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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Structure optimization of turbocharger air-to-air intercooler for an air-cooled engine based on porous-media-model</title>
      <link>https://trid.trb.org/View/2701190</link>
      <description><![CDATA[Enhancing the flow and heat-transfer performances of the turbocharger intercooler can improve the overall performance of vehicle engines. Given the immense quantity of grids involved, numerically simulating the full-scale model of intercoolers becomes infeasible. Currently, most of the existing simulations and optimizations of intercoolers are based on the local fin model. A few studies try to employ the porous-media-model to investigate full-scale intercoolers, but they usually focus on water-to-air intercoolers. The applicability of the porous-media-model for full-scale air-to-air intercoolers simulation and optimization still needs further verification. Hence, it is urgent to explore efficient numerical simulation and optimization method for the full-scale air-to-air intercooler. Based on the porous-media-model, this study proposes an efficient numerical simulation method of the full-scale air-to-air intercooler. And it is validated by the air-cooled diesel engine bench test. The mean relative errors of the hot-side pressure-drop and the outlet temperature are 4.28% and 1.52% respectively. Then, on the basis of the efficient numerical simulation method, the optimal-Latin-hypercube sampling method, the general regression neural network (GRNN) surrogate model, and the multi-objective genetic algorithm (GA) are further combined to construct an optimization method of the full-scale intercooler. The optimization method is able to decrease the hot-side pressure-drop of the intercooler by 6.83% and maintain the heat-transfer performance. Finally, the flow mechanisms of performances improvement of the optimized intercooler are analyzed.]]></description>
      <pubDate>Wed, 20 May 2026 09:10:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2701190</guid>
    </item>
    <item>
      <title>Study on the effect of structural optimization of TCD combustion chamber on engine performance under plateau environment</title>
      <link>https://trid.trb.org/View/2691727</link>
      <description><![CDATA[The geometry of diesel engine combustion chamber directly affects the fuel atomization and combustion process. In order to meet the increasingly stringent emission regulations, this study took a certain model of diesel engine as the object, and used AVL FIRE 2020 R1 software to optimize the geometry of the prototype ω-type combustion chamber under the premise of unchanged compression ratio (CR). A TCD (T: turbocharged, C: charger air cooling, D: diesel particulate filter) combustion chamber with center boss structure and protrusion structure was designed, and the structural parameters of the TCD combustion chamber were further optimized. The computational fluid dynamics (CFD) method was used to analyze the effects of different combustion chamber geometries on the performance and emission characteristics of diesel engines. The results show that the combustion performance of the TCD combustion chamber is mainly affected by the combustion chamber diameter. Too large or too small a combustion chamber diameter will reduce the indicated power. The indicated power of the optimized TCD combustion chamber is 0.98% higher than that before optimization, and 8.26% higher than that of the ω-type combustion chamber. In addition, the soot emissions of the optimized TCD combustion chamber are reduced by 67.33% compared with the design before optimization, and 88.46% compared with the ω-type combustion chamber.]]></description>
      <pubDate>Mon, 27 Apr 2026 14:58:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/2691727</guid>
    </item>
    <item>
      <title>Development of Pistons Suitable for Compact Air-Cooled Engines</title>
      <link>https://trid.trb.org/View/2547890</link>
      <description><![CDATA[For the realization of carbon neutrality, the authors are working on research to improve the thermal efficiency of engines for motorcycles. Friction losses in the cylinder bore account for about 40% of the total friction losses of the engine, which is directly related to thermal efficiency improvement. Air-cooled engines are suitable for motorcycles due to their simplicity and light weight, but it is difficult to achieve both efficiency and reliability. Friction in the cylinder is generated by piston scuffing. The oil film distribution of the piston-skirt (=skirt) is thin at the center of the skirt and thick at the edge. To reduce piston friction, it is effective to make the thin oil film at the center of the skirt thicker. On the other hand, to reduce oil consumption, the oil film must be thinned. However, air-cooled engines, which are difficult to keep the cylinder temperature constant, cannot make the clearance between the cylinder bore and the piston small. An increase in clearance is a cause of increased oil consumption. To achieve both high efficiency and reliability of air-cooled engines, optimal control of the oil film thickness on the scuffing parts of the piston is necessary. The authors developed a piston capable of solving this difficult problem by combining CAE and laboratory tests and visualization technology. The excellent performance of the developed piston was proved by friction tests using a small air-cooled engine and oil consumption measurement results.]]></description>
      <pubDate>Thu, 12 Jun 2025 13:25:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/2547890</guid>
    </item>
    <item>
      <title>Correlations between Charge Air Cooler (CAC) Distortion Bench Tests and Flexion Fatigue on Test Specimens</title>
