Mass Flow Research Articles

Evaluation on capillary performance of multifunctional ultra-thin composite wick

Vapor chamber technology offers an effective solution for addressing challenges in battery thermal management due to its superior heat transfer efficiency per unit volume. However, achieving a lightweight and ultra-thin VC, which relies significantly on the wick structure, is crucial for its practical application. Nonetheless, reducing the thickness of the wick compromises its capillary performance, thereby impacting the thermal performance of the VC. To overcome this challenge, this paper proposes a Multifunctional Ultra-Thin Composite Wick (MUTCW) which is an integration of cover shell and wicks, aimed at enhancing capillary properties while simultaneously reducing wick thickness. A series of capillary rate-of-rise experiments were conducted to comprehensively evaluate the performance of the MUTCW. The results demonstrate that a MUTCW sintered with a 0.1 mm #200 mesh layer exhibits the most favorable capillary performance, with a wick coefficient of 19.299, an average capillary velocity of 3.5 mm/s, and an average mass flow rate of 3.32 mg/s.

Experimental demonstration of a water electrolysis Hall Effect Thruster (WET-HET) operating with a hydrogen cathode

This study presents the first experimental demonstration of a Hall Effect Thruster operating with water electrolysis-derived constituents: oxygen for the anode (thruster) and hydrogen for the cathode, both from pressurised bottles. In contrast to prior research where the thruster was operated with oxygen to the anode and xenon/krypton to the cathode, this investigation uses an advanced set-up that safely allowed the combined use of pressurised oxygen and hydrogen. Firstly, a comparative assessment between the established plasma filament cathode (utilised in previous research) and a novel LaB6 cathode (referred to as Hydrocat), both krypton-fuelled, is conducted. Results show a different IV curve for these cathodes, but negligible disparities in thruster performance for fixed discharge power and anode mass flow. Thrust, anode specific impulse, thrust-to-power ratio, and both, anode and total efficiency of the system using oxygen (anode) and hydrogen (cathode) are then presented and compared against oxygen (anode) and krypton (cathode). The cathode successfully operated on hydrogen, with a reduction in thrust performance of under 10% compared to when krypton is used as the cathode propellant. This performance difference can be attributed to different factors, such as the reduced efficiency of the cathode running with hydrogen due to a higher ionisation potential and the cathode propellant’s contribution to thrust, more significant when using heavier propellants such as xenon/krypton compared to hydrogen. The impact of changing the hydrogen-oxygen ratio is also assessed and shown to have no impact on the thruster’s performance. The most optimal performance was obtained at the highest discharge power tested (Pd=1953±1 W), using a hydrogen:oxygen ratio of Φ = 1:25. This operating point corresponded to a thrust of 20.9±0.2 mN, anode specific impulse of 2130±20 s, thrust-to-power ratio of 10.7±0.5 mN/kW, anode thrust efficiency of 11.2±0.3 %, and total efficiency of 10.1±0.3 %.

Thermal characterization of Sutterby nanofluid flow under Riga plate: Tiwari and Das model

This investigation uses the Tiwari and Das nanofluid model to enhance the heat transfer rate in Sutterby nanofluid over a Riga plate. The effects of heat source/sink, viscosity dispersion, and mass flow for water-based fluids are also considered in this work. Sutterby fluid has been utilized to investigate the rheological features of nanofluids. The transverse Lorentz force produced by the Riga plate assists in the flow down the plate by producing an electromagnetic field. The main aim of this investigation is to evaluate the presence of two different types of nanoparticles in water, specifically silicon carbide [Formula: see text] and copper [Formula: see text]. Dimensionless variables are first used to convert the mathematical model into a non-dimensional form. The similarity approach is then used to further rewrite the non-dimensional partial differential equations into a set of similarity equations. The bvp4c function in MATLAB software provides a numerical solution to these equations. The effects on temperature and velocity profiles of many physical factors, including the Reynold number, heat source/sink, and Deborah number, have been analyzed and presented. Furthermore, using tables, a detailed analysis of the skin friction coefficient and local Nusselt numbers is conducted. The results show that convective flow is suppressed when solid nanoparticles are added to the base fluid. The velocity distribution improves as Deborah and Reynold’s numbers get a higher value. Also, the temperature field improves by incrementing exponential and thermal heat source/sink parameters.

