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The study optimizes the design of a 5 kg MmNi 4.6 Al 0.4 filled hydrogen storage device to achieve a quicker hydrogen absorption time using a coupled COMSOL Multiphysics® 5.6-Central Composite Design-Desirability approach. A straight tube of AISI 316L with 3 mm (d o) and 2 mm (d i) is taken as the heat transfer tube, and an array configuration with triangular pitch placement is utilized for structuring the tubes into the hydrogen storage device to enhance the heat extraction rate. The optimization is performed for the optimal placement of tube-to-tube distance (between 2d o and 4d o) on the responses hydrogen absorption time, weight ratio, and thermal power. The reactor is simulated comprehensively, comprising a water dome enabling a single inlet and outlet for water flow passage, thereby ensuring realistic fluid flow characteristics rather than multiple inlets across the tubes (which is generally adopted by researchers in the literature). The complete construction of the reactor ensures the utmost similar weight ratio and fluid flow pattern to the ones when built and eases the simulation relatively. The optimal tubing placement is evaluated as 2.75d o using the desirability approach (weight ratio maximum, thermal power maximum, absorption time minimum). The geometry for the optimal solution is built, and the simulation results showed a remarkable accuracy within ±3% with the desirability approach predicted data. The optimal case can attain 100% saturation in 510 s at a thermal power of 1.82 kW/kg h and a weight ratio of 0.875 when hydrogen is supplied at 15 bar and water fed at 288 K and 15 lpm. Further, the parametric studies of varying the supply pressure, inlet water temperature, and flow rate are analyzed, and the reactor is scaled up 2 and 4 times, and all results are documented. [Display omitted] • MO-optimization of embedded array structured tube H 2 -reactors using WR, IBT, and TP. • Comprehensively 3D designed and simulated 5, 10, and 20 kg MmNi 4.6 Al 0.4 reactors. • The optimized 5, 10, and 20 kg designs can extract 1.8 kW/kg hydride TP. • The reactors with and without dome have a mean deviation of 5.45% in estimating wt%. [ABSTRACT FROM AUTHOR]

From the uncontrolled proliferation of invasive plants, several challenges for the environment arise. Invasive wetland grasses biomass can be collected for biofuel production, thus offering a sustainable solution for invasive plants' management and contributing to the renewable energy sector. The straw-like shoot biomass of common reed (Phragmites australis), widespread across temperate and tropical zones, has been examined to assess its potential use for energy purposes. We seek to determine the fuel-energy characteristics of common reed biomass, which are necessary for converting it into energy through combustion. A comprehensive analysis was conducted to determine the physical and chemical properties of biomass according to the ISO standards for solid biofuels. These properties included calorific values, moisture, ash and volatile matter contents, and contents of C, H, N, and major and minor elements, as well as ash melting behaviour. The measured values were also compared to standard limits for different classes of densified biofuels. Based on the results, the net calorific value (15.33 MJ/kg ar) and other parameters met the requirements for the class A quality of non-woody briquettes and pellets. The only parameters which exceeded the class A limits were ash content (7.1% d.b.) and Cl content (0.16% d.b.). The findings of this study are important for the potential utilisation of common reed biomass for bioenergy as a step towards contribution to the Sustainable Development Goals. [ABSTRACT FROM AUTHOR]

ObjectivesThe natural draft cooling towers with flue gas injection (NDCT-FGI) is a crucial retrofitting technique for enhancing the efficiency of thermal power plants. However, its operational impacts on existing systems are significant and cannot be overlooked. Therefore, the current status of NDCT-FGI technology and its problems in operation were analyzed, and the countermeasures were put forward.MethodsThrough comprehensive analysis of the existing research, the causes and formation mechanism of environmental impact, cooling tower corrosion, and deterioration of circulating cooling water quality caused by the technical transformation of NDCT-FGI were discussed.ResultsThe protective distance can be reasonably set by the simulation results of flue gas emission trajectory and pollutant landing concentration by computational fluid dynamics (CFD). Installation of baffles at the tower top can prevent flue gas washdown during the extreme weather conditions. Different anticorrosive coatings are recommended for various parts of the cooling tower to extend its service life. To control and optimize cooling water quality, the advanced water treatment techniques are necessary for optimizing chemical dosing, and the management of effluent and makeup water must be carefully controlled to ensure operational sustainability.ConclusionsBy implementing appropriate and effective countermeasures, the negative impacts of NDCT-FGI retrofitting can be mitigated, thereby enhancing both the environmental and economic benefits for thermal power plants.

The efficient use and understanding of photovoltaic thermal (PVT) modules require accurately evaluating the temperature of their photovoltaic cells. But due to their specific composition, measuring this temperature directly is usually very complicated, if not impossible in practice. In this article, we present an original methodology to estimate the temperature of the cells of a PVT module. In order to do this, we simultaneously conduct experiments on both PVT and PV modules equipped with identical PV cells, and compare their electrical performance. The temperature of the PV module's back side is measured and used to estimate the temperature of the PV cells. The latter is then combined with the electrical power output difference between PV and PVT modules in order to obtain, through a specifically developed thermal model, the cell temperature of the PVT module. In addition, an experimental comparative analysis of different PVT modules is presented. The methodology and the results are promising but the experimental measurements used are subject to significant uncertainties that impact the accuracy of the estimation. The model uses an innovative approach to estimate the PV cell temperature of PVT modules, and recommendations are provided to optimize experimental data measurement accuracy in order to use this model in the best possible conditions. [ABSTRACT FROM AUTHOR]

