A finite time thermodynamic (FTT) model of HI decomposition membrane reactor under different sweep modes is established. The sweep flow rate, reaction inlet pressure, permeable membrane thickness and reactor length are taken as decision variables, and the multi-objective optimization is carried out to maximize HI conversion rate, H₂ recovery rate and total entropy generation rate. It is found that the HI conversion rate and H₂ recovery rate are consistent to some extent within a given range of decision variables, but they cannot reach the optimum with the total entropy generation rate at the same time. Compared with the co-current sweep mode, the target values of Pareto front have higher HI conversion and H₂ recovery in the countercurrent sweep mode. Different decision methods are used to select the optimal solution. TOPSIS decision point in cocurrent mode and LINMAP decision point in counter-current mode had smaller deviation factors and could be used as the optimal solution for reactor parameter design.

The common bulkhead tank is one of the most efficient forms for cryogenic propellants, and the non-loss storage technology in the common bulkhead tank is the key issue. A cold shield model designed for the common bulkhead and zero boil-off storage is built based on the liquid oxygen/liquid methane common bulkhead and zero boil-off storage experiment system. The coefficient of temperature variation that considers the location variation characteristic and time variation characteristic of the temperature during the transient heat transfer and flow process is proposed. Compared with the nonuniformity coefficient, the coefficient of temperature variation is more suitable to evaluate the thermal uniformity of the cold shield. The results show that the cold shield with coiler performs an excellent thermal uniformity, the maximum coefficient of temperature variation of the cold shield is 3.85%.

The safe operation of high-power electronic chips highly requires high-efficiency heat dissipation techniques. Flow boiling heat transfer has received widespread attention due to the high heat transfer coefficient. To accurately simulate the complex two-phase process of flow boiling in a microchannel, a phase change model based on the volume of fluid (VOF) method with phase interface temperature correction is proposed in this paper. The flow boiling heat transfer process in a single microchannel with a single microcolumn is simulated to investigate the effects of heat flux and inlet subcooling by analyzing the evolution of two-phase flow process and temperature field. The results show that due to the local vapor coverage, there is a turning point of thermal resistance for flow boiling in microchannel under different working conditions, and high heat flux corresponds to higher bubble growth rate and nucleation area. A high subcooling will delay the turning point, but the overall thermal resistance will increase.

Based on the adaptive demand of the defrosting control method, the degradation of heating capacity (DHC) method was developed in this work to identify the frosty state, and the defrosting effect was evaluated adopting a fully connected neural network (FNN) classification model. Results indicated that in the monitoring case of the ASHP system, the proposed DHC method can effectively identify the frosty state, and the defrosting effect recognition accuracy achieved 91.3% for the trained FNN classification model in the testing data set. Compared with the original defrosting control method, the defrosting frequency, heating loss and power consumption were respectively reduced by 66.3%, 1775 MJ and 1829 MJ, and the SCOP was increased by 8.6% throughout the heating season. The promising results in this work will provide an innovative approach for the implementation and optimization of the defrosting control strategy of the ASHP system in practical operation.

Integrating direct air carbon capture (DAC) with renewable integrated energy systems (IES) provides an effective pathway to regional carbon neutrality. The reasonable configuration approach is a prerequisite for the stable, flexible, economic and zero-carbon operation of the overall system. Conventional configuration approaches cannot reflect the dynamic CO₂ mass transfer characteristics and energy consumption differences of DAC adsorption and desorption, resulting in suboptimal or infeasible configurations. To this end, this paper constructs the configuration-oriented DAC models to reflect its dynamic operation characteristics. Based on this, a DAC-IES configuration scheme is established with the annual total costs including investment costs, operation and maintenance costs, renewable curtailment penalties, and negative-carbon environmental benefits as the objective function to obtain the optimal capacity and collaborative operation strategy of each equipment, revealing the flexible operation mechanism of DAC under the background of intermittent fluctuation energy supply. The case study validates the effectiveness and superiority of the proposed configuration method. The analysis also indicates that the flexible operation of DAC systems enables better coordination with renewable energy and more cost-effective carbon capture. 