Region-Specific CD16+ Neutrophils Promote Colorectal Cancer Progression by Inhibiting Natural Killer Cells.

The colon is the largest compartment of the immune system, with innate immune cells exposed to antigens in the environment. However, the mechanisms by which the innate immune system is instigated are poorly defined in colorectal cancer (CRC). Here, a population of CD16+ neutrophils that specifically accumulate in CRC tumor tissues by imaging mass cytometry (IMC), immune fluorescence, and flow cytometry, which demonstrated pro-tumor activity by disturbing natural killer (NK) cells are identified. It is found that these CD16+ neutrophils possess abnormal cholesterol accumulation due to activation of the CD16/TAK1/NF-κB axis, which upregulates scavenger receptors for cholesterol intake including CD36 and LRP1. Consequently, these region-specific CD16+ neutrophils not only competitively inhibit cholesterol intake of NK cells, which interrupts NK lipid raft formation and blocks their antitumor signaling but also release neutrophil extracellular traps (NETs) to induce the death of NK cells. Furthermore, CD16-knockout reverses the pro-tumor activity of neutrophils and restored NK cell cytotoxicity. Collectively, the findings suggest that CRC region-specific CD16+ neutrophils can be a diagnostic marker and potential therapeutic target for CRC.

Functional and financial analysis of an inclined step solar desalination using phase change nanomaterials

ABSTRACT Recent decades have seen a shortage of water, which has led scientists to concentrate on solar desalination technologies. The present study examines the solar water desalination system with inclined steps, while considering various phase change materials (PCMs). The findings suggest that the incorporation of PCM generally enhances the productivity of the solar desalination system. Additionally, the combination of nanoparticles has been used to PCM, which is a popular technique utilized nowadays to improve the efficiency of these systems. The current investigation involves the transient modeling of a solar water desalination system, utilizing energy conservation equations. The equations were solved using the Runge–Kutta technique of the ODE23s order. The temperatures of the salt water, the absorbent plate of the glass cover, and the PCM were calculated at each time. Without a phase changer, the rate at which fresh water is produced is around 5.15 kg/m2·h. The corresponding mass flow rates of paraffin, n-PCM I, n-PCM III, n-PCM II, and stearic acid are 22.9, 28.9, 5.9, 11.9, and 73 kg/m2·h. PCMs, with the exception of stearic acid, exhibit similar energy efficiency up to an ambient temperature of around 29°. However, at temperatures over 29°, n-PCM II outperforms other PCM.

Investigation of the Map Width Improvement in a Radially Reduced Diffuser Design Concept for a Centrifugal Compressor

Abstract Often, an improvement in performance at one operating point in a compressor/turbine operating map will lead to a reduction in performance at another area. For example, improving the efficiency of a compressor at design point (DP) may result in a reduction of efficiency at other operating points or it may result in a reduced stable operating range. In order to reduce the compressor cost and weight, a 15% radial reduction was applied to the diffuser passage length of a high pressure ratio centrifugal compressor. The diffuser endwall was diverged to achieve an appropriate area ratio from diffuser inlet to outlet. Two different vane shapes were considered with the radially reduced diffuser passage. The first diffuser vane was a scaled version of the baseline airfoil vane shape and this was used to develop an understanding of the impact of the passage length reduction and diverging endwall. The second vane geometry was parameterized using an unconventional method derived from published literature and optimized to improve performance at DP. Increased losses were generated through the diffuser passages of the radially reduced designs, but this was compensated for by lower losses through the volute due to more desirable flow at volute inlet. As a result, the radially reduced designs not only matched the performance of the baseline configuration, but also succeeded in achieving a marginal efficiency improvement. Furthermore, despite not being one of the goals of the optimization procedure, an extension of the stable operating range of 36% and 20% at the highest speed condition was achieved for the scaled and optimized designs, respectively. The current study focuses on understanding the physical reasons that generated this significant enhancement to the compressor operating range. In order to acquire the desired understanding, experimental data is presented to validate the Computational Fluid Dynamics (CFD) model and a detailed numerical investigation is presented to explain the changes in the flow field within the radially reduced designs. The study focuses on low flow rate operating points, necessitating the use of an Unsteady Reynolds Averaged Navier-Stokes (URANS) approach to analyse the flow. Detailed scrutiny of the flow field revealed a secondary flow feature in the diffuser passage which resulted in higher diffuser passage losses at DP but stabilised the flow as it developed for lower mass flow rate operating points.