Copyright of Power Generation Technology is the property of Power Generation Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Methods and types (qualitative, quantitative or mixed) of control of central heating installations in residential buildings are presented. Measurements were made for a radiator in a central heating system that was powered by a heating node substation. The output temperature of the heat node supplying the residential building, in which the test stand was located, was compared with the measured supply and return temperature. Indoor room temperature, outdoor air temperature, inflow and outflow temperature on the vertical supplying the heater were also recorded and analysed. These data were compared with the control charts of the heat networks allowing for direct readings of the required feed water temperature for a given outdoor temperature according to the Heat Energy Enterprises data. The differences are accordingly presented. The actual measurements, read at the test stand located on the 2nd floor of the 4-storey building with input parameters of 90/70 °C during the entire month of December 2022, are recorded every 6 hours and are tabulated and displayed in comparison charts with the calculated parameters. Inflow and outflow temperatures values on the vertical supplying the heater and the values of outdoor temperature measured by a sensor were analysed. The temperatures supplied to the radiators in the apartments were also compared with the requirements of electronic heating cost allocators contained in the PN EN 834 standard. New design temperatures for the central heating installation were proposed due to the requirements of the electronic heating cost allocator. [ABSTRACT FROM AUTHOR]

This paper presents an interior permanent magnet eddy current heater (IPMECH) that can be driven by wind turbine, which can realize the direct conversion of wind energy to thermal energy. A power analysis method for the IPMECH is proposed. The key to this method is to consider the influence of the skin effect on the distribution of eddy currents based on Coulomb's law, Maxwell's equation, and the Lorentz force law. Firstly, the equivalent magnetic circuit model is established, and the mathematical analytical expressions of air gap magnetic flux density (MFD), torque and thermal power of the IPMECH are derived. Then, the air gap MFD, torque and thermal power of the IPMECH are calculated, respectively. Finally, the analytical method (AM) is verified by the finite element method (FEM) and experiments. The results show that the proposed AM is sufficient to calculate the air gap MFD and thermal power of the IPMECH. The AM provides a quick and easy way to optimize and design an IPMECH. [ABSTRACT FROM AUTHOR]

This paper proposes an investigation of a novel design of receiver absorber tube (circular-trapezoidal shaped) for parabolic trough concentrator (PTC) system aiming at catching a part of the lost (reflected) solar rays due to effects related to the incidence angle deviation and thus improving the PTC's thermal performance. Although they are always present in PTC, the effects of the deviation angle are often not considered in the literature. These effects are considered here in view of presenting a better and more useful focal area, the optimal circular-trapezoidal absorber tube shape is determined according to the maximal limit of the deviation angle that allows catching the maximum amount of solar rays. The corresponding model is established considering it as a two-dimensional problem and the derived deviation angle coefficient is compared to that obtained for a traditional circular-shaped tube. Moreover, the energy balance model is adapted to simulate the thermal efficiency of the considered tubes as a function of the deviation angle with some assumptions. The obtained results prove that from a deviation angle value of 0.1 deg, the gain in efficiency becomes more significant; it can reach 5% and even be higher for a deviation angle value of 0.5 deg. Finally, comsol multiphysics software package was used to determine the pressure drops, temperature, and velocity field distributions, considering a deviation angle value of 0.2 deg. The results confirm that the proposed tube absorbs more heat than the traditional one. [ABSTRACT FROM AUTHOR]

In order to explore the combustion characteristics of the biomass vibrating grate furnace and realize the control and optimization of the unit combustion process, the mechanism model of the grate combustion process was established through the analysis of the biomass fuel characteristics and combustion mechanism. Moreover, the dynamic change of the grate fuel amount was studied, and the key parameters such as furnace temperature and flue gas oxygen content were predicted. The influence of periodic vibration of grate on combustion state in furnace was discussed. The results show that the amount of fuel in the grate is related to the current feed rate and fuel burning rate. The fuel has a large storage capacity on the grate, which leads to a large delay between the fuel burning and the current feeding. The predicted values of furnace temperature and flue gas oxygen content can follow the measured values well, and their changes are in accord with the combustion characteristics. The periodic vibration of the grate will cause the periodic change of the combustion state in the furnace. When the grate vibrates, the fuel combustion speed, furnace temperature, furnace pressure will increase, and the oxygen content of the flue gas will be reduced. As the vibration of the grate stops, these parameters return to the steady state level.

The layout of multiple natural draft dry cooling towers could have a significant influence on the performance of the cooling system in concentrated solar power (CSP) plants; however, this has never been quantified. Hence, this work used computational fluid dynamics (CFD) modeling to analyze the cooling capacity of two short natural draft dry cooling towers (NDDCTs) on a common site for a range of tower spacings, wind-speeds, and wind incidence angles. The results show that the cooling performance of the towers is a strong function of tower spacing and their orientation with respect to the wind direction. It was found that when the wind came at a 90-deg wind incidence angle (i.e., normal to a line drawn between the two towers), their cooling capacity was improved at tower spacings of less than 1.8 tower diameters (1.8D), though for the other tower spacings, there was no interaction between the towers. However, with the wind at 45 deg to the towers, the flow around the towers resulted in a decrease in their cooling capacity at tower spacings of 1.8D and 2.6D. Most interestingly, it was found that orienting the towers in line with the prevailing wind direction delivered improvements in the cooling capacity of up to 30%. This is due to the windward tower acting as a passive windbreak. Hence, as CSP plant capacity is increased, and additional cooling towers are required, these should be placed close to any existing tower and oriented along the line of the prevailing winds. [ABSTRACT FROM AUTHOR]

