A Rational Basis for Correlating Data on COMPRESSION-IGNITION ENGINE PERFORMANCE at Different Intake and Exhaust Conditions1

Indirect calorimetry involves measurement of CO(2) produced and O(2) consumed by an organism. These measurements are then used to calculate energy output, metabolic rate (MR), and respiratory quotient (RQ), a relative assessment of carbohydrate and lipid oxidation. By far the most difficult aspect of indirect calorimetry is measurement of O(2). Moreover, the abundance of O(2) (20.95%) relative to CO(2) (0.03%) in ambient conditions dictates that measurement errors of O(2) have greater implications on calculations of MR and RQ. Because compressed air is not feasible for use with animals in long-term experiments, changes in ambient conditions are nearly unavoidable. A self-correcting indirect calorimetry system was designed and constructed utilizing differential O(2) and CO(2) analyzers and a blank cage to monitor ambient conditions periodically. The system was validated by changing ambient O(2) and CO(2) concentrations by infusing N(2) into the system during a test butane burn. MR and RQ were largely unaffected by these changes in ambient conditions, and inclusion of a blank cage in the system accounted for slight calibration offsets. MR and RQ were measured in mice (n = 95) with and without correction for any small changes in ambient conditions measured in the blank cage. Coefficients of variation for MR and RQ were significantly decreased by taking into account ambient conditions measured in the blank cage (P < 0.001), which resulted in a 2.3% increase in precision for measurement of MR. This system will be used to more accurately assess long-term measurements of energy balance in the many murine models of leanness and obesity to gain better insights into pathophysiology and treatment of human obesity.

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;In this paper, 20%H₂ (20% hydrogen in natural gas-hydrogen blends, by volume) is selected as the test fuel, and the ignition timing and EGR ratio are adjusted to optimize the performance, combustion, and emissions of a natural gas-hydrogen engine. An experimental investigation on the effect of ignition timings, EGR ratios on combustion behaviors and emissions of a spark-ignition engine fuelled with natural-gas and hydrogen blends was conducted.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;When increasing the ignition timing at specified EGR ratio, engine power output will give its peak value at MBT timing. Large EGR introduction decreases engine power output and increases combustion duration. Effective thermal efficiency shows an increasing trend at the small EGR ratio and a decreasing trend with further increasing EGR ratio.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;With advancing the ignition timing, the flame development duration is increased, and the rapid combustion duration and total combustion duration are decreased. All of these three kinds of combustion duration are increased with the increase of EGR ratio.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;HC concentration is decreased and NOx concentration is increased with advancing the ignition timing while CO emission varies little with the ignition timing. NOx concentration is decreased with the increase of EGR ratio. HC emission is increased with the increase of EGR ratio. CO and CO₂ emissions show little variations with the EGR ratio and ignition timing.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;Based on the above analysis, a MAP containing ignition timings and EGR ratios for 20%H₂ fuel blend is presented, and this will provide the reference and guidance to engine designers and engineers. In addition, through optimizing ignition timing and EGR ratio, high efficiency and low emission spark-ignition engine can be realized fueled with natural gas-hydrogen blends.&lt;/div&gt;&lt;/div&gt;

The effects of drugs and self-selected circadian activity rhythm of the canary: Go¨ran Wahlstro¨m — Department of Pharmacology, University of Uppsala (Sweden)

