Energy Flow Rate Research Articles

Mixing and ignition characteristics of laser-induced solid fuel pyrolysis under wide-range variation of crossflow

A theoretical model has been developed to elucidate the thermal initiation laser ignition process of solid fuel. This model comprehensively explores both the heating process of solid fuel and the mixing process of gas-phase pyrolysis gases with crossflow conditions. A two-dimensional transient numerical model has been established and validated through experimental investigations across a spectrum of crossflow fluxes (ranging from 20 to 150 kg/m2/s) and pressures (ranging from 0.15 to 1.83 MPa). The study involves a quantitative analysis of the influence of key macroscopic parameters, including laser energy levels, combustion pressure, and flow rates, on essential mixing characteristics. The solid fuel heating process is segmented into two distinct phases: a preheating phase and a pyrolysis phase, with the latter exhibiting considerably higher heating rates. Notably, a direct linear relationship is observed between the laser energy levels and the rate of heating. It reveals that the dynamics of pyrolysis product mixing are primarily determined by the solid fuel pyrolysis rate and the prevailing crossflow conditions. The dimensionless penetration depth, which measures the extent of pyrolysis product mixing with crossflow, demonstrates an exponential positive correlation with pyrolysis rates and oxidizer flow rates while displaying a negative correlation with combustion pressure. This analysis includes the quantitative determination of proportionality constants and power exponents within the correlations. Finally, the study delves into the intricate interplay between crossflow conditions and the criteria for laser ignition, specifically ignition temperature and the flammable lower limit.

Planetary Energy Flow and Entropy Production Rate by Earth from 2002 to 2023.

In this work, satellite data from the Clouds and Earth's Radiant Energy System (CERES) and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments are analyzed to determine how the global absorbed sunlight and global entropy production rates have changed from 2002 to 2023. The data is used to test hypotheses derived from the Maximum Power Principle (MPP) and Maximum Entropy Production Principle (MEP) about the evolution of Earth's surface and atmosphere. The results indicate that both the rate of absorbed sunlight and global entropy production have increased over the last 20 years, which is consistent with the predictions of both hypotheses. Given the acceptance of the MPP or MEP, some peripheral extensions and nuances are discussed.

Determination of Effective Parameters for Hydropower Plants’ Energy Generation: A Case Study

The current study aims to conduct a comprehensive analysis of the key parameters that affect the energy output of the Bagisli Hydropower Plant, located on the Zap River in the Dicle (Tigris) basin of Turkey. It considers the daily data for the time interval of 2016–2019 related to flow rate, precipitation, and temperature in relation to the generation of electricity. The relationship between energy output and flow rate is evident; however, the energy production is limited by the design flow rate. The largest flow rates were seen during the spring season after the occurrence of peak precipitation, which exhibited a shifting pattern. Similarly, energy generation also reaches its highest level during this time period. Another outcome of this study is that there is no apparent association between daily precipitation and daily energy generation. Moreover, a novel correlation with an R2 value of 0.89 has been proposed, in the deviation band of ±20%, to estimate energy generation when only flow rate data are available.

Nitrogen fixation by rotational gliding arc plasma at surrounding conditions

Nitrogen fixation (NF) was investigated in a rotational gliding arc plasma based on various energy inputs, flow rates, and N2:O2 ratios under atmospheric conditions. For practical application, the effect of water content in the feed, self-heating during plasma discharge, prolonged operation, and comparison between plasma and thermal process for N2 oxidation were also conducted. The comparison results reveal that NF by the gliding arc plasma is superior to the thermal process in terms of NOx yield and energy consumption at low temperatures and atmospheric pressure. Herein, energy input and flow rate are two controlled factors that significantly influence NOx production rate. Simultaneously, O2 content played a crucial role in determining NOx yield, selectivity of NO/NO2, and energy consumption. Observations during plasma discharge indicated an initial rise in gas and reactor body temperatures, coinciding with decrease in total NOx formation. Moreover, the presence of water had a negative effect on NOx yield. Accordingly, the optimized conditions for NF by gliding arc plasma for NOx formation was identified at a N2 to O2 ratio of 3:2 without water vapor in the feed gas. Furthermore, a 14-h continuous operational test validated the robustness of our reactor configuration, affirming its long-term viability. The study concludes by performing oxidation of the NOx gas followed by dissolution in water, successfully generating nitric acid. These findings underscore the potential of gliding arc plasma for efficient NF processes, offering insights into optimal operational conditions and downstream applications for nitric acid generation.

