Heat exchangers are a prolific application found in all things that concern fluid and power; they are mission-critical applications that affect overall performance in aircraft of all sizes. Yet, for years, heat exchangers have been constrained, by traditional manufacturing, in terms of limited geometric freedom and lengthy lead times. Consider the following • Heat exchangers are commonly fabricated with stainless steel and then gold brazed, which can be extremely costly • Each weld joint costs $100; in traditionally manufactured fuel and high-pressure systems, there could be hundreds of welds • There can be a lack of integration with other systems like electrical motors or conformal cooling with batteries. Assembly integration, testing, and validation are lengthy and difficult. Additive manufacturing (aka 3D printing) has opened new possibilities for thermal conductivity and heat-exchanger design that enable end users to push the limits of what is possible.
The fuel economy of recent small size DI diesel engines has become more and more efficient. However, heat loss is still one of the major factors contributing to a substantial amount of energy loss in engines. In order to a full understanding of the heat loss mechanism from combustion gas to cylinder wall, the effect of hole size and rail pressure under similar injection rate conditions on transient heat flux to the wall were investigated. Using a constant volume vessel with a fixed impingement wall, the study measured the surface heat flux of the wall at the locations of spray flame impingement using three thin-film thermocouple heat-flux sensors. The results showed that the characteristic of local heat flux and soot distribution was almost similar by controlling similar injection rate except for the small nozzle hole size with increasing injection pressure.
For improving the thermal efficiency and the reduction of hazardous gas emission from IC engines, it is crucial to model the heat transfer phenomenon starting from the intake system and predict the intake air’s mass and temperature as precise as possible. Previously the authors developed an empirical equation based on an experimental setup of an intake port model of an ICE in order to be implemented into the engine control unit and numerical simulation software for heat transfer calculations. The authors developed an empirical equation based on the conventional Colburn analogy with the addition of Graetz and Strouhal numbers. Introduced dimensionless numbers were used to characterize the entrance region, and intermittent flow effects, respectively.
Graphite plays a crucial role in friction materials, since it has good thermal conductivity, lubricity and act as a friction modifier. The right type, amount, shape, and size of the particles control the performance of the brake-pads. The theme of the study was investigating the influence of size of graphite particles (having all other specifications identical) on performance properties of brake-pads containing graphite particles in the average size of 60 µm, 120 µm, 200 µm and 400 µm. Physical, mechanical and chemical characterization of the developed brake-pads was done. The tribological performance was studied using a full- scale inertia brake dynamometer following a Japanese automobile testing standard (JASO C406). Tribo-performance in terms of fade resistance, friction stability and wear resistance were observed best for smaller graphite particles. It was concluded that smaller size serves best for achieving best performance properties barring compressibility.
High temperature distribution in disc brake mounted within in-wheel motor driven vehicle has several negative effects on braking performance. This is mainly due to the enclosed nature of the braking system. This paper aims to determine the effect of contact geometry on temperature distribution and thermal buckling in such a brake. Numerical analysis is conducted to investigate the variation of temperature field on the brake disc at different cover angles of pads while maintaining the same moment of friction. The effect of different radial positions of the pads is a second consideration in the current work, using a transient modeling approach. To validate the simulation results, an approximate, analytical solution is derived according to energy conservation. The results show that, for the same work done by the pads, the maximum temperature on the disc increases with a decrease in the pad cover angle.
Abstract: Attapulgite, a unique clay mineral is a crystalloid hydrous magnesium-aluminium silicate, composed of silicon oxide, aluminium oxide, magnesium oxide, iron oxide etc. having formula Mg5Si8O20(HO)2(OH2)4•4H2O. Its structure is somewhat between laminated and chain structure having very high surface area and porosity. Its magnesium silicate structure resembles a brick wall with every second brick missing. This leaves elongated porous channels that are highly absorbent. Its fibers were proven to be excellent substitute for asbestos in brake-pads. Hardly anything in details is reported on its exact role in controlling tribo-properties of friction materials (FMs) especially Cu-free FMs. Hence, in this work a series of brake-pads with five types was formulated and developed with increasing amount of attapulgite (0, 5, 10 and 15 wt. %) by compensating with inert barite particles in Cu-free FMs.