Copyright of Power Generation Technology is the property of Power Generation Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The single-well closed-loop heat extraction technology can realize efficient exploitation of mid-to-deep geothermal resources. A two-dimension heat transfer model is established. The effects of flow rate, inlet temperature, length and diameter of insulated tubing on heat extraction power and outlet temperature were investigated by the two-way absolute grey correlation analysis method. Results indicate that thermal power increases with the increase of displacement and length of insulated tubing, and decreases with the increase of injection temperature, outer diameter of insulated tubing and inner diameter of insulated tubing. [ABSTRACT FROM AUTHOR]

Purpose. Justification of rational control parameters of heat pumps to ensure energy-efficient operation of hydroelectric power plants in heating mode. Development of an automated methodology for calculating rational parameters for a complex system of hydroelectric power station (HPS) operating in heating mode. Methodology. Mathematical analysis and modeling. Findings. The application of the heat pump to ensure the heating mode at the hydroelectric power station for the needs of heating and hot water supply of buildings is analytically substantiated, as well as the rational parameters of the heat pump, which ensure the efficient heating mode at the hydroelectric power station, are determined. It is impractical and inefficient to pass the full flow of water passing through the hydraulic unit through the heat pump, because in this case the energy consumption in the heat pump compressor is several times higher than the consumption of the hydraulic unit in pumping mode, which devalues the proposed measure as an energy-saving measure. Therefore, the limiting and rational values of the design and operating parameters of the heat pump and heat accumulator, which ensure the heating mode of operation of the HPS to meet the needs of hot water supply, were substantiated. According to the proposed technology, the operation of a hydro unit with a typical capacity of 120 MW in the heating mode for various energy consumptions for the electric drive of the heat pump compressor was investigated. In accordance with these costs, the values and ratios of the electricity and heat generation shares of the modernized HPS changed. The proposed unconventional technology for converting hydroelectric power plants to the heat generation mode allows for wide effective maneuvering in different proportions of electric and thermal generation, unlike CHP and other power plants. The technology under consideration allows for virtually no consumption of non-renewable energy resources, providing consumers with both electric and thermal energy. Originality. The technology of using a heat pump to transfer the operation of the hydroelectric power station to the heating mode (heating and hot water of residential buildings) is substantiated. An automated technique for determining the rational parameters of heat pump (HP) for the implementation of HPS heating technology has been developed. The developed automated technique allows to calculate the values of operational parameters of HP for the balance and arbitrary modes, which ensure the heating operation of the HPS to meet the current needs of heating and hot water supply. Practical value. The use of a heat pump at a hydroelectric power station for heating and hot water supply allows you to save a third of conventional fuel consumption compared to a boiler unit.

This paper presents the use of sliding pressure inventory control (SPIC) of a 10 MW supercritical carbon dioxide Brayton cycle for concentrated solar power, incorporating printed circuit heat exchangers. Load regulation using SPIC for three representative ambient conditions 45 °C, 30 °C, and 15 °C are considered. While a wide operating range from 10 MW to less than 1 MW part load is obtained, a notable cycle efficiency decline at part load is also seen. Irreversibility analysis reveals that deterioration in recuperator and turbomachinery performance are primarily responsible for cycle performance degradation at part load. Nevertheless, useful inferences are obtained from the 10 MW SPIC irreversibility study. With a slightly increased value of heat exchanger length, a non-condensing 1 MW subcritical CO2 cycle operating between 35 bar/53 bar is found to be as efficient as a 1 MW supercritical CO2 cycle operating between 88 bar/210 bar. The major benefit of choosing the subcritical CO2 cycle for 1 MW scale applications is the significantly reduced turbomachinery speed (~26,000 rpm) in comparison with supercritical CO2 turbomachinery (~67,000 rpm) for the same power scale. These advantages are found to be true for air-based ideal gas cycles operating between 35 bar/53 bar too, with the latter requiring nominally smaller heat exchangers than the subcritical CO2 cycle. The final choice of working fluid, however, for these low-pressure cycles would depend on practical considerations, such as material compatibilities at high temperatures, corrosion considerations, and cost. [ABSTRACT FROM AUTHOR]

Design of an additively manufactured molten salt (MS) to supercritical carbon dioxide (sCO2) primary heat exchanger (PHE) for solar thermal power generation is presented. The PHE is designed to handle temperatures up to 720 °C on the MS side and an internal pressure of 200 bar on the sCO2 side. In the core, MS flows through a three-dimensional periodic lattice network, while sCO2 flows within pin arrays. The design includes integrated sCO2 headers located within the MS flow, allowing for a counterflow design of the PHE. The sCO2 headers are configured to enable uniform flow distribution into each sCO2 plate while withstanding an internal pressure of 200 bar and minimizing obstruction to the flow of MS around it. The structural integrity of the design is verified on additively manufactured (AM) 316 stainless steel sub-scale specimens. An experimentally validated, correlation-based sectional PHE core thermofluidic model is developed to study the impact of flow and geometrical parameters on the PHE performance, with varied parameters including the mass flowrate, surface roughness, and PHE dimensions. A process-based cost model is used to determine the impact of parameter variation on build cost. The model results show that a heat exchanger with a power density of 18.6 MW/m3 (including sCO2 header volume) and effectiveness of 0.88 can be achieved at a heat capacity rate ratio of 0.8. The impact of design and AM machine parameters on the cost of the PHE are assessed. [ABSTRACT FROM AUTHOR]

