the influence of oil steam properties on the performance of the system has not been studied. In order to promote the industrial application of SVQS system and accurately evaluate its performance, the flow fields at a series of oil steam model with different densities and viscosities in a ?600 mm×4150 mm SVQS system were simulated by the commercial software FLUENT 2019 R3. The influences of oil steam properties on the dimensionless tangential velocity and pressure drop were studied respectively by single factor analysis. The distribution law of residence time of different oil steam in SVQS were analyzed by employing the scalar transport equation. The simulation result showed that the dimensionless tangential velocity of oil steam in SVQS increased as the density increasing or decreasing of viscosity and the maximum dimensionless tangential velocity can reach 0.912. Both density and viscosity had logarithmic function relations with the dimensionless maximum tangential velocity. The residence time of oil steam in SVQS reduced with the increasing of density of oil steam or the decrease of viscosity that the minimum average residence time was 6.279 s. It was found that the pressure drop and drag coefficient were not only affected by the structural parameters of the SVQS system, but also impacted by the viscosity of oil steam. Both pressure drop and drag coefficient had a logarithmic function relationship with the viscosity of oil steam. Meanwhile, the formulas of dimensionless tangential velocity, pressure drop and resistance coefficient related to oil steam parameters were obtained by fitting, which had good universality and can provide data for the structural optimization of SVQS system.

Analysis of characteristics of liquid falling film flow on corrugated sheet packing

Junhua LIAO Peng XUE Mengjing ZHAO Junjie LIU Ling JIN

The Chinese Journal of Process Engineering. 2021, 21(11): 1287-1296. DOI: 10.12034/j.issn.1009-606X.220422

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The falling film flow characteristics of the liquid in corrugated sheet packing are the key factors affecting its mass transfer performance. In this work, a falling film flow experimental bench was built and combined with computational fluid dynamics to study the falling film flow of the corrugated sheet, the influence of spray density and corrugation tilt angle on flow characteristics was analyzed, and quantitative information of average liquid film thickness and the effective wetting area was obtained through three-dimensional simulation. The results showed that the three-dimensional CFD model can accurately predict the liquid falling film flow behavior and calculate the characteristic parameters. The flow of liquid on the corrugated sheet was not homogeneous but was classified as two kinds of forms: groove flow and rivulet flow. As the spray density was low, the liquid flow formed a groove flow in the trough while it changed as rivulet flow along the adjacent ripples when the spray density reached 400 m3/(m2?h), compared with channel flow, the rivulet form was more beneficial to increase the contact area of gas and liquid. However, no matter which flowed mode, the overall wettability of the corrugated sheet was poor, and the thickness distribution of the liquid film was not uniform, which was not conducive to mass transfer. The tilt angle of the corrugation had a greater influence on the flow characteristics of the falling film, after extensive research on the tilt angle, it was found that when the tilt angle was 90°, it was more conducive to increasing the effective wetting area and reducing the average liquid film thickness. The results of this study have theoretical guiding significance for controlling the liquid film thickness and increasing the effective wetting area during the falling film flow, and also have application value for improving the corrugated sheet structure and increasing the mass transfer efficiency.

Extraction of vanadium and zinc by sulfuric acid leaching from descloizite

Kelun ZHANG Bo LI Yonggang WEI Hongao XU

The Chinese Journal of Process Engineering. 2021, 21(11): 1297-1303. DOI: 10.12034/j.issn.1009-606X.220376