The electrochemical performance of a lithium-ion battery is strongly affected by the temperature. During charge and discharge cycles, batteries are subjected to an increment of temperature that can accelerate aging and loss of efficiency if critical values are reached. Knowing the thermal parameters that affect the heat exchange between the battery surface and the surrounding environment (air, cooling fins, plates, etc…) is fundamental to their thermal management. In this work, thermal imaging is applied to a laminated lithium-ion battery as a non-invasive temperature-indication method. Measurements are taken during the discharge phase and the following cooling down until the battery reaches the ambient temperature. The 2d images are used to analyze the homogeneity of the temperature distribution on the battery surface. Then, experimental results are coupled with mathematical correlations.
Mechanical friction and heat transfer in internal combustion engines are two highly researched topics, due to their importance on the mechanical and thermal efficiencies of the engine. Despite the research efforts that were done throughout the years on both these subjects, engine modeling is still somewhat limited by the use of models which do not fully represent the phenomena happening in the engine. Developing new models require experimental data which is accurate, repeatable and which covers wide range of operation. In 2018-01-0121, the conventional pressurised motored method was investigated, and compared with other friction determination methods. The pressurised motored method proved to offer a good intermediate between the motored tests, which offer good repeatability, and the fired tests which provide the real operating conditions, but lacks repeatability and accuracy.
The implementation of increasingly stricter regulations on CO2 emissions by the European Community is pushing the automotive industry towards a radical change. In a rush to electrify their model ranges, global carmakers are investing heavily on developing new electrified powertrains. Within this context, this work focuses on the analysis of electric axles drives (eAxles) for a BEV (battery electric vehicle) sport car, with the aim to develop an analytical tool useful to perform predictive analysis in the concept design phase. Through a parametric definition of the procedure, the tool with its 2800 lines of code is able to “adapt” to any drivetrain layout analysed. The tool actually allows to enter more than 100 input values including lubrication conditions (oil viscosity and operating temperature), gears (number, macrogeometry, mesh), bearings (number, type, geometry, mounting layout, angle mesh), shafts, oil seals, external layout and external fluid conditions.
Piston is the most imperative part of an automotive engine in which it exchanges drive due to expanding gas in the cylinder to the crankshaft through the piston rod. During the combustion of fuel charge inside the ignition chamber, high pressure and temperature are developed and the piston is imperiled to high mechanical and thermal stresses. The main objective of the proposed work is to analyse the stress distributions and thermal behaviour of uncoated A356 - 5% SiC - 10% Fly ash HMMC piston crown and Plasma sprayed Yttrium Stabilized Zirconia(Y-PSZ) coated A356 - 5% SiC - 10% Fly ash HMMC piston crown. A356 - 5% SiC - 10% Fly ash HMMC were fabricated via squeeze casting to improve the performance of a petrol engine. A structural model of an HMMC piston crown was made using CREO software and structural and thermal analysis was done using ANSYS. Further coupled field analysis is done to find the stress and temperature distribution on the piston.
Recent years, researches are more focused on various enhancement methods for compact heat exchangers without altering the surface area of the heat exchangers. The advancements in the area of Nano fluids with better thermal properties have helped in development of light-weight, highly efficient automobile radiators. The main objective of this project is to increase the thermal performance of the radiator and thereby reducing the size of the radiator. In this project a numerical model with porous medium approach was developed and validated. Nano fluids (Aluminium oxide, Copper oxide, Graphite) of different volumes (ranging from 1%-13% in an interval of 2) are used along with water and it was observed that the heat transfer rate of the radiator is increased by 4.49% and the volume of the radiator is reduced by 5.4% for the addition of 5% of Aluminium oxide in water.
To tackle the problem arising due to emissions and to reduce them, complex after-treatment system is used. For efficient working of the after-treatment system it must operate at enough high temperature even at low loads for better conversion efficiency. Also, there is different temperature requirements for different catalyst used in SCR (Selective catalyst reduction) system. For this, various on engine strategies are implemented on modern diesel engines such as multiple fuel injection, late fuel injection, high fuel injection pressure and exhaust gas recirculation. Thermal management of exhaust gasses is an operating condition which must be triggered when there is need of elevated temperatures for efficient functioning of the after-treatment system. Thermal management includes SCR thermal management and regeneration.