Effects of rapeseed protein addition on soybean protein-based textured protein produced by low-moisture extrusion: Changes in physicochemical attributes, structural properties and barrel flow behaviors

This study investigated the potential of rapeseed protein as a novel alternative protein source in meat analogs produced by extrusion cooking technology. To study the substitutability of rapeseed protein to soybean protein, the addition ratios of rapeseed protein to soybean protein in the extrusion experiment were 0:50, 10:40, 20:30, 30:20, 40:10 and 50:0 (w/w), respectively. The results showed that adding 0–20% rapeseed protein not only decreased the specific mechanical energy and mass flow rate of the mixture during extrusion, but also enhanced the hardness and chewiness of the extrudates while reducing their elasticity and resilience. In addition, increasing the amount of rapeseed protein may lead to decreased expansion characteristics, internal pore structure, and water absorption rate of the extrudates, as well as a decrease in brightness and an increase in redness on the surface. Weibull model could well describe the rehydration behavior for dynamic fitting of the extrusion rehydration process. Moreover, with the increase of rapeseed protein substitution, the content of disulfide bonds, and the proportion of relatively ordered protein secondary structures with high stability increased, and the degree of protein denaturation decreased. Besides, the degree of starch gelatinization reduced and the thermal stability of extrudates improved. Interaction analysis indicated that disulfide bonds are the primary force maintaining protein-mediated interactions in the extrudates. The incorporation of rapeseed protein shortened the mean residence time of molten feedstock and shifted the flow state to plug flow. Overall, our investigation suggests that within low levels of addition (≤20%, w/w), rapeseed protein has the potential to partially substitute for the soybean protein-based textured proteins. High substitution levels or complete substitution are not feasible due to the relatively low expansion and rehydration rates.

Performance assessment of a solar aided dual-fuel supercritical steam power plant for power boosting under different operating loads

Fuel supply due to political conflict and decarbonization is the most challenging standup for the energy sector and electricity generation. Therefore, the present study introduces a thermodynamic analysis for a modeled supercritical solar aided power plant (SAPP) using two types of fuel at different operating loads, i.e., 50%, 75%, and 100%. The proposed SAPP is investigated in terms of energy, exergy, and steam flow rates to verify the advantages of using SAPP over conventional power plants. In the SAPP, the condensate water passes into the heat exchangers using a working fluid of Therminol VP-1. Additionally, the turbine extraction steam at 100% load is minimized, and it is eliminated at 50% and 75% loads. The results show that the recovered amount of feed water extraction increases the mechanical power for SAPP-based natural gas in comparison with the conventional supercritical steam power plant by 16, 21, and 9.7% at an operating load of 50%, 75%, and 100%, respectively. Consequently, SAPP-based natural gas maintains an increase in the overall energy efficiency compared with the CPP of 13.7, 17, and 1.9% at an operating load of 50%, 75%, and 100%, respectively. As well, the mechanical power of the SAPP-based oil fuel increases compared with CPP by 25.7, 27.6, and 17.4% at 50%, 75%, and 100% loads, respectively. Whereas, the overall energy efficiency enhances due to using the SAPP-based oil fuel compared with that of the CPP by 20.6, 21.9, and 7% at a load of 50%, 75%, and 100%, respectively.

Energy harvesting induced by the vibration of reciprocating-piston compressor subjected to repetitive impulse