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;The increased availability of natural gas (NG) in the United States (US) and its relatively low cost compared to diesel fuel has heightened interest in the conversion of medium duty (MD) and heavy duty (HD) engines to NG fueled combustion systems. The aim for development for these NG engines is to realize fuel cost savings and reduce harmful emissions while maintaining durability. Transforming part of the vehicle fleet to NG is a path to reduce dependence on crude oil.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;Traditionally, port-fuel injection (PFI) or premixed NG spark-ignited (SI) combustion systems have been used for MD and HD engines with widespread use in the US and Europe. But this technology exhibits poor cycle efficiency and is load limited due to knock phenomenon. Direct Injection of NG during the compression stroke promises to deliver improved thermal efficiency by avoiding excessive premixing and extending the lean limits which helps to extend the knock limit.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;In this work, a single cylinder engine with 14:1 compression ratio (CR) was used to investigate spark ignited direct injection (SIDI) NG combustion using an integrated spark injector-igniter. Two parameters controlling dilution were investigated (i) increased air charge resulting in an increased air-fuel ratio (AFR) and (ii) exhaust gas recirculation (EGR). The impact of these parameters on fuel consumption, combustion stability, phasing, knock, and emissions of NOx, HC, CO is investigated and reported in this work. Partially stratified combustion (PSC) SOI and SPK timings from previous work will be used as a starting point to investigate the effects. Overall, both AFR and EGR were effective in controlling knock and NOx emissions; however, EGR required lower levels to obtain the desired effect. The use of charge dilution in the PSC range showed promise of trading off knock and combustion stability to within acceptable limits, thus demonstrating potential for increased load operation.&lt;/div&gt;&lt;/div&gt;

&lt;div class="htmlview paragraph"&gt;In-cylinder reactions of several internal combustion engine configurations were investigated using a highspeed four-spectral infrared (IR) digital imaging device. The study was conducted with a greater emphasis on the preflame processes by mutually comparing results from different engine-fuel systems.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;The main features of the methods employed in the study include that the present multi-spectral IR imaging system permits us to capture progressively changing radiation emitted by new species produced in-cylinder fuel-air mixtures prior to being consumed by the heat-releasing reaction fronts.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;The study of the Diesel or compression-ignition (CI) engine reactions was performed by varying several parameters, e.g. injection pressures, intake air temperature, fuel air ratio, and the start of injection. They were investigated also for the following mixture preparation-ignition methods: (1) direct-injection of Diesel fuel; (2) homogenous charge (fumigation) ignited by pilot injection and (3) homogeneous charge self-ignition.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;For the spark-ignition (SI) engine processes, the reactions were investigated using different fuels including gasoline and propane, which were introduced by either the port-fuel-injection unit or carburetor.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;The sequential images captured of in-cylinder preflame reactions were compared with those of the subsequent combustion reactions. In particular, they are expected to serve as an overall survey of visualizing the preflame processes in the cylinder.&lt;/div&gt;

&lt;div class="htmlview paragraph"&gt;To examine the effects of exhaust gas recirculation (EGR) on the exhaust emissions and on the cycle-by-cycle variation of combustion process in a methanol engine, the authors have tried to measure the emissions of total hydrocarbon, carbon monoxides, nitric oxides and formaldehyde and to record the cylinder pressure development histories of 1000 cycles duration. Moreover, the standard deviation of peak pressure Pmax, the heat release rate and the averaged pressure history are analyzed.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;The results are compared with those of gasoline fueled operation.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;The results are summarized as follows:&lt;/div&gt; &lt;div class="htmlview paragraph"&gt; &lt;ol class="list nostyle"&gt; &lt;li class="list-item"&gt; &lt;span class="li-label"&gt;(1)&lt;/span&gt;&lt;div class="htmlview paragraph"&gt;In the case of a methanol-fueled engine operated under exhaust gas recirculation (EGR), similar to that already carried out in a gasoline-fueled engine, the concentration of NOx, in the exhaust gas can be decreased but those of formaldehyde (HCHO) and unburned methanol are increased.&lt;/div&gt; &lt;/li&gt; &lt;li class="list-item"&gt; &lt;span class="li-label"&gt;(2)&lt;/span&gt; &lt;div class="htmlview paragraph"&gt;The effect of EGR, such as 20% of it, on Nox reduction is the same as those of hydrous methanol of 50% water content.&lt;/div&gt; &lt;/li&gt; &lt;li class="list-item"&gt; &lt;span class="li-label"&gt;(3)&lt;/span&gt; &lt;div class="htmlview paragraph"&gt;In the case of EGR applied to an EFI engine, its output and thermal efficiency are decreased within the lean mixture region (λ&amp;gt;1.0) but these recover and the concentration of hydrocarbon is decreased by raising the fuel temperature.&lt;/div&gt; &lt;/li&gt; &lt;li class="list-item"&gt; &lt;span class="li-label"&gt;(4)&lt;/span&gt; &lt;div class="htmlview paragraph"&gt;When the optimum conditions of the EGR and fuel temperature are selected, it is possible to improve the exhaust gas characteristics concerning NOx, THC, etc., while the decreased in engine output and thermal efficiency is reduced to the minimum.&lt;/div&gt; &lt;/li&gt; &lt;/ol&gt; &lt;/div&gt;

