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Viewing 1 to 30 of 7437
2014-11-11
Technical Paper
2014-32-0044
Simone Vezzù, Carlo Cavallini, Silvano Rech, Enrico Vedelago, Alessandro Giorgetti
Abstract The deposition of thick, pore-free, high-performance copper alloy matrix composite coatings is a topic of interest for several industrial applications, including friction materials, high-strength electrical contacts, and welding electrodes, among others. This study investigates the use of cold spray to deposit CuCrZr/Al2O3 cermet coatings on aluminum alloy 6060. The objective is to integrate copper-based materials with aluminum-based materials, ensuring a high degree of mechanical and thermal contact, using a low temperature process that does not adversely affect the properties of the base materials. This technique can be used to produce integral coolers and aluminum-based bearings for automotive and motorcycle applications. Fused and crushed alumina and gas-atomized CuCrZr powder blends have been used as initial feedstocks, with compositional weight ratios of 65/35 and 80/20 (ceramic/metal). The coatings have been characterized in terms of microstructure and morphology, coating microindentation hardness, cohesion strength, and adhesion strength to the aluminum alloy substrate.
2014-11-11
Technical Paper
2014-32-0028
T Manikandan, S Sarmadh Ameer, A Sivakumar, Davinder Kumar, R Venkatesan, VenkataKalyana Kumar
Abstract The Instant Mileage Assistance (IMA), as the name indicates, is a system to guide the vehicle users to realize maximum fuel economy (mileage). This system is targeted to provide users with instantaneous mileage indication depending on the current driving pattern, correct gear operating zone (in case of a geared vehicle) through gear up/down shift assist indication and the accurate distance the vehicle can travel before the fuel tank is empty, thereby assisting the user in harnessing maximum fuel economy the vehicle can deliver and also safely reach the next refilling station. The instantaneous mileage is calculated by mapping the distance travelled by the vehicle and the respective amount of fuel consumed, during a particular period of time, and is displayed using an instrument cluster. When the fuel level in the tank reaches a known threshold, the distance to empty is in turn calculated from the instantaneous mileage value hence providing a more accurate and realistic indication to the user.
2014-11-11
Technical Paper
2014-32-0080
Jens Steinmill, Ralf Struzyna
Abstract At a micro-CHP unit the target size of the engine controller is not mechanical torque but thermal and mechanical power. Accordingly, these demands must be implemented by the engine controller. This means that on the one hand a mechanical demand is answered under the boundary condition of the highest actual efficiency and that on the other hand thermal demands have to be processed. Since the thermal- and mechanical power output is coupled with the actual efficiency, exceeding the nominal load of the thermal power, the actual efficiency can be regulated in order to answer the demand. This can be done in consideration of the maximum achievable actual efficiency. Limits are set by the combustion stability and thermal protection functions. The functions are modelled with Matlab/Simulink and the ECU code for a rapid control prototyping system is generated. A dynamic engine test bed for internal combustion engines up to 12 kW was built to verify the motor control functions. The measurement technology for all standard measurements of combustion engines has been selected accordingly to the expected measurement range of small engines.
2014-11-11
Technical Paper
2014-32-0108
Sejun Lee, Kyohei Ozaki, Norimasa Iida, Takahiro Sako
Abstract Recently, a potentiality of Dedicated EGR (D-EGR) concept SI engine has been studied. This concept engine had four cylinders and operated with exhaust gas supplied from the single cylinder to the intake manifold. Compared with conventional SI engines, it was able to increase thermal efficiency and decrease CO, HC, and NOx emission by the high D-EGR ratio 0.25. In this study, numerical analysis of a SI engine with D-EGR system with various D-EGR ratios was conducted for detailed understanding the potentiality of this concept in terms of thermal efficiency and NOx emission. #1 cylinder of assumed engine was used as D-EGR cylinder that equivalence ratio varied from 0.6 to 3.4. Entire exhaust gas from #1 cylinder was recirculated to the other cylinders. The other cylinders run with this exhaust gas and new premixed air and fuel with various equivalence ratios from 0.6-1.0. To study the effect of D-EGR ratio, the number of engine cylinders was considered from 3 to 6, same meaning with D-EGR ratio 0.5-0.2.
