bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermoelectric Exhaust Heat Recovery to Maximize Brake Thermal Efficiency of Advanced Diesel Engines: Modeling and Baseline Analysis
Authors: Sok Ratnak , Kusaka Jin 
Published: November 2022

Abstract
This work demonstrates the enhancement of brake thermal efficiency (BTE) of an advanced, turbocharged, production-intent 2.2 L diesel engine with a thermoelectric waste heat recovery system (TEG-WHR). The integrated engine model with the TEG is developed using 0D/1D software. Experimental data from the corrugated fin TEG under fin pitch = 1.0–2.0 mm, inlet gas temperatures (200–300 °C), and mass flow rates (5.0–15.0 g/s) are used for validating the model. The TEG model can reproduce measured pressure drop, heat transfer, and thermal performance characteristics. A 1-cylinder engine model parented from the advanced turbocharged diesel engine is developed. Under motoring and firing conditions, measured exhaust pressure, temperature, velocity, mass flow rate, and enthalpy are validated under various valve timings. Finally, the 3-layer TEG model is connected to the 4-cylinder engine to maximize its performance under a highly efficient (peak BTE) operating condition at 2250 RPM. Optimal size and thermoelectric module arrangement of the TEG system in the engine system considering a tradeoff between the TEG generated electrical power and engine pumping losses are suggested. The effective power of 1.1 kW and 1.1 % BTE improvement are obtained from the 3-sheet TEG system. As a result, a 49.9 % engine BTE is demonstrated without brake power loss.
Cooled Spray Technology for Particulate Reduction in a Heavy-Duty Engine
Authors: Klingbeil Adam , Heher Brett , Flores Manuel , Triana Padilla Antonio , Lavertu Thomas , Tinar Tristen , Ellis Scott 
Published: November 2022

Abstract
Diesel Engine Emission Reduction Technologies like Ducted Fuel Injection and Cooled Spray use passive hardware elements near the fuel injector spray holes to improve combustion and reduce particulate matter, with minimal impact on other performance parameters. This paper discusses the fabrication, installation and testing of Cooled spray inserts in a heavy-duty diesel engine. A cylinder head assembly with a Cooled Spray insert design, developed by Wabtec, allows use of multiple insert geometries for test purposes. As there are multiple test geometries planned and because proper alignment of the insert and injector is critical for the combustion process, manual alignment of the Cooled Spray device to the fuel injector is required. The location of injector holes within the cooled spray insert are imaged using a fiber-optic borescope. Imaging of the alignment with different injectors shows varying degrees of alignment success, suggesting that the injector nozzle variation may contribute to the misalignment between the individual nozzle holes and the fuel passages of the insert. Prior to the engine testing, a one-dimensional thermodynamic engine model provided boundary conditions for single cylinder engine testing. Finally, engine performance of the cooled spray insert is compared to the baseline engine performance. The test results show that an alignment improvement of 0.15mm reduced Filter Smoke Number by 85%. Additionally, Cooled Spray caused 70% reduction in Filter Smoke Number compared to the non-Cooled Spray for one condition while showing emissions parity or increases at other conditions.
Comparing the Injection Strategy of Gasoline Compression Ignition vs. Alcohol Compression Ignition: A Partial Review and Experimental Comparison
Authors: Gainey Brian , Yan Ziming , Gandolfo John , Lawler Benjamin 
Published: November 2022

