Large Energy Loss Research Articles

Enhanced Interface Compatibility by Ionic Dendritic Molecules To Achieve Efficient and Stable Perovskite Solar Cells.

Poly(3-hexylthiophene) (P3HT) represents a promising hole transport material for emerging perovskite solar cells (PSCs) due to its appealing merits of high thermal stability and appropriate hydrophobicity. Nonetheless, large energy losses at the P3HT/perovskite interface lead to unsatisfied efficiency and stability of the devices. Herein, two ionic dendritic molecules, 3,3'-(2,7-bis(3,6-bis(bis(4-methoxyphenyl)amino)-9H-carbazol-9-yl)-9H-fluorene-9,9-diyl)bis(N,N,N-trimethylpropan-1-aminium) iodide and 3,3'-(2,7-bis(bis(4-(bis(4-methoxyphenyl)amino)phenyl)amino)-9H-fluorene-9,9-diyl)bis(N,N,N-trimethylpropan-1-aminium) iodide, namely, MPA-Cz-FAI and MPA-PA-FAI, are rationally designed as the interlayer to enhance interfacial compatibility. The dendritic backbone with conjugated structure endows the hole transport layer with high conductivity, derived from the more ordered microstructure with larger crystallization and higher connectivity of domain zones. Besides, a better energy level alignment is established between P3HT and perovskite, which enhances the charge extraction and transport yield. In addition, the peripheral methoxy groups enable effective defect passivation at the interface to suppress nonradiative recombination and the quaternary ammonium iodide serving as side chains enable efficient interfacial hole extraction contributing to enhanced charge collection yield. As a result, the dopant-free P3HT-based PSCs modified with MPA-Cz-PAI deliver a champion efficiency of 19.7%, significantly higher than that of the control devices (15.4%). More encouragingly, the unencapsulated devices demonstrate competitive environmental stability by retaining over 85% of its initial efficiency after 1500 h of storage under humid conditions (70% relative humidity). This work provides an effective molecular design strategy for interface engineering, envisaging a bright prospect for the further development of efficient and stable perovskite solar cells.

Search for heavy, long-lived, charged particles with large ionisation energy loss in pp collisions at sqrt{s} = 13 TeV using the ATLAS experiment and the full Run 2 dataset

This paper presents a search for hypothetical massive, charged, long-lived particles with the ATLAS detector at the LHC using an integrated luminosity of 139 fb−1 of proton–proton collisions at sqrt{s} = 13 TeV. These particles are expected to move significantly slower than the speed of light and should be identifiable by their high transverse momenta and anomalously large specific ionisation losses, dE/dx. Trajectories reconstructed solely by the inner tracking system and a dE/dx measurement in the pixel detector layers provide sensitivity to particles with lifetimes down to mathcal{O} (1) ns with a mass, measured using the Bethe–Bloch relation, ranging from 100 GeV to 3 TeV. Interpretations for pair-production of R-hadrons, charginos and staus in scenarios of supersymmetry compatible with these particles being long-lived are presented, with mass limits extending considerably beyond those from previous searches in broad ranges of lifetime.

A novel two-stage thermophotovoltaic-thermoelectric system based on micro combustion

Aiming at solving the problem of low energy conversion efficiency due to high energy loss in micro-combustion power system, this work innovatively proposed a two-stage thermophotovoltaic-thermoelectric energy conversion system. The effects of the inlet velocity and the equivalence ratio on the energy conversion efficiency of the two-stage thermophotovoltaic-thermoelectric energy conversion system are investigated. The results indicate that two-stage thermophotovoltaic-thermoelectric energy conversion system significantly alleviates the problem of large energy loss in the micro-combustion power system and improves the energy output and energy conversion efficiency of the micro-combustion power system. As the inlet velocity increases, the total output efficiency of the micro-photovoltaic module, thermoelectric module and the overall system decreases. Under the H2/air flow condition with an inlet velocity of 6 m/s and an equivalence ratio of 1.0, the total system reaches its a maximum energy conversion efficiency of 5.05% and generates an output power of 6.17 W.