2014-11-01
Technical Paper
2014-01-9129
Filip Nielsen, Åsa Uddheim, Jan-Olof Dalenbäck
Abstract Fuel consumption of vehicles has received increased attention in recent years; however one neglected area that can have a large effect on this is the energy usage for the interior climate. This study aims to investigate the energy usage for the interior climate for different conditions by measurements on a complete vehicle. Twelve different NEDC tests in different temperatures and thermal states of the vehicle were completed in a climatic wind tunnel. Furthermore one temperature sweep from 43° to −18°C was also performed. The measurements focused on the heat flow of the air, from its sources, to its sink, i.e. compartment. In addition the electrical and mechanical loads of the climate system were included. The different sources of heating and cooling were, for the tested powertrain, waste heat from the engine, a fuel operated heater, heat pickup of the air, evaporator cooling and cooling from recirculation. It was found that a separation of the sources and sink was possible and increased the understanding of the energy usage.
2014-10-13
Technical Paper
2014-01-2596
Bo Hu, Colin Copeland, Chris Brace, Sam Akehurst, Alessandro Romagnoli, Ricardo Martinez-Botas, J.W.G Turner
Abstract Engines equipped with pressure charging systems are more prone to knock partly due the increased intake temperature. Meanwhile, turbocharged engines when operating at high engine speeds and loads cannot fully utilize the exhaust energy as the wastegate is opened to prevent overboost. The turboexpansion concept thus is conceived to reduce the intake temperature by utilizing some otherwise unexploited exhaust energy. This concept can be applied to any turbocharged engines equipped with both a compressor and a turbine-like expander on the intake loop. The turbocharging system is designed to achieve maximum utilization of the exhaust energy, from which the intake charge is over-boosted. After the intercooler, the turbine-like expander expands the over-compressed intake charge to the required plenum pressure and reduces its temperature whilst recovering some energy through the connection to the crankshaft. It is anticipated that such a concept has benefits for knock resistance and energy recovery despite suffering higher pumping losses.
2014-10-13
Technical Paper
2014-01-2594
Xinyu Wang, Yadong Deng
Abstract Automotive exhaust-based thermoelectric generator (TEG), which effectively converts exhaust thermal energy into electrical energy, can gradually improve the utilization efficiency of energy. The heat exchanger of TEG is one of the most important components for heat transfer, so as to realize energy saving and emission reduction. Hence, its configuration and thermal performance should be intensively studied. In this paper, a new configuration of heat exchanger, whose heat transfer area is regular octagon, is designed in comparison with the pervious rectangle one. In order to improve average temperature and thermal distribution uniformity, typical CFD software named FLUENT is used to simulate the multi-coupling of temperature - fluid - solid, and the temperature distribution on heat transfer area is gained. Moreover, the temperature distribution will be analyzed to evaluate the merits and weaknesses of configuration and thermal performance. By adopting different guiding fins, setting various height and thickness parameters of guiding fins, varieties of heat exchangers are modeled and simulated.
2014-10-13
Technical Paper
2014-01-2600
Le-zhong Fu, Zhijun Wu, Liguang Li, Xiao Yu
Abstract The present work discusses a novel oxyfuel combustion method named internal combustion rankine cycle (ICRC) used in reciprocating engines. Water is heated up through heat exchanger by exhaust gas and engine cooling system, and then injected into the cylinder near top dead center to control the combustion temperature and in-cylinder pressure rise rate, meanwhile to enhance the thermo efficiency and work of the combustion cycle. That is because injected water increases the mass of the working fluid inside the cylinder, and can make use of the combustion heat more effectively. Waste heat carried away by engine coolant and exhaust gas can be recovered and utilized in this way. This study investigates the effect of water injection temperature on the combustion and emission characteristics of an ICRC engine based on self-designed test bench. The results indicate that both indicated work and thermal efficiency increase significantly due to water injection process. The increase of water injection temperature results in higher peak in-cylinder pressure and improves MEP.