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;The air pollution is increasing at an alarming rate now a day mainly due to emissions coming out of automotive vehicles. The exhaust emissions gases are hazardous to human health. The increased number of vehicles on road will make the scenario even worse. In order to control the pollution level, the regulatory bodies are now implementing stringent emission norms. In India, the regulatory authorities has framed the transition of BS IV to BS VI emission norms in 2020 by skipping the BS V emission norms which makes the automotive industries to work on more advanced fuel management technologies. It is more tedious to control the tail pipe emissions beyond BS IV emission norms with the conventional carburetor system since it is operating on open loop system. It is evident that in order to meet the stringent emission norms we need to have a closed loop system which controls the Air Fuel Ratio (AFR) close to stoichiometric to increase the conversion efficiency of the catalytic converter. The vehicle with fuel injection system can able to work on closed loop system, but the fuel injection system is not cost effective.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;This paper illustrates the development of a cost effective smart engine management system for two wheeler application to meet the upcoming emission norms with some modification from the conventional carburetor system. Instead of controlling the fuel flow to keep the AFR close to the stoichiometric as in fuel injection system, the smart engine management system has a sophisticated air control mechanism to make the AFR close to stoichiometric. The carburetor was modified to incorporate an air control solenoid which is operated on the pulse width modulation to vary the air flow according to our requirement. The lambda sensor measures the AFR from the exhaust pipe and provides information to the ECU.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;Based on the feedback from the lambda sensor, TPS, CPS, etc., the ECU maintains the AFR stoichiometric by controlling the flow through the air control solenoid with varying duty cycles. The vehicle performance test was carried out with vehicle having smart engine management system (Electronic carburetor) and also with fuel injection equipped vehicle on the chassis dynamometer. The test results show that the air fuel ratio of the electronic carburetor vehicle was maintained close to stoichiometric as in fuel injection vehicle which in turn reduce the emission to a considerable extent. Hence the smart engine management system caters a new way for an efficient low cost fuel management system.&lt;/div&gt;&lt;/div&gt;

Micro-algae are a large and diverse group of simple typically autotrophic organisms which have the potential to produce greater amounts of non-polar lipids and biomass than most terrestrial biodiesel feedstocks. Having emerged as one of the most promising sources for biodiesel production, they are gaining research interests in the current energy scenario due to their phenomenal growth potential (&lt; 21 days log phase) in addition to relatively high lipids production which are also excellent source of biodiesel. In this study, engine performance and emission profile was performed using biodiesel fuels and blends from micro-algal technology in a compression ignition engine. The technology of micro-algae involved open pond cultivation and the use of photo-bioreactor model BF-115 Bioflo/celli Gen made in the US of 14 litre capacity (200 Lux light intensity) and flowrate of 2.5L/min. The micro-algal species used were Chlorella vulgaris and Scenedesmus spp. The biodiesel produced were blended with conventional diesel (AGO) at different proportions. The performance parameters evaluated include: engine power, torque, brake specific fuel consumption (BSFC), smoke opacity, thermal gravimetry, thermal efficiency, exhaust gas temperatures and lubricity while the varying effects of emission pollutants during combustion were also studied. Results showed that viscosity, density and lubricity have significant effects on engine output power and torque than when throttled with AGO which was used as control. Combustion efficiency and emission profile were better than the AGO due to the oxygenated nature of the micro-algal biodiesel which brought about complete combustion. A striking deduction arrived is that oxygen content of the algal biodiesel had direct influence on smoke opacity and emissions in the engine and also thermo-gravimetrically stable for other thermal applications. The engine tests (BSFC, BTE, ThE, MechE, EGT) and overall emissions (CO2, CO, VOCs, HC, SOx, NOx) were within acceptable limits and comparable with AGO. The implication of the study is that Micro-algal technology is feasible and can revolutionise development in biodiesel industry.

