Heat Addition Research Articles

Predicting Drying Performance of Osmotically Treated Heat Sensitive Products Using Artificial Intelligence

The main goal of this research is to develop and apply a robust Artificial Neural Networks (ANNs) model for predicting the characteristics of the osmotically drying treated potato and apple samples as a model heat-sensitive product in vacuum contact dryer. Concentrated salt and sugar solutions were used as the osmotic solutions at 27C. Series of experiments were performed at various temperatures of 35C, 40C, and 55C for conduction heat input under vacuum ( −760 mm Hg) condition. Some experiments were also performed in a pure vacuum without heat addition. Dimensionless moisture content (DMC), effective moisture diffusivity, and mass flux were considered as the performance parameters in this study. Results revealed that the osmotic dehydration using a concentrated sugar solution shows a higher reduction in the initial moisture loss of 19.87% compared to 5.3% in the salt solution. Furthermore, a significant enhancement of drying performance of about 27% in DMC was observed for both samples at vacuum and 40C compared to pure vacuum drying conditions. Using the experimental data, a robust artificial neural network (ANN) was proposed to describe the osmotic dehydration’s behavior on the drying process. The ANN model outputs are the dimensionless moisture contents (DMC), the diffusivity, and the mass flux. Whereas the ANN inputs were the drying time, the percent of sugar solution, and the percent of salt solution. For the ANN apple’s model, the minimum root mean square error (RMSE) values were 0.0261, 0.0349 and 0.0406, for DMC, diffusivity, and mass flux, respectively. Whereas the best correlation coefficients of the above three parameters’ determination values were 0.9909, 0.9867 and 0.9744, respectively. For the ANN potato’s model, the minimum RMSE values were 0.0124, 0.0140 and 0.0333, for DMC, diffusivity, and mass flux, respectively. And the best correlation coefficients of the parameters’ values were found 0.9969, 0.9968 and 0.9736, respectively. Accordingly, the ANN model’s prediction has a perfect agreement with the experimental dataset, which confirmed the ANN model’s accuracy.

Petrogenesis and geodynamic setting of the Late Carboniferous granodiorite porphyry in Miaoergou pluton, southern West Junggar