The energy and power industry is an important field for CO2 emission reduction. The CO2 emitted by thermal power enterprises is a major cause of global climate change, and also a key challenge for China to achieve the goals of "carbon peaking and carbon neutrality." Therefore, it is essential to scientifically and accurately predict the CO2 emissions of key thermal power enterprises in the region. This will guide carbon reduction strategies and policy recommendations for leaders, and also provide a valuable reference for similar regions globally. This study utilizes the factor analysis method to extract the common factors influencing CO2 emissions based on the carbon verification data of 17 thermal power enterprises in Gansu Province. Additionally, the DISO (distance between indices of simulation and observation) index is employed to comprehensively evaluate three prediction models, namely multiple linear regression, support vector regression, and GA-BP neural network. Ultimately, this study provides a reasonable prediction of CO2 emissions for the aforementioned enterprises in Gansu Province. The results show that the three common factors obtained by factor analysis, namely energy consumption and output factor, energy quality factor, and energy efficiency factor, can effectively predict the CO2 emissions from thermal power enterprises. In the three prediction models, GA-BP neural network has the best overall performance with DISO value of 0.95, RMSE value of 11848.236, and MAE value of 7880.543. Over the period 2022–2030, CO2 emissions from 17 thermal power enterprises in Gansu Province are predicted to increase. Under the low-carbon, scenario baseline, and high-carbon scenarios, the CO2 emissions will reach 71.58 Mt, 79.25 Mt, and 87.97 Mt, respectively, by 2030. [ABSTRACT FROM AUTHOR]

This paper presents an investigation of the performance indices employed in combined or multigeneration thermal systems. Specifically, the following thermal systems will be considered: (1) combined cooling and power (CCP) systems; (2) combined heating and power (CHP) systems; and (3) combined cooling, heating, and power (CCHP) systems. The investigation will highlight the main problems and limitations related to using these indices. We will propose a new procedure for evaluating the performance of CCP systems that can be generalized for use in other combined or multigeneration systems. Employing the subsystems forming any multigeneration system as a reference, the relative saving ratios of energy and exergy are calculated. These saving ratios are used as metrics for the goodness of multigeneration systems. We will also use them to calculate equivalent energetic and exergetic efficiencies of multigeneration systems. These equivalent efficiencies will be used as performance indicators of a multigeneration system as if it were producing only one of its products. The new procedure will be applied to three case studies in this paper. Results of this work indicate that the equivalent exergetic efficiency of power generation (ψP,eqv) is the most meaningful and accurate performance index for assessing the performance of multigeneration systems. [ABSTRACT FROM AUTHOR]

The present study proposes a Quonset-type greenhouse integrated with a thin-film photovoltaic thermal (GiPVT) system combined with an earth-air heat exchanger (EAHE) for crop cultivation in harsh hot climate conditions. A periodic thermal model in terms of input climatic and design parameters has been developed to evaluate the GiPVT system's thermal performance. This model is based on the energy balance equations of the GiPVT system, and it calculates PV roof temperature, greenhouse air temperature, and plant temperature for a given climatic data, i.e., solar irradiation and ambient air temperature. Furthermore, the thermal load leveling for the GiPVT system is determined to assess the thermal comfort status within the enclosed space of the system. The results indicate that EAHE successfully reduces greenhouse air temperature and increases the thermal comfort level inside the GiPVT system. Corresponding to the optimum flowrate of 0.5 kg/s, the maximum temperature of the plants and greenhouse is reduced by 20 °C and 21 °C, respectively. Moreover, the present GiPVT system produces 29.22 kWh of electrical energy per day, making the system self-sustainable. [ABSTRACT FROM AUTHOR]

Phase-change materials (PCMs) can be used to develop thermal energy storage systems as they absorb large amount of latent heat nearly at a constant temperature when changing phase from a solid to a liquid. To prevent leakage when in a liquid state, PCM is shape stabilized in a polymer matrix of high-density polyethylene (HDPE). The present research explores the injection-molded mechanical and thermal properties of different PCM/HDPE composite ratios. The tensile strength and modulus of elasticity at room temperature and with the PCM fully melted within the composite are measured. Additionally, the hardness, latent heat of fusion, phase-change temperature, and thermal conductivity are investigated. An analysis of microstructures of the composite is used to support the findings. The PCM within the PCM/HDPE composite gives it the benefit of thermal storage but causes a decrease in mechanical properties. [ABSTRACT FROM AUTHOR]

In the essential operation and control of the intelligent power plants, the primary goal is to balance both powers generated on the generation side with the power demand on the demand side. But, the structural variation of the power systems with a continuing escalation of customer demand is changing load demand continuously. Due to these problems, it is a continuous requirement to control and accommodate the escalation power need of the customer. The system's frequency is affected by disturbance and mismatching between power generation and power demand. The novel design of a hybrid Neuro-fuzzy system is used in the Automatic Generation Control (AGC) model of two equal-areas power systems. Installing non-conventional energy sources allows power producers and consumers to prefer power transactions in an economic scenario. The Distribution Generation (DG) is incorporated into the proposed model. The first design, the two equal-area AGC, uses a classical PID Controller considering DG. Second, the two equal- areas AGC design is investigated by considering Adaptive Neuro-Fuzzy Interface (ANFIS) with integrated Distributed generation. The simulation results show that an ANFIS incorporated with a DG-based PID controller exhibits more robust performance than the studied PID without and with the DG-based method. The reduction in vibration amplitude and the damping time provided by a PID-ANFIS-based AGC controller with the integration DG is 83.75%, much less than Classical Controllers. [ABSTRACT FROM AUTHOR]

The paper presents a solution methodology for a dynamic electricity generation scheduling model to meet hourly load demand by combining power from large-wind farms, solar power using photovoltaic (PV) systems, and thermal generating units. Renewable energy sources reduce the coal consumption and hence reduce the pollutants' emissions. Because of uncertain wind velocity and solar radiation, the share of solar and wind units is restricted to certain limits of demand, considering ramping requirements. The solar and wind units start quickly, while the thermal units start slowly. The commitment to renewable energy units is made through a proposed optimistic optimizer to restrict the power generation share. Economic and environmental objectives of thermal units are unified using a price penalty factor, and the hybrid sine–cosine algorithm (HSCA) optimization method solves the problem. A forward approach is applied to handle the dynamic electricity generation scheduling optimization problem. HSCA incorporates local mutation and hill-climbing heuristics to reduce global operating costs and emission pollutants' while allocating generation to the devoted units. To handle the constraints, replacement and heuristic techniques are applied. The proposed method is verified on a system having solar PV units and wind power plants connected to 6, 13, and 40 thermal generating units, respectively. [ABSTRACT FROM AUTHOR]