2014-10-13
Technical Paper
2014-01-2592
Dhaminda Hewavitarane, Sadami Yoshiyama, Hisashi Wadahama, Xin Li
Abstract High temperature liquids held in a subcooled state are capable of storing large amounts of energy and then explosively releasing this energy when depressurized in a phase change process known as “Flashing”. The rapid volume expansion that results from this flashing has been harnessed to drive an expansion engine working on a cycle called “The Superheated Liquid Flash, Boiling” (S.L.F.B) cycle. The first stage showed that multiphase convective boiling of the unflashed water off the heated walls of the expansion unit supplemented the Flash work output. Furthermore, Flashing was seen to improve the effectiveness of convective boiling off the walls. The results were shown to be repeatable in a modified piston engine. Convective boiling was again shown to be able to supplement the power output under specific conditions. Engine power was seen to be directly related to the peak In-Cylinder pressure, which in turn was directly related to the mass and temperature of the injected subcooled water.
2014-10-13
Technical Paper
2014-01-2857
Jose Serrano, Pablo Olmeda, Francisco Arnau, Artem Dombrovsky
Abstract These days many research efforts on internal combustion engines are centred on optimising turbocharger matching and performance on the engine. In the last years a number of studies have pointed out the strong effect on turbocharger behaviour of heat transfer phenomena. The main difficulty for taking into account these phenomena comes from the little information provided by turbocharger manufacturers. In this background, Original Engine Manufacturers (OEM) need general engineering tools able to provide reasonably precise results in predicting the mentioned heat transfer phenomena. Therefore, the purpose of this work is to provide a procedure, applicable to small automotive turbochargers, able to predict the heat transfer characteristics that can be used in a lumped 1D turbocharger heat transfer model. This model must be suitable to work coupled to whole-engine simulation codes (such as GT-Power or Ricardo WAVE) for being used in global engine models by the OEM. Moreover, the procedure must be capable to predict heat transfer effects using available data as external geometrical parameters of the turbocharger.
2014-09-30
Technical Paper
2014-01-2429
C Venkatesan, V Faustino, S Arun, S Ravi Shankar
Abstract The automotive industry needs sustainable seating products which offer good climate performance and superior seating comfort. The safety requirement is always a concern for current seating systems. The life of the present seating system is low and absorbs moisture over a period of time which affects seat performance (cushioning effect). Recycling is one of the major concerns as far as polyurethane (PU) is concerned. This paper presents the development of an alternative material which is eco-friendly and light in weight. Thermoplastic Polyolefin (PO) materials were tried in place PU for many good reasons. It is closed cell foam which has better tear and abrasion resistance. It doesn't absorb water and has excellent weathering resistance. Also it has a better cushioning effect and available in various colours. Because of superior tear resistance, it is possible to eliminate upholstery and would reduce system level cost. The development involves testing and characterization of the materials, making of prototypes and validations.
2014-09-30
Technical Paper
2014-01-2406
Marco Carriglio, Alberto Clarich, Rosario Russo, Enrico Nobile, Paola Ranut
Abstract The main purpose of this study is the development of an innovative methodology for Heat Exchangers (HE) design to replace the conventional design procedures. The new procedure is based on the definition of a software package managed by modeFRONTIER, a multi-objective optimization software produced by ESTECO, able to create HE virtual models by targeting several objectives, like HE performance, optimal use of material, HE minimal weight and size and optimal manufacturability. The proposed methodology consists first in the definition of a workflow for the automatic CFD simulation of a parametric model of a periodic HE cellular element. This is followed by the definition of a Response Surface (meta-model) covering all the possible range of parameters' combination, the definition of a “bridge”, e.g. low-fidelity - standard or macroscopic - models to extend the behavior of the liquid and air HE cellular elements to a real scale HE, and an optimization process to obtain the optimal HE design for any proposed application and requirements.
