Charge Air Temperature Research Articles

Effect of charge air temperature on E85 dual-fuel diesel combustion

The scope of this experimental engine study was to explore the effect of charge air temperature on E85 ethanol/gasoline blend dual-fuel combustion. The E85 was injected in the intake manifold, while diesel fuel was direct injected into the cylinder with a common-rail injection system. The study focused on medium and high load conditions at 1500rpm. The diesel injection timing parameters were kept in every test case the same as in the original diesel production engine. The results showed that charge air temperature influenced the ignition delay, the cylinder pressure rise rate (PRR) and the maximum cylinder pressure by altering the E85 combustion phasing, while the changes on the diesel fuel combustion were minor. Lower charge air temperatures allowed higher E85 injection rates without the risk of a too high PRR, especially at high load conditions. The increase of the E85 rate allowed by lower charge air temperature, decreased nitrogen oxide emission, but simultaneously increased carbon monoxide and unburned total hydrocarbon emissions and decreased combustion efficiency.

Diesel engine performance improvement with suitable low cost technologies for tractor applications

Off-road engines for tractor applications are developed with limited space due to packaging constraints and low cost targets. Hence major challenges faced by several off-road engine manufactures are to achieve higher power density and to comply emission legislation with low cost modifications. Henceforth in this work a cost-effective research approach is investigated for conversion of naturally aspirated (NA) engine to turbocharged intercooled for off-road diesel engines performance improvement. Further, reducing the charge air temperature into the engine by using water spray cooled intercooler strategy minimised the combustion temperature, consequently power and torque increased. To reduce the exhaust emission such as oxides of nitrogen (NOx), strategies such as cooled exhaust gas recirculation (EGR) are computationally optimised. This analysis is executed for selection of the EGR cooler tube to achieve better exhaust gas cooling effectiveness. In addition to the NOx reduction strategy, substrate volume for lean NOx trap is also optimised to investigate its effectiveness in this research work.

Effect of Cetane Improver on Autoignition Characteristics of Low Cetane Sasol IPK Using Ignition Quality Tester1

This paper investigates the effect of a cetane improver on the autoignition characteristics of Sasol IPK in the combustion chamber of the ignition quality tester (IQT). The fuel tested was Sasol IPK with a derived cetane number (DCN) of 31, treated with different percentages of Lubrizol 8090 cetane improver ranging from 0.1 to 0.4%. Tests were conducted under steady state conditions at a constant charging pressure of 21 bar. The charge air temperature before fuel injection varied from 778 to 848 K. Accordingly, all the tests were conducted under a constant charge density. The rate of heat release was calculated and analyzed in detail, particularly during the autoignition period. In addition, the physical and chemical delay periods were determined by comparing the results of two tests. The first was conducted with fuel injection into air according to ASTM standards where combustion occurred. In the second test, the fuel was injected into the chamber charged with nitrogen. The physical delay is defined as the period of time from start of injection (SOI) to point of inflection (POI), and the chemical delay is defined as the period of time from POI to start of combustion (SOC). Both the physical and chemical delay periods were determined under different charge temperatures. The cetane improver was found to have an effect only on the chemical ID period. In addition, the effect of the cetane improver on the apparent activation energy of the global combustion reactions was determined. The results showed a linear drop in the apparent activation energy with the increase in the percentage of the cetane improver. Moreover, the low temperature (LT) regimes were investigated and found to be presented in base fuel, as well as cetane improver treated fuels.

Effect of Charge Air Temperature on Specific Fuel Consumption in Intercooled Direct Injection Diesel Engines Used for Power Generation

This paper presents the results of a study carried out to determine the variations of Specific Fuel Consumption (SFC) and fuel efficiency in day time and night time operation of an intercooled direct injection diesel engine of 17MW used for electrical power generation. In the study pressure development curves for 18 cylinders were obtained and the Mean Indicated Pressure (MIP) and crank positions for the Peak Pressure, Kinetic Burning (KB), and Diffusive Burning (DB) points were analyzed. The results showed a reduction of 1.9% in SFC in the night time operation in which the charge air temperature was lower and relative humidity was higher than those of day time. The reasons for changes in SFC are explained with the changes in the in-cylinder pressure curves. Further, the fuel efficiency was found to be increased in the night time by 0.8%.

Effect of Refrigerant Charge and Inlet Air Temperature on One A/C System

This study describes the results on the performance of one vehicle air conditioning system. The coefficient of performance, evaporator cooling capacity, compressor power consumption, total mass flow rate, vapor mass flow rate, liquid mass flow rate and oil in circulation, pressures and temperatures of refrigerant at every component (inlets and outlets) are measured and analyzed with the variation of the outside temperatures at the evaporator and condenser, the speed of the compressor, refrigerant charge and oil charge. The systematical experimental results obtained from this real-size test system depict the relations between the above parameters in a vehicle air conditioning system, which constitute a useful source for vehicle air conditioning systems design and analysis. The vapor quality (two-phase flow) measurements realized in this work provide an extremely important tool for diagnosing the system performances.