Because process heaters are typically located outside, their operation is subject to the weather. Heaters are typically tuned at a given set of conditions; however, the actual operating conditions may vary dramatically from season to season and sometimes even within a given day. Wind, ambient air temperature, ambient air humidity, and atmospheric pressure can all significantly impact the O2 level, which impacts both the thermal efficiency and the pollution emissions from a process heater. Unfortunately, most natural draft process burners are manually controlled on an infrequent basis. This paper shows how changing ambient conditions can considerably impact both CO and NOx emissions if proper adjustments are not made as the ambient conditions change. Data will be presented for a wide range of operating conditions to show how much the CO and NOx emissions can be affected by changes in the ambient conditions for fuel gas fired natural draft process heaters, which are the most common type used in the hydrocarbon and petrochemical industries. Some type of automated burner control, which is virtually non-existent today in this application, is recommended to adjust for the variations in ambient conditions.

Multi-pulse fuel injection in diesel engines enables a large flexibility in controlling the fueling profile, such that the engine performance can be maintained subject to disturbances, i.e., ambient condition changes and fuel injection deviations. Based on linearized systems, current fuel injection controller synthesis methods do not consider ambient condition changes as well as the nonlinear impact on the combustion process by varying the multi-pulse fuel injection profile. In this paper, we propose an infinity-norm Lyapunov function based controller synthesis method using a control-oriented quadratic engine model. With closed-loop stability and performance guarantees, the synthesis method explicitly considers the quadratic engine behavior and the influence of varying intake conditions. Using a data-based engine model that is fitted with measurements, we numerically demonstrate the reference regulation capability and the fast convergence rate of the fuel injection controller.

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Fuel film dynamics in the intake manifold are considered to develop air fuel ratio (AFR) control strategy with on-line system identification for a V2 engine in this paper. A1000 cc four-stroke two-cylinder, water-cooled port injection SI engine is used as the target engine to develop the engine model in Matlab/Simulink. The model which consists of charging, fueling, combustion, friction, and engine rotational dynamics is used to verify the proposed AFR control. Since the fuel film dynamics changes with different engine operating conditions, the fuel film parameters are often listed as look-up tables for fuel film dynamics calculation in the conventional AFR control. However, those parameters might be inaccurate during transient engine operation. Different intake port temperature will affect the accuracy of those fuel film parameters as well. In order to solve this problem, recursive least square (RLS) is used to identify those parameters on-line. Kalman filter is utilized to estimate the AFR using a narrow-band oxygen sensor. Model predictive control is used to design the proposed AFR controller using the identified parameters of fuel film dynamics and estimated AFR. Simulation results show that those parameters identified using RLS are more accurate to describe the transient fuel film dynamics than that from look-up tables. In addition, using the proposed AFR control strategy, AFR can be controlled at the desired value both in steady state and transient engine operation.&lt;/div&gt;&lt;/div&gt;

&lt;div class="htmlview paragraph"&gt;Reduction of flow resistance in an intake system is essential for increasing the output of a four-stroke engine. Evaluation method regardless engine displacement or number of valves or cylinder must be required in intake system design. This study proposes intake loss coefficient as total evaluation method from flow in an intake port to charging flow into a cylinder. A three-dimensional, general-purpose Computational Fluid Dynamics (CFD) code was used to calculate an intake loss coefficient. A correlation was confirmed between an intake loss coefficient and the engine power output. Intake loss coefficients and the CFD technique may be used for efficient optimization of the shape of an intake system.&lt;/div&gt;