In Situ Reconstruction of Hole‐Selective Perovskite Heterojunction with Graded Energetics Toward Highly Efficient and Stable Solar Cells

AbstractPerovskite solar cells (PSCs) have demonstrated a high power conversion efficiency, however, the large energy loss due to non‐radiative recombination is the main challenge for further performance enhancement. Here, a surface treatment strategy is developed by heat‐induced decomposition of a thin interlayer 2,7‐Naphthaleneditriflate (NAP) to in situ reconstruct perovskite energetics. It is verified that the reconstructed perovskite surface energetics match better with the upper hole transport layer compared to the intrinsic condition. Spontaneous generation of n/n− homojunctions between the perovskite film bulk and the surface region promotes hole extraction, enhancing built‐in electric field, and thus significantly suppresses charge recombination at such perovskite hole‐selective heterojunctions. Moreover, the surface decomposed fluorine‐rich complexes passivate the defects and improve the crystallinity of the perovskite film. These advantages are confirmed by a remarkably improved efficiency from 20.52% for the control device to 23.37% for the treated one with excellent stability. The work provides a promising approach of in situ reconstructing perovskite surface and interface for the design of highly efficient and stable PSCs.

HPSA: a high-performance smart aggregate for concrete structural health monitoring based on acoustic impedance matching method

Piezoceramic-based ultrasonic transducers have demonstrated the feasibility and effectiveness of functioning as smart aggregates (SAs) to detect damages for concrete structures in laboratory-sized structural members. The restriction of its further engineering application is the limited propagation distance due to the large energy loss during wave transmission. Aiming to reduce the energy loss of piezoceramic-based sensors, the authors proposed a high-performance piezoceramic-enabled SA based on acoustic impedance matching principle. The main contribution to the performance enhancement comes from the proposed surface treatment of the lead zirconate titanate patch and acoustic impedance matching layer. Comparative experiments with commercial SAs validate the improved performance. Besides, a field test with different wave propagation distances fully illustrates the perspective of the proposed superior transducer in large infrastructure engineering applications.

Tunable polarization-drived superior energy storage performance in PbZrO 3 thin films

Antiferroelectric PbZrO₃ films have great potential to be used as the energy storage dielectrics due to the unique electric field-induced phase transition character. But the phase transition process always accompanies polarization hysteresis effect that induces large energy loss and lowers the breakdown strength, leading to inferior energy storage density as well as low efficiency. In this work, the synergistical strategies by doping smaller ions of Li⁺-Al³⁺ to substitute Pb²⁺ and lowering the annealing temperature from 700℃ to 550℃ are proposed to change the microstructure and tune the polarization character of PbZrO₃ films, excepting to dramatically improve the energy storage performances. The prepared Pb_(1-x)(Li_0.5Al_0.5)_xZrO₃(abbreviated as P_(1-x)(L_0.5A_0.5)_xZO) films exhibit ferroelectric-like (<em>FE</em>) rather than antiferroelectric (<em>AFE</em>) character once the doping content of Li⁺-Al³⁺ ions reaches 6 mol%, accompanying a significant improvement of energy storage density of 49.09 J/cm³,but energy storage efficiency is only 47.94% due to the long-correlation of ferroelectric domains. Accordingly, the low-temperature annealing is carried out to reduce the crystalline degree and the polarization loss. P_0.94(L_0.5A_0.5)_0.06ZO films annealed at 550℃ deliver a linear-like polarization rather than ferroelectric-like behavior annealed at 700℃, the lowered remanent polarization as well as improved breakdown strength (4814 kV/cm) result in the superior energy storage density of 58.7 J/cm³ and efficiency of 79.16%, simultaneously possessing excellent frequency and temperature stability, and good electric fatigue tolerance.

Effects of incident angle of sealing ring clearance on internal flow and cavitation of centrifugal pump