Abstract
Gasoline compression ignition and compression ignition with a high cooling potential alcohol fuel, like wet ethanol 80 or methanol, are both promising alternatives to conventional diesel compression ignition that can improve efficiency and reduce criteria pollutants in the transportation sector. The fuel properties of gasoline are diametrically opposite of alcohol fuels and thus, the fuels behave differently in compression ignition. In this work the optimal compression ignition strategy with each fuel is studied. Data from the literature and experimental data presented in this work show that using a combination of partially-premixed and mixing-controlled combustion with gasoline in compression ignition enables robust control over the heat release process without incurring a significant efficiency penalty. Contrarily, the high cooling potential, of the alcohol fuels (∼6% of their lower heating value) means that heat absorption from evaporation and heating of the injected fuel can have a significant negative impact on efficiency if the fuel is injected near top dead center. However, the high cooling potential of the fuel enables robust control over the heat release process in a partially-premixed combustion strategy, which is not true of regular-grade gasoline (under all conditions). Overall, this work shows that on a light-duty diesel-engine architecture, compression ignition with gasoline, wet ethanol 80, and methanol can all achieve similar fuel conversion efficiencies. Compression ignition with gasoline resulted in a higher combustion efficiency compared to the alcohol fuels at the expense of higher engine-out NOx emissions and soot emissions. At 1500 rpm and 10 bar net indicated mean effective pressure, gasoline compression ignition achieved a net fuel conversion efficiency of 44.3% with an engine-out NOx level of 0.89 g/kWh and an FSN of 0.86. At the same operating condition, wet ethanol 80 compression ignition achieved a net fuel conversion efficiency of 44.0% with an engine-out NOx level of 0.21 g/kWh and an FSN of 0.03.
An Experimental Comparison of Cyclic Variations in Diesel-Natural Gas and POMDME-Natural Gas Dual Fuel Combustion
Authors: Narayanan Abhinandhan , Hariharan Deivanayagam , Krishnan Sundar , Srinivasan Kalyan 
Published: November 2022

Abstract
Cyclic variations in internal combustion engines are caused by various factors, including combustion mixture stratification, in-cylinder flows, local fluctuations in air-fuel ratio, etc. Cyclic variations have a profound impact on engine performance and emissions. In this study, cyclic variations in dual fuel combustion are analyzed, comparing diesel – natural gas (NG) and polyoxymethylene dimethyl ether (POMDME) – NG dual fuel combustion. Cyclic variability was initially quantified using the coefficient of variation (COV) of IMEPg computed from experimental cylinder pressure data. The cases analyzed in this study had a COV of IMEPg greater than or around 5%, which was the lower limit of onset of instability for this engine. Experiments were performed at two fixed start of injection (SOI) of high-cetane fuel: 310 CAD and 350 CAD. For all experiments, a constant load of 5 bar IMEPg was maintained and the intake boost pressure and rail pressure, were fixed at 1.5 bar and 500 bar respectively. For each case, 1000 cycles of cylinder pressure data were recorded, filtered, and processed using an in-house heat release analysis code for each cycle. A comparison between individual cycles and the “ensemble averaged cycle” was made for both diesel-NG and POMDME-NG combustion. For the early SOI of 310 CAD, the peak cylinder pressure fluctuations of individual cycle were found to be ± 15 bar for both fuel combinations, compared to the ensemble averaged cycle, and &lt; 1/10th of the cycles had an IMEPg lower than 0.05 bar of the ensemble averaged cycle. However, the peak pressure fluctuations were found to be lower for POMDME-NG (± 3 bar) than diesel-NG dual fuel combustion at 350 CAD SOI, indicating lower cyclic variations. The higher reactivity of POMDME helped reduce fluctuations in combustion phasing in the retarded SOI. The presence of cycles of deterioration and cycles of recovery were also observed with diesel-NG combustion for 310 CAD SOI, and the scatter in the IMEPg return map was similar for both fuel combinations. The IMEPg return map for POMDME-NG combustion was less scattered at the 350 CAD SOI.
Operating Range and Emissions From Ammonia-Hydrogen Mixtures in Spark-Ignited Engines
Authors: Swift Evan , Kane Seamus , Northrop William F. 
Published: November 2022