In this study, discrete event time-variant parameter of a lumped SISO dynamical system is obtained for a novel energy harvester. The harvester utilizes the resonance vibration of a coupled fluid-mechanic system, which is comprised of a reciprocating-piston, a tunable oscillator and twin electric turbine generators. The system model is simplified by an underdamped spring-mass-damper with tunable parameters subjected to periodic or arbitrary impulse forces. We developed a method that solves general problems underlining non-homogenous ordinary second order differential equation with discrete event time-variant parameters. The method uses the superposition to compile the general solution by segmenting the problem into ODE equations with constant coefficient. Each segment corresponds to a change in system, and it is solved analytically with recursively updated initial conditions. We utilized this method to tune the system’s natural frequency such that the accumulated energy is maximum within desired time range. We obtained the general solution of the displacement response due to varying parameters and input impulse force. We obtained the displacement peaks and their time of occurrence that could help understand the structural design limitation. We showed system displacement responses (constructive and destructive) corresponding to various impulse repetition patterns. We derived the relationship between energy, volume displacement, and volumetric flow rate (or piston velocity) and provided illustrative case studies. One finding shows that for a given impulse condition the accumulative energy exhibits local maximum and minimum within a narrow band of natural frequency range. The simulations showed the feasibility of generating considerable power from electric turbine when the air flow is driven by a resonating piston.

Experimental performance evaluation of water source heat pumps in different circumstances and comparison to air source heat pumps

This study aims to present a novel experimental method for studying the performance of wa-ter source heat pumps which have not received sufficient attention, although this is particu-larly important for hot regions with great potential of hot water sources. The experimental model has special characteristics as it allows to investigate the performance of heat pumps under different operating conditions and allows a comparison between different types of heat pumps without the need to install a ground heat exchanger. The ground heat exchanger is known to be the most expensive part of any experimental model. In addition to that, it only allows to study the performance under specific conditions. The ground heat exchanger was replaced by a secondary heat pump that allows to provide an environment that simulates the different operating conditions of different types of heat pumps. It was found that water source heat pumps are more efficient than air source heat pumps with efficiency that increases with increasing water source temperature. It was found that increasing the water source tempera-ture from 5 to 20 oC, improved the rate of heat extracted from the water source by 11.3% and the coefficient of performance by 2.8% for each degree. Another important feature of water source heat pumps is the stability of the energy flow rates, which is a guarantee of higher sea-sonal performance coefficients. It can be concluded that hot regions with high potential of hot water sources has valuable opportunities to invest in the field of water source heat pumps with the consequent significant energy savings.

Techno-economic analysis of renewable fuels production from sewage sludge through hydrothermal liquefaction

In this work, techno-economic evaluation of renewable fuels production from sewage sludge using hydrothermal liquefaction method is investigated. The process design of the plant includes wastewater treatment for sewage collection, hydrothermal liquefaction for biocrude production, hydroprocessing for biocrude upgrading, and hydrogen production. A steady-state simulation is first conducted to predict the mass and energy flow rates of the plant for the manufacture of renewable fuels. Then, the economic calculation is performed to obtain a minimum selling price (MSP) of the renewable fuels using the results of a steady-state simulation. The MSP of renewable fuels is obtained at US$4.04/ Gasoline Gallon Equivalent (GGE). The predicted value closely matches the literature findings. Furthermore, the analysis of sensitivity is conducted to find the influential parameters that affect the MSP of renewable fuels.It is found that biocrude yield and operating cost have a significant effect on the MSP of renewable fuels. This study provides the feasibility of large-scale production of the renewable fuels from the sludge and also guides future plant design/optimization. This will drive further research and development activities towards to circular economy.

Self-Sustaining Control Strategy for Proton-Exchange Membrane Electrolysis Devices Based on Gradient-Disturbance Observation Method

This paper proposes a self-sustaining control model for proton-exchange membrane (PEM) electrolysis devices, aiming to maintain the temperature of their internal operating environment and, thus, improve the electrolysis efficiency and hydrogen production rate. Based on the analysis of energy–substance balance and electrochemical reaction characteristics, an electrothermal-coupling dynamic model for PEM electrolysis devices was constructed. Considering the influence of the input energy–substance and the output hydrogen and oxygen of PEM electrolysis devices on the whole dynamic equilibrium process, the required electrical energy and water molar flow rate are dynamically adjusted so that the temperature of the cathode and the anode is maintained near 338.15 K. The analytical results show that the hydrogen production rate and electrolysis efficiency are increased by 0.275 mol/min and 3.9%, respectively, by linearly stacking 100 PEM electrolysis devices to form a hydrogen production system with constant cathode and anode operating temperatures around 338.15 K in the self-sustaining controlled mode.