2014-09-30
Technical Paper
2014-01-2395
Gurunathan Varun Kumar, Meer Reshma Sheerin, Vedachalam Saravana Prabu, Kallikadan Jean, Chaitanya Rajguru, Murugesan Dinesh, Andrew Croft
Abstract Automotive climate control systems are evolving at a rapid pace to meet the overall vehicle requirements and the user expectations for comfort and convenience. This poses a challenge in the product development life cycle of multi-platform vehicle systems with respect to development time and optimal performance in the Heating, Ventilation and Air Conditioning (HVAC) system. This paper proposes rapid HVAC plant model design and development using simplified one-dimensional (1D) simulation models for fast simulations. The specific accuracy limitations of such a simplified model are overcome using limited three-dimensional computational fluid dynamics (3D CFD) modelling. User-level control strategy is developed in an integrated simulation environment that includes a reference 1D model and a control algorithm simulator. The simulation data is used to study and analyse the temperature and airflow distribution in the system. Based on these results, simpler models for the HVAC system are derived.
2014-09-30
Technical Paper
2014-01-2341
Salvador Sermeno, Eric Bideaux, Tessa Morgan, Duc Nguyen
Abstract Vehicle thermal management covers the engineering field of solutions that maintain the complete vehicle in acceptable operating conditions regarding component and fluid temperatures in an engine. The maximum efficiency rating of a Diesel engine reaches up to 45%. In order to improve the fuel efficiency of the vehicle one can reduce the losses generated by the cooling system. Ideally, the full motive force of the engine should be used for propulsion and new and more efficient energy sources have to be explored to power the secondary systems (cooling, compressed air…). This paper introduces a dynamic programming algorithm which is used to determine the maximum gains during operation for a given architecture of the cooling system of a Heavy Duty Truck. The algorithm, based in Bellman principle, will determine the best control trajectory for the pump and the fan according to energetic and control goals (fuel economy, regulation of temperature…). For this purpose, a reduced model of the cooling system based on energy balance equations has been determined and validated through simulations.
2014-09-30
Technical Paper
2014-01-2343
Manfei Bai, Gangfeng Tan, Yadong Deng, Wenying Wang, Hui Yan
Abstract To make full use of engine exhaust heat and further improve the utilization of the energy efficiency of the heavy truck, thermoelectric module is used to contribute to thermoelectric power generation. The hot-end temperature of the module varies with the engine operating condition because it is connected with the exhaust pipe. The cold-end of the thermoelectric module is mainly cooled by engine cooling system. Increasing the temperature difference between the hot-end and cold-end of the thermoelectric module is a good way to improve the thermoelectric conversion efficiency. For the poor controllability of the hot-end temperature of the thermoelectric module, this study puts forward by lowering the cold-end temperature of the thermoelectric module so as to ensure the improvement of the thermoelectric conversion efficiency. The cooling circle for the cold-end of the thermoelectric module which is independent of the engine cooling system is built. The nucleate boiling flow is adopted to strengthen the heat transfer from the thermoelectric module cold side to the cooling water.
2014-09-30
Technical Paper
2014-01-2325
Michael Franke, Shirish Bhide, Jack Liang, Michael Neitz, Thomas Hamm
Abstract Exhaust emission reduction and improvements in energy consumption will continuously determine future developments of on-road and off-road engines. Fuel flexibility by substituting Diesel with Natural Gas is becoming increasingly important. To meet these future requirements engines will get more complex. Additional and more advanced accessory systems for waste heat recovery (WHR), gaseous fuel supply, exhaust after-treatment and controls will be added to the base engine. This additional complexity will increase package size, weight and cost of the complete powertrain. Another critical element in future engine development is the optimization of the base engine. Fundamental questions are how much the base engine can contribute to meet the future exhaust emission standards, including CO2 and how much of the incremental size, weight and cost of the additional accessories can be compensated by optimizing the base engine. This paper describes options and potentials to improve the base engine for future commercial and industrial engines.
2014-09-16
Technical Paper
2014-01-2202
Gene Tu, Wei Shih, Walter Yuen
Abstract To meet pulse power mode component cooling application needs, we developed, fabricated and tested a concept to use energy storage material and phase change material to enhance the heat dissipation of a conventional heat sink. Test results demonstrated the ESM/PCM heat sink has unique thermal performance. Under the same working condition, the peak temperature of ESM/PCM heat sink is 1.5°C lower than of a conventional heat sink. An optimized design can lead to a significant weight reduction for the heat sink in applications with high peak load and low duty power cycle power.