Unsupervised literature mining approaches for extracting relationships pertaining to habitats and reproductive conditions of plant species

IntroductionFine-grained, descriptive information on habitats and reproductive conditions of plant species are crucial in forest restoration and rehabilitation efforts. Precise timing of fruit collection and knowledge of species' habitat preferences and reproductive status are necessary especially for tropical plant species that have short-lived recalcitrant seeds, and those that exhibit complex reproductive patterns, e.g., species with supra-annual mass flowering events that may occur in irregular intervals. Understanding plant regeneration in the way of planning for effective reforestation can be aided by providing access to structured information, e.g., in knowledge bases, that spans years if not decades as well as covering a wide range of geographic locations. The content of such a resource can be enriched with literature-derived information on species' time-sensitive reproductive conditions and location-specific habitats.MethodsWe sought to develop unsupervised approaches to extract relationships pertaining to habitats and their locations, and reproductive conditions of plant species and corresponding temporal information. Firstly, we handcrafted rules for a traditional rule-based pattern matching approach. We then developed a relation extraction approach building upon transformer models, i.e., the Text-to-Text Transfer Transformer (T5), casting the relation extraction problem as a question answering and natural language inference task. We then propose a novel unsupervised hybrid approach that combines our rule-based and transformer-based approaches.ResultsEvaluation of our hybrid approach on an annotated corpus of biodiversity-focused documents demonstrated an improvement of up to 15 percentage points in recall and best performance over solely rule-based and transformer-based methods with F1-scores ranging from 89.61 to 96.75% for reproductive condition - temporal expression relations, and ranging from 85.39% to 89.90% for habitat - geographic location relations. Our work shows that even without training models on any domain-specific labeled dataset, we are able to extract relationships between biodiversity concepts from literature with satisfactory performance.

Computational and Experimental Research on the Influence of Supplied Gas Fuel Mixture on High-Temperature Fuel Cell Performance Characteristics

Currently, the process of creating industrial installations is associated with digital technologies and must involve the stage of developing digital models. It is also necessary to combine installations with different properties, functions, and operational principles into a single system. Some tasks require the use of predictive modeling and the creation of “digital twins”. The main processes during the fuel cell modeling involve electrochemical transformations as well as the movement of heat and mass flows, including monitoring and control processes. Numerical methods are utilized in addressing various challenges related to fuel cells, such as electrochemical modeling, collector design, performance evaluation, electrode microstructure impact, thermal stress analysis, and the innovation of structural components and materials. A digital model of the membrane-electrode unit for a solid oxide fuel cell (SOFC) is presented in the article, incorporating factors like fluid dynamics, mass transfer, and electrochemical and thermal effects within the cell structure. The mathematical model encompasses equations for momentum, mass, mode, heat and charge transfer, and electrochemical and reforming reactions. Experimental data validates the model, with a computational mesh of 55 million cells ensuring numerical stability and simulation capability. Detailed insights on chemical flow distribution, temperature, current density, and more are unveiled. Through a numerical model, the influence of various fuel types on SOFC efficiency was explored, highlighting the promising performance of petrochemical production waste as a high-efficiency, low-reagent consumption fuel with a superior fuel utilization factor. The recommended voltage range is 0.6–0.7 V, with operating temperatures of 900–1300 K to reduce temperature stresses on the cell when using synthesis gas from petrochemical waste. The molar ratio of supplied air to fuel is 6.74 when operating on synthesis gas. With these parameters, the utilization rate of methane is 0.36, carbon monoxide CO is 0.4, and hydrogen is 0.43, respectively. The molar ratio of water to synthesis gas is 2.0. These results provide an opportunity to achieve electrical efficiency of the fuel cell of 49.8% and a thermal power of 54.6 W when using synthesis gas as fuel. It was demonstrated that a high-temperature fuel cell can provide consumers with heat and electricity using fuel from waste from petrochemical production.

