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Monetite (CaHPO4) was coated on the Ti-6Al-4 V substrate by hydrothermal method. SEM, XRD, EDS, XPS, Raman spectroscope, and tensile test were used to characterize the morphology, phase constitutes...

Solar desalination holds significant promise for the water-energy nexus. Recent advances in passive solar desalination using thermal localization show great potential for high-efficiency freshwater production, which is particularly beneficial for areas without well-established water and energy infrastructure. However, there is a significant knowledge gap between laboratory scale innovation and commercial adoption. In this review, we discuss two critical factors – water production and reliability – which, if addressed systematically, could enable high-performance thermally-localized solar desalination systems. We show that optimizing heat and mass transfer of the entire device and recycling the latent heat of condensation are important to enhance total water production. Meanwhile, we discuss the potential of novel system architectures and fluid flow engineering to enable anti-fouling and robust desalination devices. In addition, we present techno-economic analysis that highlights the balance between water production, reliability, and cost. A criterion for economic feasibility is provided by comparing the price of desalinated water with commercially available bottle and tap water, which provides a roadmap for future development of solar desalination technologies.

Air-conditioning and refrigeration systems are essential facilities of health care, transportation and food preservation, which make people able to live and work at the coldest and warmest climates in the planet. These technologies have been applied to a wide range of scenarios, including the distributed air-conditioning, food, medicine, health and sport for people’s daily life, and centralized air-conditioning, heat pump and cryogenics in commercial and industrial applications. In the near future, global warming, urbanization and pursuit of higher living standard will continue to push the demand of air-conditioning. Food preservation for the increasing global population and fresh food e-commerce require more cold storage. Space detection, low-temperature imaging and cryogenic medical treatment will push the cryogenics forward. Except for these listed applications, there are also many other driven forces for the next-step development of air-conditioning and refrigeration, which make its future progress complicated. A comprehensive summary of the current status is necessary for air-conditioning and refrigeration, which will also provide us the basis to analyze its future perspectives. Three typical air-conditioning and refrigeration technologies are introduced at first. These include the refrigeration/heat pump, temperature-humidity control and cryogenics. Vapor compression refrigeration, absorption refrigeration, adsorption refrigeration, ejector refrigeration, solid state refrigeration, refrigeration without thermodynamic cycles and heat pumps are introduced for the first topic, which focuses on the temperature manipulation in normal temperature range. Condensation dehumidification, solution dehumidification, solid desiccant dehumidification and evaporative cooling are introduced for the second topic, which focuses on the interaction of temperature and humidity of air. Gas liquefaction and cryocooler are introduced for the third topic, which focuses on the thermal energy removal under low temperature. Conventional and emerging applications of these technologies are introduced afterwards. The refrigeration and dehumidification could support a wide range of application including air-conditioning, data center cooling, solar cooling, electrical vehicle thermal management and food/drug preservation. The applications of heat pumps include the clean heating supply and industrial heat recovery. The cryogenics could be applied for air liquefaction, liquefied natural gas, hydrogen storage, cryobiology/cryomedicine and big science project. Based on the previous analysis, future challenges on efficiency enhancement, eco-friendly refrigeration and application promotion are presented at last. The efficiency enhancement is driven by the numerous equipments of air-conditioning and refrigeration in use, which consume a large portion of total power consumption of mankind. It could be achieved through the innovation on heat exchanger, thermodynamic cycle and intelligent control. The eco-friendly refrigeration is driven by the environmental protection policies. Low GWP and ODP refrigerants including HFOs and natural refrigerant will be effective solutions. Small-sized heat exchanger with less refrigerant charge is also important. The application promotion is driven by the fact that air-conditioning and refrigeration have already become the basic technology supporting the emerging technologies. Except for the traditional applications, the air-conditioning and refrigeration technologies are becoming fundamental technologies for many multidisciplinary fields, including the data center cooling, electrical vehicle thermal management, clean heating, industrial waste heat recovery, cryobiology/cryomedicine, and big science project.

Investigations of the commercial aircraft impact effect on nuclear island infrastructures have been drawing extensive attention, and this paper aims to perform the safety assessment of Generation III nuclear power plant (NPP) buildings subjected to typical commercial aircrafts crash. At present Part II, based on the verified finite element (FE) models of aircrafts Airbus A320 and A380, as well as the NPP containment and auxiliary buildings in Part I of this paper, the whole collision process is reproduced numerically by adopting the coupled missile-target interaction approach with the finite element code LS-DYNA. The impact induced damage of NPP plant under four impact locations of containment (cylinder, air intake, conical roof and PCS water tank) and two impact locations of auxiliary buildings (exterior wall and roof of spent fuel pool room) are evaluated. Furthermore, by considering the inner structures in the containment and raft foundation of NPP, the structural vibration analyses are conducted under two impact locations (middle height of cylinder, main control room in the auxiliary buildings). It indicates that, within the discussed scenarios, NPP structures can withstand the impact of both two aircrafts, while the functionality of internal equipment on higher floors will be affected to some extent under impact induced vibrations, and A380 aircraft will cause more serious structural damage and vibrations than A320 aircraft. The present work can provide helpful references to assess the safety of the structures and inner equipment of NPP plant under commercial aircraft impact. Keywords: Nuclear power plant, Finite element, Aircraft, Dynamic response, Vibration analyses