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;In the quasi-dimensional modeling of the spark-ignition combustion process, the burn rate calculation depends, among other influences, on the laminar flame speed. Commonly used models of laminar flame speeds are usually developed on the basis of measurement data limited to boundary conditions outside of the engine operation range. This limitation is caused by flame instabilities and forces flame speed models to be extrapolated for the application in combustion process simulation. However, for the investigation of, for example, lean burn engine concepts, reliable flame speed values are needed to improve the quality and predictive ability of burn rate models. For this purpose, a reference fuel for gasoline is defined to perform reaction kinetics calculations of laminar flame speeds for a wide range of boundary conditions. In order to define a reference fuel as representative as possible for standard gasoline, the influence of octane number and hydrogen-to-carbon ratio on the laminar flame speed of a toluene reference fuel (TRF) is investigated. Furthermore, the necessity to use a TRF instead of a primary reference fuel is shown. The reaction kinetics calculation results are then investigated to give possible explanations for the influence of boundary conditions like temperature, pressure, fuel composition, residual exhaust gas and air-fuel ratio on the laminar flame speed. Additionally, they are used to identify and illustrate the shortcomings of the widely used &lt;i&gt;Heywood-&lt;/i&gt;approach, which belongs to the extrapolating flame speed models mentioned above. In a next step, the calibration parameters of an existing, more advanced model are adapted to match the flame speeds calculated for the TRF. This model is then expanded to cover the admixture of ethanol and finally employed in engine simulation to exemplarily show the prediction of burn rate changes due to a variation of exhaust gas recirculation rate or air-fuel equivalence ratio.&lt;/div&gt;&lt;/div&gt;

A quasi-steady-state model has been developed to evaluate of the potential of variable flow strategies to improve the overall thermal efficiency of Photovoltaic Thermal (PVT) collectors. An adaption of the Duffie-Beckman method is used to simulate the PVT in which the overall loss coefficient and heat removal factor are updated at each timestep in response to changes in flow rate and ambient conditions. A novel simulation method was developed to simulate a building heating loop connected to the solar loop via a thermal storage tank or counterflow heat exchanger. The model was validated with published data and with a parallel TRNSYS simulation. The results of the investigation show that optimizing flow rate has significant potential to improve thermal efficiency. This benefit was found to be dependant on ambient and process loop conditions, and was limited to the counterflow heat exchanger case rather than that with a thermal storage tank.

&lt;div class="htmlview paragraph"&gt;This paper presents a study of fuel performance in spark ignition engines in relation to abnormal combustion phenomena such as surface ignition and rumble. This was accomplished by observation of the distribution of flame arrivals at ion gaps located within the engine cylinders, or peak pressure position, in terms of crank angle degrees.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;By this means, the surface ignition behavior and mass burning rates of LIB (leaded isooctane-benzene) and commercial fuel components were studied in multi-cylinder engines at 10:1 and 12:1 C.R. Additional information was obtained in two instrumented CFR engines operated at 10:1 and 6.75:1 C.R.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;It is concluded that the abnormally high peak cylinder pressures giving rise to rumble result from cycles in which combustion occurs early. Early combustion was caused by deposit-ignition of the charge but was also strongly affected by mass burning rate of the charge. Differences in mass burning rate between fuels also affected rumble differently for this reason. Furthermore, the mass burning rate for any fuel tested was greatly increased by the presence of combustion chamber deposits or by finely divided leaded deposits aspirated into the engine.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;A large part of the rumble intensity difference noted between the 0 and 100 LIB reference fuels (benzene + 3 cc TEL and iso-octane + 3 cc TEL) may be accounted for by the difference in their burning rates (10-14%). Whether or not this will be a factor in rating rumble by audible means depends on where the ignition timing is set. However, even when allowance is made for burning rate, the 0 LIB fuel shows more early ignitions than 100 LIB in the presence of either accumulated or aspirated deposits. It is, therefore, concluded that these fuels differ also in their tendency to be ignited by deposits.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;This information suggests that when rating the rumble tendencies of fuels and engines, a distinction should be made between rumble caused by fuel burning rate differences and that caused by deposit ignition tendency.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;Phosphorus added to the fuel in sufficient concentration was found to change the nature of the deposits and thus minimize rumble by reducing deposit-ignition. However, it did not prevent rumble due to early combustion caused by an increased burning rate of the charge.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;In a 10:1 C.R. multicylinder engine, significant differences in rumble tendency were found between cylinders. These differences resulted apparently from variations in fuel-air ratio and other factors that could influence the deposits formed and the mass burning rate of the fuel charge.&lt;/div&gt;