Chemical looping can achieve high product selectivity using lattice oxygen in oxygen carriers for partial oxidation of methane. Oxygen carrier La_1−xSr_xFe_0.8Al_0.2O₃ was prepared by sol-gel method for chemical looping dry reforming of methane. The reaction performance of the oxygen carrier doped with different proportions of Sr was tested by thermogravimetric and fixed bed reactor. The experimental results showed that the oxygen capacity of x=0.4 oxygen carrier in La_1−xSr_xFe_0.8Al_0.2O₃ is as high as 1.88 mmol·g⁻¹, with excellent reaction performance and less carbon deposition. The stability of the oxygen carrier La_0.6Sr_0.4Fe_0.8Al_0.2O₃ was further tested for 20 redox cycles. The oxygen carrier maintained excellent redox performance, achieving 61.2% methane conversion, 97.1% CO selectivity, and 1.81 H₂/CO. The material characterization results displayed that the morphology and crystal structure of the oxygen carrier were stable. The results show that La_0.6Sr_0.4Fe_0.8Al_0.2O₃ is an excellent oxygen carrier suitable for chemical looping dry reforming of methane.

Carnot battery (CB) is a novel electricity storage technology which could realize electricity storage and waste heat recovery simultaneously. The thermal integrated CB (TI-CB) only utilizes the waste heat energy during the charging process in previous study. The waste heat energy utilization is insufficient. A CB with thermal integration during charging and discharging process (DTI-CB) is proposed in this paper. The waste heat energy is effectively integrated with DTI-CB in all periods through being coupled to the Organic Rankine cycle (ORC). A thermo-economic evaluation of the proposed DTI-CB is conducted. Compared with TI-CB, the power output capacity could be increased 95.67% and the Levelized cost of storage could be reduced 30.90%. The thermoeconomic performance of the proposed DTI-CB performs better than those of the single ORC and CB under the conditions with relatively higher heat utilization load. 

A Kalina-organic Rankine combined cycle model is built in this paper. Constructal thermodynamic optimization of the combined cycle is conducted under the condition of the fixed total heat transfer area of the heat exchangers by combing constructal theory with finite time thermodynamics. The combined cycle thermal efficiency is chosen as the optimization objective, and the structural parameters of the components in the combined cycle are employed as the optimization variables. The optimal performances among the combined cycle, single Kalina cycle and single organic Rankine cycle are compared under the same conditions. The results show that the combined cycle thermal efficiency after optimization is improved by 40.83% compared with the initial design point. Compared to single Kalina cycle and single organic Rankine cycle, the combined cycle net power output of the combined cycle is improved by 49.89% and 66.82%, respectively, while the combined cycle thermal efficiency is improved by 57.76% and decreased by 4.69%, respectively. The optimization results can be used to guide the optimal designs of low-temperature waste heat resource utilization systems.

Based on the quantum law of corresponding states and considering the structural differences between hydrogen isomers, a mathematical model was developed for predicting the transport parameters of low-temperature orthohydrogen and parahydrogen. The results were examined and analyzed, and it was found that the quantum correspondence state principle method could predict the viscosity and thermal conductivity of orthohydrogen and parahydrogen in the temperature range of 20∼100 K and pressure range of 0.01∼10 MPa with good accuracy. The pressure has a significant impact on the prediction accuracy of the model, and the prediction error of the correspondence state principle is basically controlled within 6% when the ambient pressure is less than 1 MPa. Further correction of the physical constants in the model is expected to improve the prediction accuracy of the correspondence state principle.

Constructing a high-efficiency refrigeration cycle is essential for developing efficient refrigeration systems and achieving energy savings and emission reductions in the refrigeration industry. The traditional approaches to constructing refrigeration cycles are often based on expert experience, resulting in subjective and suboptimal cycle structure. This paper proposes an automatic method for constructing a refrigeration cycle with an ejector based on graph theory and heat exchanger separation. The mathematical description of the ejector structure and cycle configuration are determined, and an algorithm for constructing a refrigeration cycle with an ejector is established. The proposed method is applied to construct a refrigeration cycle with an ejector and two-phase recuperator used for freezing. The constructed cycle improves the energy efficiency ratio by 23% compared to the classical refrigeration cycle with an ejector for recovering expansion work.