位于西准噶尔南部的庙尔沟岩体主体由碱长花岗岩和少量紫苏花岗岩组成。本文在前人工作基础上，以岩体东南边缘新发现的花岗闪长斑岩为研究对象，开展岩石学、年代学和Hf同位素以及全岩地球化学研究，确定花岗闪长斑岩形成时代、揭示岩石成因类型及源区属性、探讨其与碱长花岗岩和紫苏花岗岩岩浆演化成因联系及其形成的深部动力学过程。锆石U-Pb定年结果显示，花岗闪长斑岩形成于317.4±1.9Ma，为晚石炭世早期岩浆活动的产物，明显早于紫苏花岗岩（~307Ma）和碱长花岗岩（~303Ma）。岩石地球化学数据表明，花岗闪长斑岩具有较高硅、中等铝，贫钙、铁、镁，富集Rb、K、Th、U，强烈亏损Nb、Ta、Ti的特征，为钙碱性弱过铝质I型花岗岩；紫苏花岗岩更多的表现出钙碱性-高钾钙碱性镁质I型紫苏花岗岩特征；碱长花岗岩为碱性准铝质-弱过铝质A型花岗岩。锆石Hf同位素分析结果表明，花岗闪长斑岩、紫苏花岗岩和碱长花岗岩均具有高正的ε_Hf（t）值（+11.6~+15.8）和年轻的二阶段模式年龄（325~600Ma），表明其原始岩浆主要起源于亏损地幔新衍生的年轻地壳物质。综合分析认为，庙尔沟岩体花岗闪长斑岩形成于晚石炭世早期洋壳俯冲背景，由底侵的、受流体交代的幔源基性岩浆与其诱发的年轻下地壳酸性岩浆在深部混合而成。紫苏花岗岩和碱长花岗岩形成于弧后伸展背景，前者是伸展初期继续底侵于下地壳的幔源玄武质岩浆降温释放大量的水和热诱使早期侵位于下地壳的镁铁质岩石再次发生部分熔融的产物，后者是伸展后期大规模软流圈地幔上涌底垫加热年轻中下地壳使其部分熔融而成。;The Miaoergou pluton, located in southern West Junggar, is mainly composed of alkali-feldspar granites with small amount of charnockites. On the basis of previous researches, this paper mainly focuses on the newly discovered granodiorite porphyry in southwestern margin of the Miaoergou pluton. A comprehensive study of petrographical, zircon U-Pb geochronological and in-situ Hf isotopic, whole-rock geochemical analyses were carried out to determine its diagenetic age and reveal the petrogenesis, the nature and composition of the magma source of this porphyry, and furthermore, to discuss the genetic relationships among the granodiorite porphyries, alkali-feldspar granites and charnockites and their geodynamic processes. LA-ICP-MS zircon U-Pb dating for the granodiorite porphyry yielded crystallization age of 317.4±1.9Ma, defining an early Late Carboniferous magmatic event in southern West Junggar, which is significantly earlier than the ages of charnockites (~307Ma) and alkali-feldspar granites (~303Ma). The geochemical characteristics indicate that the studied granodiorite porphyries belong to cal-alkaline weakly peraluminous I-type granite, and are characterized by slightly high silicon, medium aluminum, but low ferrum, calcium and magnesium, and also enrichment in Rb, K, Th, U with pronounced negative Nb, Ta and Ti anomalies. The charnockites possess calc-alkaline to high-K calc-alkaline magnesian I-type charnockite affinities, which were previously considered A-type granites by some geologists, while alkali-feldspar granites belong to alkaline metaluminous to weakly peraluminous A-type granites. In-situ zircon Hf isotope analyses show that these granites have high positive ε_Hf(t) values (+11.6~+15.8) and very young two-stage Hf model ages of 325~600Ma, indicating that the magma was sourced from juvenile crust originated from depleted mantle during the Late Neoproterozoic to Early Carboniferous period. In association with previous analysis, it is proposed that the Miaoergou granodiorite porphyries were formed in an oceanic crust subduction setting during early Late Carboniferous. They are probably the products of the acidic magma formed by partial melting of the juvenile lower crust and mixed with the underplated basaltic magma derived from the fluid metasomatic mantle wedge in the deep crust to some extent. Both the charnockites and alkali-feldspar granites were formed in a back-arc extensional setting related to the northwestward subduction of the Junggar oceanic crust. The charnockites may be generated by re-melting of juvenile lower crust mafic rocks, probably triggered by addition of water and heat released from cooling of underplated depleted mantle-derived basaltic magma during the incipient rifting stage of the back-arc basin, and the alkali-feldspar granites may be generated by partial melting of the juvenile middle-lower crust induced by the large-scale upwelling of asthenosphere during the later stage of the back-arc extension.

Computational and sensitivity analysis of a dual purpose solar chimney for buildings

The solution(s) to issues of electric power availability is a great concern in many places in both underdeveloped and developing countries. A solution to this problem is proposed in the use of the Solar Chimney (SC). In this study the potentials of using the Solar Chimney is analysed as a means of improving the power problem and providing ventilation at the same time in building in Nigeria. The Solar chimney (SC) being a natural flow device that uses solar irradiation to cause buoyancy in flowing air by means of the addition of heat, thereby converting the solar thermal energy of the sun into kinetic energy in the flowing air. The SC had been developed for the purpose of ventilation for over two millennia now, while the SC has also been developed in recent time for power generation. In this study computational analysis was carried out using the ANSYS Fluent CFD package together with a statistical package “Design Expert” to carryout sensitivity analysis to determining the potentials of the SC system for buildings. A 23 factorial experiment was simulated and analysed on a 4 m × 4 m × 4 m room. Results revealed by the simulated factorial experiments that the effect of interactions of parametric factors of the SC, chimney height, width and Solar heat flux, were of great importance. The power output from the SC is about 25 W/m2, with a channel velocity of 1.5 m/s. The room temperature was maintained as its initial value of 300 K, with an increase in room average velocity to about 1.5 m/s.