The power peaking factor (PPF) is an important parameter that needs to be considered to maintain the reactor's stability, safety and efficiency. The present study discusses the power density distribution in the reactor core by calculating the PPF to increase the reactor safety margin and minimize the possibility of a high power density at a certain point causing core failure in the Molten Salt Reactor (MSR), which is one of the Generation-IV reactors with fuel and coolant dissolved in molten salt. Important parameters discussed in the present study are the distribution of the reactor core region and the fuel composition in each region during the reactor operation time of 2,000 days. Analysis was performed for 3 different thermal power: 150, 450 and 1,000 MWth as a representative to determine the behavior of PPF at small to large power by taking the reference design of the FUJI U3 reactor developed by ITMSF (International Thorium Molten-Salt Forum) Japan. FliBe (Lithium and Beryllium Fluoride) is used as the coolant, and the fuel mixture is 233UF4-ThF4. The calculation was conducted using SRAC2006 with PIJ and CITATION modules that solve the neutron diffusion equation providing power distribution values and effective multiplication factors. As a result, the MSR with 4 core regions produces a more balanced power distribution, a better PPF value, and a good effective multiplication factor for 2,000 days of operation time compared to the reference design. [ABSTRACT FROM AUTHOR]

To understand the heat transfer performance of the middle-deep U-bend geothermal well, the 2500 m deep U-bend geothermal well was taken as the research object at the Hebei University of Engineering. This study established a mathematical and physical model of heat transfer in a U-bend geothermal, and the influence of geothermal gradient and lithologic changes on heat transfer performance was considered. The established model was verified based on the experimental data. Numerical simulation results show that a reasonable reduction of inlet temperature can increase thermal power. The thermal power of the geothermal well will increase by about 40 kW for every 1°C reduction of inlet temperature. The thermal power can be increased with a reasonable increase in the flow rate of the circulating fluid, but the increment of the thermal power decreases gradually. The simulation results show that the thermal power and outlet temperature of a deep U-bend geothermal well can be effectively improved by appropriately reducing the inlet temperature, increasing the flow rate, increasing the collection length, increasing the well depth, increasing the insulation length of the vertical well section and using low thermal conductivity insulation materials. The research results from this study could provide a reference for the heat transfer system optimization of the middle-deep U-bend geothermal well. [ABSTRACT FROM AUTHOR]

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Maintaining a continuous thermal convective power supply is very essential in many industries and thermal systems, this is because it helps in improving the efficiency of engineering machines and engines. Thus, hybridized electromagnetic nanoparticle in a heat supporting non-Newtonian fluid is a good platform to enhance thermal power energy. Based on its usefulness, this study focuses on the hybridization of zirconium dioxide (ZrO2) and copper (Cu) tangent hyperbolic nanofluid in ethylene-glycol(EG) (C2H6O2) solvent for thermal power optimization. With quadratic Boussinesq approximation, the fluid is influenced by electromagnetic induction and thermal convection. Via similarity quantities, an invariant derivative model is obtained. The model is completely solved using weighted residual method coupled with partition and one-third Simpson’s quadrature technique. The presented outputs revealed that entropy generation is minimized and thermodynamic equilibrium is achieved with rising values of the electric and magnetic field terms. Heat propagation is augmented with an enhanced electric field loading and nanoparticle volume fraction for hybrid nanofluid than unitary nanofluid. Also, current density is build-up for rising Williamson and thermal convection terms.

With the rapid increase of penetration level of new energy power generation, the construction of auxiliary service market is facing new challenges. The stricter requirements of the power plant unit AGC are proposed by the power system. How to coordinate and control the output of hydropower and thermal power units to increase the use of hydropower while meeting the requirements of AGC regulation is a problem to be solved. Under the condition of interconnection of units in the whole network, an optimal control strategy for joint commissioning of hydropower and thermal power plants that meets the performance conditions of ‘two rules’ is proposed in this paper. The strategy establishes the connection between hydropower and thermal power units. Combined with the output characteristics and economic characteristics of hydropower units and thermal power units, a coordinated optimization control strategy model of hydropower and thermal power AGC units suitable for the ’two rules’ assessment rules is proposed for each objective and constraint condition in the joint scheduling of hydropower and thermal power. The optimal mathematical model with multiple objectives is constructed to realize the distribution of AGC among different types of power plants and units, which can give full play to the regulation ability of hydropower and thermal power. The proposed strategy achieves the efficient use of clean energy and reduces the grid’s overall operating costs to achieve energy conservation and emission reduction. Simulation results verify the superiority of the proposed strategy.

