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The compound parabolic concentrator is a non-imaging concentrator that can concentrate solar radiation without tracking system. However, as the concentration ratio increases, the maximum half acceptance angle and the effective working hours decrease. To increase the effective working hours at high concentration ratio, a tracking solar collector is proposed that integrates the compound parabolic concentrator and flat microchannel tube. This new solar collector can track solar radiation by rotating the two reflective surfaces around their respective starting lines. A two-dimensional model is developed for the irradiation concentration of the tracking compound parabolic concentrator. For the geometry of the compound parabolic concentrator and solar irradiant angle, the optimal rotation angles of the reflective surfaces are determined to minimize the irradiation loss. The effects of the rotation angle of the two reflective surfaces on the concentration performance are simulated. The simulation results show that in the tracking mode, the averaged heat flux on the surface of the absorber can reach 7.61 kW m−2 when the concentration ratio and truncation ratio are 8 and 0.5, respectively. Even when the incident angle of solar irradiation is 30°, the averaged heat flux is still 5.12 kW m−2. Compared with other kinds of reflector, the concentration performance of the compound parabolic concentrator is merely influenced by the tracking error. The positive and negative tracking errors lead to different declining rates of normalized optical efficiency and the influence of positive tracking error is more acceptable. [ABSTRACT FROM AUTHOR]

SiC was first synthesized using the sol-gel method and subsequent carbothermal reduction method, then xCo/SiC-700 and 30%Co/SiC-T catalysts were prepared by hydrothermal method and thermal treatment. The structure of the catalysts was characterized by XRD, SEM/TEM, XPS, H 2 -TPR, CO 2 -TPD, etc. Their catalytic activities for ammonia decomposition to produce hydrogen were investigated in a fixed-bed reactor. The results showed that the synthesized SiC had a high specific surface area and could evenly disperse Co 3 O 4 nanoparticles, which increased the exposure of active sites and improved the adsorption capacity on the catalyst surface. N 2 -TPD indicates that 30%Co/SiC-700 has a high N 2 adsorption capacity, effectively preventing hydrogen reduction of Co 3 O 4 nanoparticles in the catalyst during ammonia decomposition. CO-TPD shows that Co has the best dispersion on 30%Co/SiC-700 catalyst. CO 2 -TPD shows the higher the catalyst's basicity, the stronger ammonia's decomposition ability. Among the synthesized catalysts, 30% Co/SiC-700 showed the best catalytic activity for ammonia decomposition, with the ammonia conversion of 78.3% and hydrogen production of 25.0 mmol H 2 gcat−1 min−1 at 550 °C under 30,000 mL gcat−1 h−1. [Display omitted] • The SiC support and 30%Co/SiC-700 catalyst were successfully prepared. • The active components of 30%Co/SiC-700 catalyst is mainly Co 3 O 4 nanoparticles. • The Co 3 O 4 nanoparticles are highly dispersed on the SiC surface, increasing the distribution of active sites. • The ammonia conversion rate of 30%Co/SiC-700 catalyst is 78.3% at 550 °C. [ABSTRACT FROM AUTHOR]

• Zeotropic immiscible binary mixtures were used as working fluids. • Emulsion was produced during the oscillation. • Zeotropic immiscible binary mixtures could widen the range of working temperature of pulsating heat pipe. • The lowest thermal resistance of the pulsating heat pipe is 0.1634 °C/W. • Pulsating heat pipe with binary mixtures can achieve a stable one-way pulsation cycle. Working fluid is an important influencing factor for the heat transfer performance of a pulsating heat pipe (PHP). In this study, zeotropic immiscible working fluid was proposed based on the difficult start and easy dry-out with large heat flux of PHP. Deionized water mixed with HFE-7100 was used as the working fluid. The volume mixing ratios used were 4:1, 2:1, 1:1, 1:2, and 1:4, and the heating power ranged from 20 W to 250 W with inclination angles of 30°, 45°, 60°, 75°, and 90°. The filling ratio was 50%. Result shows that at a high heating power (210 W, 250 W), the PHP with mixtures could quickly start and achieve a stable one-way pulsation cycle with low thermal resistance. Meanwhile, the dry-out phenomenon of the working fluid with high boiling point had been inhibited because of the working fluid with low boiling point and high saturation vapor pressure, thereby raising the heat transfer limit of the PHP. During operation, the two working fluids were pulped and stirred to form an emulsion, which promoted the heat transfer between them. When the mixing ratio was 1:1, the two working fluids could be uniformly mixed, the contact surface between them was large, and the heat transfer property performed well. The lowest thermal resistance achieved with mixing ratio of 1:2 was 0.1634 °C/W due to some of the HFE-7100 would exist in gaseous form when the heating power was high (250 W, with an inclination angle of 90°). [ABSTRACT FROM AUTHOR]