As derived concepts of exergy, the application of the energy quality and energy grade has achieved great success in the practice of thermal science in the past four decades. However, their concepts and calculations have not been fully clarified, and the summary and induction of relevant applications are very rare in the literature database. Based on literature research, this paper explains the history of the energy quality and energy grade concepts, and expands the calculations and corresponding environmental reference states in detail. Moreover, analysis methods derived from the concepts and their applications are reviewed to better understand the functions of energy quality and energy grade. In addition, the concept of energy potential in the context of thermodynamics is preliminarily sorted out. This paper clearly shows the history and progress of the research in the field of energy quality, energy grade, and energy potential, which is helpful for the definition and thinking of related concepts.

In this paper, the ion diffusion coefficients and thermal conductivity of solid polymer electrolytes (SPE) containing poly(ethylene oxide) (PEO) and lithium bis(trifluoromethanesulfonylimine) salt (LiTFSI) with different end group of PEO are investigated and the structural properties are analyzed to study the ion transport and heat conduction mechanisms. The results showed that the poly(ethylene glycol) dimethyl ether (PEGDM) based SPE has better ion transport performance because more free lithium ions can be transported. However, the thermal conductivity of PEGDM is worse because the phonon spectrum is shifted to higher frequencies, which suggests that enhanced high-frequency phonon scattering leads to lower thermal conductivity. These findings provide valuable guide for PEO-LiTFSI electrolyte design.

Based on a quasi-steady-state simulation model, a method to optimize the cooling-down rate of an auto-cascade refrigeration system operating with a rectifying column and multi-component mixed refrigerant is proposed in the paper. Targeted on the maximum cooling capacity, the optimal suction pressure-evaporating temperature curve for a specified mixed refrigerant concentration can be obtained, which can be matched by the sectional suction pressure adjustment in the practical applications to reduce the overall cooling-down time, and the concentration of mixed refrigerant can be optimized to further improve the cooling-down rate based on this way. The fastest overall cooling-down time is achieved using the R50/R1150/R290/R600a as the mixed refrigerant (0.35/0.25/0.15/0.25 by mole) and corresponding shifting parameters (including two shifting temperatures −20°C and −105°C) and three shifting suction pressure 700 kPa, 600 kPa and 550 kPa) for the sectional suction pressure adjustment, when the air temperature in the test chamber is dropped from 20°C to −100°C. Calculation results also show that the optimal concentrations are different for different evaporating temperatures, and the cooling-down rate can be improved further if the concentration of the mixed refrigerant can be adjusted during the cooling-down process. The optimization methods used in this paper can also provide references for researches on cooling-down processes of other refrigeration systems using multi-component mixed refrigerants.

Proton exchange membrane fuel cells are widely used in the field of electric vehicles, and the flow field design has an important impact on the performance of the battery. In this paper, the effects of three different flow fields on the gas distribution, temperature distribution and water removal performance of the battery were studied through three-dimensional multiphase and multiphysical field numerical simulation. The results show that the slot flow field design can significantly enhance the lateral mass transfer under the ribs. Compared with the parallel flow field, the uniformity of the distribution of gas, temperature, current density and liquid water is significantly improved, and the performance is improved.

The optimal cogeneration share coefficient can guide the capacity configuration of cogeneration units and maximize the economic benefits of cogeneration. In this paper, a method for determining the techno-economic optimal cogeneration share coefficient considering the energy consumption characteristics of variable load conditions is proposed, the off-design working condition analysis model of cogeneration system is developed, and the variable load energy consumption characteristics of the case unit are calculated. The techno-economic cogeneration share coefficient is optimized. The results show that the optimal techno-economic heating coefficients are 0.750 and 0.702 respectively when considering and ignoring the energy consumption characteristics of variable load conditions, and the corresponding annual cost saving relative error without considering characteristics of variable load conditions reaches 22.0%. More accurate techno-economic benefits of cogeneration will be obtained by considering the energy consumption characteristics of variable load conditions.