Sound propagation in narrow tubes including effects of viscothermal and turbulent damping with application to charge air coolers

Charge air coolers (CACs) are used on turbocharged internal combustion engines to enhance the overall gas-exchange performance. The cooling of the charged air results in higher density and thus volumetric efficiency. It is also important for petrol engines that the knock margin increases with reduced charge air temperature. A property that is still not very well investigated is the sound transmission through a CAC. The losses, due to viscous and thermal boundary layers as well as turbulence, in the narrow cooling tubes result in frequency dependent attenuation of the transmitted sound that is significant and dependent on the flow conditions. Normally, the cross-sections of the cooling tubes are neither circular nor rectangular, which is why no analytical solution accounting for a superimposed mean flow exists. The cross-dimensions of the connecting tanks, located on each side of the cooling tubes, are large compared to the diameters of the inlet and outlet ducts. Three-dimensional effects will therefore be important at frequencies significantly lower than the cut-on frequencies of the inlet/outlet ducts. In this study the two-dimensional finite element solution scheme for sound propagation in narrow tubes, including the effect of viscous and thermal boundary layers, originally derived by Astley and Cummings [Wave propagation in catalytic converters: Formulation of the problem and finite element scheme, Journal of Sound and Vibration 188 (5) (1995) 635–657] is used to extract two-ports to represent the cooling tubes. The approximate solutions for sound propagation, accounting for viscothermal and turbulent boundary layers derived by Dokumaci [Sound transmission in narrow pipes with superimposed uniform mean flow and acoustic modelling of automobile catalytic converters, Journal of Sound and Vibration 182 (5) (1995) 799–808] and Howe [The damping of sound by wall turbulent shear layers, Journal of the Acoustical Society of America 98 (3) (1995) 1723–1730], are additionally calculated for corresponding circular cross-sections for comparison and discussion. The two-ports are thereafter combined with numerically obtained multi-ports, representing the connecting tanks, in order to obtain the transmission properties for the charged air when passing the complete CAC. An attractive formalism for representation of the multi-ports based on the admittance relationship between the ports is presented. From this the first linear frequency domain model for CACs, which includes a complete treatment of losses in the cooling tubes and 3D effects in the connecting tanks is extracted in the form of a two-port. The frequency dependent transmission loss is calculated and compared to the corresponding experimental data with good agreement.

Dimethyl Ether 예혼합 압축 착화 엔진에서 흡기중 CO2농도와 흡기온도 변화가 연소에 미치는 영향

This study focused on the effects of the CO₂ gas concentration in fresh charge and induction air temperature on the combustion characteristics of homogeneous charge compression ignition with dimethyl ether (DME) fuel, which was injected at the intake port. Because of adding CO₂ in fresh charge, start of auto-ignition was retarded and burn duration became longer. Indicated combustion efficiency and exhaust gas emission were found to be worse due to the incomplete combustion. Partial burn was observed at the high concentration of CO₂ in fresh charge with low temperature of induction air. However, indicated thermal efficiency was improved due to increased expansion work by late ignition and prolonged burn duration. Start of auto-ignition timing was advanced with negligible change of burn duration, as induction air temperature increased. Burn duration was mainly affected by oxygen mole concentration in induction mixture. Burn duration was increased, as oxygen mole concentration was decreased.

An automotive engine charge-air intake conditioner system: Thermodynamic analysis of performance characteristics

A first law thermodynamic model has been developed and used to characterize the performance of an automotive engine charge-air intake conditioner system. This system employs a compressor, intercooler, and expander to provide increased charge density with the possibility of reducing, the charge-air temperature below the sink temperature. The model was validated against experimental measurements. The variation of system effectiveness with compressor, intercooler, and expander efficiency was quantified and system operating limits were identified. While the expander was found to have a greater effect than the compressor, the performance of the system was shown to be most dependent upon intercooler effectiveness.

Evaluation of Losses in a Diesel Engine Cycle and Improvement of Its Thermal Efficiency (Capabilities of Diesel Engine Combined Cycle)

The Diesel engine and gas turbine combined cycle has an ability of getting much better thermal efficiency than any other type of cycles owing to its high temperature in the heat receiving process. Increase of expansion ratio in the diesel engine cycle minimizes the exergy loss in the process connecting diesel engine cycle and gas turbine one, and leads a thermal efficiency improvement about 4%. Although disuse of charge air cooling and furthermore heating of the charge air with the exhaust gas from turbine cause reduction of specific power output, they diminish the exergy losses in the heat receiving process in the cylinder and the exhaust process from turbine, and bring an improvenment of thermal efficiency by several %. The charge air temperature rise accompanying further improvement of the combined cycle thermal efficiency, requires the development of high efficiency gas turbine, and realization of the new methods for protecting diesel engine cylinder wall to higher temperature of working gas.

Development of Lean Burn High-Output Spark-Ignited Gas Engines(Experimental Study of Knocking in Lean Burn Gas Engines).

The study of knocking is key to increase the BMEP of lean burn gas engines. According to the results of FFT analysis of cylinder pressure in a 260 mm prototype engine, the peak frequency generally matches the calculated knocking frequency at a sound velocity of 900 m/s. The more severe the knocking intensity becomes, the higher the temperature of the combustion components becomes. The upper position of the liner wall and the side of the piston head show the highest rate of temperature increase. The knocking occurrence and its intensity are dependent on charge air temperature, O2 concentration, ignition timing, or a combination of these. However, at an O2 concentration above 13.5%, the influence of these parameters on kncoking is almost negligible. Therefore, increasing the excess air ratio is an effective way to increase engine output while suppressing the occurrence of knocking.

Influences of Charge Air Humidity and Temperature on the Performance and Emission Characteristics of Diesel Engines

The effects of humidity and temperature of intake air on the performance and emission characteristics of diesel engines were systematically investigated in order to improve their design and operations. A fourstroke diesel engine with a displacement volume of 3856 cc was employed as the test engine. The intake air was conditioned to various temperatures and humidities via an air-conditioner before entering the intake port of the engine. This study shows that the air consumption rate, brake torque, and nitrogen oxides decrease, while the brake specific fuel consumption, carbon monoxide, and sulfur dioxide increase with both the temperature and humidity of the charge air. However, the effects of the humidity on the formation of the carbon monoxide and sulfur dioxide emissions are more significant at a higher temperature of the charge air. Furthermore, charge air temperature tends to increase the percentage of C02 in the exhaust while decreasing the percentage of excess oxygen.