Carbon control in the thermal power generation industry is crucial for achieving the overall carbon peak target. How to predict, evaluate, and balance the allocation of inter provincial carbon emissions has a significant impact on the decision-making of reasonable allocation of inter provincial carbon emissions in the target year. Therefore, this paper uses Monte Carlo-ARIMA-BP neural network and ZSG-DEA model to conduct temporal trend prediction and carbon emission quota allocation research. We propose the "intra provincial and inter provincial" framework for carbon emissions trading in thermal power plants, which aims to break through the barriers in carbon emission rights exchange among provinces. The conclusions are as follows: (1) the growth trend of carbon emissions from thermal power is gradually slowing down and is expected to peak before 2030. (2) Inner Mongolia, Jiangsu, and Shandong have high input–output efficiency, and are all the main output provinces for carbon emission quota allocation. After being adjusted using the ZSG-DEA model, they can still be at the forefront of efficiency. (3) The "intra provincial and inter provincial" framework for carbon emissions trading can effectively predict and allocate the carbon emission demand of each province from time and space dimensions, balance the carbon emission rights and interests of each province, and provide forward-looking planning suggestions for inter provincial carbon emission rights exchange. [ABSTRACT FROM AUTHOR]

In this work, an innovative design for a solar water heating system using a flat-shaped heat pipe as a heat transfer device is presented to pave the way for a substantial increase in the thermal performance of these systems. An analytical study is utilized to investigate the thermal performance of the solar water heating system. The analytical results of the flat-shaped heat pipe system are compared with the results of the evacuated tube solar water heating system with a U-tube, thermosyphon, and closed-loop pulsating heat pipe. It is found that the water temperature difference between the inlet and outlet of the flat-shaped heat pipe system is substantially higher than the U-tube, thermosyphon, and closed-loop pulsating heat pipe system by as much as 31.4, 22.5, and 18.5 °C, respectively, at a nominal 0.6 l/min mass flowrate. Furthermore, utilizing the flat-shaped heat pipe in the solar water heating system optimizes the thermal conductivity of the solar setup due to a reduction in the condenser section length. These reductions also lead to a large reduction in the weight and cost of the system. [ABSTRACT FROM AUTHOR]

Heat collection performance simulations using the system advisor model (SAM) with typical meteorological year weather data from four geographic locations are used to investigate (a) the optimum overall tilt of piecewise-focusing (PWF) collectors, and (b) PWF collector performance in comparison to the SAM default central receiver system. Results show that the overall tilt angle is not critical, but values up to 50 deg are best at non-tropical latitudes, even when output in summer is more valuable than in winter. For tropical latitudes, 40 deg of tilt is sufficient. Increasing PWF collector width relative to height is advantageous. Depending on location, PWF collector performance is 66-90% better than for the SAM default 100 MWe central receiver system, per square meter of reflector or heliostat. Using SAM's detailed control over system parameters, it is shown that the PWF collector's superior performance is derived mainly from better geometry (smaller cosine losses), but the near-absence of atmospheric attenuation and the smaller receiver heat losses are also significant. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the transient behavior of a salinity gradient solar pond (SGSP) under Mediterranean climate. For this purpose, a 2D numerical model is developed in which the absorption of solar radiation by different layers of saline water, the wind effect at the SGSP free surface, the heat losses from the SGSP free surface, and the development of the double-diffusive convection in the lower and upper convective zones are considered. The governing equations of continuity, momentum, thermal energy, and diffusion are solved using the finite volume method with SIMPLE algorithm. The validity of the numerical model developed in fortran 95 programing language is achieved through the comparisons of the results computed with the available numerical and experimental results obtained by literature studies. Results show that the developed numerical model can predict transient behavior of the SGSPs with a good accuracy. As an application of this model, the temperature, salt concentration, energy stored, and storage efficiency variations of a proposed SGSP are analyzed under Mediterranean climate. The results show that the lower convective zone (LCZ) temperature increases from 15 °C to around 95 °C whereas the temperature of the upper convective zone (UCZ) varies sinusoidally depending on that of the ambient air. Furthermore, the salt concentration of the LCZ decreases from 250 kg/m³ to around 248 kg/m³ while that of the UCZ increases from 50 kg/m³ to about 52 kg/m³. Additionally, the thermal energy stored is around 135 MJ with an efficiency of about 38%, which confirms the capacity of the SGSP to store thermal energy as sensible heat. [ABSTRACT FROM AUTHOR]

In this investigation, a vertical multi-effects diffusion solar distillation unit was designed and evaluated to optimise the production of fresh water. The primary objective was to elucidate the impact of brine feed rate and the number of stages on the water yield, addressing the prevalent challenge of low yield typically associated with solar-assisted distillation. Experiments were conducted across a range of feed rates: 240, 480, and 720 mL/h for a single stage; 480, 960, 1920, and 2880 mL/h for a three-stage setup; and 960, 1920, and 2880 mL/h for a five-stage setup. A consistent gap distance of 16 mm was maintained in all configurations. To ensure comprehensive understanding of the process, parameters such as ambient and feed water temperatures, solar intensity, and total dissolved solids (TDS) were meticulously documented. Results revealed a positive correlation between water yield and both the number of stages and the feed rate. The maximum water yield observed was 1252 g/h m², achieved with a five-stage setup, a feed rate of 2880 mL/h, and an average solar intensity of 721 W/m². This setup also enabled a significant reduction in TDS by 78%. Contrarily, an increase in feed rate was associated with increased TDS measurements of the distillate. [ABSTRACT FROM AUTHOR]

Thermoelectric generators (TEGs) panel is used to produce electrical energy by converting thermal energy into electrical energy depending on the temperature differences (ΔT) between the two sides of the panel, which can generate electrical power over 24 h for different climate conditions (hot, cold, wet or dry). The TEGs panel was designed using Solidworks and the prototype of the TEGs panel was carried out in this study for practical testing and evaluation. The TEGs panel performances and the limitation, including parameters such as power generation, efficiency, response time was studied. In this study, the TEGs panel was exposed to sunlight and cubic ice to consider temperature variations throughout the day. The results showed that the TEGs panel generates electric powers of 8.04437 W and 80.40171 W during the cubic ice and sunlight tests, respectively, for temperature differences (ΔT) of 18 °C and 3.3 °C. The electric power from this test can be used to charge a small mobile phone. It was indicated that the theoretical results by the MATLAB program are closely resemble the laboratory results. Furthermore, the correction ratio for the power of MATLAB validation was 6.59%, while the correction ratio for the efficiency was 5.46%. The response time of the system was ranged from 2 to 6 min, which it is indicating the time needed for the TEGs panel to respond effectively to changes in temperatures. After incorporating the correction ratios from MATLAB simulation, the results showed that the maximum electric power and a maximum efficiency (η) are 57.44 W and 13.5%, respectively, when the temperatures difference (ΔT) reaches 70 °C. This study presents a prototype of a versatile power generator (TEGs panel) offers free energy which can be utilising in insulation of building walls and power generation at the same time.