Abstract
Ammonia combustion in engines is a promising approach for decarbonization of the energy sector. If made from renewable energy sources, anhydrous “green” ammonia combustion results in zero net carbon dioxide emissions. As a renewable energy storage medium, green ammonia is superior to both compressed hydrogen and batteries for long term energy storage. Combustion of pure ammonia in spark-ignited engines is challenged by low laminar flame speeds and high required ignition energy. Partially converting ammonia to hydrogen and nitrogen through local decomposition is a practical method for enhancing ammonia flame speed and reactivity. This work experientially examines anhydrous ammonia/hydrogen combustion and emissions using a single-cylinder variable compression ratio engine over a range of operating conditions. The study finds that high combustion stability (CoV &lt; 2%) and high efficiency (gITE &gt; 40%) are both possible using only 5% volumetric H2 addition. Experimental results show that rich operation is favorable due to low NOx (&lt; 100ppm) and N2O (∼20 ppm). Roughly 1% unburned NH3 was found in the exhaust, which increased during rich operation. Hydrogen addition decreased NH3 emissions and aided smooth operation while worsening NOx emissions. While ammonia displayed a high knock tolerance like natural gas, heat release analysis indicated that spark-assisted compression ignition combustion was achieved at advanced spark timing and elevated intake temperature. Initial range finding experiments and modeling presented in this work provide a basis for further investigation into the role of rich engine operation and in-cylinder turbulence to enhance ammonia combustion at low hydrogen blending levels.
Effects of the Tip Clearance Size on the Tip Leakage Flow in an Axial Compressor Operating With Supercritical Carbon Dioxide
Authors: Gou Jinlan , Ma Can , Wu Jun , Li Bangming , Lin Yuansheng 
Published: November 2022

Abstract
The closed Brayton cycle operating with supercritical carbon dioxide is an attractive option for geothermal, nuclear and solar energy conversion. As one of the key component, the performance of the supercritical carbon dioxide compressor attracts lots of attention. Up to now, most studies focused on the centrifugal compressor and the design method of the axial compressor operating with supercritical carbon dioxide is far to matured. The effects of the tip clearance size on the tip leakage flow in an axial compressor are numerically investigated in the present work, with different tip clearance size and operating points. To fully take advantages of the matured design method of the air compressor, a similar air compressor is simulated as a comparison group. The results show that the flow characteristics especially the static pressure coefficient and tip leakage vortex structure is almost the same between S-CO2 compressor and the similar air compressor with small tip clearance size. This is also suitable for the large tip clearance size at low and middle span, while obvious discrepancy arises at high span. The tip leakage vortex of S-CO2 compressor is stronger and more downstream than the air compressor. Understanding these effects is helpful to extend the abundant experience of the air compressor to design S-CO2 compressor.
The Comprehensive Performance Comparison Research Between Two Types of Radiators Applied in Electronic Equipment
Authors: Huang Chonghai , Zhang Yelei , Yang Xiaohu , Ke Hanbing , Xiao Qi 
Published: November 2022

Abstract
The development direction of miniaturization and low noise of electronic equipment in nuclear power plant puts forward higher requirements for radiators. Two experimental systems were constructed to test the volume, noise and heat transfer performance of air-cooled radiator and micro-pump-driven water-cooled micro-channel radiator that can be applied to electronic equipment of nuclear power plant. The experimental results show that the comprehensive performance of micro-pump-driven water-cooled micro-channel radiator is better than that of the air-cooled radiator. Compared with the air-cooled radiator, the micro-pump-driven water-cooled micro-channel radiator can reduce the temperature rise of heat source by more than 20°C, and the volume is only 38% of the air-cooled radiator. For the micro-channel using in the present study, the flow rate of cooling water is the main factor which affects the heat transfer performance of radiator when the flow rate of cooling water is lower than 2.5L/min. However, when the flow rate of cooling water is more than 2.5L/min, the increase of cooling water flow rate has little impact on heat transfer performance, and the self-structure of the radiator and thermal resistance have become the main factors restricting the improvement of heat transfer performance.
The Effect of a Honey-Comb Porous Plate on the Critical Heat Flux Under Reduced Pressure Conditions
Authors: Wu Feifei , Mori Shoji 
Published: November 2022

Abstract
Enhancement of pool boiling heat transfer using a honeycomb porous plate (HPP) under atmosphere pressure has been experimentally examined. The previous research found that the critical heat flux (CHF) could be enhanced by up to three times above that of a plain surface. Considering the operating temperature in microelectronic devices, boiling at sub-atmospheric pressures for maintaining the lower surface temperature while removing high heat flux is required. Under circumstances of low pressure, there is a scarcity of research about boiling heat transfer for porous materials. Liquid supply is promoted by capillary action and vapor escape is facilitated by separating liquid flow channels from vapor flow channels in the HPP, and the CHF was expected to be improved even at reduced pressure conditions. Therefore, the CHF in saturated water boiling through an HPP at low pressure was studied in the current research. A more generalized understanding of the system pressure and the enhancement effect was provided, which made it possible to mitigate the enhancement technology bottlenecks through electronic devices and looked upon as further elaboration of the boiling heat transfer mechanism on honey-comb porous surfaces. There were three different pressures (51 kPa, 76 kPa and 100 kPa) investigated on the HPP; the results on the plain surface under the identical operating conditions were the same for each of the three pressures tested on the HPP.
Application of Probabilistic Safety Analysis in Analysis of Impact of Fangjiashan Nuclear Power Plant’s Load-Following Operation
Authors: Liu Deyi , Zha Sixing , Wu Jian , Cao Yong , Chen Honghao 
Published: November 2022

