Ali Turkcan

Comparison of performance and combustion parameters in a heavy-duty diesel engine fueled with iso-butanol/diesel fuel blends

This study discusses the suitability of iso-butanol/diesel fuel blends as an alternative fuel and determines their effects on the performance and combustion characteristics of a heavy-duty diesel engine. For this purpose, various iso-butanol/diesel fuel blends containing 5%, 10% and 15% iso-butanol were prepared in volume basis and tested in a turbo-charged, six-cylinder direct injection diesel engine at the speed of 1400 rpm and three different loads (150, 300 and 450 Nm). The results indicate that when the test engine was fueled with the iso-butanol/diesel fuel blends, the brake thermal efficiency decreased, while the brake specific fuel consumption increased with proportion to using conventional diesel fuel. When iso-butanol/diesel fuel blends were used, the heat release rate, the peak cylinder gas pressure slightly increased compared to the neat diesel fuel use. Although the iso-butanol/diesel fuel blends have poor performance values at partial engine loads, their fuel properties affected the combustion and injection characteristics. They caused reductions in CO, NOx emissions and smoke opacity. However, unburned HC emission slightly increased.

An Experimental and Modeling Study to Investigate Effects of Two-Stage Direct Injection Variations on HCCI Combustion

In this study, homogenous charge compression ignition (HCCI) combustion with two-stage direct injection (TSDI) strategies was modeled with stochastic reactor model (SRM) and validated by using the experimental results of the TSDI gasoline HCCI engine. For the experimental study, a diesel engine was converted to an electronically controlled HCCI gasoline engine. The effects of injection timings and injection ratios on the HCCI combustion characteristics were studied at high equivalence ratio and constant engine speed. The injection timings (first and second) and fuel quantity for each injection were adjusted to get desired mixture formation in the cylinder. During the experiments, the maximum cylinder gas pressure, pressure rise rate and start of combustion were directly controlled by using the second fuel injection timing and injection ratio. Using optimal second fuel injection timing and injection ratio caused a reduction on NOx and HC emissions. The model results of the HCCI combustion were in good agreement with the experimental results. Both of the experimental and modeling results showed that the second fuel injection timing had a strong effect on the HCCI combustion when compared to the first injection timing.

Energy and Exergy Analysis of an R134A Automotive Heat Pump System for Various Heat Sources in Comparison with Baseline Heating System

Performance of an automotive heat pump (AHP) system using R134a and driven by a diesel engine has been evaluated in this study. For this purpose, an experimental AHP system capable of providing a conditioned air stream by utilizing the heat absorbed from the ambient air, engine coolant and exhaust gas was developed. The experimental system was equipped with instruments for measuring engine torque and speed, refrigerant and coolant mass flow rates, refrigerant and air temperatures as well as refrigerant pressures. The system was tested by varying the engine speed, engine load and air temperatures at the inlets of the indoor and outdoor coils. Using experimental data, an energy analysis of the system was performed, and its performance parameters for each heat source were evaluated for transient and steady-state operations. Then, the performance of the AHP system for each source was compared with that of the system using other heat sources and with that of the baseline heating system. The investigated performance parameters include air temperature at the outlet of the indoor coil, heating capacity, coefficient of performance and exergy destruction rates in the components of the AHP system. The total exergy destruction rate in the AHP with engine coolant is higher than those in the AHP with ambient air and with exhaust gas mainly because of the greater refrigerant mass flow rate and heating capacity.

The effects of ethanol-gasoline blends on combustion and performance in a DI-HCCI engine

In this study, the effects of two stage direct injection (TSDI) strategy were investigated on the combustion and performance of an engine fueled with ethanol-gasoline blends. A diesel engine was converted to an electronically controlled HCCI engine. For each injection the injection timings and fuel quantity were adjusted to get desired mixture formation in the cylinder. The first injections were selected to be during the intake stroke and second injections were at the end of the compression stroke by using different injection ratios. Three different fuels (gasoline, E10 and E20) were used at the same energy input and constant engine speed conditions. The results showed that the maximum pressure rise rate (MPRR) increased with earlier start of first injection (SOI2) timing by using ethanol-gasoline blends. It was found that start of second injection (SOI2) timing has strong effects on the HCCI combustion and performance parameters when compared to the SOI1 timing although injection ratio (IR) and fuel blends were changed. The maximum cylinder gas pressure (Pmax), indicate mean effective pressure (imep) and thermal efficiency can be directly controlled by using the SOI2 timing at high and low equivalence ratio conditions. It was observed that the operating ranges of the ethanol-gasoline fuel blends were extended, as the MPRRs of these blends were decreased with the use of optimum injection parameters at high equivalence ratio.