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Vanadium lead zinc ore contains a variety of valuable metals with high V grade and high economic value. In this work, vanadium and zinc were extracted from the mine by sulfuric acid leaching method, and the thermodynamics of the leaching process was analyzed. The effects of sulfuric acid concentration, liquid-solid ratio, leaching time, stirring rate and leaching temperature on the leaching rate of vanadium, lead and zinc were studied through conditional experiments. The results showed that the hydrolysis of V in the leaching solution and hydrolysis products containing V remained in the leaching residue at high pH and higher temperatures, which affected the leaching rate of V. The optimum leaching conditions were as follows: sulfuric acid concentration 200 g/L, liquid-solid ratio 3:1, leaching time 30 min, stirring rate 200 r/min and leaching temperature 30℃. Under the optimum conditions, the V leaching rate was 97.90%, the Zn leaching rate was 97.11%, the Fe leaching rate was less than 1%, and the Pb leaching rate was less than 0.01%. The results of kinetic analysis showed that the reaction rate of leaching process was controlled by diffusion process. In the acid leaching process, V and Zn entered the leaching solution, and Pb and Fe remained in the leaching residue. The resulting leaching solution can be separated by ion exchange or extraction. The leaching residue contained 0.41wt% vanadium, 0.61wt% zinc, 15.50wt% iron and 47.70wt% lead. The main components were PbSO₄ and FeO(OH), which can be returned to the pyrometallurgical lead smelting system.

The simultaneous recovery of lead and tin in zinc oxide dust by carbothermic reduction

Foguang LEI Minting LI Chang WEI Zhigan DENG Xingbin LI Gang FAN

The Chinese Journal of Process Engineering. 2021, 21(11): 1304-1314. DOI: 10.12034/j.issn.1009-606X.220399

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A carbothermic reduction peocess was used to achieve the simultaneous separation and recovery of lead, tin and zinc in zinc oxide dust. The effects of pretreatment to remove fluorine, chlorine and sulfur (Na2CO3-alkali washing and calcination) and adding additives (CaO and bentonite) on the volatilization rate of lead and tin in carbothermic reduction process were investigated. The results show that the volatilization rate of lead and tin were 78.58% and 95.97% respectively when the dust was not pretreated and the conditions were the temperature of 1300℃, the reductant dosage of 14.04% and the holding time of 120min. Under the same conditions, alkali washing and calcination could reduce the volatilization rate of lead and tin. After alkali washing, the volatilization rate of lead and tin reduced to 12.97% and 16.99% respectively. After calcination, the volatilization rate of lead and tin reduced to 30.46% and 57.83% respectively. Increasing the dosage of CaO is beneficial to reduce the volatilization rate of lead and tin. When the dosage of CaO was 5%, the volatilization rate of lead and tin drops to 32.16% and 57.7% respectively. Increasing the dosage of bentonite promotes the volatilization of lead, but has no obvious effect on volatilization of tin. When the dosage of bentonite was 5%, the volatilization rate of lead and tin drops to 37.44% and 83.25% respectively. Using this process, lead-tin alloy (Pb＞70%，Sn＞5%) and crude zinc (Zn＞63%，Pb＞9%) are finally obtained at the same time.

Comparative study on typical vertical flame spread characteristics of EPS insulation material under concave structure

Xinjie HUANG Jinda GAO Zhijie ZHOU Xiaofeng ZHANG Junjie HU

The Chinese Journal of Process Engineering. 2021, 21(11): 1315-1322. DOI: 10.12034/j.issn.1009-606X.220315

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The vertical upward and downward flame spread characteristics of insulation material EPS in the concave structure were studied by building a small-scale flame spread experimental platform. The changes of parameters such as flame structure characteristics, flame spread speed, mass loss rate, flame temperature were comparatively analyzed. The research results showed that in the process of vertical upward spreading, EPS appeared stagnant combustion; this was mainly caused by the large gas flow generated by the chimney effect. However, in the process of vertical downward spreading, the flame spread speed was obviously accelerated due to the increase of EPS accumulated in the process of flame spread and the effect of the reverse stack effect. During the upward spreading process, the length of the pyrolysis zone was significantly longer than the pyrolysis zone spreading downwards. At the same time, the flame was basically inclined to both sides of the concave groove, and the molten dripping of the material can be clearly seen, but it was spreading downwards almost no molten spilled liquid. The mass loss rate in the process of flame spread was affected by the flame height to a great extent, which was mainly manifested in two stages: initial oscillation stage and stable oscillation stage. The influence of the stack effect on it was transient and temporary. In the unburned area, the flame temperature experienced two temperature peaks, and the first peak was larger than the second peak in the case of upward spread; while the first peak was smaller than the second peak for downward propagation. This was mainly due to the structure of the flame and the directional characteristics of the chimney effect, resulting in the generation of two different peak sizes. The research results of this work can provide early theoretical and reference value for the study of flame spread characteristics under actual concave structures.