High-energy fluid at the outlet of the impeller might get access to the impeller inlet via the sealing ring clearance of the centrifugal pump with shrouded impeller. In this case, the great velocity and energy differences between the fluid at the inlet and outlet of the impeller might trigger unsteady flows during the collision with large energy loss produced. As a result, the flow status of the impeller inlet can be exacerbated; causing that the centrifugal pump is susceptible to cavitation. A centrifugal pump with a low specific speed was studied in this paper. To begin with, five incident angles, that is the original angle (90°), 75°, 60°, 45°, and 30° were formed between the incident section of the sealing ring clearance and the inlet circumference of the impeller through changing the front cover of the impeller and the outer contour of the centrifugal pump. Then, the accuracy of the calculation results of the prototype pump (90°) was verified experimentally with analyses on the entropy generation, velocity streamline, backflow at the inlet section, internal entropy generation distribution of the centrifugal pump, and distribution of cavitation in specific conditions at the incidence of clearance of the centrifugal pump with different incident angles of sealing ring clearance. As can be seen from the results, changing the incident angle of the sealing ring clearance exerts a certain influence on the external characteristics of the centrifugal pump. To be specific, the sealing ring clearance with a small incident angle can lower the flow loss in the front cavity flow area and the impeller flow area of the centrifugal pump as well as can restrain the backflow prewhirl at the inlet section of the centrifugal pump and the cavitation inside the centrifugal pump.

Versatile Processability by Breaking the Symmetrical Chemical Structure of Nonfullerene Acceptors

Despite the outstanding photovoltaic performance of symmetrical Y6, its use is limited in that only chloroform (CF), a highly volatile processing solvent, can induce favorable morphology. This dependence on a particular solvent poses an obstacle to mass production. Here, we investigate the effect of symmetry‐breaking of nonfullerene acceptors (NFAs) on device performance and processability by employing chlorobenzene (CB) or CF processing solvents. In organic solar cells (OSCs) based on a symmetrical Y6 acceptor, a significant difference in the power conversion efficiency occurs between the OSCs fabricated using CB and those fabricated using CF. However, in OSCs based on IPC‐BEH‐IC2F with asymmetrical structure, no difference in photovoltaic performance occurs between the two OSCs. Grazing‐incidence wide‐angle X‐ray scattering measurements indicate that IPC‐BEH‐IC2F exhibits nearly identical diffraction features in both the CB‐ and CF‐processed photoactive films, whereas Y6 shows markedly different stacking structures. Because of these morphological features, OSCs based on Y6 are associated with a relatively large energy loss difference in CB and CF, whereas OSCs based on IPC‐BEH‐IC2F show no significant difference in energy loss. The introduction of an asymmetrical structure can therefore be an important strategy to enhance the versatile processability of OSCs based on NFAs for future mass production.

Determining role of W+ ions in the densification of TiAlWN thin films grown by hybrid HiPIMS/DCMS technique with no external heating

Hybrid high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) with substrate bias synchronized to the high mass metal-ion fluxes was previously proposed as a solution to reduce energy consumption during physical vapor deposition processing and enable coatings on temperature-sensitive substrates. In this approach, no substrate heating is used (substrate temperature is lower than 150 oC) and the thermally activated adatom mobility, necessary to grow dense films, is substituted by overlapping collision cascades induced by heavy ion bombardment and consisting predominantly of low-energy recoils. Here, we present direct evidence for the crucial role of W+ ion irradiation in the densification of Ti0.31Al0.60W0.09N films grown by the hybrid W-HiPIMS/TiAl-DCMS co-sputtering. The peak target current density Jmax on the W target is varied from 0.06 to 0.78 A/cm2 resulting in more than fivefold increase in the number of W+ ions per deposited metal atom, η = W+/(W + Al + Ti) determined by time-resolved ion mass spectrometry analyses performed at the substrate plane under conditions identical to those during film growth. The DCMS is adjusted appropriately to maintain the W content in the films constant at Ti0.31Al0.60W0.09N. The degree of porosity, assessed qualitatively from cross-sectional SEM images and quantitatively from oxygen concentration profiles as well as nanoindentation hardness, is a strong function of η(Jmax). Layers grown with low η values are porous and soft, while those deposited under conditions of high η are dense and hard. Nanoindentation hardness of Ti0.31Al0.60W0.09N films with the highest density is ∼33 GPa, which is very similar to values reported for layers deposited at much higher temperatures (420–500 oC) by conventional metal-ion-based techniques. These results prove that the hybrid HiPIMS/DCMS co-sputtering with bias pulses synchronized to high mass metal ion irradiation can be successfully used to replace conventional solutions. The large energy losses associated with heating of the entire vacuum chamber are avoided, by focusing the energy input to where it is in fact needed, i.e., the workpiece to be coated.