Drag Control by Hydrogen Injection in Shocked Stagnation Zone of Blunt Nose

The main motivation of the current study is to propose a high-pressure hydrogen injection as an hybrid active flow control technique in order to manipulate the flow-field in front of a blunt nose during hypersonic flight. Hydrogen injection can lead to self-ignition under the right environment conditions in a stagnation zone, and may cause thermal heat addition through combustion and provide the counterjet effect together by pushing bow shock upstream. The axisymmetric numerical simulations for the hemispherical blunt nose are performed at a Mach 6 freestream flow with 10000 Pa pressure and 293 K temperature. The sonic and supersonic hydrogen and air injections are compared for drag reduction at the same stagnation pressure ratio PR and momentum ratio (RMA). The sonic air and hydrogen injection scenarios show similar performance in terms of drag reduction and similar SPM flow features, but hydrogen injection has a mass flow rate 3.76 times lower than air. Supersonic hydrogen injection at Mj 2.94 behaves differently than supersonic air injection and can achieve up to 60 % drag reduction at lower PR and LPM mode with lower mass flow rate. Additionally, air injection achieves a drag reduction of 40 % in SPM mode at higher PR with very high mass flow rate.

Parametric analysis of a semi-closed-loop linear joule engine generator using argon and oxy-hydrogen combustion

The paper introduces a novel semi-closed-loop Linear Joule Engine Generator (LJEG) using argon as the major working fluid and oxy-hydrogen combustion for heat addition. The linear compressor and expander in the LJEG apply double-acting piston configuration to maximise power density, and an oxy-hydrogen-argon reactor has ultra-high heat transfer efficiency and emits ultimate zero carbon, NOx, and particulate emissions. The proposed LJEG is developed from a previous lab-scale LJEG prototype using air as the working fluid. A comparison study demonstrates the advantages of the new conceptual design; substituting air with argon as the major working fluid resulted in increased system speed, decreased indicated power, and over 60% indicated efficiency improvement. A further parametric analysis was conducted using a validated model to reveal the influence of different intake and exhaust valve timing, compressor/expander diameter ratio, electric load, and operating temperature. The analysis shows that the system efficiency decreases with the extended intake duration, but it could be improved with the extension of expander exhaust duration. Power output increases with longer expander intake duration, however, its relationship with diameter ratio of compressor and expander is dependent on adopted expander exhaust valve timing, a peak power output of 4.7 kW could be achieved at expander intake temperature of 1073 K. System operating temperature for the optimal performance is also highly dependent on valve timings. Piston stroke length is adversely affected by an increase in compressor/expander diameter ratio and operating temperature. Peak system efficiencies of 40% and 60% could be achieved when the compressor/expander diameter ratio is 0.70 and 0.93, respectively.