An integrated model of heat source and heat sink, in which circular section isothermal liquid cooling channels are embedded in a cylindrical heating body with uniform heat generation,is established. Based on the constructal theory, given the cross-sectional area of cylindrical heating body and the ratio of channel cross-sectional area as the constraints, the influence of the distribution of liquid cooling channels on the heat dissipation capacity of the integrated model is studied with the number and the radius of liquid cooling channels as design variables, and the optimal constructs with the different ratios of cross-sectional area of liquid cooling channels are obtained. When the ratio of channel cross-sectional area and the number of channels are given, there are optimal center distances, which make the overall heat dissipation performance of heat source-heat sink reach the optimal, but the optimal center distances corresponding to the two indexes are different. When the ratio of crosssectional area of channels is given, the dimensionless maximum temperature and the dimensionless entransy equivalent thermal resistance decrease with the increase of channel number. When the number of channels is given, the dimensionless maximum temperature and the dimensionless entransy equivalent thermal resistance decrease with the increase of the ratio of cross-sectional area of channels. The results obtained in this paper can provide theoretical guidelines for the thermal design of efficient cooling of cylindrical devices.

The application, screening, evaluation and funding of National Natural Science Foundation of China programs in Engineering Thermophysics and Energy Utilization Discipline in 2023 are summarized and statistically analyzed. The strategic research, funding proposals in the field of energy conversion and utilization under the carbon peaking and carbon neutrality goals are introduced. The outstanding achievements funded by the discipline in 2023 and future work in 2024 are introduced as well.

In order to reduce the energy and water consumption of the cooling system in data center (DC), a DC cooling scheme coupled with radiative sky cooling (RSC) was proposed on the basis of mechanical cooling and direct air-side economizer, the corresponding system configuration and operation strategy were designed, and the mathematical model was established. A modular container DC in Xi’an coupled with the proposed scheme was simulated, and the energy and water saving effects as well as the environmental economic benefits were evaluated. In addition, the regional adaptability of the cooling scheme in 10 typical cities in China was analyzed. The results showed that, the energy saving and emission reduction rate of the proposed coupled cooling scheme (CM) can be attained 55% compared with the mechanical cooling (MCM), and increased by 5.2% compared with the outdoor air humidification scheme (OAHM). Meanwhile, the water consumption is reduced by 18.7%. Additionally, compared with MCM, the energy saving and emission reduction rate of CM in the studied 10 cities is between 42.9% and 78.1%, better energy saving and water saving benefits can be obtained.

R1234ze(E) and R600a are considered as promising environmental-friendly alternative refrigerants and accurate heat transfer data is essential when R1234ze(E) and R600a are applied in engineering practice. In this study, heat transfer coefficient prediction models are developed by using R1234ze(E) and R600a experimental data through a back-propagation (BP) neural network. The prediction result of new models is better than the classical heat transfer model in the literature. To expand the prediction ability of the model, a more general heat transfer prediction model based on R1234ze(E) and R600a is also developed. For R1234ze(E), the average relative deviation (ARD) of prediction results is 4.08%, average absolute relative deviation (AARD) is 8.46%, λ10% is 70.2%; for R600a, the ARD of prediction results is −3.59%. AARD is 6.98%, λ10% is 76.4%. The ARD range of the prediction results for six works of literature is −17.9% to 26.8%, AARD is no more than 27.6%, and λ30% is not less than 60.0%, which shows that the model in this study has certain prediction accuracy and universality.

In the field of active thermal utilization of nuclear energy, high temperature heat pipes (HTHPs) need to have a large length and ensure superior temperature uniformity. However, the existing research focuses on theoretical prediction of the performance and preparation of the HTHP with a relatively short length. In this paper, the HTHP with the length-diameter ratio of 67 is first prepared, the frozen start-up characteristic is theoretically analyzed, and the frozen start-up and steady heat transfer performance are experimentally studied, and a heating method that could give full play to the excellent heat transfer performance of the HTHP with a large length-diameter ratio is proposed. The HTHP with the length-diameter ratio of 200 is further prepared, and its heat transfer performance is qualitatively verified. The frozen start-up process is investigated by quantitative experiments, and the heat transfer law in the laryngeal region of the super-long HTHP is found.