Phosphorus mass flows and economic benefits of food waste management: the case study of selected retail and wholesale fresh markets in Thailand

AbstractThis study aims to investigate the mass flow and the phosphorus flow of food waste in order to propose a viable technique for its recovery from food waste in retail and wholesale fresh markets. These markets are significant food waste sources, including valuable elements such as organic carbon, nitrogen, and phosphorus. This research provides critical data that can inform and guide the development of sustainable and cost-effective waste management strategies. The results indicate that retail markets generate 13.47 tons/d of food waste, while wholesale markets produce a staggering 192.62 tons/d. For phosphorus flow analysis, the data show that retail markets produce 12.80 kg P/d, while wholesale markets produce 40.79 kg P/d. Uncooked food waste is a major cause of phosphorus loss in retail and wholesale markets. An estimated 3.65 kg P/d is lost from retail and 20.72 kg P/d from wholesale. Separating food waste from general waste and recovering the phosphorus content is essential to reduce P loss. According to this study, separating food waste and selling it as animal feed (Scenario 1) or using it to create organic fertilizer (Scenario 2) are more profitable than the current waste management practice. These options can generate around 180,000 and 960,000 USD/year, respectively. Currently, it is not cost-effective to produce concentrated P fertilizer (scenario 3) due to the high energy and technology required. The study’s results can guide policymakers toward comprehensive food waste management in fresh markets and sustainable phosphorus recovery for food and agricultural production. Graphical abstract

A nonlinear disturbance observer for sliding mode control of surge in centrifugal compressors via TCV actuator

Surge is a form of dynamic instability created as an unstable pattern in the flow of fluid and can severely affect centrifugal compressor performance by causing fluctuations in flow and pressure parameters. Due to the heavy and costly damage that the surge may cause in various industrial processes such as petrochemical plants, it is necessary to design an appropriate control system to reduce the effect of this phenomenon. The problem of active surge control of a centrifugal compressor using the throttle control valve (TCV) in the presence of compressor parametric uncertainties as well as large demands on upstream and downstream loads is investigated in this work. The control objective was to design a robust control system that can stabilize the compressor over a wide operating range without knowing the upper bound for the uncertainties and load demand. The controller should also react quickly by generating a smooth control signal without saturating the control input. These objectives are achieved by designing a sliding mode controller along with a nonlinear disturbance observer. The performance of the proposed disturbance observer-based controller is evaluated under various operational and load conditions and the results are compared against fuzzy type 1, conventional sliding mode, and wavelet-based neural network robust adaptive controllers. The results show that the proposed method can tolerate large disturbances without any knowledge on the upper bound of the incident disturbance, both on the downstream pressure and upstream mass flow which is highly desirable in practice. The comparative study proves the efficacy of the proposed method using various performance measures. The study also confirms the superior robust performance and stability of the proposed method in front of matched and mismatched disturbances as well as model uncertainties especially close to the instability boundary. Although choosing a TCV actuator has made the control system design easier, the sensitivity of the control valve to flow coefficient and zero calibration under different operating ranges of the compression system is studied carefully and some recommendations for the users are provided.

Power Augmentation of Gas Turbine Using Exhaust Flue Gas Operated Vapor Absorption Machine

Industrial gas turbines (GT) that operate at constant speed are constant-volume-flow combustion machines. As the specific volume of air is directly proportional to the temperature, an increase in air density results in a higher air mass flow rate at low air ambient temperatures. This results more mass of air is now passes through same volume gas turbine space. Consequently, the gas turbine power output increases proportionally with the increase in air mass flow rate. For geographic regions where warm and humid months are predominant throughout the year, significant power loss occurs during these months, and a higher rate of expensive fuel is fired at reduced power output. A gas turbine inlet air cooling technique is a useful option to enhance GT output. One of the innovative options for power augmentation of gas turbine is inlet air conditioning using a vapor absorption machine (VAM). Using VAM for GT intake air conditioning has the advantage over other systems in that it can be operated from waste heat. Many gas turbine machines, particularly natural gas pumping stations, are operated without heat recovery steam generator (HRSG) or heat recovery option. Valuable heat energy is escaped with exhaust flue gas in these systems. This paper demonstrates how GT exhaust waste heat can be utilized for its own power generation enhancement. In this study, a flue gas-based vapor absorption machine is selected for cooling the inlet air of a 26 MW gas turbine, which is used to drive the booster compressor of a natural gas pumping station. The capacity of the VAM for the required cooling effect has been calculated. The expected GT power enhancement from intake air gas conditioning has also been estimated in this paper.