Thermal-flow calculations for a thermal waste treatment plant

Thermal waste treatment plants are an answer to the important problem of waste neutralization on the one hand, while inspiring various emotions in society due to their impact on their planned or existing sites on the other. The primary benefit from incinerating waste is the ability to reuse it as fuel to produce energy. The paper presents thermal calculations that present the performance of the entire thermal waste treatment plant, which depends on the final use of the energy it produces. The equations developed make it possible to monitor the energy flow rate in the various components of the power unit, taking into account losses in the boiler and turbine condenser.

Research on variable speed constant frequency energy generation based on deep learning for disordered ocean current energy

As one of the most promising new energy sources today, ocean current energy has become an important part of energy strategies. There are short-term disorderly fluctuations in the flow rate of ocean current energy. The uncontrolled input of kinetic energy from the ocean current can lead to poor quality of power generated by current energy generators. The existing technology of current energy generation uses mechanical rigid transmission, which is prone to fatigue damage and low reliability under variable load fluctuations. In this paper, a joint simulation platform based on AMESim and Simulink is constructed based on 50kW hydraulic transmission and control power generation equipment. This paper establishes a mathematical model of the hydraulic transmission control system and proposes a constant frequency control algorithm based on a deep learning prediction model to improve the steady-state accuracy of the hydraulic motor speed. This paper proposes a deep learning prediction model based on EWT (Empirical Wavelet Transform)-LSTM (Long Short-Term Memory)-CNN(Convolutional Neural Network), which improves the prediction accuracy by 12.26% compared to short-term memory neural network. The model improves the motor speed dynamic accuracy by 90%, the standard deviation index by 78.11%, and the maximum deviation by 86.10% compared to the feed-forward Proportional Integral Derivative (PID)control algorithm. Therefore, the model can effectively improve the quality of the system’s power generation. At the same time, the time cost of the model for a single prediction is less than the sampling time of other control algorithms. In this paper, the simulation results are verified by a 50kW hydraulic transmission control experimental bench. The constant frequency control algorithm based on the deep learning prediction model can effectively improve the constant frequency dynamic accuracy of the motor of the hydraulic transmission control power generation equipment, which in turn improves the system power generation quality.

Energy-dependent film growth of Cu and NiTi from a tilted DC magnetron sputtering source determined by calorimetric probe analysis

Plasma-based processes are key applications in microsystems technology and are mainly used for the deposition and modification of thin films. A strong dependence on used equipment and materials can easily affect plasma processes and results in many differences of process characteristics like energy flow and deposition rates. For a deeper understanding of inclined magnetron-deposited thin films, a passive thermal probe was used to investigate the correlation between the film growth of two commonly used metallic target materials (Cu and Ni 46.8/Ti 53.2) and the energy flow from the plasma to the substrate. The special design of the sputtering system with a fixed angle of 45° between targets and substrate allows homogeneous coating of 200mm wafers with 100mm targets. The passive thermal probe measurements were performed radially across the substrate area for two different magnetron positions. Complementary surface and cross-sectional analysis of the deposited layers by atomic force microscopy, focused ion beam technique, and fracture edge analysis by scanning electron microscopy were performed on thin film samples on silicon substrate to investigate the growth rate and structure of the films. The films deposited in these experiments exhibit randomly oriented crystalline grains and heavily position-dependent change in surface topography and morphology from compact films to columnar growth, for Cu and NiTi respectively.

Non-invasive thermal energy flow rate sensor for turbulent pipe flows

A non-invasive thermal energy flow rate sensor based on a combination of transient heat flux and temperature measurements has been developed. A heat flux sensor and a thin-film thermocouple are covered by a thin-film electric heater and clamped onto the outer surface of a pipe. A one-dimensional transient thermal model is applied before and during activation of the external heater to provide estimates of the fluid heat transfer coefficient and thermal resistance. A parameter estimation code is used to estimate the unknown parameters by using the minimum root mean square error between the analytical and experimental sensor temperature values. The sensor was tested with two different fluids (water and diesel oil) and with two different pipe diameters (d=25.4mm and d=12.7mm). Experiments were completed over a range of Reynolds number from 2000 to 25,000 and a range of fluid temperature from 20 °C to 50 °C. Correlations for the fluid temperature and the fluid velocity were within ±0.13 K and ±5% of the direct measurements. The resulting non-invasive thermal energy flow rate sensor can be used to estimate a fluid velocity and a fluid temperature in heating and cooling pipe applications.