Effect of prior cyclic damage on rock failure exposed to triaxial multistage unloading confining pressure and cyclic loads

AbstractA series of triaxial alternative unloading and damage‐controlled cyclic loading tests were conducted on deeply buried granodiorite. The testing results reveal that the prior cyclic loading damage influences rock volumetric deformation, stiffness degradation, damage evolution, and failure modes. Rock volumetric deformation and hysteresis ratio increase with increasing prior cyclic damage, and the subsequent damage propagation is the most severe for a sample subjected to high cyclic damage. A larger hysteresis ratio indicates large plastic deformation and energy loss. In addition, a damage evolution model was proposed based on the irreversible radial strain, and it well describes the damage propagation at the respective cyclic loading stage (CLS) and unloading confining pressure stage (UCPS). Moreover, as prior damage increases, the dominant failure mode changes from shear failure to mixed shear–tensile failure and then to tensile failure. It is suggested that rock failure is cyclic damage dependent; damage fully develops under high cyclic damage.

Reducing Trap Density in Organic Solar Cells via Extending the Fused Ring Donor Unit of an A-D-A-Type Nonfullerene Acceptor for Over 17% Efficiency.

The high trap density (generally 1016 to 1018 cm-3 ) in thin films of organic semiconductors is the primary reason for the inferior charge-carrier mobility and large nonradiative recombination energy loss (ΔEnr ) in organic solar cells (OSCs), limiting improvement in power conversion efficiencies (PCEs). In this study, the trap density in OSCs is efficiently reduced via extending the donor core of nonfullerene acceptors (NFAs) from a heptacyclic unit to a nonacyclic unit. TTPIC-4F with a nonacyclic unit has stronger intramolecular and intermolecular interactions, affording higher crystallinity in thin films relative to its counterpart BTPIC-4F. Thus, the D18:TTPIC-4F-based device achieves a lower trap density of 4.02×1015 cm-3 , comparable to some typical high-performance inorganic/hybrid semiconductors, with higher mobility and inhibited charge-carrier recombination in devices. Therefore, the D18:TTPIC-4F-based OSC exhibits an impressive PCE of 17.1% with a low ΔEnr of 0.208eV, which is the best known value for A-D-A-type NFAs. Therefore, extending the donor core of NFAs is an efficient method for suppressing trap states in OSCs for high PCEs.

Synergistic Effect of Surface p-Doping and Passivation Improves the Efficiency, Stability, and Reduces Lead Leakage in All-Inorganic CsPbIBr2 -Based Perovskite Solar Cells.

Wide-bandgap inorganic cesium lead halide CsPbIBr2 is a popular optoelectronic material that researchers are interested in because of the character that balances the power conversion efficiency and stability of solar cells. It also has great potential in semitransparent solar cells, indoor photovoltaics, and as a subcell for tandem solar cells. Although CsPbIBr2 -based devices have achieved good performance, the open-circuit voltage (Voc ) of CsPbIBr2 -based perovskite solar cells (PSCs) is still lower, and it is critical to further reduce large energy losses (Eloss ). Herein, a strategy is proposed for achieving surface p-type doping for CsPbIBr2 -based perovskite for the first time, using 1,5-Diaminopentane dihydroiodide at the perovskite surface to improve hole extraction efficiency. Meanwhile, the adjusted energy levels reduce Eloss and improve Voc of the CsPbIBr2 PSCs. Furthermore, the Cs- and Br-vacancies at the interface are filled, reducing structural disorder and defect states and thus improving the quality of the perovskite film. As a result, the target device achieves a high efficiency of 11.02% with a Voc of 1.33V, which is among the best values. In addition to the improved performance, the stability of the target device under various conditions is enhanced, and the lead leakage is effectively suppressed.

Experimental study on the energy flow of a commercial heavy-duty vehicle under the C-WTVC of cold and warm start

In order to improve the actual performance of China-VI heavy-duty vehicle (HDV), the energy flow test on a HDV was conducted under the C-WTVC (Chinese-World Transient Vehicle Cycle). Then, the transient energy distribution of heavy-duty diesel engine was compared with different start condition. Results show that, the energy flow is greatly affected by the variation of actual vehicle conditions. The percentage of coolant energy fluctuates between 6% and 76%. In the urban cycle, the exhaust energy is slightly higher under cold start condition due to the high engine speed at the beginning of this condition. In the expressway cycle, the coolant loss ratio fluctuates slightly and stabilizes around 20% and the percentage of exhaust energy is around 32% in the later constant speed stage. What’s more, idle and variable working conditions can cause a large energy loss, such as the acceleration and deceleration of C-WTVC. All those provide guidance for improving the actual energy efficiency of HDVs.

