Unconventional Engine Research Articles

Tribological characteristics of piston rings in a single-piston hydraulic free-piston engine

PurposeA free-piston engine (FPE) is an unconventional engine that abandons the crank system. This paper aims to focus on a numerical simulation for the lubricating characteristics of piston rings in a single-piston hydraulic free-piston engine (HFPE).Design/methodology/approachA time-based numerical simulation program was built using Matlab to define the piston motion of the new engine. And a lubrication mode of piston rings was built which is based on the gas flow equation, hydrodynamic lubrication equation and the asperity contact equation. The piston motion and the lubrication model are coupled, and then the finite difference method is used to obtain the piston rings lubrication performances of the FPE. Meanwhile, the lubrication characteristics of the new engine were compared with those of a corresponding conventional crankshaft-driven engine.FindingsThe study results indicate that compared with the traditional engine, the expansion stroke of the HFPE is longer, and the compression stroke is shorter. Lubrication oil film of the new engine is thicker than the traditional engine during the initial stage of compression stroke and the final stage of the power stroke. The average friction force and power of the hydraulic free piston engine are slightly lower than those of the traditional engine, but the peak friction power of the FPE is significantly greater than that of the traditional engine. With an increase in load, the friction loss power and friction loss efficiency decrease, and with a decrease in equivalence ratio, the friction power loss reduces, but the friction loss efficiency decreases first and then increases.Research limitations/implicationsIn this paper, only qualitative analysis was performed on the tribological difference between conventional crankshaft engine and HFPE, instead of a quantitative one.Practical implicationsThis paper contributes to the tribological design method of HFPE.Social implicationsNo social implications are available now, as the HFPE is under the development phase. However, the authors are positive that their work will be commercialized in the near future.Originality/valueThe main originality of the paper can be introduced as follows: the lubrication and friction characteristics of the new engine (HFPE) were investigated and revealed, which have not been studied before; the effect of the HFPE’s special piston motion on the tribological characteristics was considered in the lubrication simulation. The results show that compared with the traditional crankshaft engine, the new engine shows a different lubrication performance because of its free piston motion.

An experimental research on the combustion and heat release characteristics of a free-piston diesel engine generator

Free-piston engine generator (FPEG) is an unconventional engine; which is characterized by freely moving pistons without crankshaft system. This paper focused on an experimental analysis for the combustion and heat release characteristics of a free-piston diesel engine generator. An experimental prototype was established to test the operation performances of the new engine under different injection conditions. Experimental results show that the actual compression ratio of the FPEG is influenced by the injection advance position (IAP), which decreases with injection position advancing; but the peak in-cylinder gas pressure varies in positive correlation with the IAP. Moreover, the heat release characteristics of the unconventional engine were also analyzed using the experimental data. The results indicate that at the optimum injection position, the ignition delay of the FPEG prototype is 0.86ms and generally shorter than a corresponding conventional crank engine due to its faster piston motion around the top dead center; and the heat release process has more significant pre-mixed combustion, which differs from the conventional engine situation. The heat release center of the FPEG at all injection position lags a stable time after injection; and the departure time of heat release center (DTHC) is increased significantly with the retarded injection. Meanwhile, a particularfeature was found that the optimum efficiency of the FPEG does not occur in the lowest DTHC condition due to its variable compression ratio.

Combustion characteristics analysis of a free-piston engine generator coupling with dynamic and scavenging

Free-piston engine generator is an unconventional engine, which abandons the crank and connecting rod mechanism. This paper focused on a numerical simulation for the research on the combustion characteristics of a free-piston diesel engine generator. An iteration numerical simulation method was presented by adopting coupled models of zero-dimensional dynamics, multidimensional scavenging and combustion. According to the coupled parameters of these models, the effects of the piston motion on combustion process were investigated compared with a corresponding traditional crank engine. The results indicate that compared with the conventional engine, the free-piston engine generator has a longer combustion duration due to its faster piston mean velocity in combustion process. While the heat release before top dead center, the isochoric heat release, and the heat release during the premixed combustion period both were lower than the traditional engine, and the post-combustion became more intense for the free-piston engine, thus a slight disadvantage of indicated efficiency was found. In addition, the in-cylinder average gas temperature and pressure were generally lower than the traditional engine, which contribute to the distinct advantages in NO discharge of the free-piston engine generator.