Effect of metal on corona discharge plasma in a honeycomb catalyst and optimization of the critical parameters for ethylene removal

This work focused on the factors affecting the effective generation of corona discharge plasma in a honeycomb catalyst reactor. Pd, Co, and Ag were used as the active metal catalysts to investigate the plasma formation and decomposition of ethylene. Unlike the Ag-coated honeycomb catalyst, which resulted in excessive arcing, the Co-coated honeycomb monolith was able to generate stable plasma, but the discharge power was insufficient to decompose ethylene at an acceptable level. The incorporation of a small amount of Pd with Co significantly enhanced the discharge power and the ethylene removal performance. The catalytic activity of the prepared catalyst for the removal of ethylene was evaluated using plasma catalytic oxidation and thermal catalytic oxidation. ANOVA was used to assess the effect of single process factors and their relationships in the plasma process. All the process factors such as specific energy input (SEI), ethylene concentration, and flow rate were found to affect the ethylene conversion, CO2 selectivity, and energy efficiency (EE). Under the optimal conditions, i.e., an SEI of 80 J/L, an ethylene concentration of 20 ppm, and a flow rate of 20 L/min, the ethylene conversion was 85 %, CO2 selectivity was 70 %, and EE was 0.86 g/kW h.

Flow-through in-situ evaporation membrane enabled self-heated membrane distillation for efficient desalination of hypersaline water

Water crisis and high salinity water treatment are growing challenges for the world. The recently emerged self-heating or surface heating membrane distillation (MD) can be a promising way to obtain fresh water from saline and other wastewater sources. However, its inherent drawbacks such as intolerance to high feed flow rate, low flux, and loss of heat energy through bulk feed stream, limit its realistic applications. Herein, we successfully demonstrate a novel trilayered flow-through in-situ evaporation membrane (FTIEM) enabled membrane distillation process. The PEI-PDA-SBA-15 is spray coated as a top layer of FTIEM, which functions as hydrating, salt screening and thermally insulating layer, thus, it prevents the loss of heat from the middle joule heating layer (i.e., COOH-MWCNTs-PVA layer, where the water evaporation occurs) to the bulk feed stream, while the bottom PVDF microporous membrane permits only vapor to pass through under an appropriate vacuum pressure. The power required for membrane heating is provided by using a D.C. supply. During MD desalination of sea water, the FTIEMs achieve the lowest specific heating energy of 0.024 KWhL−1. In addition, the FTIEMs upon long –term MD operation using hypersaline water as feed, exhibit excellent stability and performance with maximum flux and salt rejection of 29.25 Lm−2h−1 and 99.99 % respectively. Our findings may encourage the development of FTIEMs for desalination of hypersaline water.

The macroecology of community energy use in terrestrial vertebrates

Energy is a fundamental macroecological property as it governs all ecological processes and interactions. Understanding variation in community energy use and its correlations is crucial to knowing how communities function across the globe. As an organism’s metabolic rate equates to its rate of energy flow, individual rates can predict community-level functioning. Here, daily rates of community energy flow are calculated for 118 bat, 109 bird, and 196 non-volant small mammal inventories from around the world. These were scaled up from individual metabolic rates that were obtained for the 416 bat, 1880 bird, and 562 small mammal species present in the samples. While controlling for spatial autocorrelation, rates were contrasted and compared to various ecological, environmental, geographic, and anthropogenic variables, using a method of sequential regression that renders the variables orthogonal to each other, thus addressing the issue of collinearity. In all groups, there is a strong positive correlation between community energy use and community mass, with biomass being the primary determinant of community energy flow. More surprisingly, there are strong biogeographic differences within and between groups. Bat communities have consistently higher rates of energy flow in the Neotropics, while small mammal communities have higher rates relative to mass in Holarctic realms. Investigations of individual-level patterns reveal that these differences are a direct result of contrasting patterns of abundance, average individual mass, and metabolic rates. These results indicate that community energy use is strongly linked to differences in ecology and evolutionary history within and among groups.