The infrared radiative signature of the military target is determined by the emissivity of the infrared atmospheric window and the temperature level. Conventional infrared stealth coatings exhibit low emissivity across the whole infrared band but lack effectively radiative cooling through non-atmospheric window. This work designs a set of infrared stealth multilayered films structure based on deep neural network, incorporating germanium, platinum, and silicon arranged in order for compatible radiative cooling. The analysis reveals that the structure achieves a low average emissivity of 0.20/0.23 within the infrared atmospheric window detection bands of 3∼5 μm and 8∼14 μm, while maintaining a high average emissivity of 0.87 within the non-atmospheric window band of 5∼8 μm, thus facilitating efficient radiative cooling. Furthermore, the designed structure shows strong robustness regarding the polarization and incidence angle of the incoming electromagnetic wave. The spectral selectivity of the structure is attributed to the selective transmission of the germanium layer, the Fabry-Perot resonance generated by the Pt-Si-Titanium alloy TC4, as well as the intrinsic absorption of the Pt layer and TC4 substrate.

Turbine design is a complex and empirical process. To reduce the difficulty of turbine design, this paper proposed a method with uniform flux along radial direction and verified its advantages by the design case of E3 turbine. The results show that the through-flow design is basically consistent with the spanwise distribution of parameters in 3D CFD simulation. The results show that the through-flow prediction is basically consistent with the 3D CFD prediction. And the new design scheme reduces the secondary flow loss at the root of the first rotor and increases the turbine efficiency by 0.5%. The proposed through-flow design method has some advantages in improving calculating stability, reducing time cost and improving turbine aerodynamic performance.

A two-dimensional axisymmetric mathematical model was developed for an adiabatic hydrogen storage reactor based on the magnesium hydride and magnesium hydroxide. A sandwich reactor was proposed and compared with conventional sleeve reactor, the effect of hydrogen pressure and Mg(OH)₂ thermal conductivity on hydrogen storage and thermal storage performance of the sandwich reactor was investigated. The results show that the sandwich reactor exhibits a larger heat transfer area and lower heat transfer thermal resistance than conventional sleeve reactor, which results in faster heat transfer and hydrogen storage rates. Increasing the hydrogen pressure can enhance the heat transfer between metal hydride and thermal storage material and accelerates the hydrogen and heat storage rates. In addition, improving the thermal conductivity of Mg(OH)₂ is essential to further improve the performance of the sandwich MgH₂-Mg(OH)₂ reactor.

The Brayton cycle is characterized by high efficiency and compactness, making it suitable for use in nuclear reactor thermal-electric conversion systems. In the present work, a system simulation model was built based on EBSILON software for four open Brayton cycle configurations: simple cycle, simple regenerative cycle, reheat regenerative cycle, and intercooled reheat cycle, and key parameters were analyzed. The cycle parameters were optimized with the objectives of cycle efficiency and power density, and compared with the closed Brayton cycle. The results revealed that among the four configurations, the reheating and recuperative cycle achieved the highest cycle efficiency at 25.44%, while the simple recuperative cycle demonstrated the highest power density, reaching 171.13 kW·m⁻³. Improving the open cycle into the closed Brayton cycle increased the maximum cycle efficiency by 12.56 percentage points and the maximum power density by 11.87 kW·m⁻³.