The effectiveness of policy on consumer choices for private road passenger transport emissions reductions in six major economies

The effectiveness of fiscal policy to influence vehicle purchases for emissions reductions in private passenger road transport depends on its ability to incentivise consumers to make choices oriented towards lower emissions vehicles. However, car purchase choices are known to be strongly socially determined, and this sector is highly diverse due to significant socio-economic differences between consumer groups. Here, we present a comprehensive dataset and analysis of the structure of the 2012 private passenger vehicle fleet-years in six major economies across the World (UK, USA, China, India, Japan and Brazil) in terms of price, engine size and emissions distributions. We argue that choices and aggregate elasticities of substitution can be predicted using this data, enabling us to evaluate the effectiveness of potential fiscal and technological change policies on fleet-year emissions reductions. We provide tools to do so based on the distributive structure of prices and emissions in segments of a diverse market, both for conventional as well as unconventional engine technologies. We find that markets differ significantly between nations, and that correlations between engine sizes, emissions and prices exist strongly in some markets and not strongly in others. We furthermore find that markets for unconventional engine technologies have patchy coverages of varying levels. These findings are interpreted in terms of policy strategy.

Photovoltaic Based Vapour Compression Refrigeration System for Vaccine Preservation

The performance evaluation of photovoltaic based vapour compression refrigeration system was carried out in the Department of Unconventional Energy Sources and Electrical Engineering, Dr. PDKV Akola. The DC refrigerator was powered by a field of solar panels, a battery bank, and a solar charge controller. It was observed that the energy consumption of a photovoltaic operated vapour compression refrigerator was typically 429 - 660 W per day for recommended storage condition of vaccines (2-8℃).The performance of thermoelectric refrigerator had found impact of ambient temperature on its performance in terms of cooling effect and power consumption which was more than the vapour compression refrigerator. The output power of the photovoltaic system was determined at no load and full load conditions. The experimental data were used for the calculation of the energy and exergy efficiencies of the PV systems. The average photovoltaic efficiency was found to be 8.4 and 8.2% for no load and full load conditions while exergy efficiency was 11.4 and 11.2%, respectively multiple regression analysis carried out to predict the power output, photovoltaic efficiency and exergy efficiency and showed significant results.

Industry/Research Collaboration Advances Oil and Gas Technologies

R&D on Campus - Universities are working hard to anticipate the demand for new technologies and techniques as oil and gas exploration delves into deeper waters, harsher climates, and unconventional fields. Numerous universities are teaming up with the industry on projects such as modeling software, heavy oil technologies, fines migration, drilling technologies, and foam to enhance oil recovery and production. Through these research collaborations, more efficient methods are being developed to meet the increasing global consumption of oil and gas. Petroleum Engineering Department, Colorado School of Mines, US The Petroleum Engineering Department at the Colorado School of Mines has a large undergraduate and graduate enrollment and a healthy mix of multidisciplinary research efforts including the Unconventional Natural Gas and Oil Institute; the Marathon Center of Excellence for Reservoir Studies; the Fracturing, Acidizing, Stimulation Technology Consortium; the Energy Modeling Group; the Unconventional Reservoir Engineering Project; and the Physics of Organics, Carbonates, Clays, Sands, and Shales Consortium. One area of focus is the Routes to Sustainability for Natural Gas Development and Water and Air Resources project in the Rocky Mountain Region. For this project, the Petroleum Engineering and the Civil and Environmental Engineering departments are working with their sister school, the University of Colorado at Boulder, and seven other institutions in a Sustainability Research Network (SRN) funded by a 5-year grant from the US National Science Foundation. The mission of the SRN is to provide a logical, science-based framework for evaluating environmental, economic, and social trade-offs between the development of natural gas resources in the Rocky Mountain Region and the protection of water and air resources. The SRN plans to give the results of these evaluations to the public in a way that will improve policies and regulations governing oil and gas exploration. “Our goal is to find the balance between maximizing the development of natural gas and oil resources for the benefits of short-term reduction of CO2 emissions from power generation and transportation, national energy independence, and national job growth, while minimizing damage to water and air resources and risks to human health,” said Joseph N. Ryan, faculty director of the research project.