A new quantitative method via on-line mass spectrometer: Application in biomass char/NO reaction

A novel quantitative analysis method via on-line mass spectrometer (OMS) was developed to calculate the mass flows of the reactants and products for the reaction between NO and biomass char in micro-fluidized bed. The experimental results showed that the quantitative method could accurately calculate the mass flow rate of each gas even though there were ion currents overlapping at mass-to-charge ratio (m/z) = 12,16, and 28 when CO, CO2 and N2 were simultaneously present in OMS. Furthermore, the method facilitated the quantitative analysis of gaseous reactants and products, thereby enabling the assessment of mass conversions of carbon (C) and nitrogen (N) in the NO reduction reaction. It was observed that CO was the predominant carbon-containing product in the reaction involving biomass char and NO at 900 °C, with over 96 % of nitrogen in NO participating in the reduction reaction being converted to N2. This study also revealed that increasing the fluidization number, NO concentration, and temperature in the micro-fluidized bed could significantly accelerate the conversion processes of C and N in the reduction of NO by biomass char. The peak mass flow rates of CO, CO2, and N2 were found to increase correspondingly with higher NO concentrations and temperature levels. The NO reduction process over sawdust char was compared to that of corncob char, showing a higher maximum NO reduction efficiency. The reaction order with respect to NO concentration was determined to be 0.82 for corncob char and 0.68 for sawdust char. Additionally, the apparent activation energies were determined to be 92.35 kJ/mol for corncob char and 125.60 kJ/mol for sawdust char, respectively.

Viability of an Open-Loop Heat Pump Drying System in South African Climatic Conditions

Drying agricultural produce consumes a considerable amount of energy. As an energy-efficient system, a heat pump can improve the energy efficiency of the drying process and hence reduce the energy consumption, especially in South Africa, where both sub-tropical and temperate weather conditions dominate. The objective of this research is to experimentally investigate the impacts of weather conditions on the operational conditions and thermal performance of an open-loop air-source heat pump drying system. The experimental investigation was conducted in a climate chamber where the climate conditions were simulated from −10 °C to 20 °C with an interval of 10 °C for the typical temperature range of the harvesting season in South Africa. The findings indicate that ambient temperatures have a significant impact on both the operating conditions and thermal performance of an open-loop heat pump system; the change in ambient temperatures from −10 °C to 20 °C leads to a 141.6% improvement in the suction pressure, a 214.2% increase in the discharge pressure, and 30.1% increase in the compression ratio, as well as a consequent increase of 130.6% in the refrigerant mass flow rate (from 0.0067 to 0.0155 kg/s), resulting in a corresponding increase in the coefficient of performance (COP) of the heat pump drying system by about 42.1%. Therefore, this study suggests that, while using an open-loop air-source heat pump drying system utilising R134a refrigerant is feasible in South Africa, it may be practically limited to regions with warm climates or during warmer seasons.

Predictions of locations of flash point and calcite scaling of geothermal fluids in wellbore by chemical and thermodynamic simulations