A thermo-economic model was used to analyze the thermodynamic and economic characteristics of a geothermal ORC system. The evaporation and condensation temperatures of typical hydrofluoroolefins (HFOs) working fluids including R1224yd(Z), R1233zd(E) and R1336mzz(Z) were optimized to obtain the maximum net power. The thermo-economic characteristics were analyzed and compared with the traditional working fluids R601, R601a and R245fa. The results show that the evaporation and condensation parameters of R1224yd(Z) and R245fa are close under the optimal conditions. When the geothermal water inlet temperature is lower than 130°C, the net output power of R1336mzz(Z) is the maximum among the selected fluids, which is 1.47%∼1.89% more than that of R1233zd(E); but the heat exchanger area increases by more than 17%. When the geothermal water inlet temperature is higher than 130°C, the net output power of R245fa is the maximum, and the power generation cost is reduced by 15.5%∼16.8% compared with R1336mzz(Z).

With the improvement of the integration and power density of electronic devices, the high power consumption and high integration of electronic chips will make the heat dissipation of electronic devices continue to increase. Therefore, heat dissipation has become one of the main bottlenecks in the performance development of high-performance electronic devices. In this paper, a microchannel heat sink with airfoil ribs is proposed, and the airfoil ribs can enhance heat transfer by locally accelerating of fluid flow and mixing of fluid flow. ANSYS FLUENT was used to analyze the influence of the main geometric parameters of airfoil rib such as attack angle, exit angle, length and number on the flow and heat transfer characteristics of microchannel. It is found that the influence of rib length and rib number on the flow resistance and heat transfer performance of the microchannel is more significant than that of the attack angle and the exit angle. Compared with smooth microchannel, the proposed microchannel with airfoil ribs shows better comprehensive heat transfer enhancement performance under the constrain of same pressure drop.

In order to obtain the optimum design parameters of the supercritical carbon dioxide power system, this paper establishes a thermal analysis model of system and main equipment. parameter performance analysis and multi-objective optimization design of the supercritical carbon dioxide power generation device system with a heat pipe reactor is carried out. We develop an optimal solution set of power generation device system parameters with an output power of 1 MW(e), and conduct system sensitivity analysis. The research results indicate that increasing system parameters can achieve the goal of improving system cycle efficiency, but it also increases the size and scale of the equipment, which is unfavorable for improving compactness. The sensitivity of various main thermal parameters to system efficiency and volume varies greatly. The final optimization solution can be selected from the optimum solutions set in this article, based on the size of the available space, in order to obtain the optimum design parameters with better efficiency and compactness.

The performance of film cooling on a turbine vane is affected by many factors such as blowing ratio, surface curvature, and pressure gradient. In this paper, the Pressure Sensitive Paint (PSP) measurement technique is used to measure the film cooling effectiveness of gas turbine guide vane. The full coverage film cooling effectiveness in the blowing ratio (0.5∼2.5) have been measured in experiments, and the results of single-row film cooling effectiveness are analyzed. The results are as follow: With the increase of blowing, the film cooling effectiveness of the pressure surface increases. While such of suction surface first increases and then decreases because of surface curvature and pressure gradient. The jet flow has a better attachment effect to the surface in leading edge region under low blowing ratio, while the compound angle lead to convergence towards the mid-plane of vane under high blowing ratio. By comparing the superposition results with the full coverage experiment, the applicability of Sellers model to the vane cascade condition is studied.

As one of the key components in the hypersonic precooling engine, the precooler should reduce the temperature of hot air in a very short time, and its flow and heat transfer performance has an important impact on the performance of the precooled engine. In this paper, a new type of hybrid printed circuit heat exchanger is proposed in view of the large differences in the two-side mass flow rates and working pressures in the precooler. The numerical results show that along the flow direction of low-temperature helium, the temperature and convective heat transfer coefficient of low-temperature helium and high-temperature air increase gradually, and the change after Z=130 mm is obviously greater than the previous change. Increasing the mass flow on the air side increases the pressure loss on the air and helium sides. However, increasing the helium-side mass flow reduces the air-side pressure drops. The heat transfer rate per unit volume increases with the increase of the mass flow on both sides.