Ocean Heat Storage in Response to Changing Ocean Circulation Processes

AbstractOcean heat storage due to local addition of heat (“added”) and due to changes in heat transport (“redistributed”) were quantified in ocean-only 2xCO2 simulations. While added heat storage dominates globally, redistribution makes important regional contributions, especially in the tropics. Heat redistribution is dominated by circulation changes, summarized by the super-residual transport, with only minor effects from changes in vertical mixing. While previous studies emphasized the contribution of redistribution feedback at high latitudes, this study shows that redistribution of heat also accounts for 65% of heat storage at low latitudes and 25% in the midlatitude (35°–50°S) Southern Ocean. Tropical warming results from the interplay between increased stratification and equatorward heat transport by the subtropical gyres, which redistributes heat from the subtropics to lower latitudes. The Atlantic pattern is remarkably distinct from other basins, resulting in larger basin-average heat storage. Added heat storage is evenly distributed throughout midlatitude Southern Ocean and dominates the total storage. However, redistribution stores heat north of the Antarctic Circumpolar Current in the Atlantic and Indian sectors, having an important contribution to the peak of heat storage at 45°S. Southern Ocean redistribution results from intensified heat convergence in the subtropical front and reduced stratification in response to surface heat, freshwater, and momentum flux perturbations. These results highlight that the distribution of ocean heat storage reflects both passive uptake of heat and active redistribution of heat by changes in ocean circulation processes. The redistributed heat transport must therefore be better understood for accurate projection of changes in ocean heat uptake efficiency, ocean heat storage, and thermosteric sea level.

ZYOFIELD: Alat pasteurisasi fermentasi berbasis teknologi pulsed electric field sistem fuzzy logic dalam pengolahan yoghurt

Yogurt is a fresh and healthful fermented milk drink. This drink is made by a pasteurization process to eliminate pathogen bacteria in milk. The process was followed by a fermentation process with the help of Streptococcus thermophilus and Lactobacillus bulgaricus bacteria. The conventional pasteurization and fermentation process take a relatively long time, where the pasteurization process takes 15 minutes and the fermentation process takes 48 hours. In addition to the long process, the thermal pasteurization process can decrease the taste, color, and nutritional content of milk. The purpose of this research is to create a tool that can speed up the manufacture of yogurt without reducing the nutritional content of milk. ZYOFIELD is a tool that combines a Pulsed electric field (PEF) with an automatic fermentation system. PEF becomes a new method of milk pasteurization without the addition of heat, where the process temperature is 25o C so it may not reduce the important content in milk. This method utilizes an electric shock with a voltage of 20-80 kV to inactivate the pathogen bacteria within a short time of 5 minutes. ZYOFIELD is integrated with a controlled fermentation system where the fermentation temperature is maintained at 40-45° C, where at this temperature the fermentation process becomes optimum for 6 hours. The temperature on the fermentor is controlled by a fuzzy logic intelligent control system to regulate the temperature of the fermentation.

Combining brine or CO2 geothermal preheating with low-temperature waste heat: A higher-efficiency hybrid geothermal power system

Abstract Hybrid geothermal power plants operate by using geothermal fluid to preheat the working fluid of a higher-temperature power cycle for electricity generation. This has been shown to yield higher electricity generation than the combination of a stand-alone geothermal power plant and the higher-temperature power cycle. Here, we test both a direct CO2 hybrid geothermal system and an indirect brine hybrid geothermal system. The direct CO2 hybrid geothermal system is a CO2 Plume Geothermal (CPG) system, which uses CO2 as the subsurface working fluid, but with auxiliary heat addition to the geologically produced CO2 at the surface. The indirect brine geothermal system uses the hot geologically produced brine to preheat the secondary working fluid (CO2) within a secondary power cycle. We find that the direct CPG-hybrid system and the indirect brine-hybrid system both can generate 20 % more electric power than the summed power of individual geothermal and auxiliary systems in some cases. Each hybrid system has an optimum turbine inlet temperature which maximizes the electric power generated, and is typically between 100 °C and 200 °C in the systems examined. The optimum turbine inlet temperature tends to occur where the geothermal heat contribution is between 50 % and 70 % of the total heat addition to the hybrid system. Lastly, the CO2 direct system has lower wellhead temperatures than indirect brine and therefore can utilize lower temperature resources.

Concurrent Heat and Intermittent Hypoxic Training: No Additional Performance Benefit Over Temperate Training.