Investigations of the commercial aircraft impact effect on nuclear island infrastructures have been drawing extensive attention, and this paper aims to perform the safety assessment of Generation III nuclear power plant (NPP) buildings subjected to typical commercial aircrafts crash. At present Part III, the local damage of the rigid components of aircraft, e.g., engine and landing gear, impacting the steel concrete (SC) structures of NPP containment is mainly discussed. Two typical SC target panels with the thicknesses of 40 mm and 100 mm, as well as the steel cylindrical projectile with a mass of 2.15 kg and a diameter of 80 mm are fabricated. By using a large-caliber air gas gun, both the projectile penetration and perforation test are conducted, in which the striking velocities were ranged from 96 m/s to 157 m/s. The bulging velocity and the maximal deflection of rear steel plate, as well as penetration depth of projectile are derived, and the local deformation and failure modes of SC panels are assessed experimentally. Then, the commercial finite element program LS-DYNA is utilized to perform the numerical simulations, by comparisons with the experimental and simulated projectile impact process and SC panel damage, the numerical algorithm, constitutive models and the corresponding parameters are verified. The present work can provide helpful references for the evaluation of the local impact resistance of NPP buildings against the aircraft engine. Keywords: Nuclear power plant, Aircraft, Engine, Steel concrete, Perforation

Investigations of the commercial aircraft impact effect on nuclear island infrastructures have been drawing extensive attention, and this paper aims to perform the safety assessment of Generation Ⅲ nuclear power plant (NPP) buildings subjected to typical commercial aircrafts crash. At present Part I, finite element (FE) models establishment and validations for both the aircrafts and NPP buildings are performed. (i) Airbus A320 and A380 aircrafts are selected as the representative medium and large commercial aircrafts, and the corresponding fine FE models including the skin, beam, fuel and etc. are established. By comparing the numerically derived impact force time-histories with the existing published literatures, the rationality of aircrafts models is verified. (ii) Fine FE model of the Chinese Zhejiang Sanao NPP buildings is established, including the detailed structures and reinforcing arrangement of both the containment and auxiliary buildings. (iii) By numerically reproducing the existing 1/7.5 scaled aircraft model impact tests on steel plate reinforced concrete (SC) panels and assessing the impact process and velocity time-history of aircraft model, as well as the damage and the maximum deflection of SC panels, the applicability of the existing three concrete constitutive models (i.e., K&C, Winfrith and CSC) are evaluated and the superiority of Winfrith model for SC panels under deformable missile impact is verified. The present work can provide beneficial reference for the integral aircraft crash analyses and structural damage assessment in the following two parts of this paper. Keywords: Safety assessment, Nuclear power plant, Aircraft, Numerical simulation, Finite element

Passive vapor generation systems with interfacial solar heat localization enable high-efficiency low-cost desalination. In particular, recent progress combining interfacial solar heating and vaporization enthalpy recycling through a capillary-fed multistage architecture, known as the thermally-localized multistage solar still (TMSS), significantly improves the performance of passive solar desalination. Yet, state-of-the-art experimental demonstrations of solar-to-vapor conversion efficiency are still limited since the dominant factors and the general design principle for TMSS were not well-understood. In this work, we show optimizing the overall heat and mass transport in a multistage configuration plays a key role for further improving the performance. This understanding also increases the flexibility of material choices for the TMSS design. Using a low-cost and free-of-salt accumulation TMSS architecture, we experimentally demonstrated a record-high solar-to-vapor conversion efficiency of 385% with a production rate of 5.78 L m−2 h−1 under one-sun illumination, where more than 75% of the total production was collected through condensation. This work not only significantly improves the performance of existing passive solar desalination technologies for portable and affordable drinking water, but also provides a comprehensive physical understanding and optimization principle for TMSS systems.

The electric quadrupole moment of $^{49}$Sc was measured by collinear laser spectroscopy at CERN-ISOLDE to be $Q_{\rm s}=-0.159(8)$ $e$b, and a nearly tenfold improvement in precision was reached for the electromagnetic moments of $^{47,49}$Sc. The single-particle behavior and nucleon-nucleon correlations are investigated with the electromagnetic moments of $Z=21$ isotopes and $N=28$ isotones as valence neutrons and protons fill the distinctive $0f_{7/2}$ orbit, respectively, located between magic numbers, 20 and 28. The experimental data are interpreted with shell-model calculations using an effective interaction, and ab-initio valence-space in-medium similarity renormalization group calculations based on chiral interactions. These results highlight the sensitivity of nuclear electromagnetic moments to different types of nucleon-nucleon correlations, and establish an important benchmark for further developments of theoretical calculations., Comment: Accepted by Physics Letters B (2022)

Sensible heat transportation with water is widely adopted in traditional heating network, which suffers from the low energy transportation density and inevitable heat loss for long-distance heat tr ...