Highlights • An in-house code was developed to simulate the propagation process of the solar radiation rays. • The effect of CPC deformation on the concentrating characteristics was analyzed. • Heat flux has two peaks on the external surface of the heat receiver. • Certain translation and internal rotation of CPC was allowed. • The down offset and right and left offset of the heat receiver should be avoided. Abstract Compound parabolic concentrators (CPC) have immense potential for middle-and-low temperature heat collection of solar energy. In this study, the propagation process of solar radiation rays in a CPC–tubular solar collector was simulated using an in-house MATLAB code by the Monte Carlo ray tracing (MCRT) method. The effects of ray incidence angle, CPC concentration ratio, and truncation residual ratio on the heat flux distribution on the tubular heat receiver were analyzed. Moreover, the effects of CPC deformations on concentration characteristics were analyzed, involving the rotation and translation of the reflective surface, the truncation of the involute starting point, and the position offset of the heat receiver. The heat flux distribution exhibited two evident peaks on the heat receiver external surface due to the concentration effect of the CPC. A small internal rotation, a small internal or external translation of the reflective surface, and the truncation of the involute starting point had mere effect on the heat flux distribution on the heat receiver. Therefore, the reflective surface can be allowed to have certain translation and internal rotation when machining a CPC. The downward, rightward, and leftward offsets of heat receivers should be avoided in the assembly of heat receivers and CPCs. [ABSTRACT FROM AUTHOR]

An experimental study on heat-transfer performance of a flat-plate closed loop pulsating heat pipe (FCLPHP) with C60 nanofluid was carried out. The C60 nanofluid was a mixture of ethanol and C60 nano-particles at three different concentrations of 0.1 wt%, 0.2 wt% and 0.3 wt%. The experimental results show that increasing C60 nanofluid concentration improves the thermal performance of the FCLPHP, but reduces the critical heat load, at which FCLPHP begins to dry out. The critical heat load was reduced from 70 W for base fluid to 35 W for nanofluid with concentration of 0.3 wt%. In order to evaluate the improvement of the heat transfer performance of the nanofluid FCLPHP, improving rate τ is used. The higher the τ value, the greater the degree of improvement is. It is found that τ firstly increases up to a maximum value and then decreases gradually with the increase of heat load. The maximum τ value was 36% when the heat load was 20 W at a concentration of 0.3 wt%. A regression model was proposed for the FCLPHP, with which a sensitivity analysis was made. The analysis shows that the heat load impacts the thermal performance more than the concentration does. [ABSTRACT FROM AUTHOR]