To examine whether concurrent heat and intermittent hypoxic training can improve endurance performance and physiological responses relative to independent heat or temperate interval training. Well-trained male cyclists (N = 29) completed 3 weeks of moderate- to high-intensity interval training (4 × 60 min·wk-1) in 1 of 3 conditions: (1)heat (HOT: 32°C, 50% relative humidity, 20.8% fraction of inspired oxygen, (2)heat + hypoxia (H+H: 32°C, 50% relative humidity, 16.2% fraction of inspired oxygen), or (3)temperate environment (CONT: 22°C, 50% relative humidity, 20.8% fraction of inspired oxygen). Performance 20-km time trials (TTs) were conducted in both temperate (TTtemperate) and assigned condition (TTenvironment) before (base), immediately after (mid), and after a 3-week taper (end). Measures of hemoglobin mass, plasma volume, and blood volume were also assessed. There was improved 20-km TT performance to a similar extent across all groups in both TTtemperate (mean ±90% confidence interval HOT, -2.8% ±1.8%; H+H, -2.0% ±1.5%; CONT, -2.0% ±1.8%) and TTenvironment (HOT, -3.3% ±1.7%; H+H, -3.1% ±1.6%; CONT, -3.2% ±1.1%). Plasma volume (HOT, 3.8% ±4.7%; H+H, 3.3% ±4.7%) and blood volume (HOT, 3.0% ±4.1%; H+H, 4.6% ±3.9%) were both increased at mid in HOT and H+H over CONT. Increased hemoglobin mass was observed in H+H only (3.0% ±1.8%). Three weeks of interval training in heat, concurrent heat and hypoxia, or temperate environments improve 20-km TT performance to the same extent. Despite indications of physiological adaptations, the addition of independent heat or concurrent heat and hypoxia provided no greater performance benefits in a temperate environment than temperate training alone.

Development of a High Protein Beverage Based on Amaranth.

The objective of this study was to formulate a beverage based on amaranth proteins, stable and nutritious. The process of obtaining the beverage was based on the existing knowledge about starch separation techniques and techno-functional properties of the amaranth proteins. Gums, gellan and xanthan were added to the protein extract and it was heat-treated at 80°C during 20min. A beverage with a composition similar to skim cow's milk was obtained (3.42 ± 0.08; 0.60 ± 0.06; 1.9 ± 0.4; 0.43 ± 0.01; 3 and 90.58 ± 0.01% for proteins, lipids, fiber, ashes, carbohydrates and water, respectively). Thermal treatment caused the denaturation and aggregation of the proteins, while the addition of gums induced a decrease in the sensitivity to heat treatment of the proteins. Formation of protein aggregates and gum-protein complexes was characterized by electrophoresis, differential scanning calorimetry, and particle size distribution. Heat treatment and addition of gums generated macrocomplexes with enhanced absolute value of ζ-potential, which contributed to the high colloidal stability of amaranth-based beverage. This beverage is suitable for vegans, celiac patients, and lactose intolerants.

Microstructure and wear behavior of a Cr-Mo-Nb alloyed manganese steel

In this study, microstructure and wear behavior of chromium, molybdenum and niobium alloyed manganese steel were examined and compared to manganese steel containing a low chromium content. Two heat treatments were applied one at 1050 °C and the other at 1100 °C followed by water quenching. The microstructures were characterized by optical microscopy and scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS). Rockwell C hardness (HRC) and Vickers microhardness were also measured. Wear behavior in dry conditions was investigated under a load of 300 N using pin-on-disc method. Tribological behavior in boundary lubricated conditions under a load of 60 N at high temperature (100 °C) was studied using a custom-made reciprocating tribometer by measuring the mass loss and the friction coefficient. 5W-40 engine oil was used as lubricant. AFM analysis and roughness 2D and 3D of the tested samples were measured. The results show that the as-cast microstructure of the studied manganese steels consists of an austenitic matrix and secondary carbides. Heat treatments at high temperatures change the microstructure and favors the formation of martensite and retained austenite. The increase of heat treatment temperature and addition of Cr, Mo and Nb increase the rate of the formed martensite, which improves the hardness, the wear resistance and the tribological behavior. 5W-40 engine oil favors the formation of tribofilm under the mechanical action during the test, which decreases the friction coefficient of heat treated chromium, molybdenum and niobium alloyed manganese steel. In addition, this oil promotes a polishing wear of the same steel heat treated at 1100 °C and colored martensite in blue.