The ideology behind the project is to change the helical angle of the baffles that are attached to the heat exchanger so that it increases the flow rate of high viscous fluids. Thermo-water powered effectiveness examinations were done on five trisection helical confound heat exchangers with unmistakable tendency edges, puzzle shapes or contact examples, and one segmental astound heat exchanger (SEG). Examinations of thermo-water powered in general execution were performed on five trisection helical perplex warmness heat exchangers with exceptional tendency edges, confound shapes or association examples, and one segmental puzzle warmness heat exchanger (SEG). A relative assessment of three regions bewilder plans with tendency edges of 10 degree (10°S), 15 degree (15°S), and 20 degree (20°S); an oval confound conspire with a tendency edge of 15 degrees (15°E), and a hub cover area perplex plot with a tendency edge of 20 degrees (20°D) become executed.
Off highways vehicles especially tractors are prone to operate on fields where tractors are exposed to dry crops, chaffs (the husks of corn or other seed separated by winnowing or threshing) and particles which can catch fire easily when it is exposed to surface/skin temperature of more than 200 degree Celsius. It will be a basic projection that tractor will be having vertical exhaust tube at a height but there are certain tractors and applications where exhaust pipe must be below certain height, and which will be close to the ground. In these scenarios the skin temperature of exposed exhaust tail pipe part must be within a limit and that must be within the existing design. Break firing point of chaffs and husk also experimented at different moisture level. Several options are being verified on different heat flow and geometry changes, additional air entry jet nozzle with double pipe arrangement.
Currently automotive design is facing multi facet challenges such as reduction in greenhouse gases, better thermal management, low cost solution to market, etc. Considering these challenges, effort has been taken to improve thermal management of engine while optimizing the cost of engine. Engine Lubrication system consist of Engine oil and oil cooler, which play vital role in thermal management as well as optimization of frictional losses by ensuring proper lubrication and cooling of engine components. For better thermal management of engine, a lubrication system is designed without Oil cooler, proto type made and tested. This paper deals with evaluation of various engine performance parameter and engine temperature with and without oil cooler for light duty Diesel engines on passenger car application. Further solution of Oil cooler removal and Engine cooling improvement with the help of oil change is validated at vehicle level to understand real world behavior of the system.
During braking a large amount of kinetic energy being taken form into thermal energy thereby increasing the brake disc temperature around 200oC to 400oC in motorcycles and ATVs, which forces to improve the heat transfer in brake disc through grooves and holes thereby minimising the clamping force. In which the present study is mainly done to improve the clamping force on the brake disc through re-coined the shape of grooves with various disc materials by design and analysis route. The brake disc solid work model was developed with slanted rectangular grooves along the radial direction of Aluminium metal matrix composite (AA8081 reinforced with 15wt% of SiC and 3wt% of Gr), Stainless Steel (SUS 410), Gray Cast iron (Grade 250) materials data set. The couple field analysis attempts of both thermal and structural analysis was done to find the impact on the brake disc heat transfer rate, deformation, von mises stress and strength which were analysed by ANSYS workbench.
The ever-increasing need of effective transportation puts automobile component manufacturers in a non-avoidable situation to improve and maintain safety systems. In a cruises part brake disc of the braking system plays a vital role in effective braking of the vehicle. The main aim of this proposed study is to varying groove patterns and angles were designed and dynamic analysis was performed for two different post processed brake disc materials. By using solidworks a brake disc with proper slots and groove pattern (j hook) was designed for improved bite, debris, clearance, reduced distortion /vibration and effective heat transfer through convection process. In which two different materials namely zinc based AA7075-T6 and AS4C (carbon fibers) was taken as a as condition and for further post processing route via short peening as consider as a disc material. The properties was measured and given as input data set in ansys workbench for further processing.
In automobiles, the most commonly used braking system is disk brake. The disk is the important component in either slowing or stopping the vehicle. When a brake is applied, there occurs friction between the brake pad and the disk. Due to this action, a large amount of heat is generated. In order to reduce the generated heat, different sandwich structures were designed. The main objective is to analyze the thermal behavior of the sandwich ventilated structures of different profiles and compare their results and suggest the suitable ventilation structure that highly influences the convective heat transfer of the brake disc under on-road rigorous braking conditions. The chosen brake disc material is titanium alloy. The profiles which are analyzed are X-core, Corrugated, Round O-core and Honeycomb. The heat transfer and the pressure drop characteristics of the sandwich structures were found with one face sheet heated by constant heat flux and cooled by forced air convection.