Managing head and neck cancers is an excellent example of the importance of teamwork, with head and neck surgeons, clinical oncologists, radiologists, pathologists and other allied health professionals specialised in this disease site working together. The reliable imaging and dedicated pretreatment work-up entailing the comprehensive anatomical description of tumour involvement by the radiologists, the expertise of surgeons in performing en-bloc gross tumour resection, the uneventful speedy postoperative rehabilitation and recovery by the speech therapists and nutritionists, as well as the dedicated treatment planning of clinical oncologists in delivering precise preoperative or postoperative (chemo)radiotherapy to maximise the therapeutic potentials are the pillars of treatment success. A multidisciplinary tumour board involving all of these key players is essential to provide the highest level of recommendation based on evidence-based medicine and to bring patients new hopes and the best chance of cure. This review illustrates the seamless collaborative teamwork within a well-established multidisciplinary tumour board in managing one of the most intractable cancers in the East, taking enlightenment and inspiration from the West.

In this forward-looking perspective, the current technologies for low-temperature waste heat recovery are first analyzed from two aspects: (i) the local waste heat recovery technology and (ii) global optimization of energy flow network. Based on the analysis, barriers for the further promotion of waste heat recovery are outlined, and they include the lack of global optimization methodology, distributed waste heat recovery system with high costs, and mismatches between waste heat source and demand. To address these issues, perspectives on three aspects are provided. First, advanced graphical analysis and optimization methodology integrating the heat exchange and energy conversion can promote the user-friendly optimization. Second, concentrated waste heat recovery and supply can save the investment, installation area and operation costs, thereby making the waste heat recovery cost-effective. Third, thermal storage, thermal transportation and high temperature heat pump can better couple the waste heat source and user demand from time-scale, spatial scale and energy grade, respectively. Visions for the future are combined with technical details to provide comprehensive perspectives for the next-step waste heat recovery.

Absorption thermal storage is attractive due its small thermal loss during long term storage, which is advantageous for seasonal solar thermal storage. For the long term storage, high energy storage density is favorable to ensure a compact system. In this paper, the novel absorption seasonal thermal storage cycles with multi-stage output processes are proposed. Comparing to the conventional cycle with single stage output, larger concentration glide could be achieved by the proposed cycles under the same condition, resulting in high energy storage density. Performances of the water-LiBr absorption thermal storage cycles with double stage output and triple stage output are calculated and compared with that of the conventional single stage cycle. Energy flows, effects of temperature parameters, and working pair comparison are analyzed. For typical condition of solar thermal charging in summer and heat output in winter with output temperature of 50 °C, the proposed cycles with double stage output and triple stage output have 75.4% and 82.3% less heat losses, and achieve 7.32 times and 6.78 times higher energy storage densities than the single stage cycle. The proposed absorption thermal storage cycle with multi-stage output could be a good option for seasonal solar thermal energy storage.

Large amount of waste heat is dissipated in industries, resulting in energy waste and environment pollution. Waste heat recovery with absorption heat pump is one of the attractive solutions. In this paper, we present the theoretical study and test of a power plant waste heat recovery system with large scale LiBr-water absorption heat pumps for district heating. Waste heat from steam condenser with temperature of ∼35 °C is recovered by the absorption heat pumps driven by steam with pressure of ∼0.25 MPa from the turbine. Heat output from the absorption heat pumps is used to preheat the return water of district heating network from ∼45 °C to ∼80 °C. The return water is further heated by the steam to ∼105 °C for heating supply. Large temperature lift of the return water is achieved by the serial absorption heat pumps. Theoretical analysis of the system is presented, showing advantages compared to the conventional absorption heat pump and original heating supply system. On-site test showed that COP of 1.77 and heating capacity of 63.57 MW were achieved by one serial absorption heat pump, with waste heat inlet/outlet temperature of 34.63/28.33 °C and return water inlet/outlet temperature of 45.94/81.34 °C.

Steam generation process is closely related to energy conversion and cleaner energy utilization, and the industrial steam is even regarded as the currency of heat with significant social and economic value. Herein, the possible industrial steam generation paths are analyzed based upon thermodynamics analysis, in which fossil fuel, electric, and heat‐pump heating are considered. The large‐temperature‐lift heat‐pump heating for steam generation is proved to be a most reasonable way with high‐efficiency and wide adaptability. Furthermore, a possible system sketch is proposed, in which the heat pump is used for preheating for low‐temperature evaporation and the generated steam can be thus compressed with a steam compressor to the expected high‐temperature (pressure) steam. The key parameters of the heat pump for steam generation are ascertained and the subsequent optimization space is discussed. The results show that the proposed steam‐generation path has clear performance advantages and potential for industrial steam generation, which could be a sustainable heating system for industry.