      <link>https://trid.trb.org/View/1802699</link>
      <description><![CDATA[Diesel engine turbo chargers are operating and will operate at higher temperatures and pressures due to meeting increasing emissions restriction standards.]]></description>
      <pubDate>Thu, 21 Dec 2023 13:51:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/1802699</guid>
    </item>
    <item>
      <title>Advantages of Cooling Airflow Control Devices Using by Internal Combustion Engines</title>
      <link>https://trid.trb.org/View/1790774</link>
      <description><![CDATA[The cooling airflow control devices are news in automotive engineering. The authors of this paper have achieved some patents in this field, with car engines application. The purpose was to improve engine performances. In the paper the construction of the cooling airflow control, as they are patented, tests made on some cars and corresponding experimental date are presented. Analyzing the experimental results an improving of combustion process could be observed. The cooling airflow devices are patented in mechanical and electronic form, and a prototype of mechanical device was made. The efficiency of these devices is significant below 5°C environmental temperature.]]></description>
      <pubDate>Wed, 20 Dec 2023 16:58:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/1790774</guid>
    </item>
    <item>
      <title>Development of All-Nylon Charge Air Cooler for Automotive Applications</title>
      <link>https://trid.trb.org/View/1790840</link>
      <description><![CDATA[The preliminary experimental results of an all-nylon charge air cooler development for automotive application are presented. The results achieved during the project deployment in terms of performance comparison between metal and nylon Charge air Coolers are reported. Data related to both bench and road tests are presented and discussed.]]></description>
      <pubDate>Tue, 19 Dec 2023 17:03:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1790840</guid>
    </item>
    <item>
      <title>Improving aero-thermal environment in vehicle under-hood through small modification upstream the cooling module</title>
      <link>https://trid.trb.org/View/2154993</link>
      <description><![CDATA[The control of vehicle cooling airflow is one of the key issues of under-hood thermal management as well as the reduction of cooling drag. Aerodynamic analysis using full vehicle CFD method was conducted to further improve the cooling efficiency of a production vehicle equipped with an air-guide. Existing under-hood airflow problem of the original vehicle was first analyzed, and then several modified schemes using various deflectors in the area between the front bumper and the condenser were proposed. The comparison of the under-hood airflow characteristics of each modified scheme and the original model was carried out. The simulation results revealed that sealing the cavity between the front bumper and the anti-collision beam could improve the airflow rate through the cooling module with a reduction in the total air intake volume from the grilles, while blocking the channel from the upper grille opening to the cavity could increase the airflow evenness through the cooling module. The aerodynamic and thermal tests in wind tunnels demonstrated that, for the best scheme with three deflectors at 40 km/h, the temperature of the coolant and the exhaust pipe were reduced by 6.6°C and 15°C, respectively, with a minor reduction in C[subscript d,grilleopen], compared to those of the original vehicle. With less cooling airflow rate, the scheme with a single deflector blocking the upper channel of the cavity achieved similar cooling effect as the best scheme, the reductions of the coolant temperature and the exhaust temperature at 40 km/h were around 6.6°C and 13°C, respectively, with a similar value of C[subscript d,grilleopen], compared to those of the original vehicle.]]></description>
      <pubDate>Tue, 20 Jun 2023 14:16:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2154993</guid>
    </item>
    <item>
      <title>Multi-objective surrogate model-based optimization of a small aircraft engine air-intake duct</title>
      <link>https://trid.trb.org/View/2046813</link>
      <description><![CDATA[Aviation industry is constantly striving for more efficient design processes in respect to optimal time, human and computational resources utilization. This implies a need for application of an approximation techniques enabling for fast responses generation with maintained level of results quality. This study focuses on an advancement of aerodynamic shape optimization process of a small aircraft engine intake system by introduction of a surrogate modelling step into the design loop. The multi-objective metamodel assisted optimization is carried out in order to reduce pressure losses along the engine intake duct and increase flow homogeneity at the engine compressor intake plane. Latin Hypercube Design method is utilized in order to sample the design space. A set of initial objective function evaluations is generated with application of Reynolds-averaged Navier–Stokes solver. The ensemble of samples is further used to train a Kriging-based surrogate model. The Efficient Global Optimization algorithm basing on the Expected Improvement function is employed to gradually increase the metamodel prediction quality by usage of sequential sampling technique. Finally, the optimal point predicted by the Kriging surrogate is validated against the high-fidelity model with usage of the Computational Fluid Dynamics code. The paper presents an application of the abovementioned methodology to the design process of the I-31T aircraft turboprop engine intake system. Proposed Kriging-based optimization workflow is utilized in order to reduce pressure losses and improve flow homogeneity in the engine air-intake duct.]]></description>