2014-09-16
Technical Paper
2014-01-2203
Daniel Schlabe, Jens Lienig
Abstract This paper describes a novel Thermal Management Function (TMF) and its design process developed in the framework of the Clean Sky project. This TMF is capable of calculating optimized control signals in real-time for thermal management systems by using model-based system knowledge. This can be either a physical model of the system or a data record generated from this model. The TMF provides control signals to the air and vapor cycle which are possible sources of cooling power, as well as load reduction or shedding signals. To determine an optimal cooling split between air cycle, vapor cycle, and its associated ram air channels, trade factors are being used to make electrical power offtake and ram air usage (i.e. drag) comparable, since both have influence on fuel consumption. An associated development process is being elaborated that enables a fast adaptation of the TMF to new architectures and systems. This will be illustrated by means of a bleedless thermal management architecture.
2014-09-16
Technical Paper
2014-01-2192
Philip Abolmoali, Javier A. Parrilla, Awatef Hamed
Abstract The optimal integration of vehicle subsystems is of critical importance in the design of future energy efficient fighter aircraft. The INVENT (INtegrated Vehicle ENergy Technology) program has been dedicated to this endeavor through modeling/simulation of thermal management, power generation & distribution, & actuation subsystems. Achieving dual cooling & power generation capability from a single subsystem would be consistent with current efforts in system integration optimization. In this paper, we present a reconfiguration of an archetypal closed-loop air cycle system for a modern fighter as an open-loop gas generator cycle operating interchangeably between refrigeration and auxiliary power modes. A numerical model was developed within NPSS to assess maximum power extraction capabilities of a system originally designed for cooling purposes under different operating conditions. Presented results demonstrate variations in maximum power extraction, flow rates, and turbomachinery performance parameters over a range of flight altitudes and Mach numbers.
2014-09-16
Technical Paper
2014-01-2190
Michael Ellis, William Anderson, Jared Montgomery
Under a program funded by the Air Force Research Laboratory (AFRL), Advanced Cooling Technologies, Inc. (ACT) has developed a series of passive thermal management techniques for cooling avionics. Many avionics packages are often exposed to environment temperatures much higher than the maximum allowable temperatures of the electronics. This condition prevents the rejection of waste heat generated by these electronics to the surrounding environment and results in significant ambient heat gain. As a result, heat must be transported to a remote sink. However, sink selection aboard modern aircraft is limited at best. Often, the only viable sink is aircraft fuel and, depending on mission profile, the fuel temperature can become too high to effectively cool avionics. As a result, the electronic components must operate at higher than intended temperatures during portions of the mission profile, which reduces component lifetime and significantly increases the probability of failure. To address this issue, ACT developed two passive thermal management approaches for avionics packages: heat pipe assemblies to reduce the internal temperature gradient and a Loop Heat Pipe (LHP) to transport thermal energy to alternative sinks.
2014-09-16
Technical Paper
2014-01-2191
Mark Donovan, Pedro Del valle
As aviation enters the future, new technologies and philosophies are required to keep up with ever changing demands and increased market competition. Aircraft designers are required to come up with new and innovative ways to optimise systems and improve efficiencies. Onboard thermal management is an area that can take advantage of several new technologies to do just that. This paper is based on the development project “Advanced Thermal Management in Aeronautics” (ATMIA). Project ATMIA focuses on the use of Loop Heat Pipes (LHPs) in the aeronautical industry, specifically their onboard feasibility and the unique requirements found on an aeronautical platform such as those due to vibrations, gravitational forces and the need for disassembly due to maintenance. LHPs are passive two-phase devices that allow free-energy heat transportation between certain subsystems without needing additional power consumption. Their use in aeronautics is interesting as they can passively transport seemingly “waste” heat to areas where it can be reused.
2014-09-16
Technical Paper
2014-01-2195
James H. Graham, Roger Dixon, Peter Hubbard, Ian Harrington
On future UAVs it is envisaged that the power requirements of all on-board electrical systems will increase. In most flight (mission) situations the installed power generation will have adequate capacity to operate the aircraft. It is possible that during abnormal situations such as coolant blockage the generators on-board may be forced to operate under very high load conditions. The main failure mechanism for a generator is overheating and subsequent disintegration of windings, hence the research problem being addressed here is to manage the loads upon the generator to prevent overheats. The research presented here summarizes the modeling of the generator and formation of the load management system. Results are presented showing the system reallocating loads after a fault during flight, preventing overheat of the generators and successfully completing the mission.