Heat pump is effective to recover ultra-low grade waste heat, and includes compression and absorption heat pumps. However, the driving source of these heat pumps are different. This makes the efficiency comparison unfair, and multi-criterion comparison is necessary. In this paper, the compression and absorption heat pumps are compared under the same condition, where 30 °C waste heat is recovered to provide 60 °C domestic heating supply. Analyses with coefficient of performance (COP), second law efficiency, exergy efficiency and exergy rate are carried out. Exergy-to-energy ratio of driving source, instead of temperature, is used to unify the evaluation of different driving sources. Results show that compression heat pump has higher COP but lower exergy efficiency, indicating more irreversible loss. This is followed by double effect, single effect and double lift absorption heat pumps. The high COP lead to effective recovery of exergy from waste heat, with higher exergy rate. However, the strong sensitivity of COP versus temperature lift in compression heat pump makes it more effective under small temperature lift, while absorption heat pumps are more effective under higher temperature lift. The multi-criterion comparisons provide both deeper understanding about heat pumps and useful framework for waste heat recovery analysis.

In order to improve the anticorrosion ability of a Mg-5Zn-1.5Ca alloy used as a bone replacement material, this study prepared the MnCaP conversion coating, which was formed from a phosphating solution mixed with a MnCl2 solution of 0.05 molarity, on a magnesium (Mg) alloy. After forming a MnCaP conversion coating on a Mg alloy, micro-arc oxidation (MAO) proceeded for improving the anticorrosion ability of the sample. As a result, when the 0.05MnCaP coating on a Mg alloy was immersed in the simulated body fluid (SBF), the corrosion current, pH value change, and hydrogen evolution volume of the SBF solution are lower than a uncoated Mg alloy. From the SEM and EDS analyses for a corroded 0.05MnCaP coating on a Mg alloy, the manganese (Mn) phosphate in a lumpy-rock form and the calcium (Ca) phosphate in a flake form alternate to each other densely, so that the coating can effectively prevent a Mg alloy from corrosion.

Using conventional fossil fuels causes both energy crisis and environmental pollution. Renewable energy with the merits of almost unlimited availability and environmental-friendliness provides a perfect solution to the problem. Solar energy is widely recognized as one of the most important renewable energy resources due to its even distribution, safety and serving as sources for others. In past decades, global solar thermal capacity increases rapidly and now it has been widely used worldwide to provide heating and cooling. To understand the current progress of relevant technologies and the future development, this paper briefly summarizes the current situation of solar heating and cooling, and then some new achievements in related areas and potential future market penetration are discussed. It is found that solar hot water heating system's development is in fast lane in recent years with evacuated tube solar collector dominating the mass market. How to integrate solar collecting system with different types of buildings is the main research and development direction for solar building heating system. Large-scale district water heating system and solar PVT system as the most promising solutions attract extensive attentions. For solar cooling, efforts have been made to improve the efficiency of conventional solar thermal cooling methods in terms of adsorption and absorption technology. In addition to technical development, economic analysis of solar heating and cooling system is also discussed. Return of investment period is widely adopted to evaluate the economic performance. Results reveal that low initial cost and advantageous allowance are the most efficient ways to make solar heating and cooling system economically attractive. This paper is presented and recommended by 5th International Conference on Nuclear and Renewable Energy Resources.

Absorption chiller is a widely used technology owing to its capability to utilize low grade thermal energy including solar thermal energy and waste heat. Yet, most solar absorption cooling systems need cooling tower to dissipate heat rejection into ambient. The use of cooling tower increases both the initial investment and water consumption, which can be improved by air-cooled solar absorption cooling system. In this paper, to give the best absorption cycle options under different conditions, five absorption refrigeration cycles suitable for air-cooled solar cooling including three double lift absorption cycles and two semi-GAX (Generator-Absorber heat eXchange) absorption cycles were compared. Steady-state simulation is carried out. Efficiencies of these cycles were calculated with LiBr-water and water-ammonia working pairs in the scenario of air-cooled solar cooling. Heat source temperatures of 75–100 °C from non-concentrating solar collector and air temperatures of 20–40 °C were considered. Both air-conditioning condition with evaporation temperature of 5 °C and sub-zero condition with −10 °C were discussed. It is found that mass-coupled semi-GAX absorption cycle with ammonia-water is suitable for air-conditioning with higher heat source temperatures, mass-coupled double lift absorption cycle with water-LiBr is suitable for air-conditioning with lower heat source temperature and mass-coupled double lift absorption cycle with ammonia-water is suitable for sub-zero conditions.