Organic Rankine cycle (ORC) technology can be used for low-grade thermal power generation, and has broad application prospects in renewable energy development and waste heat recovery. With the “double carbon” goal proposed, low-carbon energy and power system has become an inevitable trend. Therefore, the environmental performance index of ORC technology is more and more important. This paper summarizes the research status of the environmental protection performance of the ORC technology in the whole life cycle, summarizes the analysis process of the life cycle assessment (LCA) of the ORC technology, classifies the relevant research according to the type of heat source, summarizes its environmental impact characteristics, evaluates the environmental protection performance of common working fluids, and finally discusses the development trend of the life cycle research of the ORC technology. The study found that the existing inventory data in life cycle assessment is mostly secondary data, and the Recipe method is the most commonly applied evaluation method. The equipment production and substance leakage in the ORC system are important factors affecting its environmental performance.

Based on traditional compressed air energy storage mode, this study proposes a novel cogeneration system integrated methanol chemical looping combustion with compressed air energy storage. In the new system, the air compressor power consumption of the chemical looping combustion is eliminated in discharging process by utilizing excess electricity. Compared with conventional compressed air energy storage, the CO₂ separation without energy consumption can be realized in discharging process of the new system. At the same time, the low temperature compression heat is stored in the charging process. Then the stored heat is used for low temperature methanol reduction reaction, improving low temperature thermal energy grade. The system was simulated in Aspen plus software. Additionally, the effects of oxidizer reaction temperature, pressure, and air flow rate on system performance were studied. Furthermore, based on the reference system of conventional chemical looping combustion, a comparative study of performance was carried out. Besides, compared with conventional chemical looping combustion, the thermal efficiency, electrical efficiency and exergy cycle efficiency of the new system were improved by 16.53%, 5.82% and 9.20%, respectively.

In modern warfare, infrared stealth of military objectives plays an important role in improving their survival and breakout capabilities. In this paper, aiming at the multispectral infrared stealth, i.e., narrow-band high absorption at the active detection wavelength of near-infrared laser (1.54 μm), low emission in the two atmospheric window bands and taking into account the radiative heat dissipation requirements in the non-atmospheric window bands, we combine the rigorous coupled-wave analysis and deep learning methods to reversely design the Ge/Ag/Ge multilayer film circular hole metasurface structure. By analyzing the potential physical mechanisms and the emission and absorption characteristics at different angles for the optimized structure parameters, the multi-band synergistic stealth is achieved.

For MgCO₃/MgO thermochemical energy storage (TES), conversion rate of MgO carbonation is increased from 2% to more than 60% with alkali nitrates. However, its reaction mechanism is still controversial. In this paper, the catalytic mechanism of molten alkali nitrate is proposed by molecular dynamics research on MNO₃-MgO-CO₂ before chemical reaction. The interaction between molten MNO₃ and solid MgO results in lattice distortion, which weakens the Mg-O bond. The active sites are formed at vacancy defects, which is easy to adsorb CO₂ molecules so that they can combine with O₂− and absorb a large amount of CO₂ molecules in the three-phase boundary area. What’s more, structure-activity relationship between carbonation performance and vacancy concentration, active site distribution, the three-phase interface wettability were put forward. The methods of controlling the macroscopical properties of materials are further discussed, which would provide guiding principles for the preparation of high performance composite TES carriers in subsequent applications.

Supercritical carbon dioxide (sCO₂) power cycle has a more compact structure and higher efficiency. However, dramatic variations in thermophysical properties of working fluid and the coupling of multiple nonlinear physical processes such as fluid transport process and energy transfer process make conventional modelling and solving methods more difficult to simulate the cycle accurately and efficiently. This study constructs the heat current model of the sCO₂ power cycle and proposes an efficient solution algorithm based on the generalized Benders decomposition. The proposed algorithm categorizes system governing equations according to their linear or (explicit/implicit) nonlinear mathematical properties,and variables’ gradient information is used to update unknown variables iteratively. Compared to conventional algorithms, the new solution method owns better robustness and has a 48% larger convergence range regarding the deviation of initial values. Besides, the proposed algorithm is more efficient when the initial value deviation is small.