• The sensitivity of air-assisted atomizers' atomization characteristic to operation conditions among snow making process was investigated. • A transparent atomizer was designed, structured and tested for observing the two-phase flow morphologies inside atomizer. • Four mixing patterns inside mixing chamber appear in sequence by rising the air supply pressure. • The air-assisted atomizers with the mixing mode of air and water injected independently is recommended for outdoor snow-makers. Air-assisted atomizers play a crucial role in generating nuclei and promoting heterogeneous nucleation in outdoor snow-makers. The change of operation conditions for snow-makers leads to a marked variation of atomization characteristic of air-assisted atomizers, which directly influences the nuclei generating and snow-making efficiency. This paper investigates the sensitivity of air-assisted atomizers' atomization characteristic to operation conditions in snow-makers. For this purpose, a transparent device is designed, structured and tested. The water-air mixing process was presented, and the atomization behaviors of two air-assisted atomizers with different mixing modes were compared in order to find an appropriate mixing mode for outdoor snow-makers. Results show that the spray cone angle first goes up and then falls down with the increase of air-water pressure ratio, while Sauter mean diameter (SMD) decreases monotonically. The unbalanced air-water pressure ratio results in the failure of atomization because of the choking phenomenon. Inside the air-assisted atomizers, there are four stable mixing patterns in sequence, i.e., full water, churning flow, annular flow and full air. With the variation of the mixing pattern, the interaction between water and air changes, which causes different atomization characteristics under different operation conditions. Another interesting finding is that the atomizers with the mixing mode in which air and water are injected independently have remarkably better performance in avoiding choking situation and improving mass flow rate, which can be a better choice for outdoor snow-makers. [ABSTRACT FROM AUTHOR]

• A novel type of gravity pulsating heat pipe with large space pool boiling is designed. • The flow pattern and heat transfer performance were investigated using a high-speed camera. • There are three working stages of gravity pulsating heat pipes with different heat inputs. • Gravity pulsating heat pipe has stable thermal performance under high heat input. Herein, a gravity pulsating heat pipe (GPHP) is proposed to enhance the gravity effect of the working fluid (WF) reflux and increase the heat transfer limit for solving the dry-up issue at the evaporation section of a conventional pulsating heat pipe (PHP) reaching the heat transfer limit under high heat input. The upper and lower parts of the GPHP comprise 10 single parallel-loop open annular channels and cavities without channels, respectively. Using an electrical coolant, HFE-7500, as the WF, the heat transfer characteristics and flow pattern changes of the GPHP under different heat inputs (30–230 W) were experimentally investigated. The results showed that heat input considerably affects the GPHP thermal performance. Under different heat inputs, three heat transfer stages occur, namely low heat-input steady-state operation stage (70–130 W), transition stage (150–170 W) and high heat-input steady-state operation stage (190–230 W). The GPHP starts quickly and abruptly, with a good and stable heat transfer performance under a low-heat input, and the heat exchange is mainly sensible. In the transition stage, because the temperature of the evaporation section exceeds the critical point of nucleate boiling, a large amount of liquid–vapour is formed by gasifying the liquid WF, which fills the cavity structure. Meanwhile, a stable vapour film is formed on the heating wall, which promotes the accumulation of liquid WF at the GPHP's upper part, preventing the heat transfer between the heating wall and WF and deteriorating the heat transfer. Finally, the liquid WF flows back to the evaporation section under high heat input, destroying the vapour distribution in the cavity. Therefore, the heat transfer of the GPHP reaches a stable operation state. At this stage, the proportion of sensible heat transfer decreases and that of the latent heat increases. The cavity structure in the lower part of the GPHP follows a typical pool-boiling process, which has four stages: convective heat transfer, nucleate boiling, transition boiling and film boiling. [ABSTRACT FROM AUTHOR]

ENCD (http://www.bio-server.cn/ENCD/) is a manually curated database that provides comprehensive experimentally supported associations among endocrine system diseases (ESDs) and long non-coding ribonucleic acid (lncRNAs). The incidence of ESDs has increased in recent years, often accompanying other chronic diseases, and can lead to disability. A growing body of research suggests that lncRNA plays an important role in the progression and metastasis of ESDs. However, there are no resources focused on collecting and integrating the latest and experimentally supported lncRNA–ESD associations. Hence, we developed an ENCD database that consists of 1379 associations between 35 ESDs and 501 lncRNAs in 12 human tissues curated from literature. By using ENCD, users can explore the genetic data for diseases corresponding to the body parts of interest as well as study the lncRNA regulating mechanism for ESDs. ENCD also provides a flexible tool to visualize a disease- or gene-centric regulatory network. In addition, ENCD offers a submission page for researchers to submit their newly discovered endocrine disorders-genetic data entries online. Collectively, ENCD will provide comprehensive insights for investigating the ESDs associated with lncRNAs. Database URLhttp://www.bio-server.cn/ENCD [ABSTRACT FROM AUTHOR]