On the circulation heat losses in domestic hot water systems in residential buildings

The share of domestic hot water (DHW) systems in total energy consumption of buildings, especially in Nearly Zero-Energy Buildings (NZEBs), is rising and will continue doing so in the future, because most energy efficient measures are dedicated for heating/cooling systems. Besides, the amount of detailed field research on DHW systems is limited in comparison to heating/cooling systems. This article identifies the problem of excessive heat losses in the circulation lines of the DHW installation in residential buildings supplied from the district heating network. The analysis used the measurement and operational data for the summer season, i.e. the period of May–September 2018 for nine multi-family buildings located in Lublin (Poland). The buildings are divided into three groups according to the cubic volume: below 5000 m3, 5000 ÷ 10,000 m3 and above 10,000 m3. The research was conducted in two variants. Method I concerns the heat losses from circulation only at night and days, when hours with the power needed to heat DHW is lower than assumed values on the basis of DHW consumption, while method II covers all hours of the day. The obtained average results of circular heat losses range from 9.36 ÷ 25.38 % for method I and 22.96 ÷ 69.14 % for method II. The largest energy losses were recorded in the summer months, mainly August and July, while the smallest losses were recorded for May, June and September during the school year. The obtained calculations and their results are the basis for determining the information on the dependence of heat losses on circulation pipes and the size of buildings.

Automatic Snorkeling Electronic Equipment Enabled by Self‐Breathing Flexible Aqueous Aluminum‐Air Battery

AbstractSnorkeling equipments have played a vitally important role in various underwater operations, such as military, rescue activities, underwater research, archeology, and so on. However, existing snorkeling styles, represented by mechanical lifting system, artificial diving, and submarine mode (water storage and drainage), still face numerous challenges in the issues of large energy loss, complex structure, or environmental unfriendliness. Especially for small flexible equipments, an efficient and convenient way of snorkeling is of prime importance to various underwater explorations for a long time. Here, for the first time, an automatic snorkeling electronic equipment driven by a self‐breathing flexible aqueous aluminum‐air battery (Self‐BAAAB) which integrates functions of the snorkeling and the electric energy supply is designed. The self‐BAAAB battery consists of naturally inspired spongy sodium polyacrylate (PANa) hydrogel that acts as a flexible electrolyte and vertical N–O doped graphene fiber (NOGF) as an ORR/OER/HER trifunctional electrocatalyst. Benefited from the trifunctional catalytic properties and the aluminum metal stripping, the Self‐BAAAB consumes oxygen gas in the routine discharge process while the gas in turn is released during the charging process due to electrolysis of water in the super‐absorbing hydrogel, which triggers the sharp density variation of Self‐BAAAB, driving the “automatic snorkeling” feature of electronic equipment underwater. This work provides new insights into the design of the snorkeling electronic equipments and would promote the high efficiency of underwater operations, especially in a complex environment.

Changes to mixed layer acoustic energy from spice and isopycnal tilt

Mixed layer acoustic propagation is predicted for fields that approximate two dynamically separate sources of sound speed variation: the tilting of isopycnals and “spice,” density compensated temperature and salinity changes. These fields are decomposed from a transect measurement over approximately 1000 km of the northeast Pacific Ocean. At a frequency with only one mixed layer mode, both fields contain blocking features, defined as sound speed structures less than 5 km wide that create significant acoustic energy loss. The transect shows two distinct regions where blocking features are caused by tilt or spice, indicating the acoustic importance of these dynamic processes depends on location. Statistics of mixed layer acoustic energy are investigated at two frequencies, averaging one or three mixed layer modes, both with and without blocking features. The spice field was found to produce higher loss than the tilt field. Both fields create more loss at lower frequencies when locations with blocking features were included, and more loss at higher frequencies without blocking features. Mixed layer mode amplitudes demonstrate more mixed layer modes at the higher frequency increases mode coupling, both preventing large scale acoustic energy loss and creating a more consistent loss mechanism.