Geothermal energy, as a renewable energy source, has been intensively developed recently because its utilization can reduce CO2 emission, climate warming and sea level rising, and be beneficial to promote sustainable development. However, scaling in the wellbores often happens during the rising of geothermal fluids. At present, the methods to explore the scaling location principally focus on real measurement techniques and numerical simulation method. In comparison with the former, the latter is extremely time- and labor-saving to predict the scaling location based on the coupling model. In this study, the flash point and scaling locations of two geothermal wells in Hebei province are numerically simulated via ECO2N equation of state module in TOUGHREACT software, and the factors affecting the flash point and scaling locations of geothermal wells are explored. At the same time, the mechanism of geothermal fluid flash is analyzed. The prediction results show that the relative errors of scaling locations in geothermal well I and II are 5.43 % and 6.82 % compared to the field measured data; the pressure and temperature of geothermal fluids at well bottom can be calculated based on the related parameters of wellhead fluid; the locations of flash point and scaling can be determined according to the sudden increases of CO2 partial pressure and scaling amount, respectively. Furthermore, the liquid mass flow rate, CO2 mass flow rate and wellbore diameter have prominent influence on the locations of flash point and scaling, while wellbore diameter have significant effect on the amount of calcite scaling. The above conclusions provide useful guidelines for the next scaling removal and control in the production wellbore during the utilization of the geothermal energy.

Numerical Investigation of Innovative Photovoltaic–Thermal (PVT) Collector Designs for Electrical and Thermal Enhancement

Photovoltaic–thermal (PVT) technology is gaining popularity due to the diminishing availability of traditional fossil fuels and escalating environmental concerns. Enhancing the heat dissipation of PVT to improve its electrical and thermal performance remains a significant task. This study simulates the thermodynamic and heat transfer characteristics in multiple novel PVT structures by examining the impact of various factors such as collector materials, radiation intensity, mass flow rate, and inlet temperature. This work also identifies the optimal mass flow rate for locations with different solar radiation. The numerical results indicate that the electrical efficiency of a designed cylindrical structure has increased by 1.73% while the thermal efficiency has increased by 8.29%. Aluminum is identified as the most cost-effective material for the collector. The optimal mass flow rates in selected locations of Xining, Taiyuan, and Turpan are 0.36 kg/s, 0.35 kg/s, and 0.30 kg/s, respectively. The numerical results provide valuable insight into optimizing the design and operating conditions of PVT systems.

Examining the potential of sigma-thermic heat transfer fluid and its nanofluid in a natural circulation loop through CFD studies

This study investigates the impact of hot heat exchanger (HHX) inlet temperature on Sigma-thermic heat transfer fluid (STHF or STF) performance in a natural circulation loop. Various fluids, including STHF and STHF-based nanofluids, with volumetric concentrations ranging from 0.5% to 3%, are employed in the loop. The primary objective is to analyze the thermal performance of the loop under different conditions, focusing on temperature distribution, Nusselt number, friction factor, effectiveness, and mass flow rate. 3D numerical simulations are conducted, and the numerical model is validated against existing literature. The developed model incorporates considerations for viscous dissipation and axial conduction to predict the heat transfer potential of the loop. As the HHX inlet temperature increases, the mass flow rate rises. Notably, STHF/CuO nanofluids exhibit a more substantial enhancement than other nanofluids. At a 1 vol% concentration, the mass flow rate increases by 9.5%, 4%, and 2.7% for STHF/CuO, STHF/Al2O3, and hybrid nanofluids, respectively, compared to pure STHF. The study reveals significant improvements in mass flow rates and heat transfer efficiency with increasing HHX inlet temperatures, especially with STHF/CuO nanofluids. The total entropy generation reduction is notable, with percentages ranging from 2% to 18.5% for various nanofluids compared to pure STHF.

Experimental Investigation on Thermal Performance of Solar Air Heater using Nano-PCM

Herein, the performance of a solar air heater (SAH) is experimentally investigated, utilising an array of tubes as the absorbent part. The study evaluates the impact of incorporating Al2O3-paraffin wax as a non-PCM storage medium in comparison to a traditional flat-plate solar air heater, specifically under Najaf-Iraq climate conditions. The SAH is positioned at an inclination of 32.1 degrees with respect to the horizon, allowing it to align optimally with the solar direction. The results reveal notable differences in thermal performance characteristics among the various models. The highest thermal efficiency values are observed for distinct configurations: the proposed model achieves about 55.2%, the wax-supported model reaches 55.9%, and the nano-PCM-reinforced model attains 57.7%, while the traditional model lags at 48.2%. Furthermore, an analysis of different air mass flow rates highlights a crucial finding. Specifically, an air mass flow rate of 0.01 kg/s results in a higher temperature exiting from the system compared to a flow rate of 0.02 kg/s. This is attributed to the extended interaction time between the passing air and the absorbing surface, facilitating enhanced heat exchange. Consequently, the system's thermal efficiency experiences an increase. The study underscores the superior thermal performance and efficiency of the tube array nano-PCM collector type under Najaf city-Iraq climate conditions.