In the solar absorption cooling systems, concentrating collector can be adopted to achieve higher driven temperature and improve the system performance. The Compound Parabolic Concentrator (CPC) is a good option with both concentrating and stationary features. With higher working temperature, solar absorption cooling system with concentrating collector has more choices of absorption chillers than the system with non-concentrating collector. The aim of this paper is to find the better chiller choice for solar absorption cooling systems with CPC. The analyzed LiBr-water absorption chillers include the single effect chiller, the double effect absorption chiller and a novel variable effect chiller built by the author. Simulation is carried out in TRNSYS. Model of the variable effect absorption chiller is first derived from MATLAB artificial neural network (ANN) toolbox based on experimental data, and then built in TRNSYS. Performance of the three systems is calculated under the same condition. Performance of the three systems is compared to get the better choices. The impacts of the solar collector area, cutoff driven temperature and storage tank volume on the solar cooling fraction, auxiliary heat input, average chiller COP and average solar efficiency are analyzed. The variable effect system has high solar cooling fraction, low auxiliary heat input and high solar efficiency. The single effect system has medium solar fraction, high auxiliary heat input and medium solar efficiency. The double effect system has low solar cooling fraction, low auxiliary heat input and low solar efficiency.

In this paper, a sorption thermal storage system with large concentration glide is proposed to achieve long term thermal storage with high energy storage density. The system consists of a storage subsystem and a cooling subsystem. In the charging process, the condensation of the storage subsystem is cooled by the cooling subsystem. The pressure of storage subsystem is decreased and its concentration glide is enlarged. The ammonia-water solution is chosen as working pair considering the subzero working condition. Performances of the proposed system and the conventional system are calculated and compared under heat input temperature of 90 °C. For the heating supply with temperature of 40 °C under ambient temperature of −10 °C, the proposed system obtains COP of 0.18 and energy density of 293.9 kJ/kg. The conventional system cannot deliver heat output under the same condition. For the cooling supply with temperature of -5 °C under ambient temperature of 30 °C, the proposed system obtains COP of 0.27 and energy density of 466.9 kJ/kg. Compared with the conventional system, 138% energy density enhancement and 21% COP degradation are achieved. The proposed system has higher energy density than the conventional system, especially when the heat source temperature or evaporation temperature is low.

In solar absorption cooling system, the instability of solar power causes mismatch between the solar collector and the absorption chiller. The variable effect absorption cycle was proposed to improve this. In order to investigate its solar driving performance, a Compound Parabolic Collector (CPC) driving variable effect LiBr-water absorption cooling system is simulated. Model of the variable effect LiBr-water absorption chiller is built through artificial neural network (ANN) modeling based on 450 groups of experimental data. Good agreement between the prediction and experimental data is achieved with correlation coefficient of 0.994. The CPC driving absorption cooling system is then built in TRaNsient SYstem Simulation program (TRNSYS) based on the chiller model. The daily performance of this system is calculated and analyzed. The variable effect chiller can work with low driving temperature, which guarantees a long working period. Besides, the variable effect chiller has high COP under high driving temperature, which ensures a competitive overall efficiency. The calculation shows that average chiller COP of 0.88 and solar COP of 0.35 are obtained. The effects of solar collector area, storage tank volume and cut-off driving temperature on the system performance are analyzed. The optimal solar collector area and tank volume are obtained.

In-situ TiB2/AZ80 composite was prepared by a simple casting method, and then hot-rolling. Effects of TiB2 reinforcements on the microstructural evolution of composite were investigated. In-situ TiB2 particles could refine the as-cast grains of AZ80 alloy, and promote recrystallization through particle stimulated nucleation (PSN) effect. Due to the grain refinement and the PSN effect of TiB2, the twin induced recrystallization mode in AZ80 alloy is transformed into grain boundary and particle dominated recrystallization process in the TiB2/AZ80 composite, which suppresses the generation of coarse shear bands during rolling and improves the rolling ability. At the same time, the morphology of TiB2 particle clusters was continuously modified with the increase of rolling passes, and finally formed fiber-like distribution characteristics. Fine grain strengthening and thermal mismatch strengthening are the main strengthening mechanisms of the composite sheet. Internal toughening mechanisms are texture weakening, the proliferation of more dislocations, higher Schmidt factor and more uniform strain distribution induced by the PSN effect. In addition, external toughening ones should attribute to bending and deflection of cracks resulting from fiber-like particle distribution characteristics. Thus, the strength and toughness of the TiB2/AZ80 composite were simultaneously enhanced.