      <pubDate>Fri, 30 Dec 2022 16:58:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/2046813</guid>
    </item>
    <item>
      <title>Improving Cylinder Cooling Using Tapered Fins and Baffle Plates between Fins in Air-Cooled Engines</title>
      <link>https://trid.trb.org/View/1820589</link>
      <description><![CDATA[The authors aim to maximize the performance of air-cooled engines (such as motorbike engines and small stationary engines) by increasing cylinder cooling and by maintaining uniform temperature around the cylinder circumference. In typical engine designs, air cools the front of the cylinder better than the rear. In an effort to increase cooling at the rear, this research experiments with tapered fins that contract air flow to the cylinder axis between the fins, and with baffle plates mounted between fins symmetrically with respect to a plane through the axis of the cylinder. In a wind tunnel at air velocities between 20 and 60 km/h, the authors compared cylinders with conventional fins, cylinders with tapered fins, cylinders with baffle plates between conventional fins, and cylinders with baffle plates between tapered fins. The authors measured the temperature inside the cylinder to determine the heat release, and the authors measured the temperature on the fin surface to determine the temperature distribution around the cylinder circumference. The authors also visualized the air flow over the fin surface, using the oil film method, and between fins, using the smoke wire method, to understand how tapered fins and baffle plates contributed to cylinder cooling. Results indicate that both tapered fins and conventional fins with baffle plates between fins increased cylinder cooling, compared with conventional fins without baffle plates. Furthermore, the cylinder fitted with both tapered fins with the tapered portion closest to the rear, and baffle plates between fins, enjoyed the greatest cylinder cooling.]]></description>
      <pubDate>Wed, 10 Aug 2022 16:38:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1820589</guid>
    </item>
    <item>
      <title>Experimental Validation of a Carburetor Model in One-Dimensional Engine Software</title>
      <link>https://trid.trb.org/View/1816421</link>
      <description><![CDATA[This work presents a carburetor model written in FORTRAN and coded into a user routine object in a one-dimensional engine software program, GT-Power. The model was compared to experimental data from a single cylinder, carbureted, spark ignition, gasoline, air cooled engine. The model, which the user subroutine was coupled with, was the GT-Power model created and calibrated for the engine tested. The model gave an error of less than 15 percent compared with measured engine performance. When the user routine object was connected, the results compared between the GT-Power model and the experimental data showed good agreement of 20 percent error or less for the wide open throttle case.]]></description>
      <pubDate>Wed, 01 Jun 2022 15:49:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1816421</guid>
    </item>
    <item>
      <title>Impact Of Condenser Opening Area On A/C Performance of the Automotive HVAC System</title>
      <link>https://trid.trb.org/View/1832026</link>
      <description><![CDATA[Bumper opening area projected on condenser to total condenser core area is referred to as condenser opening area. The condenser opening area plays a vital role in A/C Performance of vehicle particularly during idling and initial cooling of vehicle. This paper presents detail study on effects of condenser opening area on A/C performance. Based on theory, the effect of condenser opening area is studied and it is validated by experimental results. Depending on these results an optimum value of condenser opening area required for best A/C performance is concluded.]]></description>
      <pubDate>Fri, 18 Mar 2022 12:17:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1832026</guid>
    </item>
    <item>
      <title>Simulation Analysis of a Dry Cooling Equipment</title>
      <link>https://trid.trb.org/View/1834131</link>
      <description><![CDATA[The exhaust cooling is an important index which measures the performance of the flameproof diesel engine. In this paper, a modification model is built for enhancing the cooling performance of exhaust, based on the reference model of the dry cooling equipment. The annular nozzle direction, extend plate of guide, bellows and elbow are introduced and studied in the model as the modification way. Considering the Coanda and Venturi effects, the comprehensive comparison of fluid velocity, temperature, pressure and mixture coefficient is implemented, and the optimum horizontal dimension of throat is summarized. The simulation results indicate the modification model shows better performance in reducing exhaust temperature and pressure than the reference model.]]></description>
      <pubDate>Wed, 23 Feb 2022 16:16:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/1834131</guid>
    </item>
    <item>
      <title>Experimental Investigation of the Pressure Drop during Water Condensation inside Charge Air Coolers</title>
      <link>https://trid.trb.org/View/1847489</link>