2014-09-16
Technical Paper
2014-01-2224
Stephen Emo, Jamie Ervin, Travis E. Michalak, Victor Tsao
Abstract Numerous previous studies have highlighted the potential efficiency improvements which can be provided to aircraft thermal management systems by the incorporation of vapor cycle systems (VCS), either in place of, or in conjunction with, standard air cycle systems, for providing the needed thermal management for aircraft equipment and crews. This paper summarizes the results of a cycle-based VCS control architecture as tested using the Vapor Cycle System Research Facility (VCSRF) in the Aerospace Systems Directorate of the Air Force Research Laboratory at Wright-Patterson Air Force Base. VCSRF is a flexible, dynamic, multi-evaporator VCS which incorporates electronic expansion valves and a variable speed compressor allowing the flexibility to test both components and control schemes. The goal of this facility is to reduce the risk of incorporating VCS into the thermal management systems (TMS) of future advanced aircraft. In this paper, the authors discuss the hardware configuration, as well as the differences between a baseline control architecture (consisting of evaporator superheat and system capacity control) and the suggested cycle-based control.
2014-09-16
Technical Paper
2014-01-2225
Hidefumi Saito, Shoji Uryu, Norio Takahashi, Noriko Morioka, Hitoshi Oyori
Abstract To improve an energy optimization issue of ECS for MEA, we propose our concept in which ACS is replaced with VCS. A VCS is generally evaluated as auxiliary or limited cooling system of an aircraft. Cooling demand of commercial aircraft usually becomes large due to ventilation air at hot day conditions. In case of using conventional VCS for whole cooling demand, the ECS becomes too heavy as aircraft equipment. Though ACS's light weight is advantageous, the issue that VCS will be available for aircraft ECS is important for saving energy. ECS of commercial aircraft should work for three basic functions, i.e. pressurization, ventilation, and temperature control. The three functions of the ECS for bleed-less type of MEA can be distributed among equipment of the ECS. MDFAC works for pressurization and ventilation. Therefore, we should select appropriate system for only temperature control. For the function of temperature control, system with higher COP should be selected due to energy saving.
2014-09-16
Technical Paper
2014-01-2213
Noriko Morioka, Hidefumi Saito, Norio Takahashi, Manabu Seta, Hitoshi Oyori
Abstract Electrical power management is a key technology in the AEA (All-Electric Aircraft) system, which manages the supply and demand of the electrical power in the entire aircraft system. However, the AEA system requires more than electrical power management alone. Adequate thermal management is also required, because the heat generated by aircraft systems and components increases with progressive system electrification, despite limited heat-sink capability in the aircraft. Since heat dissipation from power electronics such as electric motors, motor controllers and rectifiers, which are widely introduced into the AEA, becomes a key issue, an efficient cooling system architecture should be considered along with the AEA system concept. The more-electric architecture for the aircraft has been developed; mainly targeting reduced fuel burn and CO2 emissions from the aircraft, as well as leveraging ease of maintenance with electric/electronic components. The AEA should pursue more efficient and eco-friendlier systems, which are easier to maintain than those of conventional aircraft/MEA (More-Electric Aircraft), to enhance benefits for passengers and operators.
2014-09-16
Technical Paper
2014-01-2220
Jesse Miller, John Hoke, Frederick Schauer
Abstract Two compact intercoolers are designed for the Rotax 914 aircraft engine to increase engine power and avoid engine knock. A study is performed to investigate the effects of unsteady airflow on intercooler performance. Both intercoolers use air-to-liquid cross flow heat exchangers with staggered fins. The intercoolers are first tested by connecting the four air outlets of the intercooler to a common restricted exit creating a constant back pressure which allows for steady airflow. The intercoolers are then tested by connecting the four air outlets to a 2.4 liter, 4 cylinder engine head and varying the engine speed from 6000 to 1200 RPM corresponding to decreasing flow steadiness. The test is performed under average flight conditions with air entering the intercooler at 180°F and about 5 psig. Results from the experiment indicate that airflow unsteadiness has a significant effect on the intercooler's performance. Temperature spread across the intercooler's outlets varies from 30°F to 5°F as airflow unsteadiness increases.