A novel engine cooling system with two circuits operating at different temperatures

The driver of the future engine technology will be the reduction of the CO2 emissions which is strictly related to fuel consumption saving. Recent regulations on pollutant emissions and greenhouse gases require a technological effort on engine efficiency which can be made with a different set of options. It is important to consider those ones that have lower costs and a suitable ratio between CO2 reduction and cost. Relevant importance is, so, assumed by a revision of the engine cooling system, which remained substantially unchanged for several years or decades.If the engine and vehicle thermal needs are considered in a whole way, the cooling system can be rearranged realizing the integration of conventional thermal needs (engine, oil and EGR cooling) with unconventional ones (cabin conditioning, charge air cooling) realizing benefits in terms of engine efficiency and comfort.In this paper, a mathematical model of an internal combustion engine is presented. It is a lumped parameter model, physically consistent and it is used to appraise the performances of conventional and unconventional engine cooling systems and the integration in it of vehicle thermal needs. In particular, a double cooling circuit has been considered, with two different temperature levels, that allows important improvements in terms of engine warm up, fuel consumption saving and air boosting.The model has been applied to an existing engine whose experimental characterization was done concerning the heat rejection toward the cooling fluid. On this engine, a double circuit at two temperature levels has been proposed, according to a layout which redistribute in an optimal way the engine and vehicle thermal requirements.

A Mechanism for Self-Starting Thermal Engine

The conventional engine cannot start alone. The engine needs a special device to turn it on. This device is usually an electric motor that is called starter. Any other engine that uses another working cycle then Otto cycle or Diesel cycle could accede to a self-starting ability. The paper tries to use ancient ideas in order to develop a true thermal engine able to use solar and other renewable energy. This unconventional engine inherits some ideas from the perpetual motion machine solutions.

Design of a solenoid valve based active engine mount

This paper describes the design of a versatile and fully controllable active engine mount. The proposed active mount is capable of addressing vibration isolation requirements at various driving conditions. This design addresses a better ride quality that has always been demanded by the automotive industry, as well as satisfying sophisticated vibration isolation requirements for the unconventional engines, i.e. variable displacement, and hybrids. The proposed engine mount replaces the decoupler of the original design with a solenoid actuator. The mathematical model of the active mount is obtained. The dynamic characteristics of the mount are shown to be highly controllable over the operating frequency range of excitation in engines. The effectiveness of the developed active engine mount for various working conditions of engine is also evaluated. Several driving conditions are investigated and proper control strategies are utilized to demonstrate the mount's capability to fulfill the isolation requirements for each condition. The promising results, in addition to compactness, low cost, fail safety, and durability are the main advantages of the proposed active engine mount, which makes it viable for automotive applications.

Technological frames of car engines

In this paper we analyze how car users frame car engines. Car engines have been build on internal combustion (IC) technologies for more than hundred years now; however, in the last decade hybrid-electric engines have been successfully introduced. The coexistence of conventional and unconventional technologies raises the interesting question to what extent these different engine technologies are framed differently, and how they change over time. Studies of technological frames and mental models suggest that frames of established technologies are more obdurate. In this paper we analyze technological frames of a few types of car engines and how frames have shifted during market evolution between 1990 and 2005. We find that engines are framed rather differently. Frames of conventional diesel engines emphasize engine capacity (measured in kW), engine volume (measured in liters) and torque (measured in Nm), whereas for hybrids fuel efficiency is by far the most prominent attribute. Further we find that the frame of the conventional engine (diesel) is more stable than that of an unconventional engine (hybrid and full-electric), which confirms the obduracy hypothesis that is raised in earlier studies of technological frames.

A procedure to study thermo- and electrophysical properties of materials

We describe a measurement procedure and the construction of an automatic measuring complex to study thermal conductivity by an absolute stationary method and also electrical conductivity and thermal EMF of materials in a temperature range from −60 to +4400 ° C. The use of a specialized microprocessor system to perform stationary measurements and to control parameter measurement processes in combination with highgrade measuring devices and equipment developed for this procedure enables high accuracy of measurements. Test studies performed on reference samples show that the thermal conductivity measurement error does not exceed 4 and 3% for electrical conductivity and thermal EMF, respectively. In the development of devices and equipment for this measuring complex, unconventional engineering, schematic, and programming solutions are implemented. The application of a microprocessor control system together with the software developed allows the measurements to be performed automatically.