Abstract
At present, probabilistic safety analysis (PSA) has been widely used in many fields such as the design and manufacture of nuclear power plants, and PSA has gradually developed into an important tool for safety evaluation and decision-making. With the increasing peak-to-valley difference between power grid loads, the peak-shaving situation of the power system is becoming more and more severe. Due to the increase in the proportion of nuclear power in the power grid, the power system has an increasing demand for nuclear power units to participate in power grid peak-shaving. The nuclear power plant technical specifications and the nuclear power plant final safety analysis report in the nuclear safety regulations have clear requirements for the operating conditions of the nuclear power plant. As a power generation device with special safety requirements, the safest and most economical operation mode of nuclear power plants is to operate at rated load. The Chinese government and nuclear safety regulatory authorities attach great importance to nuclear power safety, and nuclear safety must be foolproof. From the perspective of probabilistic safety analysis, this paper analyzes the impact of Fangjiashan Nuclear Power Plant’s (FSJ NPP) participation in peak-shaving by using the load-following operation mode, and gives reasonable suggestions.
Investigation on the Flow and Heat Transfer Performance of Micro/Mini-Channel Liquid Cooling Heat Sink for Nuclear Control Chips
Authors: Yang Xiao-Hu , Zheng Zhaoli , Song Ping , Chen Lie , Huang Chonghai , Chen Kai 
Published: November 2022

Abstract
The “thermal barrier” problem of high-performance nuclear control chips is becoming more and more prominent with the increase of chip integration under the Moore’s Law, liquid cooling is an effective method to solve the problem of high power heat dissipation. This paper provides an analytical model of the flow and heat transfer performance of micro/mini-channel liquid cooling heat sink for high-end chips. The flow resistance model fully considers the friction loss along the way, the contraction and expansion pressure loss of the channel, and the local pressure loss at the entrance and exit; the thermal resistance model includes the spreading thermal resistance brought by the extension of the heat sink base, the conduction thermal resistance of the bottom plate, the convective thermal resistance between the coolant and the heat sink, and the capacity resistance of the coolant. Using this model, combined with numerical simulation, a typical liquid-cooling heat sink is analyzed, corresponding flow resistance and thermal resistance distribution characteristics are evaluated, and the optimal design configuration is given. The results in this paper can serve as valuable reference for the development of micro/mini-channel liquid cooling technology for high-performance chips.
Scaling and Engineering Design of Facility for Simulation of HTGR Reactor Building Response for a Break in Primary Coolant Break
Authors: Revankar Shripad T. , Kultgen Derek W. 
Published: November 2022

Abstract
Analysis and understanding the depressurization response of the HTGR reactor is essential to the understanding of accident scenarios and design of these reactors. The 350MWe GA-MHTR was used as reference reactor for the current design of the test facility. The design of the test facility was based on a well-established dynamic scaling analysis for integral system transient. The scaling accounts for integral system response, boundary mass and energy flow, system pressure, and local phenomena such as choking, convective and diffusive mixing, stratification, etc. The key phenomena determining the gas flow paths and distribution in the reactor building are depressurization, gas discharge, choked flow, venting, and mixing. Two scaled systems were developed, one 1/20 scale of the prototype and another 1/28 scale of the prototype. Based on sizes, the scale of 1/28 was chosen for the facility that would simulate all local and global phenomena in the blowdown process. The scaled 1/28 model design was then translated to engineering drawings to manufacture vessels and tanks for the test facility. The important aspect of the scaling/sizing the compartment lies in correctly scaling flow losses in the compartments, flow paths, and vent paths, gas hide-out spaces, and thermal stratification and mixing. Heat loss to the cavity walls is scaled via matching the thermal penetration depth/inertia of the model vessel (cavity) insulation material with that of the prototype concrete. The Engineering design considered the geometrical similarity to simulate the flow path and the hideout of oxygen in the reactor cavity.
Study for the Optimization of the Decommissioning Project of Nuclear Facilities
Authors: Iguchi Yukihiro , Kawasaki Daisuke , Yanagihara Satoshi 
Published: November 2022