In order to reduce the influence of alcohol-amine carbon capture system on thermal economy of coal-fired power plants, a carbon capture system was built based on rate model through ASPEN PLUS software, and built a novel carbon capture system integrating rich liquid split process, lean vapor compression process and steam superheat utilization. The results show that when the liquid-rich split ratio is 0.1 and the flash tank pressure is 0.16 MPa, the energy consumption of the novel carbon capture system is the lowest (3.09 GJ/t (CO₂)), which is 20.77% lower than that of the conventional carbon capture system. Among them, the utilization of steam superheat reduces the energy consumption of the system by 11.54%. In addition, EBSILON software was used to build the sub-critical unit thermal system coupled with the carbon capture system. The results showed that when the unit load is 127.55 MW and CO₂ capture capacity is 500000 tons/year, the boiler heat load of the novel carbon capture unit decreased by 1.87% and the coal consumption for power generation decreased by 7.22 g/kWh. It can be seen that the optimization measures adopted in this study can not only reduce the reboiler duty of the carbon capture system, but also greatly improve the thermal economy of the subcritical carbon capture unit.

Boiling heat transfer is one of the efficient heat transfer methods, which is frequently employed in multifarious industries, including the chemical engineering, energy, and thermal management of electronic components. The Lattice Boltzmann Method was applied to study the boiling heat transfer process on bionic surface, and the influence of different surface temperature and wettability on the pool boiling was investigated. The results show that the bubble on the hydrophilic surface is more likely to break away from the surface, but the onset of nucleate boiling on the hydrophobic surface is earlier. By combining hydrophilicity and hydrophobicity to form a bionic hybrid wettability surface, the heat transfer characteristic can be effectively improved. Meanwhile, regulating the spacing between hydrophobic regions can achieve efficient heat transfer performance and directional growth of bubbles.

Based on the multilayer structured thermal emitter, this work develops a performance optimization model for near-field thermophotovoltaic systems considering non-radiative combinations.The optimal near-field thermophotovoltaic system can achieve a conversion efficiency of 33.44% with temperature difference of 600 K. The performances of the near-field thermophotovoltaic system with the optimal structure at different temperatures are analyzed, including the conversion efficiency, power density and current density of photovoltaic cell. The results show that the maximum efficiency of the optimal near-field thermophotovoltaic system is 41.94%, and the maximum current density is 13390 A·m−2 with the temperature difference of 900 K. Moreover, the performance of the near-field thermophotovoltaic system can be actively regulated by covering the surface of the thermal emitter with monolayer graphene, the maximum conversion efficiency of the graphene-based near-field thermophotovoltaic system is 43.51% when the chemical potential of graphene is 0.1 eV. This work helps to accelerate the development of near-field thermophotovoltaic system in the efficient recycling of industrial waste heat.

To clarify the effect of blade deformation on the aerodynamic performance of a highly loaded counter-rotating compressor, a thermal-fluid-structure interaction method is used to analyze the character of the blade deformation and the variation mechanism of aerodynamic performance under centrifugal, aerodynamic, and thermal loads. Additionally, a method for hot-to-cold transformation is developed. The results show that the leading edges of the low-pressure rotor deform towards the suction sides, whereas the leading edges of the high-pressure rotor deform towards the pressure sides. This leads to the operating point of the low-pressure rotor moving to the stall boundary, and results in the reduction of choke mass flow and peak efficiency of the compressor. By using nonlinear static analysis with inverse solving, the cold blade profile can be generated to achieve the aerodynamic performance of the design point without the need for deformation reverse interpolation and iterative correction.

The thermal properties of ZnO with different crystal orientations were characterized by the time-domain thermoreflectance method combined with a diamond anvil cell and a heating stage in 0∼8 GPa and 300∼873 K. It is found that the thermal conductivity of wurtzite ZnO is anisotropic under both high pressure and high temperature conditions. Meanwhile, the pressure dependence of the thermal conductivity is non-monotonic, while the temperature dependence of the thermal conductivity is monotonic. This research can provide useful insights into the internal heat transport mechanism of wide band-gap semiconductors under high pressure and high temperature, and give ideas for searching for materials with high thermoelectric figure of merit.