An Analysis of Pumped Thermal Energy Storage With De-coupled Thermal Stores

Results from the first demonstration of Pumped Thermal Energy Storage (PTES) were published in 2019, indicating an achieved turn-round efficiency of 60-65% for a system capable of storing 600kWh of electricity. PTES uses a theoretically reversible thermodynamic cycle involving compression and expansion stages with constant pressure heat addition and rejection to hot and cold thermal stores. Energy storage turn-round efficiency largely depends on the isentropic efficiencies of the compression and expansion equipment, the thermal effectiveness of the thermal stores, the presence of circuit pressure drops, heat leaks to and from the system and electrical machine efficiencies. We present a simulation model of a PTES system which is used to produce an inventory of the relative magnitudes of the various system losses. We consider the feasibility of a large-scale, 1GWh nominal storage capacity, PTES system with de-coupled thermal stores; and provide comparison with the so far more investigated, coupled system. Based on ambitious yet realistic component performances, we calculate an energy storage turn around efficiency of 65.3% and 59.5% for the coupled and de-coupled systems respectively. Even with dwell times in the charged state as long as 5 days, a turn-round efficiency of over 50% is still predicted in both systems; suggesting that PTES could offer a viable large-scale, long duration energy store.

Detecting mislabelling in meat products using PCR-FINS.

Economically motivated adulteration (EMA) or misrepresentation of meat products is of concern, especially in developing countries, due to obvious health hazards and religious sensitivities. As Indian cooking involves prolonged heat treatments and addition of spices and condiments, species authentication of food, especially meat products, may be challenging. This study evaluated the efficacy of Polymerase Chain Reaction-Forensically Informative Sequencing (PCR-FINS) in meat speciation of highly processed meat. Further the prevalence of mislabelling in processed and deeply cooked meat products being sold in supermarkets and restaurants in a south Indian city was investigated. FINS targeting the mitochondrial cytochrome b gene and the ATP synthase gene was applied to identify meat species of 106 meat products labelled as chicken, beef, carabeef, mutton and pork. Mislabelling was detected in more than half of mutton (52.3%) and carabeef (55.5%), and in under a third (27.2%) of beef products. PCR-FINS is a reliable method for meat species identification even in highly processed food but there is a need for appropriate universal primers which can target all common species used in meat products. This study is the first of its kind from the South Indian state of Kerala.

State-Of-The-Art in Heat Addition during the Friction Stir Welding (FSW) Process by FSW Tool

Friction stir welding (FSW) is widely used to join different grades of aluminium alloy but for steel material it requires high speed rotation of FSW tool which develops high temperature on tool. This review paper is concerned with the effect of temperature in the FSW process and heat generation by the high speed of rotation on the FSW apparatus. The other parameter has also studied to show the effect on FSW tool in stir welding process. In this work different research papers and their work are presented. The variety of work on stir welding process is discussed by hypothetical analysis on past performance.

Characterization of particleboard made from oil heat-treated rubberwood particles at different mixing ratios

Particleboard was produced by mixing oil heat-treated rubberwood particles at different ratios, with the goal of achieving high dimensional stability. Rubberwood particles were soaked in palm oil for 2 h and heat treated at 200 °C for 2 h. The treated particles were soaked in boiling water for 30 min to remove oil and were tested for chemical alteration and thermal characterization via Fourier-transform infrared spectroscopy and thermogravimetric analysis. Particleboard was fabricated by mixing treated rubberwood particles (30%, 50%, and 70%) with untreated particles (70%, 50%, and 30%, respective to previous percentages) and bonded with urea-formaldehyde (UF) resin. The results revealed that oil-heat treated particles had greater thermal stability than the untreated particles. The addition of oil heat treated particles improved the physical properties of the particleboard with no significant reduction in mechanical strength. However, this was only valid for ratios of 70% untreated to 30% treated and 50% untreated to 50% treated. When a ratio of 70% oil heat treated particles was used, both the physical and mechanical properties were reduced drastically, due to bonding interference caused by excessive oil content. Particleboard made with a ratio of 5:5 (treated to untreated) exhibited the best physical and mechanical properties.