Abstract
Basically, decommissioning of nuclear facilities is a project that does not generate new profit because it is carried out with the reserve funds from operation, etc. Therefore, its cost should be minimized with optimization by shortening the process and minimizing the waste, etc. Meeting the requirements of exposure risk (safety) also affects the optimization. In this study, we decided to integrate these evaluation methods to develop a comprehensive optimization evaluation method.
In this study, we established an average process for the current decommissioning plans of Japanese nuclear power plants and developed a cost evaluation method including sensitivity analysis.
As a result of examining the feasibility of the deferred dismantling strategy using the above calculation method, it became clear that although there is a reduction in disposal and dismantling costs due to the natural decay of radioactive materials, the maintenance and management costs during the safe storage period account for a large proportion of the costs, and for this reason, immediate dismantling is unconditionally advantageous, at least in Japan.
The components of optimization described above are naturally subject to various uncertainties and risks. For example, there are regulatory risks, and the location of waste disposal site is subject to social acceptance, so there is a great deal of uncertainty. In the future, these factors will be incorporated into the evaluation and studied, and the optimal strategy for decommissioning and what kind of uncertainty should be focused on will be clarified quantitatively.
Research on Modeling Method and Eigenvalue Calculation of Single Dispersion of Fuel Particles
Authors: Yuan Anmin , Wu Hongchun , Li Yunzhao , Cao Liangzhi , Wang Cong , Jiang Chaofei , Yu Shenzhi , Liao Yi , Qiu Jinrong 
Published: November 2022

Abstract
Dispersed particle fuel is an advanced form of fuel with many advantages, which is safer than traditional fuel. But a strong double heterogeneity effect is formed, due to the random dispersion of fuel particles in the matrix. The homogenization and uniform distribution approximation models will thus leads to severe errors. In order to account for the influence of the double heterogeneity effect, a homogenization model, a uniform dispersion model and a random dispersion model are constructed in this paper. Then the MCX program was used for calculation, and the fuels were compared and analyzed, subject to high fuel phase volume and different enrichment. The effect of particle diameter variation on the eigenvalues of the system is revealed, and the errors introduced by the model approximation are also evaluated. It is demonstrated by the results that the double heterogeneity is negligible when the diameter of the fuel particles is less than 100μm. However, the double inhomogeneous effect is relatively enhanced under large diameter fuel particles and low enrichment, which requires high-precision calculations. This paper has a certain reference significance for the evaluation of the double heterogeneity effect of the dispersed particle fuel and the correction of the traditional homogenization calculation.
Research on the Technology Accuracy of the On-Line Fracture Assessment of Cracked Pipe in NPPs
Authors: Chen Mingya , Yu Min , Gao Hongbo , Qi Shuang , Lin Lei , Xu Decheng , Wang Weiqiang , Shi Jinhua , Peng Qunjia , Zhang Guodong 
Published: November 2022

Abstract
The cracked pipes usually need to be replaced or conservatively evaluated in the Nuclear Power Plants (NPPs). There is still a lack of effective methods for a real-time crack propagation and safety evaluation based on massive monitoring transient data. From a technical standpoint, there is a need to establish inspection and monitoring technologies. This research has carried out a re-development in the general finite element analysis (FEA) software platform which is based on our research results and the requirements of the RSE-M Code. In this paper, the re-development is introduced firstly. Then, the information of the large pipe test information from France, Japan and China is summarized. Finally, the technology accuracy of the on-line fracture assessment of a cracked pipe in the NPPs is studied. The comparative research results show that the FEA analysis and modeling method of the pipe adopted by the authors in the re-development software is reliable and can meet the requirements for the on-line fracture assessment.