Atomization is an indispensable process for achieving high-efficiency conversion in various energy applications. This study proposes a novel and simplified method to predict the droplet diameter distribution along the spray direction during atomization by swirl nozzles. The method considers the droplet breakup and coalescence and consists of three sub-models, i.e., the primary breakup model, the secondary breakup model, and the velocity model. The prediction method is verified by droplet sizing experiments using typical swirl nozzles. Combining the experimental results, the atomization process from fluid to droplets is analyzed in-depth. Results show that the present method can predict the droplet diameter distribution along the spray direction, with an average error of droplet diameter of approximately 7.7%. The effects of the orifice diameter and water supply pressure of nozzles on droplet diameter distribution are discussed. The droplet diameter decreases in the whole spray field as the water supply pressure rises. When the orifice diameter increases, the mass flow rate and Sauter mean diameter increase in the near-orifice region. However, the droplet diameter difference in nozzles reduces as the position is far away from the orifice. The proposed method can aid the design of some critical energy devices containing the atomization process. [ABSTRACT FROM AUTHOR]

Background: Patients with epithelial ovarian carcinoma (EOC) are usually diagnosed at an advanced stage with tumour cell invasion. However, identifying the underlying molecular mechanisms and biomarkers of EOC proliferation and invasion remains challenging. Results: Herein, we explored the relationship between tumour microenvironment (TME) reprogramming and tissue invasion based on single-cell RNA sequencing (scRNA-seq) datasets. Interestingly, hypoxia, oxidative phosphorylation (OXPHOS) and glycolysis, which have biologically active trajectories during epithelial mesenchymal transition (EMT), were positively correlated. Moreover, energy metabolism and anti-apoptotic activity were found to be critical contributors to intratumor heterogeneity. In addition, HMGA1, EGR1 and RUNX1 were found to be critical drivers of the EMT process in EOC. Experimental validation revealed that suppressing EGR1 expression inhibited tumour cell invasion, significantly upregulated the expression of E-cadherin and decreased the expression of N-cadherin. In cell components analysis, cancer-associated fibroblasts (CAFs) were found to significantly contribute to immune infiltration and tumour invasion, and the accumulation of CAFs was associated with poorer patient survival. Conclusion: We revealed the molecular mechanism and biomarkers of tumour invasion and TME reprogramming in EOC, which provides effective targets for the suppression of tumour invasion. [ABSTRACT FROM AUTHOR]