Thermodynamics analysis and performance optimization of a reheat – Regenerative steam turbine power plant with feed water heaters

This study investigates the thermodynamics performance analysis of a reheat-regenerative steam power plant using CyclePad V2.0 software. The impact of closed Feedwater Heaters (FWHs) on the functionality indices of the selected power plant was examined. Results of the study show that as the number of closed FWH increases from one to ten, the thermal efficiency and boiler efficiency rise from 42.17% to 45.97% and 79% to 96.4%, respectively. The fuel consumption, heat rejected to the condenser, heat rate, network output and heat input to the power cycle decrease from 9.697 kg/s to 4.686 kg/s, 209.32 kJ/kg to 129.68 kJ/kg, 8536.87 kJ/kWh to 8318.48 kJ/kWh, 152.22 MW to 102.89 MW and 361.11 kJ/kg to 237.98 kJ/kg, respectively as the number of FWHs increased. On the contrary, specific steam consumption increases from 0.0234 kg/kWh to 0.0370 kg/kWh. Moreover, fuel consumption decreases by 51.7% and the efficiency gain (η) successively diminish with increment in the number of closed FWHs. Also, both enthalpy rise and temperature rise increase with increase in the number of closed FWHs. As the number of heaters increases, so is the total temperature rise of feed water (Δtfw), by regeneration, less becomes the heat added to water in the boiler, more becomes the mean temperature of heat addition, and more is the cycle efficiency. This result implies that a decrease in operating cost of the plant and environmental impacts can be achieved with an increase in the number of closed FWHs. Hence, this study establishes the importance of closed FWHs in revamping the performance of a steam power plant.

An alternative architecture of the Humphrey cycle and the effect of fuel type on its efficiency

AbstractConventional gas turbines are a very mature technology, and performance improvements are becoming increasingly difficult and costly to achieve. Pressure‐gain combustion (PGC) has emerged as a promising technology in this respect, due to the higher thermal efficiency of the respective ideal gas turbine cycles. The current work analyzes two layouts of the Humphrey cycle for gas turbines with pressure‐gain combustion. One layout replicates the classical layout of gas turbine cycles, whereas an alternative one optimizes the use of pressure‐gain combustion by ensuring the operation of the combustor at stoichiometric conditions. In parallel, both cycle layouts are studied with two different fuels—hydrogen and dimethyl ether—to account for differences in combustion specific heat addition and its effect on cycle efficiency. The current work concludes with an attempt to benchmark the maximum losses of a plenum to achieve efficiency parity with the Joule cycle, for a given pressure gain over a PGC combustor. It is found that the cycle layout with stoichiometric combustion results in an increase in thermal efficiency of up to 7 percentage points, compared to the classic cycle architecture. Moreover, the thermal efficiency of the new layout is less sensitive to the turbine inlet temperature, especially at low compressor pressure ratios. The study of the two fuels has shown that the larger mass specific heat addition leads to higher cycle thermal efficiency and should be considered during the fuel choice. Finally, the maximum allowable plenum pressure loss that results to efficiency parity with the Joule cycle has been computed for a given combustor pressure gain. For turbine inlet temperatures above 1500°C, pressure gain above 1.6 would allow for at least 20% relative pressure drop in the plenum. The respective pressure gain becomes considerably higher for lower turbine inlet temperatures.