The shortcomings of conventional working pairs in thermal energy storage and transmission based on absorption cycle have become major obstacles for practical application. Ionic liquids (ILs) are promising alternatives, while only few ILs have been evaluated with enumeration method, by which it is difficult to create a short-term breakthrough. In this study, a prediction framework is established via relating the fundamental thermodynamic properties (absorbing ability and excess enthalpy) with cycle performance (COP and energy density) in order to clarify the maximum potential of this technology and the desirable properties of potentially interesting working fluids. A comprehensive investigation of promising IL absorbents in thermal storage/transmission has been carried out by the framework. Then, theoretical analysis shows that an optimal region with both high COP and high energy density (between 31.00 kJ/mol to 37.00 kJ/mol) could be reached, indicating 57% of improvement in energy density is possible (the highest level at current stage is 23.52 kJ/mol). To pursue the optimal performance, strong affinity between the species and decreasing trend of excess enthalpy during generation are found to be key roles. Such a theoretical framework could be further extended to the fluids design and screening of absorption thermal energy storage/transmission, as well as other related technologies.

The previously published literature based on the performance prediction of solar-powered adsorption chillers generally incorporates fixed heat/mass recovery (HR/MR) cycle times which remain unchanged during the entire course of operation of the adsorption chiller. In reality, the dynamics of the HR/MR processes are continuously subject to change due to temporal variations in the solar radiation intensity, and thus fixed HR/MR cycle times might not prove to be compatible with the actual dynamics of a transient solar-powered chiller operation. The current study proposes a numerical scheme for performance modeling of a commercial-scale adsorption chiller with adaptive HR/MR cycle times following the adsorption/desorption (ads/des) cycle. A novel model of the MR cycle has been proposed which, in accordance with the best knowledge of the authors, cannot be find anywhere else in the previously published literature. The ads/des → HR → MR → des/ads half cycle has been predicted to yield an almost 52% higher cycle-averaged value of coefficient of performance ( COP ), an almost 16% higher value of specific cooling power ( SCP ), and a roughly 146% higher value of solar COP ( COP sc ) than the ads/des → MR → HR → des/ads half cycle over the entire course of operation of the adsorption chiller till sunset.

High-temperature heat pump is gaining more and more research attention due to the efficient heat supply for industrial uses, which includes waste heat-source, water-source, and air-source types. Although air heat source has lower energy grade, its superior availability is attractive. However, large temperature lift is necessary to fill in the gap between the low temperature ambient air and high temperature supply, which cannot be fulfilled by current heat pumps. In this study, a novel air-source hybrid absorption-compression heat pump is proposed to address this issue, in which the compression sub-cycle and absorption sub-cycle are thermally coupled for stepped temperature lift. Compared with the conventional air-source heat pump, a large temperature lift (over 90 °C) and relatively good thermodynamic perfectibility (0.34) are obtained. As the temperature lift increases from 70 °C to 110 °C, the coefficient of performance changes from 1.7 to 1.2. Moreover, heat recovery between the two sub-cycles is achieved to reduce the heat exchange capacity with air, thus saving air–liquid heat exchanger area and cost. Via the integration of relatively mature technologies, the proposed system provides a feasible and efficient way to upgrade ambient heat for industrial uses, and it is technologically available in different capacities.

Membrane distillation (MD) has been proven promising in solar-driven desalination. Moreover, its unique characteristics such as simple process, module compactness, high salt rejection rate, etc. allow for a small-scale device in a distributed system. Both theoretical and experimental researches on the coupling between solar collectors and MD aiming at compact and autonomous desalination system have been devoted to enhance freshwater productivity and energy efficiency. In this paper, certain critical gaps are summarized upon a panoramic review of the current status, including limited production and energy performance compared with commercial-scale desalination, unclear relation between solar collecting area and membrane area, and few discussions on efficient condensation, etc. To tackle these challenges, perspectives on the essential future research directions are proposed. Solar direct heating and solar concentration constitute the possible resolution to enhance solar energy utilization for higher water production, which also raise the question of optimizing solar/MD areas. Meanwhile, module stacking, module internal heat recovery and external evaporation heat recovery are deemed prospective in further reducing MD energy consumption. Subsequently, an enhanced vapor condensation needs more exploration. Those aspects and a potential combination among them are the main tasks in the near future, together with more field tests on small distributed solar-driven MD systems.

Environmental scanning electron microscopy (ESEM) is a broadly utilized nanoscale inspection technique capable of imaging wet or insulating samples. It extends the application of conventional scanning electron microscopy (SEM) and has been extensively used to study the behavior of liquid, polymer, and biomaterials by allowing for a gaseous environment. However, the presence of gas in the chamber can severely degrade the image resolution and contrast. This typically limits the ESEM operating pressure below 1000 Pa. The dynamic interactions, which require even-higher sensitivity and resolution, are particularly challenging to resolve at high-pressure conditions. Here, we present an enhanced ESEM technique using phase reconstruction to extend the limits of the ESEM operating pressure while improving the image quality, which is useful for sensing weak scattering from transparent or nanoscale samples. We applied this method to investigate the dynamics of condensing droplets, as an example case, which is of fundamental importance and has many industrial applications. We visualized dynamic processes such as single-droplet growth and droplet coalescence where the operating pressure range was extended from 1000 to 2500 Pa. Moreover, we detected the distribution of nucleation sites on the nanostructured surfaces. Such nanoscale sensing has been challenging previously due to the limitation of resolution and sensitivity. Our work provides a simple approach for high-performance ESEM imaging at high-pressure conditions without changes to the hardware and can be widely applied to investigate a broad range of static and dynamic processes.