Systems analysis of advanced quiet aircraft

To achieve future goals for the reduction of aircraft community noise, it may be necessary to use unconventional engine and wing arrangements. Prediction of the resulting noise benefits cannot be made without taking into account the effect of the configuration on the whole aircraft system, including the impact on the aerodynamics, weights, and systems integration. Systems studies have been conducted that quantify the impact of various configurations on both the performance and noise of the aircraft. In this paper, the results for several systems studies are presented. In one study, a large matrix was assembled for candidate configuration options for a blended wing–body (BWB) aircraft–including engine, inlet, and nozzle types and placement options—and ranked based on prioritization between noise benefits and performance penalties. In another study, a pair of concepts was developed and evaluated with the goal of simultaneously reducing the noise produced and reducing or eliminating the production of harmful chemical emissions. Finally, a BWB configuration was studied to determine the sensitivity of the overall noise to the levels of the various engine and airframe sources, quantify the airframe shielding benefits using experimental data, and explore the effects of wing trailing-edge extensions on the shielding.

Automotive lubricants for the next millennium

During the first decades of the next millennium, automobile manufacturers will strive to achieve, in the USA, another twofold increase in energy efficiency and tenfold reduction in emission levels. On the way to achieving these goals, automobile manufacturers will be improving efficiency and emissions of internal combustion engines, while minimizing customer servicing requirements, as well as introducing new unconventional engine technologies and gradually changing energy sourcing from oil to gas, and possibly to hydrogen. Numerous supporting technologies, such as electronics, computers, sensors, fuels, catalysts, lubricants, etc., will be involved in contributing to engine system improvements. This paper describes expected improvements and changes in lubricant technology and points out the need for development of “breakthrough” technologies which could satisfy the near‐term requirements and eventually in the long term, in combination with novel surface technologies and engine design changes, lead to fill‐for‐life engine lubrication.

Studies of unconventional heat engine design, operation and efficiency: four-step quasi-Carnot cycles with a linear P/V transition

Although the ideal Carnot engine rejoices in the largest efficiency of any heat engine operating between given temperature extremes, alternative closed-loop four-step cycles in which a variable-temperature, straight-line transition replaces the Carnot high-temperature isothermal expansion appear ostensibly to offer a higher thermodynamic efficiency. This arises from the fact that higher maximal temperatures are attained; the efficiency of the equivalent Carnot engine operating between such temperature extremes reinstates Carnot supremacy by slightly transcending the unconventional engine's efficiency. Our investigations stress the importance of the second, as well as the first, law of thermodynamics, and consider operating characteristics quantitatively for specimen engines of various design.

Unconventional engineering teaching tools

AbstractThis article describes progress on the development of a new engineering course for freshman students. During the course, students work on a series of projects aimed at illustrating various aspects of the design cycle. To aid in the design, students are encouraged to experiment with personal computers equipped with multimedia, computer‐aided design software, and data acquisition hardware.

Avenues for Underwater Propulsion

This study reviews thermal propulsion systems related to underwater application, covering the conceptual idea, the technology and the mechanism. Some of the salient features of the stored chemical energy propulsion system (SCEPS) technology and the unconventional engines are discussed. While these systems have generated considerable interest in the west, they are still new in India.

Subzero engineering: At ¿40°F, with the wind howling at 60 miles per hour over permanently frozen ground, unconventional engineering techniques were required

The author discusses his experiences while he was helping to build a radio station in Nome, Alaska. He describes the environmental factors that made the job difficult, and discusses the steps that were taken to contend with them.

Future trends in aero gas turbine design—Unconventional engines

The first part of this paper was concerned with the evaluation of the now classic form of low noise, single stage front fan engine as used on all contemporary designs of large subsonic civil aircraft.This second part deals with other forms of the aircraft gas turbine which we have categorised as unconventional in the sense that they seek to achieve one or more of the following objectives: (a)a superior performance by moving towards more extreme constant pressure gas turbine cycles;(b)a superior performance by use of a different thermo-dynamic/propulsive system;(c)a performance which requires an ability to modify the thermodynamic cycle at different flight conditions;(d)uses for the engine which are additional to the normal propulsive role.In the main, these engines are, as their title suggests, not generally adopted as powerplants for production aircraft and their often specialist role must detract from their wide use in a range of aircraft. However, it could be argued that the classic design of engine will soon be approaching a plateau of achievement and therefore some degree of unconventional form will be required in future to advance aircraft performance.