Effect of coordination of acoustic wave and chemical agglomeration on fine dust agglomeration in converter

Yuqing ZHANG Yimin YIN Haiying LI Qiudong HU

The Chinese Journal of Process Engineering. 2021, 21(11): 1323-1329. DOI: 10.12034/j.issn.1009-606X.220343

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At present, air pollution caused by heavy industrial products such as iron and steel, thermal power generation and cement is still very serious in China. The main reason is the low dust removal effect of PM2.5 and PM10 particles. To solve the problem of difficult treatment of fine dust in converter flue gas, the collaborative treatment method based on acoustic waves and chemical agglomeration was used to pretreat converter flue gas dust in an evaporative cooler to improve the dust removal efficiency of fine dust. Single-factor experiment and orthogonal experiment were used to study the agglomeration effect of fine dust under different factors, such as the type of flocculants [acrylamide (PAM), sodium carboxymethyl cellulose (CMC) and xanthan gum (XTG)], flocculant concentration, acoustic frequency and acoustic field time. The results of the single-factor experiment showed that the agglomeration effect of the three flocculants was PAM>CMC>XTG from large to small, taking the increase of the peak particle size of the fine dust as the evaluation standard. The agglomerating effect was the best when the concentration of agglomerating agent was 0.1 g/L, the effect was obvious when the acoustic frequency was 33 kHz, and the effect was the best when the acoustic residence time was 15 s. The synergistic effect of the acoustic wave and chemical agglomeration was better than that of chemical agglomeration and acoustic wave alone. The results of the orthogonal experiment showed that when the concentration was 0.1 g/L, the acoustic frequency was 33 kHz, and the acoustic residence time was 15 s, the agglomeration effect was the most significant. The peak particle size increased from 3.311 μm to 43.59 μm, and the dust removal efficiency of the corresponding electrostatic precipitator reached 97%. From the experimental comparison of the coordination mechanism and the single agglomeration mechanism, the synergetic mechanism combined the advantages of a single agglomeration mechanism such as chemistry and acoustic waves, and provided a feasible basis for multi-mechanism dust removal in the industry. The results can provide reliable basic data for improving the removal of fine dust in the flue gas of iron and steel production, and lay a foundation for improving the removal efficiency of fine dust in the industrial flue gas.

Study on wettability difference of profiled fiber based on optical measurement

Feng CHEN Yuchen HU Jinjie LU Xiaolin WU Zhongli JI

The Chinese Journal of Process Engineering. 2021, 21(11): 1330-1337. DOI: 10.12034/j.issn.1009-606X.221226

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Gas-liquid coalescence filtration is widely used in process industry. The wettability of fiber material is the key factor affecting the filtration performance of coalescing element. Based on the optical measurement method, the wettability difference of liquid on the surface of single triangular, trilobal and cruciform fiber was studied. The change process of liquid contact angle and volume was analyzed, and the influence of liquid type, fiber inclination angle and profiled degree on wettability was investigated. The results showed that with the decrease of liquid surface tension, the contact angle reduced and therefore the wettability enhanced. However, the volatility of liquid was easy to cause the actual contact angle to be greater than the theoretical one. The contact angle of triethylene glycol, dioctyl sebacate and silicone oil did not change with time. The contact angle of water and ethanol gradually decreased with time, and the decreasing rate of ethanol was greater due to the higher evaporation rate. The contact angle of liquid presented a "V" shape distribution with the inclination angle of the profiled fiber, that was, there was a minimum point (inclination angle of 30°) to make the fiber wettability reach the best. When the profiled degree of the fiber increased, the contact angle difference between different liquid decreased and the overall wettability improved, which indicated that the fiber with higher profiled degree should be selected as the material of prefilter layer or drainage layer.