Novel zinc-based molten salt batteries with high voltages in medium temperature environment

Since single energy storage system like thermal storage has low energy conversion efficiency and large energy losses, integrated energy storage technology holds great promise in future energy storage modes. In order to alleviate the shortage of energy conversion efficiency in thermal storage, the combination with electrochemical energy storage will bring great improvements. However, most batteries have the limitations of operating temperature and dangerous highly reactive metals, which are not conducive to practical large-scale energy storage. To this regard, safe novel zinc-based molten salt batteries are developed which can operate in medium temperature environments and are free of highly reactive metals. The batteries realize high cell voltages of over 1 V in 300 °C by utilizing zinc metal anodes and MnO2, V2O5 cathodes in Zn–K–Cl melts and can operate at large currents more than 30 mA cm−2. The results show that Zn2+ will continuously intercalate into the cathodes during discharge processes and resulting in the transformation of the oxide cathodes and the reduction of the cathode transition metals, which indicates the discharge mechanisms based on Zn2+ intercalation. Therefore, the batteries have certain cycling capabilities which have been experimentally verified, illustrating the promising prospects of these novel zinc-based molten salt batteries.

Analysis of Gas Turbine Power Plant Production and Fuel Consumption

The main problem of gas turbine generating units operating in the simple cycle system is their relatively low thermal efficiency, which leads to large thermal energy losses. The current research aims to study the economic analysis of Kirkuk gas power plant. Field data of gas turbine unit for the year of 2019 were used. The results of the study showed that the cost of exported energy is higher than the cost of energy produced. The results showed a 23% increase in the cost of energy produced in summer compared to winter. A decrease in actual production compared to the planned production is observed by 12.8%, where the highest actual production for the month of March was 162,108 MW, while the planned was 186,000 MW. Also, the month of July witnessed a very low fuel consumption rate for natural gas compared to the rest of the months, where the average fuel consumption was 0.273 m3/kW, while the month of January has a high fuel consumption rate for natural gas compared to the rest of the year with average fuel consumption of 0.312 m3/kW. The rate of increase in fuel consumption between July and January was 14.2%, and the results also showed that the ratio of production to design capacity for January was the highest and amounted to 87%, and the highest efficiency reached 33%, while July was the lowest production rate in terms of design capacity, reaching 53% and efficiency of 29.8%.

Design of Bi-directional Pump Servo System for Asymmetric Hydraulic Cylinder

In view of the shortcomings of the traditional overflow pressure regulating and throttling speed regulation system, such as large energy loss, high oil temperature and large reversing impact, a servo two-way pump control system for asymmetric hydraulic cylinder is proposed based on Siemens S120. TIA Portal And Starter software are used for the design of hardware configuration and program debugging. SimulationX is used to simulate the stroke process of the hydraulic cylinder, at the same time, experimental verification was carried out, which provides a new idea for the low energy consumption design of hydraulic cylinder servo control system, and has important practical significance.

Role of Moisture and Oxygen in Defect Management and Orderly Oxidation Boosting Carbon-Based CsPbI2 Br Solar Cells to a New Record Efficiency.

Large energy loss (Eloss ) causedby defect-assisted recombination makes the photovoltaic performance of carbon-based perovskite solar cells (C-PSCs) inferior to that of metal-electrode ones. Herein, the influence of environmental factors (moisture and oxygen) on defect management during re-annealing process of CsPbI2 Br crystalline films is systematically studied. Density functional theory and experimental results indicate that moisture in the air can significantly reduce the oxidation kinetics of crystalline films, resulting in orderly oxidation. Concomitantly, the oxidation decomposition products PbO and CsPbIBr2 are enriched at grain boundaries, passivating surface defects efficiently. Simultaneously, energy band coupling between CsPbI2 Br and CsPbIBr2 improves the hole extraction efficiency. The photovoltage of corresponding C-PSCs is increased from 1.05 to 1.32V, indicating a reduced Eloss derived from orderly oxidation strategy. Correspondingly, the champion cell achieves an efficiency of 15.27%, and a certified efficiency of 14.7%, which is a new record efficiency for CsPbI2 Br C-PSCs.