Thermal energy storage based on sorption method is attractive in view of energy storage density, storage period, and flexibility. Three-phase sorption thermal energy storage is advantageous from high energy storage density, but its temperature lift is low. Besides, further energy storage density enhancement is needed to make the storage system more compact. In this paper, multi-functional three-phase sorption thermal energy storage cycles are proposed to achieve higher temperature lift and energy storage density simultaneously, in which different applications can be evident including interseasonal heating, combined cooling and heating in summer, and heat transformer in summer and winter. The performance of the proposed cycles for three operating modes is evaluated analytically with a working pair of LiCl/H2O, due to its high absorption and crystallization enthalpy. Results showed that the multi-functional three-phase sorption thermal energy storage cycles obtained a temperature lift of 65°C and an energy storage density up to 1307 Wh/kg, which cannot be realized with a conventional three-phase cycle. Moreover, combined cold and heat storages at 15°C and 60°C, respectively, and discharging temperature more than 100°C are achieved. With these proposed cycles, a wider range of applications could be expected for three-phase sorption thermal energy storage.

The energy level mismatch between heat sources and industry users has posed a huge barrier for the wide application of local waste heat recovery, which cannot be efficiently addressed by traditional options due to the limited temperature lift. To fill this gap, a hybrid heat transformer is proposed to achieve large temperature lift via deep thermal coupling between compression and absorption sub-cycles. Firstly, simulation shows that 42.1 kW heat output (at 100 °C) is provided with the costs of 20.0 kW electricity and 67.4 kW waste heat (at 45 °C), resulting in a COP of 2.15 and a large temperature lift of 55 °C. Secondly, an experimental prototype was established for performance validation, which stably upgraded the waste heat from 47–51 °C to 99–102 °C with an overall COP of 1.81. Further investigation shows that the proposed system is quite flexible with waste heat source temperatures of 30–60 °C and output temperatures of 90–115 °C. Such an effective heat transformer with large temperature lift could be promoted for the efficient utilization of low-grade waste heat, and contribute to the industrial decarbonization.

Energy level mismatch between waste heat and energy users poses huge barrier for local waste heat recovery. To tackle this challenge, an energy grade splitting strategy of hot water via absorption heat transformer is proposed. In this strategy, the hot water is separated into two branches. An absorption heat transformer extracts waste heat from the colder branch, and delivers heat output to increase the temperature of hotter branch. This process could deliver high temperature output and decrease the temperature of waste heat simultaneously, which meets the local waste heat recovery demand. Both experimental and modeling researches are carried out to investigate this strategy. Firstly, double effect LiBr-water absorption heat transformer is adopted for performance enhancement, and experimental investigation was carried out. Testing results showed that 391.4 kW heat output and COP of 0.618 were achieved, under colder branch temperature of 149.7 → 128.1 °C and hotter branch temperature of 151.0 → 128.1 °C. Secondly, modeling framework was built and used to evaluate the energy grade splitting performance under different conditions. Results showed that the proposed energy grade splitting strategy is effective under waste heat source temperatures of 130.0–160.0 °C, temperature lift of 5.0–20.0 °C, mass split ratio of 0.10–1.60 and temperature split ratio of 2.00–20.00. Such an effective and flexible strategy could further be promoted to other scenarios with different heat conversion technologies, and contribute to the wide application of local waste heat recovery.

Summary Nucleation site distribution is ubiquitous in many natural and industrial processes, such as liquid-to-vapor phase change, gas-evolving reactions, and solid-state material growth. However, a comprehensive understanding of nucleation site distribution remains elusive. These limitations are due to the challenge of probing micro/nanoscopic nucleation sites and inadequate statistical interpretation of the nucleation process. Here we report direct experimental observation of nucleation site distribution in droplet condensation using phase-enhanced environmental scanning electron microscopy. We also use statistical theory to demonstrate that the population of nucleation sites is governed by the Poisson distribution, whereas the nearest-neighbor distance follows the Rayleigh distribution instead of the commonly used Poisson distribution. We further show the broad applicability of these insights into nucleation site distribution to hydrogen-evolving reactions and chemical vapor deposition. Our platform, combining precise characterization and theory, advances the fundamental understanding of nucleation phenomena and guides designs from materials to devices.