Highlights • Interfacial properties of surfactant aqueous solution are studied. • Profile of vapor–liquid interface in the PHP is predicted. • Thermal performance of surfactant solution in the PHP are investigated. Abstract In this work, the thermal performance of pulsating heat pipe (PHP) using surfactant aqueous solution as working fluid was experimentally investigated. The cetyl trimethyl ammonium bromide (CTAB) was applied for preparation of surfactant solution in the concentration range of 0.025–0.25 wt%. It is found that the adding of CTAB can significantly reduce the surface tension and improve the wettability, thus enhance heat transfer between the tube wall and working fluid due to the increase in the liquid film area. The thermal performance of CTAB solution PHP depends greatly on the input power, filling ratio and surfactant concentration. Experimental results indicate that the heat transfer enhancement of PHP with CTAB solution is apparent at higher input power when the concentration is very high. Comparing to the water PHP, the thermal resistance of 0.25 wt% CTAB solution is decreased by 48.5% at the input power of 100 W when filling ratio is kept as 50%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cross-dimensional multi-physics model for hydrogen peroxide-based fuel cell is proposed. • The two-phase mass transport and multi-component reaction processes is clarified. • A novel gradient dot matrix flow field is developed to balance mass and charge transports. • Proposed flow field enables high hydrogen peroxide cover contents and low pressure drop. The direct liquid fuel cell utilizing hydrogen peroxide as an oxidant is considered to be the promising energy conversion technology, owing to its superior energy density and theoretical voltage. In the hydrogen peroxide-based fuel cells, the ever-changing two-phase mass transport and multi-component reaction processes resulting from the hydrogen peroxide self-decomposition exerts a pivotal influence on their performance. In this work, taken hydrogen peroxide self-decomposition into account, a cross-dimensional multi-physics model for the hydrogen peroxide-based fuel cell was proposed and developed to clarify the complex mechanisms of transports and reactions. In this ingeniously developed model, the multi-component reaction in the porous electrode is elucidated by a two-dimensional (2D) sub-model, the two-phase mass transport in the flow field is captured by a three-dimensional (3D) sub-model, and the one-dimensional (1D) correlation equation is served as a bridge between them. The uneven distribution of gas–liquid volume, velocity and current density and their relationships in fuel cell with serpentine flow field and dot matrix flow field were thus achieved. Furthermore, a novel gradient dot matrix flow field was developed to match the two-phase mass transport and multi-component reaction processes of hydrogen peroxide-based fuel cell. It is found that the continuously increasing pressure and velocity along flow path is balanced by the gradient-downsized ribs and the formation of large-volume oxygen bubbles is prevented by the gradient-densified ribs, achieving obviously uniformized current density distribution. Moreover, the gradient dot matrix flow field enables 54 % higher average hydrogen peroxide coverage contents (49 %) and 86 % lower average pressure drop (172 Pa) compared to the serpentine flow field, yielding 6.3 % higher peak power density (210 mW cm−2) and ultra-low extra pump power in fuel cell. This work will make contribution towards gaining profound insights into the intricate mechanisms underlying mass and charge transport, and offering invaluable guidance for the flow field design for the hydrogen peroxide-based fuel cells. [ABSTRACT FROM AUTHOR]

• An experiment setup with the function of testing single or multi-nozzles' atomization characteristics was developed. • The atomization characteristic and mechanism of a swirl nozzle for outdoor snow-makers were revealed. • The droplet diameter distribution and SMD variation were explored when twin-nozzles cooperating at different condition. • Droplet diameter variations were explained by the theories of collision and breakup. Swirl nozzles are the core component of outdoor snow-makers for forming snow crystal artificially. A general experiment setup for simulating the atomization process at the working conditions of outdoor snow-makers was developed. Phantom high-speed camera and PW180-B laser particle size analyzer (LPSA) were used to capture the dynamic atomization process and droplet diameter distributions respectively. The atomization characteristics of a single swirl nozzle and that of twin nozzles were tested and analyzed. For single nozzle, Sauter Mean Diameter (SMD) drops rapidly and then goes up gently due to the action of droplets breakup and coalescence. With the increase of the injection pressure, the SMD of the droplets decreases, and the mass flow rate of the nozzles is improved. Moreover, the spray cone angle increases rapidly and keeps a stable value. For twin nozzles, the cooperation of the swirl nozzles obviously reduces the SMDs of the atomization field because it enhances the probability of droplets collision and separation. The SMDs are determined by the cooperative distances and injection pressure. [ABSTRACT FROM AUTHOR]

In this work, two kinds of mineral based nano-oils were prepared and their lubricant properties tested. These nano-oils were used in a domestic refrigerator compressor and the performance of the refrigeratizon system was measured. It was found that the performance of the refrigerator compressor depends on the working fluid used in the compressor. When the working fluid R134a is used in the compressor, the two kinds of mineral based nano-oil behave similarly. However, the coefficient of performance is improved if R600a is used in the refrigerator compressor. The MoFe 2 O 4 –NiFe 2 O 4 nano-oil(No.1) makes the biggest impact on the refrigeration performance for a compressor using R600a as the working fluid. In this case, the COP is increased by 5.33%. These results suggest that it may be possible to enhance the energy efficiency and reliability of refrigerators using nano-oil as long as the appropriate preparation approach for the nano-oil is selected. [ABSTRACT FROM AUTHOR]