Heat treatment of polymeric PBAT/PCL membranes containing activated carbon from Brazil nutshell biomass obtained by electrospinning and applied in drug removal

Abstract This work aimed to perform a heat treatment on biodegradable polymeric membranes produced by the electrospinning technique to be used in the retention of residual drugs from water. For this, a blend with a concentration of 20 % (w/v) was produced, composed of 75 % Poly(butylene adipate-co-terephthalate) (PBAT) and 25 % poly (e-caprolactone) (PCL) (w/w), solvated in chloroform (CL) and N,N-dimethylformamide (DMF) in the proportion of 85/15 % (v/v), respectively. A portion of 10 % (w/w) activated carbon from Brazil nut shell biomass (CA-BCB) was incorporated in the polymeric solution, which was subjected to electrospinning to obtain the polymeric membranes. Thermal treatments were then carried out on the surface of the electrospun membranes. The membranes were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and membranes surface wettability by contact angle. The results of the micrograph images (SEM) showed that the incorporation of CA-BCB produced fibers with smaller diameters without changing the chemical structure of the polymers, which was confirmed by the FTIR analysis. With the addition of activated carbon, there was an increase in the thermal stability of the material, which was confirmed by TGA analysis. In the permeability tests carried out with distilled water (1290 kg h−1 m-2) and tetracycline hydrochloride solution (TCH), 1220 kg h−1 m-2 with 200 min of operation. A PBAT/PCL membrane retention capacity, with heat treatment and addition of CA-BCB, of approximately 67 % was verified. This result suggests that the membranes produced by electrospinning, together with a heat treatment, can be used to retain emerging pollutants.

Effect of Chemical Composition and Heat Treatments on the Microstructure and Wear Behavior of Manganese Steel

The present paper analyzes the effect of the chemical composition and heat treatments on the microstructure and wear resistance of manganese steels. The studied steels are melted in an electric arc furnace. Alloying elements (Cr + Ni + Nb) are added as ultra-fine powder in a well-heated ladle. Samples are subjected to two heat treatments: one at 1100 °C and the other at 1050 °C, and then quenched in water. Optical microscopy, scanning electron microscopy and X-ray diffraction are used to evaluate the microstructural changes. Hardness and microhardness measurements, mass loss and friction coefficient were also performed to determine the wear behavior of the studied steels. The results indicated that the microstructure of the manganese steel in the as-cast state consists of an austenitic matrix and cementite alloyed with manganese and chromium ((Fe,Mn,Cr)3C). Increasing chromium content increases the size of the alloyed cementite (Fe,Mn,Cr)3C. Addition of niobium leads to the apparition of new secondary carbide (NbC). The heat-treated microstructures consist of martensite, retained austenite and a small quantity of precipitates. Increasing in heat treatment temperature and addition of alloying elements (Cr + Ni + Nb) increase the hardenability of the studied steel and favor the martensitic transformation. As a result, addition of niobium and increasing in chromium and nickel contents improve hardness and wear resistance of the studied manganese steel.

Analysis of Influence of Glazing Systems on Indoor Environment of a Passive Solar Building in Lhasa

Solar energy, which is inexhaustible and clean, has been widely used in passive or positive manners. A well-constructed passive solar house can improve the indoor environment and save energy of mechanical systems. Design of glazing system plays a vital role in passive solar buildings. This paper analyses influence of glazing systems on indoor environments of a passive teaching building in Lhasa, southwest on the Tibetan Plateau, China, for the purpose of optimizing retrofitting its windows. In this project no HVAC system is used, so indoor temperature is the main factor for evaluating the performance of different glazing systems. Four glazing systems were compared by computing uncomfortable hours and net heat addition of windows, using DesignBuilder. Economy is compared as well. Results show that single lowe clear 3mm (e=0.2) glazing leads to the most comfortable indoor environment in this project. Net heat of windows and comfortable rate are suggested to assess the overall performance of glazing systems. Generally speaking, we can’t use SHGC or U-Value to determine the best glass system only in the actual situation. Careful simulation is necessary to obtain the comprehensive performance of windows in a passive solar building.