Preparation and electrochemical performance investigation of molybdenum dioxide nanorods

Zengli GAO Shouzhi YI Haiyan TANG Hongbin XU

The Chinese Journal of Process Engineering. 2021, 21(11): 1338-1345. DOI: 10.12034/j.issn.1009-606X.220355

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With high conductivity, high melting point and large specific capacity, molybdenum dioxide (MoO2) nanorods have a wide application prospect in the field of electrode materials for supercapacitors. Although there are many methods to prepare MoO2 nanorods, most of them have disadvantages of a complicated process, low yield, high production cost and easy to introduce impurities. Moreover, the prepared MoO2 products have the characteristics of non-uniform morphology, poor dispersibility and inferior electrochemical performances. In this work, the precursor of peroxymolybdic acid prepared by hydrogen peroxide and molybdenum powder was used as the source of molybdenum, and PEG (8000) was used as the template. The molybdenum-containing hybrid with a band structure was prepared by mixing the precursor and template with stirring and thermal insulation. The nano-rod-shaped MoO2 was prepared through a two-stage hydrometallurgical process using the hybrid compound as raw material. X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), X-ray energy spectrometer (EDS) and scanning electron microscope (SEM) were used to analyze the phase, surface composition and morphology of the obtained MoO2 nanorods. The electrochemical capacitance behavior of MoO2 nanorods was studied using a three-electrode system and two-electrode system, and the performance of MoO2 nanorods as electrode assembly capacitors was also investigated. The results showed that the prepared MoO2 had a rod-like structure with 500 to 800 nm in length and with 100 to 200 nm in width. The MoO2 had uniform morphology and size with good dispersion and high purity. The specific capacitance of MoO2 nanorods was 366.7 F/g for the three-electrode system at the current density of 1 A/g, and the specific capacitance for the two-electrode system was 290.4 F/g, and the capacitance retention rate was higher than 72% after 2000 cycles of charging and discharging at 5 A/g current density, both showing the good electrochemical performance of MoO2 nanorods. The research results of this study can provide a new method for the preparation of other nano metal oxides.

Preparation and characterization of temperature/pH dual response nitrifying bacteria gel spheres

Qiong WAN Yingchun REN Zhixiao ZHAO Xinyan ZHANG Wenjing WANG Jingyu HAO Xuan LI Kai JÜ

The Chinese Journal of Process Engineering. 2021, 21(11): 1346-1354. DOI: 10.12034/j.issn.1009-606X.220385

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Calcium alginate (CA) nitrifying bacterial gel spheres with uniform particle size were drop-produced by the embedding method, and the effect of different concentrations of NaCl on the diffusion and mass transfer properties and mechanical strength of CA nitrifying bacterial gel spheres was investigated using the controlled variable method. The temperature-sensitive material N-isopropylacrylamide (NIPAAm) and the pH-sensitive material acrylic acid (AA) were combined onto the surface of NaCl-modified CA nitrifying bacteria gel spheres by stepwise polymerisation to form a temperature/pH-responsive layer on the surface of the spheres. A new type of temperature/pH dual response nitrifying bacterial gel spheres was prepared. NH4+?N was used as an indicator to investigate the ammonia nitrogen removal performance of nitrobacterial gel spheres and their sensitivity to temperature and pH under different preparation conditions, and the prepared temperature/pH dual response nitrifying bacterial gel spheres were applied to the actual nitrogen removal treatment of wastewater. The results showed that the CA nitrifying bacterial gel spheres modified with a concentration of 0.3% NaCl solution had the best diffusive mass transfer performance. The best ammonia removal performance of temperature/pH dual response nitrifying bacterial gel spheres was achieved at 200 mg of NIPAAm and 4 mg of MBA in 15 mL of temperature?response solution and at 200 mg of AA and 4 mg of MBA in 10 mL of pH?response solution. When the temperature was as low as 4℃, the ammonia nitrogen removal rate could reach 29.45%, when the pH was 9, the ammonia nitrogen removal rate could still reach 35.48%. Temperature/pH dual response nitrifying bacterial gel spheres have good temperature and pH sensitivity, and also have good effect on the removal of ammonia nitrogen in the actual wastewater, which is conducive to improve the nitrification effect of nitrifying bacteria under low temperature and alkaline conditions.