This paper reports on a parametric investigation of the thermal enhancement of a double-reflector parabolic trough collector when employing an in-line mixed V-shape (IMVS) ribbed absorber tube. Three heat transfer fluids (HTFs) are investigated, and a wide range of fluid inlet temperatures are studied. Various geometric parameters of the V-shape rib are analyzed to determine the optimum design of such a modification to the wall of the absorber tube. Results show that the HTF thermal oil Syltherm 800 is superior to the other HTFs that were studied. Results also show that a lower inlet temperature of the HTF leads to better thermo-hydraulic performance. The study provides a set of values for designing a V-shape ribbed absorber tube that produces optimum thermo-hydraulic performance. The optimum ribbed tube design shows a performance enhancement of about 64% compared to a smooth tube. [ABSTRACT FROM AUTHOR]

Swirl combustion serves as a helpful flame stabilization method, which also affects the combustion and emission characteristics. This article experimentally investigated the effects of CO2 microjets on combustion instability and NOx emissions in lean premixed flames with different swirl numbers. The microjets' control feasibility was examined from three variables of CO2 jet flow rate, thermal power, and swirl angles. Results indicate that microjets can mitigate the combustion instability and NOx emissions in lean premixed burners with different swirl numbers and thermal power. Still, the damping effect of microjets in low swirl intensity is better than that in high swirl intensity. The damping ratio of pressure amplitude can reach the maximum of 98%, and NOx emissions can realize the maximum reduction of 10.1×10−6 at the swirl angle of 30°. Besides, the flame macrostructure switches from an inverted cone shape to a petal shape, and the flame length reduction at low swirl intensity is higher than that of high swirl intensity. This research clarified the control differences of mitigation of combustion instability and NOx emissions by microjets in lean premixed flames with different swirl numbers, contributing to the optimization of microjets control and the construction of high-performance burners. [ABSTRACT FROM AUTHOR]

The objective of this research was to investigate utilizing small to medium-scale wind energy in domestic heating without considerable losses by direct conversion of the wind energy to thermal energy through a hydraulic medium. For this purpose, the virtual wind turbine mathematical model was developed in Simulink. Using hardware-in-the-loop (HIL) simulation, the Simulink model was integrated with dSPACE to control the AC motor connected to a variable displacement pump. The speed of the motor was controlled using a frequency converter, to which the torque of the virtual turbine model was supplied in real-time, and the angular velocity of the motor was fed back to the system. By regulating the valve orifice, a pressure drop was created across the orifice area, which led to the generation of thermal power. In order to validate the real-time simulated turbine, the output power and the characteristic curve of the tip speed ratio (λ) based on the power coefficient (CP) resulted from the real-time simulation were reconciled with the corresponding curves of the real turbine. The results demonstrated the conformity of the real-time simulation with the real turbine. The thermal power produced was measured by measuring the temperature of the hydraulic oil.

Thermal power generation plays a major role in meeting present-day power demands. Efficient and economic controls of crucial elements like steam boiler section need superior control mechanism to ensure better efficiency. Identification of model, dynamics is a formidable task due to the strong coupling of process variables, nonlinearities in the dynamics and constraints on the control inputs. This paper presents the application of nonlinear modeling techniques to estimate boiler drum dynamics in terms of nonlinear model framework which is one of the important requirements for the design of drum water level controls schemes. The historical plant data for estimation is collected from boiler of 210 MW, Stage-II, Boiler-4 of Dr. Narla Tata Rao Thermal power Corporation (NTTPC) Ibrahimpatnam, Vijayawada. Different operating conditions are selected to estimate the nonlinear dynamics of the boiler to check with the existing Hammerstein, Wiener, model frame works. Later the nonlinear framework is modified to estimate other nonlinearities present in the system. The estimated model responses are presented to check the boiler dynamics.

Purpose. Justification of the rational parameters of heat pumps and heat accumulators to ensure the efficient operation of the hydro storage power plant (HSPP) in the heating mode. Development of an automated methodology for calculating rational parameters for a complex system of a hydro storage power plant operating in heating mode. Methodology. Mathematical analysis and modeling. Findings. Using the developed automated calculation method, it was analyzed and determined that passing through the heat pump the full flow of water passing through the hydro unit is impractical and ineffective, because the energy consumption in the heat pump compressor is many times higher than the consumption of the hydro unit in pumping mode, which devalues the proposed measure as an energy-saving measure. The use of a heat pump and a heat accumulator at the hydro storage power plant for hot water supply needs will save a third of conventional fuel costs compared to a boiler unit. The developed automated technique allows to calculate the limit and rational values of design and operating parameters of the heat pump and heat accumulator, which ensure the heating mode of operation of the hydro storage power plant to meet the needs of hot water supply. Originality. An automated methodology for calculating the parameters of a complex system has been developed for the hydro storage power plant operating in heating mode. The concept of the maximum heat capacity of the hot water supply of the heat pump is introduced. The concept of the rational heat capacity of the hot water supply of the heat pump is introduced. In addition to the maximum heat capacity and the rational heat capacity modes, the developed method allows you to calculate all the parameters of the heat pump and heat accumulator, which provide the heating mode of the hydro storage power plant, for arbitrary values of the thermal power of hot water supply, with further comparison and analysis of the investigated modes and the selection of the most promising one. Practical value. The technology of using a heat pump and a heat accumulator to transfer the operation of the hydro storage power plant to the heating mode (hot water supply of residential buildings) is substantiated. The possibility of saving conditional fuel when applying the proposed technology is proven.