      <description><![CDATA[This paper investigates the pressure drop with and without condensation inside a charge air cooler. The background to this investigation is the fact that the stored condensate in charge air coolers can be torn into the combustion chamber during different driving states. This may result in misfiring or in the worst-case lead to an engine failure. In order to prevent or reduce the accumulated condensate inside charge air coolers, a better understanding of the detailed physics of this process is required. To this end, one single channel of the charge air side is investigated in detail by using an experimental setup that was built to reproduce the operating conditions leading to condensation. First, measurements of the pressure drop without condensation are conducted and a good agreement with experimental data of a comparable heat exchanger reported in Kays and London [1] is shown. In case of condensation it is observed that the accumulated condensate leads to an increase in pressure drop. An equilibrium state is established between the condensate formed and the one discharged from the charge air cooler, which leads to pressure fluctuations. Furthermore, the amount of the accumulated condensate in the charge air cooler is considered when determining the Fanning friction factor. It is shown that with this consideration the two-phase pressure drop can be described by the single-phase Blasius approach in the investigated operating range of the charge air cooler. The mean deviation of the measured data from the correlation amounts to about 3.8%.]]></description>
      <pubDate>Tue, 26 Oct 2021 14:30:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1847489</guid>
    </item>
    <item>
      <title>Suitability Assessment of an Uncalibrated Body Force Based Fan Modeling Approach to Predict Automotive Underhood Airflows</title>
      <link>https://trid.trb.org/View/1847289</link>
      <description><![CDATA[The automotive fan is a critical component of the cooling module, providing the majority of the cooling airflow over the heat exchangers and to underbody components at low speed, idle, and key-off conditions. Accurately predicting the performance of the automotive cooling fan is critical for sizing heat exchangers and ensuring that underhood and underbody components remain below target temperatures. This is normally done with computational fluid dynamics, but in a full-vehicle simulation it is impractical to model the rotation of the fan blades using a sliding mesh approach. Thus, simplified models which capture the fan behavior are employed. In this paper, a body force-type fan modeling approach is adopted and assessed. Many industrial fan models are calibrated based on experiments or higher-fidelity simulations. This can slow the design process. The approach employed eliminates this step, requiring only fan geometry information and no a-priori performance data. An existing body force modeling approach is used. It has been shown to be suitable for fans of the type typically used in automotive cooling systems. The model is analyzed and validated against computations including the blades. The model is then applied to simulations of the flow around and through an entire vehicle at a variety of speeds. The model predicts the flow rate through the radiator to within 8% of the experimentally-measured value at idle. At high vehicle speed, the accuracy improves to 1%. The accuracy of the uncalibrated model in predicting the radiator flow rate is comparable to the current best-practice calibrated fan modeling techniques used in the industry. The impact of the findings is a reduction in the overall effort involved in simulating under-hood and underbody flows.]]></description>
      <pubDate>Wed, 29 Sep 2021 09:31:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/1847289</guid>
    </item>
    <item>
      <title>Investigation of a Piston Engine and Solid Oxide Fuel Cell Combined Hybrid Modular Powerplant for Unmanned Aerial Vehicles</title>
      <link>https://trid.trb.org/View/1847509</link>
      <description><![CDATA[This work investigates a combined internal combustion engine and solid oxide fuel cell (SOFC) hybrid powertrain for unmanned aerial vehicles (UAV). UAVs are increasingly used in large agriculture for crop management and water resource visual inspection, and in militarized applications, as they allow for safer, unmanned reconnaissance missions. The limited flight time of UAVs, as a result of the traditional lithium polymer batteries used for power, has restricted the widespread implementation of the UAV technology.         A hybrid power train, utilizing energy dense liquid fuel, provides the capability of powering a UAV for longer duration missions. The hybrid power train consists of a small internal combustion engine that acts as a partial oxidation fuel reformer, simultaneously producing mechanical shaft power. The 0.3 in³ piston engine is a typical air cooled, glow engine utilizing a 60/40 percent (by volume) mixture of methanol and nitromethane, respectively. The syngas generated by the combustion engine can then be utilized by a tubular SOFC stack to generate electrical energy for the UAV flight systems. The SOFC system operating on combustion exhaust from the engine produced a maximum of ~650 mW/cm², while the engine was continually producing ~750 W of mechanical shaft power. In case of an engine failure, the liquid fuel may be directly utilized by the SOFC system to maintain power generation. Additionally, the engine may be manually shutdown to provide silent onboard power generation. In testing, a tubular SOFC provided with direct liquid 60/40 methanol/nitromethane fuel was capable of producing above 550 mW/cm² for maximum power. The SOFC system was able to operate continuously under direct liquid fueling for 4 hours without degradation. The power produced by the proposed hybrid powertrain is expected to be sufficient to power a 15 kg UAV for long endurance missions lasting in the range of 200-500% of current recorded UAV flight duration.]]></description>
      <pubDate>Thu, 29 Jul 2021 11:58:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/1847509</guid>
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