Performance study of low temperature air heated rock bed thermal energy storage system

AbstractOne of the primary types of sensible heat storage systems in drying applications is the packed rock bed. However, to create large‐scale heat storage systems for industrial use, one must comprehend the hydrodynamic and effectiveness of the heat transport mechanism inside the bed. In this study, the thermal storage unit uses river rock as heat storage materials with equivalent particle diameters of 36 mm in bed 1 and 56 mm in bed 2. The rocks were stacked in a truncated cone‐shaped concrete wall section with an average diameter and depth of 1.1 m and 1.3 m, respectively and a volume of 2.32 m3. During the charging phase, two airflow configurations were used, one from the top with an air mass flow rate of 0.753 and 0.332 kg/m2‐s and the other from the bottom with an air mass flow rate of 0.955 kg/m2‐s. During the discharging phase, the entire flow configuration is from the bottom section. It was observed that the mass flow rate and particle equivalent diameter had an important effect on the thermal performance and behaviour of the rock bed during charging and discharging operations. Maximum efficiency was achieved with an airflow configuration provided from the bottom when charging at 0.955 kg/m2.s. Consequently, a sizable quantity of heat or energy (60 MJ) was retained. It was also observed that the relationship between air mass flow rate and particle size was significant, with smaller particles retaining more energy. When comparing bed 1 with bed 2 at this air mass flow rate, bed 1 stored 2.1 times more energy than bed 2. A wind tunnel experiment was used to measure the pressure drop in the packed rock bed. The pressure drop in the bed increases with an increase in particle Reynolds number and decreases with an increase in particle size. Rock bed heat transfer coefficient and Nusselt number were calculated using the correlation that has already been established in the literature smaller particles showed higher heat transfer coefficients and lower Nusselt numbers. This is due to the increase in particle‐to‐particle interaction and larger particle surface areas. For a given Reynolds number, the Nusselt number increases with the size of the rock particle.

Performance analysis of a gas turbine engine with intercooling and regeneration process - Part 1

Abstract Auxiliary systems, such as regeneration and intercooling, have been integrated with the primary gas generator to improve power production and fuel economy in modern gas turbine power plants. Implementing these techniques in turbine engines is challenging due to size, weight, and complex flow patterns. A solution is to use a turboprop engine with a smaller mass flow rate and simpler gas paths. The current study involves the numerical analysis of performance parameters namely, specific power (SP), thermal efficiency (η), and enthalpy based specific fuel consumption (EBSFC) of a turboprop engine using thermodynamic parameters namely, pressure ratio (PR), nozzle pressure ratio (NPR), turbine inlet temperature (TIT), regeneration efficiency (R), and intercooling efficiency (E). The results prove that the introduction of regeneration and intercooling showed significant improvement in the power developed, and reduced fuel consumption.

A method for generating quantitative vapor-phase infrared spectra of solids: results for phenol, camphor, menthol, syringol, dicyclopentadiene and naphthalene

A method is presented to generate quantitative vapor-phase infrared spectra from substances that naturally occur as solids with moderate volatility. The solid is gravimetrically dissolved into a solvent that has few infrared spectral features, typically CS2 and CCl4 separately. The solution is flowed at a constant rate from a linearly pumped syringe into a metered stream of nitrogen carrier gas regulated by a mass flow controller. The analyte/solvent mix is flash vaporized by volatilizing the solution across a heated stainless-steel surface as it emanates from the syringe tip. The N2 gas-solution mixture is flowed into a long-path White cell thermostatted at a desired temperature, the long optical path compensating for the modest analyte mixing ratio. A composite spectrum is generated from typically ten or more 760-Torr pressure-broadened spectra over the 600 to 6500 cm−1 spectral range at 0.1 cm−1 spectral resolution. The solid analytes reported here using this novel technique include dicyclopentadiene, menthol, syringol, phenol, camphor, and naphthalene.