Biomass-based renewable energy research has gained extra momentum due to the energy crisis from fossil fuels and global warming. Vacuum suction gasification can create combustible power plant synthesis gas. In vacuum gasification, palm shell biomass and wood pellets have better performance than rice husks. Palm kernel shells and wood pellets can produce stable synthetic gas for 6.5 hours, and the indicator is a flare for 6.5 hours. Another indicator is that palm shells and wood pellets can maintain a sustainable high temperature in the reactor. Rice husk is not suitable for this type of gasification. It does not maintain the high temperature necessary for the gasification process to work properly. The mass of rice husk, which is lighter than other biomass, causes the risk husk to be unable to push it down to the bottom of the reactor so that it becomes empty. This massive event will cause the biomass and temperature in the reactor to drop suddenly. The value of heat loss in the reactor wall is quite large, more than 2000 watts, which may be a factor causing the performance of vacuum gasification to not be optimal. In this experiment, the addition of water to the reactor was tested to determine the performance behavior of the system. Palm shells respond well to this treatment. This results in a sustainably better syngas output. Wood pellets do not respond well because they are easily damaged by water. The rice husks failed to respond. The syngas produced by the reactor is burned and used to boil water. In this gasification system, palm shells and wood pellets have a heating value of 5.62 kW and 5.41 kW, respectively. The efficiencies of palm shell and wood pellets were 29.20 percent and 29.96 percent, respectively.

To meet the targets of carbon emission reductions and mitigate climate change, Chinese government actively supports the development of photovoltaic power (PV). Assessing the feasibility of development model and the possibility to achieve carbon emission targets should firstly address the relationship of PV development compared to coal-fired power (CFP), this study evaluated economic and environmental effects of PV and CFP from life-cycle perspective and further forecasted the optimal proportions of PV replacing CFP in 2030 and 2050, considering land resources and energy demand changes. First, the levelized cost of energy (LCOE) of PV and CFP is 0.55–0.80 CNY/kWh and 0.40 CNY/kWh, respectively, while the carbon emission of PV was 91.95 g/kWh, much less than that of CFP (775.86 g/kWh). Second, ever-increasing carbon emission and total cost indicates replacing CFP with PV possesses great advantages for both economy and environment, while land limitations suggested PV cannot completely replace CFP. Third, to resolve the contradiction among these factors and contribute to sustainable development, this study, using learning curve and results of calculation, further worked out optimal ratio for PV and CFP which is stable at 55.21% and 44.79% during present stage, but 69.86% and 30.14% are suggested in 2050, separately. [ABSTRACT FROM AUTHOR]

The thermal and hydrodynamic structure of a conduit of a plume that has not reached the surface is presented. The relations for determining the thermal power, the plume conduit diameter, and the maximum elevation height of such a plume are presented. The superlithostatic pressure at the plume roof defines the vertical forces directed from the bottom upwards. Relations for the superlithostatic pressure are presented and its value is estimated. Hydrodynamic processes in the block above the plume are considered in the stationary approximation using the model of a high-viscosity Newtonian fluid. The plume roof is assumed to be spherical. Due to the flow in the high-viscosity block, an uplift of the day surface is formed above the plume roof. The maximum elevation has been determined. The dependence of the elevation height on the horizontal coordinate for different times is obtained. Calculations have shown that the horizontal size of the main part of the elevation y1 increases with increasing depth of the plume roof. The profile elevations in the vertical plane passing through the main ridge are obtained for different distances between the plume axes ∆y. Such profiles have been constructed for systems of eight and five linearly arranged plumes. The elevation profiles in the vertical plane normal to the main ridge indicate the existence of ridges whose axes are normal to the main ridge. Such ridges are formed during the uplift, their number is equal to the number of thermochemical plumes responsible for the uplift formation. In case where ∆y > y1, the height of the main ridge has a saw-toothed character. Calculations show that the parameters of the uplift formed by the group of plumes are close to the parameters of the uplift of the Caucasus. [ABSTRACT FROM AUTHOR]

The distributions of heat flux over the circumference of the receiver tubes have an immense influence on the performance and reliability of the parabolic trough solar thermal collectors. The location of the receiver tube and the secondary reflector configuration may largely influence the performance of the system. Therefore, in this study, the effect of receiver tube position and parabolic secondary reflector configuration has been analyzed, and the non-uniformity of solar flux distribution, heat gradient, and power output has been compared. The results of the Monte Carlo ray-tracing analysis to homogenize the receiver tube flux distribution and maximize the output power, making the use of the cutting edge solar optical simulation tool Tonatiuh, has been presented. A parabolic trough collector with a rim angle of 80 deg and aperture area of 40 m2 have been used for the analysis. It has been confirmed that the circumferential heat flux gradient and the local hot spot could be greatly diminished, while the power output tended to reduce slightly due to the shading effect of the secondary reflector. Under the conditions investigated in this work, although the output power decreased by 4.83%, flux gradient reduced significantly, and the non-uniformity of flux distribution has reduced from 0.9757 to 0.5176. A simple design procedure for receiver tube position and secondary reflector configurations to homogenize the receiver tube temperature distribution has also been proposed. [ABSTRACT FROM AUTHOR]