2014-09-16
Technical Paper
2014-01-2160
Wei Wu, Yeong-Ren Lin, Louis Chow
Abstract In this paper, we address the thermal management issues which limit the lifespan, specific power and overall efficiency of an air-cooled rotary Wankel engine used in Unmanned Air Vehicles (UAVs). Our goal is to eliminate the hot spots and reduce the temperature gradients in the engine housing and side plates by aggressive heat spreading using heat pipes. We demonstrate by simulation that, for a specific power requirement, with heat spreading and more effective heat dissipation, thermal stress and distortion can be significantly reduced, even with air cooling. The maximum temperature drop was substantial, from 231°C to 129°C. The temperature difference (measure of temperature uniformity) decreased by 8.8 times (from 159°C to 18°C) for a typical UAV engine. Our heat spreaders would not change the frontal area of the engine and should have a negligible impact on the installed weight of the propulsion assembly. We expect our approach could lead to a very significant reduction in thermal stress-induced warping which is primarily responsible for wear and high friction.
2014-09-16
Technical Paper
2014-01-2155
Javier A. Parrilla
Abstract Current industry trends demonstrate aircraft electrification will be part of future platforms in order to achieve higher levels of efficiency in various vehicle level sub-systems. However, electrification requires a substantial change in aircraft design that is not suitable for re-winged or re-engined applications as some aircraft manufacturers are opting for today. Thermal limits arise as engine cores progressively get smaller and hotter to improve overall engine efficiency, while legacy systems still demand a substantial amount of pneumatic, hydraulic and electric power extraction. The environmental control system (ECS) provides pressurization, ventilation and air conditioning in commercial aircraft, making it the main heat sink for all aircraft loads with exception of the engine fuel thermal management system. To mitigate the architecture thermal limits in an efficient manner, the form in which the ECS integrates with the engine will have to be enhanced as to reduce the overall energy consumed and achieve an energy optimized solution.
2014-09-16
Technical Paper
2014-01-2189
Andrew Slippey, Michael Ellis, Bruce Conway, Hyo Chang Yun
Abstract Carbon fiber reinforced polymer (CFRP) composite material is an attractive structural material in applications where mass is critical. The carbon fiber matrix provides strength comparable to steel with only 25% of the density. The CFRP sheet can often also be made thinner than metal with similar mechanical properties, further increasing the mass savings. However, thermal challenges have arisen with the increased use of composites. In the area of electronics enclosures, traditional metal structures conduct and spread heat over large surfaces, but composites act as insulation. Heat generated by components causes internal temperatures to rise and has detrimental impact on the performance and reliability of the electronics. A method is proposed and tested that utilizes constant conductance heat pipes (CCHPs) that penetrate through the CFRP walls. The CCHPs are capable of transporting significant heat energy through a limited cross-section with a minimal temperature penalty. CCHPs are passive, two-phase, thermal transport devices which have extremely high effective thermal conductivities on the order of thousands of W/m-K.
2014-09-16
Technical Paper
2014-01-2152
Pedro Del valle, Pablo Blazquez Munoz
Abstract Advance thermal management systems are being developed to optimise the energy balance within aircraft. This is being done in parallel to the concept of the More Electrical Aircraft (MEA) which has been developing throughout the last decades. The objective of such complex systems is to use efficiently the hot and cold sources available within the air vehicle to reduce the engine fuel consumption. A reduction of electrical power consumption, minimisation of weight, optimisation of aircraft aerodynamics (for example RAM inlets area minimisation) and the reduction of bleed air from engine all result in a fuel consumption saving. Any thermal management system to optimise energy consumption implies complex and advanced systems. This requires a high engineering effort to design and integrate the system within an aircraft due to the large quantity of variables and interfaces that need to be taken into account. Models and simulations are essential from the beginning of the system development and design phase.
Viewing 1 to 30 of 7437