Numerical simulation of cyclic performance of compressed carbon dioxide energy storage system in aquifer

The boom of renewable energy has been overshadowed by two problems: the intermittency and volatility of such energy. Largescale complementary energy storage has been required to solve these problems. This paper proposes a compressed CO2 energy storage system in aquifer (CCES-A), aiming to storage energy efficiently at a low cost. Firstly, the feasibility of compressing CO2 in the aquifer had been proved through numerical simulation, and the CO2 compression in the aquifer had been emulated by a wellbore-reservoir coupling model. The operation of the CCES-A had been divided into the establishment stage of the initial airbag, and the cyclic stage of energy storage and release. The proposed wellbore-reservoir coupling model had been applied to analyze the wellhead pressure, energy flow and energy recovery rate of weekly, monthly, and seasonal cycles, as well as the energy recovery efficiency at different injection temperatures. The simulation results showed that under the three cycles, the wellhead pressure increased with the number of cycles. The energy flow and energy recovery efficiency decreased with the growing the number of cycles. The energy recovery became more efficient with the rise of the injection temperature.

Towards quantum thermal multi-transistor systems: Energy divider formalism

A quantum thermal transistor controls the flow of thermal energy through two of its terminals in response to an external input signal on its third terminal. In recent years, several realizations of thermal transistors combining individual quantum systems have been proposed using temperatures or optical fields as the control signals. The success of the electronic transistor in modern technology partly lies in its ability to combine and make multi-transistor systems with enhanced flow control capability or even wholly different behaviors. Hence, as the next natural step, we investigate the intricacies of building composite systems combining multiple quantum thermal transistors. We identify that the interconnects of thermal transistors play a critical role in these systems by facilitating energy exchange from one transistor to another. By isolating the exact functionality of these interconnects, we develop a simple model that still captures all its essential characteristics. This model shows that directly coupling transistors allows a substantial energy transfer between them only under highly restrictive conditions. We then develop the energy divider formalism where a single properly tuned quantum harmonic oscillator acts as an intermediary between the transistors. We demonstrate that the oscillator mediates a substantial energy exchange under a considerably relaxed set of conditions and illustrate its operating principles through detailed quantum mechanical state analysis. We compare our energy divider based interconnect against the previously developed intermediate bath method and confirm that both ways achieve similar thermal energy flow rates between the transistors over a broad range of operating temperatures. At the same time, replacing an intermediate bath made up of a large number of harmonic oscillators with a single oscillator avoids many of the theoretical and practical limitations of the earlier method. For instance, time-domain simulations show that the energy divider based interconnect responds far faster to an external excitation than the corresponding intermediate bath based system. We believe the energy divider formalism provides valuable insights into the nature of thermal energy transfer within quantum thermal systems.

TAGUCHI AND RSM BASED OPTIMIATION OF ENERGY CONSUMPTION ON INTERNAL GEAR PUMPS

Internal gear pumps are used in a variety of applications for the transfer of many different types of liquids like fuel, oil and food in both the industry and daily life. Power transfer is provided in the applications of those pumps in the transfer sets, especially through the induction motor and the coupling connection. The R & D studies for the efficiency of pumps carried out worldwide account for 6% of the total, and thus energy savings of 303 trillion BTU can be achieved annually. With minimum energy consumption, high rates of energy savings will be ensured by transferring maximum amount of fuel. For this purpose, firstly a detailed literature review was made, and then industrial pump manufacturers and scientific studies were investigated. As a result of that, a new type of internal gear pair design ,which has not been manufactured so far in the industry, has been proposed. In the new pump, the effects of tooth length and the changes in the number of revolutions on flow, power and SEC results were studied. Thus, it will be possible to compare energy expenditure and flow rate with the other pumps developed. By using Response Surface Method (RSM), Taguchi Method and Anova Variance Analysis, optimum speed and tooth length were determined as 700 RPM for speed and 85 mm for tooth length by taking SEC S/N graph into account. In this way, pump production with optimum flow rate and energy consumption amount in the industry was produced, and the energy consumption value was decreased during the fuel transfer from 156,1 Wh/m3 to 92,0 Wh/m3.In addition, the change in the flow rate was found to be the most effective parameter in the 83% rate change. As for the calculation of the Ptotal results, it was determined that a 50% shaft speed and a 45% inner gear were effective.