Condensation is an important process in the Rankine cycle that significantly affects overall efficiency. Condensate typically forms a liquid film due to the high surface energy of industrial condenser materials; by engineering the condenser surface with a superhydrophobic layer, however, we can increase condensation heat transfer by an order of magnitude with the jumping droplet mode of condensation. While the basic phenomenon of jumping droplet condensation has been explored in depth, its effects on heat transfer and pressure drop in confined vapor flow inside a condenser tube, as in power plant condensers, have not been considered. Here, we report an experimental study of internal forced convective condensation with hydrophilic, hydrophobic, and superhydrophobic surfaces to study condensation in the filmwise, dropwise, and jumping droplet modes, respectively. The condenser tube samples were tested in a closed system internal flow condensation setup, and the heat transfer and pressure drop behavior were characterized over various operating conditions. In the jumping droplet mode, the heat transfer coefficient was highest at lower condensation heat flux and condenser surface subcooling, but a transition to the flooded mode at higher subcooling resulted in a heat transfer coefficient comparable to filmwise condensation. For dropwise condensation in the hydrophobic tube, the condensation heat transfer coefficient increased with the vapor velocity, similar to observations in past work. In addition to a large heat transfer coefficient, the pressure drop with the superhydrophobic tube samples was the lowest. These experimental results demonstrate the viability of harnessing the jumping droplet mode of condensation to enhance heat transfer and reduce pressure drop for internal forced convective flow condensation in industrial condensers.

High-resistance GaN with low dislocation density adopting growth mode modification has been investigated by metalorganic chemical vapor deposition. The sheet resistance of the order of 1016 Ω/sq has been achieved at room temperature by diminishing the oxygen impurity level close to the substrate with an AlN blocking layer. Attributed to this method which offers more freedom to tailor the growth mode, a three-dimensional (3D) growth process is introduced by adjusting the growth pressure and temperature at the initial stage of the GaN epitaxy to improve the crystalline quality. The large 3D GaN grains formed during this period roughen the surface, and the following coalescence of the GaN grains causes threading dislocations bending, which finally remarkably reduces the dislocation density.

A novel zone-one distance relaying algorithm for single phase to ground faults on parallel lines is proposed. The proposed algorithm only requires sampled current and voltage values at one end of the protected line to calculate the fault impedance. The adjacent circuit zero-sequence current can be calculated from the protected circuit zero-sequence current and without cross-connection. The algorithm can overcome the issues of overreach and under-reach. The study in this paper shows that the new algorithm has higher reliability than that of conventional distance relays with and without cross-connected zero-sequence current compensation. Therefore, the algorithm optimizes the performance of zone-one distance relaying for parallel transmission lines. The results are verified by the simulations using PSCAD software.

Electrical properties of GaN-based heterostructures adopting InAlN/AlGaN bilayer barriers are investigated by Hall-effect and current–voltage measurements. It is found that this structure possesses both merits of high two-dimensional electron gas (2DEG) density and low gate leakage current density, while maintaining high 2DEG mobility. Furthermore, temperature dependence of the 2DEG density in this structure is verified to follow a combined tendency of InAlN/GaN (increase) and AlGaN/GaN (decrease) heterostructures with increasing temperature from 90 K to 400 K, which is mainly caused by superposition of the effects from carrier thermal activation induced by extrinsic factors in InAlN layer and the reduced conduction-band discontinuity.

Solar driven air conditioning systems can cope with solar collectors working in a wide range of temperatures. Sorption systems, including absorption and adsorption refrigeration systems, are among the best choices for solar cooling. Five systems including modular silica gel–water adsorption chiller, single/double effect LiBr–water absorption chiller, 1.n effect LiBr–water absorption chiller, CaCl2/AC (activated carbon)–ammonia adsorption refrigerator, and the water–ammonia absorption ice maker with better internal heat recovery were presented. The above five sorption chillers/refrigerators work under various driven temperatures and fulfill different refrigeration demands. The thermodynamic design and system development of the systems were shown. All these systems have improvements in comparison with existing systems and may offer good options for high efficient solar cooling in the near future.

In this paper, different absorption refrigeration cycles are reviewed. The couplings for absorption cycle construction are summarized. Based on the coupling characteristics, the absorption cycles are classified into the following categories: single effect cycle, external-circuit coupling cycles, internal-circuit coupling cycles and the cycle combined with ejector/compressor. Cycles constructed through external-circuit coupling refer to the multiple stage cycles. In these cycles, the external-circuit heat and mass couplings are employed to improve the cycle performance or temperature lift. Cycles constructed through internal-circuit coupling refer to the GAX cycles. In these cycles, the internal-circuit heat couplings are employed to enhance the cycle flexibility and internal heat recovery. The internal-circuit mass couplings are employed to enlarge the GAX temperature overlap. In the combined cycles, ejector or compressor are integrated to improve the cooling output or decrease the driven temperature. The configurations and theoretical COP of these cycles are introduced with diagrams. Related literatures are reviewed.