In this paper, a direct-expansion heat pump water heater system integrated uninsulated micro-channel PV/T solar collector (UMC-PVT-SC) is proposed. This system can realize storage for both thermal energy and electricity, ensuring the supply of domestic hot water. The theoretical models of micro-channel PV/T solar collector, hot water storage tank, compressor and electronic expansion valve are established to investigate the performance of the micro-channel PV/T heat pump water heater system. R134a is used as refrigerant. The system performance is numerically simulated using MATLAB for different solar radiation intensity, ambient temperature and wind speed. The results show that solar radiation intensity has the largest influence on the system performance, followed by ambient temperature and wind speed. The coefficient of performance of the heat pump (COP HP) and the overall coefficient of performance (COP pvt) of the integrated system increase while the required operating time reduces, as solar radiation intensity and ambient temperature increase. The uninsulated micro-channel PV/T solar collector (evaporator) can absorb thermal energy from both ambient air and solar radiation and therefore achieve high COP HP , electric efficiency and COP pvt. Even under cold weather conditions, the proposed solar collector and heat pump heater demonstrate high efficiencies, heating and power generation capacities. When ambient temperature is −18.6 °C and solar irradiance is 322 W/m2, the collector efficiency and electric efficiency of UMC-PVT-SC are still at 0.718 and 0.244, respectively, and the COP HP and COP pvt of the heat pump heater are 3.5, 5.63, respectively. The present work is of potential value for delivering net zero. • A novel uninsulated micro-channel photovoltaic/thermal solar collector is designed. • The photovoltaic/thermal solar collector can absorb heat from air without sun. • The overall energy efficiency of photovoltaic/thermal solar collector can reach 1.86 in winter. • It is a simple and low-cost solution of the combination of solar energy and heat pump. • The solar assisted heat pump can operate independently without external electric power. [ABSTRACT FROM AUTHOR]

A set of mathematical models is developed based on energy and mass conservation to predict the mass transfer characteristics of falling film absorption of lithium bromide (LiBr) aqueous solution added with nanoparticles. Experimental measurements are conducted to validate the mathematical models, and good agreement is acquired. Simulations are performed to investigate the mass transfer of LiBr aqueous solution added with nanoparticles. Results showed that nanoparticles could significantly improve the water vapor absorption rate of nanofluid in the process of falling film absorption. Moreover, the water vapor absorption rate increased with the number of nanoparticle additives. With the same number of nanoparticles, the water vapor absorption rate of LiBr solution increased with the solution flow and with the change of solution flow trend for logarithmic curve. The mass transfer enhancement factor also increased with the number of nanoparticles. In addition, the mass transfer coefficient of absorber increased with the number of nanoparticle additives. When the flow rate of nanofluid with 0.05% and 0.1% added nanoparticles was 1.0 L min −1 , the mass transfer coefficient increased by 1.28 and 1.41 times, respectively. These results are beneficial in improving the mass transfer of the working medium used for an absorption refrigeration cycle and enhancing the performance of an absorption chiller. [ABSTRACT FROM AUTHOR]

This paper presents a statistical training data cleaning strategy for PCA-based chiller sensor Fault Detection, Diagnosis and Data Reconstruction method. Finding and removing outliers from the original training data set, the training data quality can be improved by the presented data-cleaning strategy. This can enhance the efficiency of the fault detection and increase the accuracy of the data reconstruction. Outliers cannot be easily found in the original data set used for training the PCA model. These outliers would severely affect the projection directions of PCA's two orthogonal subspaces (PC subspace and Residual subspace). Therefore, the threshold of Q -statistic is changed by the unexpected projection subspaces so that the detection efficiency of the sensor fault is decreased. The Euclidean distance was employed as an index to detect outliers from the original training data. In order to achieve optimal training data for the sensor FDDR, the z -scores of each sample's Euclidean Distance were employed as the key to remove the outliers. A field measured data set of a screw water-cooled chiller was used to validate the presented strategy. Results demonstrate that the quality of the training data is optimized and sensor fault detection efficiency, as well as the reconstruction data accuracy, is improved when compared to the normal PCA method. [ABSTRACT FROM AUTHOR]