Temperature sensitivity of methane hydrate formation in porous media near freezing point

Jianzhong ZHAO Qiang GAO Dong YANG Chi ZHANG

The Chinese Journal of Process Engineering. 2021, 21(11): 1355-1363. DOI: 10.12034/j.issn.1009-606X.220367

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Hydrate based technology is a potential approach for gas storage, separation, desalination, and carbon dioxide capture. At the same time, natural gas hydrate is also one of the potential important energy because of its huge resources. Most natural gas hydrates exist in natural porous media while it has unique properties in porous media. At the same time, with the increase of global temperature, the sensitivity of methane hydrate sediment has uncertainty on reservoir stability and potential environmental impact at low temperature. In this study, the formation process and kinetics of gas hydrates in silicon sand (0.1~0.5 mm) were investigated. The pressure and temperature profile, reaction rate, and gas uptake were studied at 273.75, 273.85, and 273.95 K. According to the change of temperature and reaction rate, the hydrate formation process presented three obvious stages. In different stages, the temperature and reaction rate showed unique characteristics, such as peak value, duration, and so on. At the same time, they were very sensitive to the reaction temperature. In the first stage, the peak value of temperature was the highest, but the duration time was the shortest. In the second and third stages, the temperature peak was gentle and the duration time was relatively long. The change of reaction rate was like that of temperature, the peak and average value of reaction rate decreased with the increase of temperature. The final gas content and hydrate saturation also slightly decreased with the increase of reaction temperature. The final saturation of hydrate, aqueous phase, and gas-phase was calculated in the pore of silicon sand. The analysis of the results showed that the commencement of hydrate growth was sensitively related to temperature, and the scatter of the onset of hydrate growth was greater at low temperatures.

Analysis of thermal properties of paraffin/silver nanoparticle CPCM in cylindrical system

Runjie ZHANG Bo LUO Zhongjie LI Guojun YANG Yixin LIN

The Chinese Journal of Process Engineering. 2021, 21(11): 1364-1372. DOI: 10.12034/j.issn.1009-606X.220349

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Because of the latent heat of phase change, phase change materials (PCM) are used in thermal management in various fields. As a new energy source, lithium power batteries have been widely used in electric vehicles in recent years. As an effective passive cooling method, phase change cooling can effectively slow down the heat accumulation of lithium batteries. To apply phase change materials to alleviate the thermal runaway of lithium batteries, a paraffin/silver nanoparticle composite phase change material (CPCM) cylindrical system was established, and the phase change model and the volume of fluid (VOF) model were used to study the melting process of phase change materials. The change of the air/paraffin gas-liquid interface and the liquid phase distribution of the paraffin was obtained during the initial period, which was in good agreement with the experimental results. On this basis, the heat absorption and heat storage of the phase change process were analyzed. In the initial stage of melting, the bottom solid-phase heat storage was higher than the wall heat flux. As the liquid phase area expanded, the melting rate decreased, and the wall heat flux was basically the same as the solid phase heat storage of the PCM. After 360 s, the heat flux on the top wall and the solid-phase heat storage continued to decrease to zero. Simultaneously, simulations of paraffin/silver nanoparticle CPCM with different mass fractions showed that adding 0.5wt%~2wt% of silver nanoparticles can improve the thermal conductivity of paraffin, but the latent heat reduced. When the phase change process was over, the heat absorbed by the material was converted into sensible heat. The heat transfer on the bottom surface was reduced and energy mainly carried out through the vertical wall. Besides, the flow of the liquid phase during the melting process was analyzed. The liquid layer of the phase change material thickened, and the Nusselt number decreased and tended to stabilize. Increasing the silver nanoparticle concentration reduced the Nusselt number.

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