Conducting and Characterizing Femto Flow Electrospray Ionization

Femto flow electrospray ionization (ESI) ranging from 240 fL/min to low pico flow (< 10 pL/min) was conducted and measured using submicron emitter tip and relay ESI configuration. Signature analyte ion intensities and profiles were obtained. Obtained flow rate and ionization current enabled size calculation for initial charged nanodroplet.

Assessment of the reliability of ionization current measurement in estimating peak pressure angle in a spark ignition engine

Ionization current measured at the spark plug during combustion in spark ignition engines has often been proposed to determine the crank-angle at combustion pressure peak, namely the peak pressure angle, for the purpose of regulating spark timing to attain maximum brake torque (MBT). The proposal is based on the assumption that agreement exists between peak pressure angle and the angular position of the ionization current second peak, although no one has ever proved it by an appropriate statistical analysis. The aim of this work, for the first time and by rigorous statistical methods, is to prove the agreement between Peak Pressure Angle and Ionization Current Second Peak Angle (ICSPA), without which a MBT control via ICSPA would be ineffective. Our experimental database consisted of about 9000 pairs of Peak Pressure Angle and Ionization Current Second Peak Angle values corresponding to 90 different operating conditions of a spark ignition engine. A two-sample comparison was first carried out between mean values of Peak Pressure Angle and Ionization Current Second Peak Angle, which showed a statistically significant difference between them. Then Bland-Altman analysis (Lancet, 1986), widely known and used for checking agreement between two different measurement methods, was conducted. It demonstrated that under almost all the experimental operating conditions, there was no agreement between the Ionization Current Second Peak Angle and the Peak Pressure Angle.

Selection of ion sensor operating parameters in quasi-static conditions

Evaluating combustion quality using sensors that allow continuous assessment of the process is one of the modern methods of engine sensory diagnostics. The proper calibration of such systems is a task that requires many studies to determine the conditions and quantities affecting the process. The analysis of significance of quantities related to the ionization signal was carried out in the article. The magnitude of the voltage generating the electric field, the type of spark plug used, the distance of the spark plug electrodes and the dynamic factor – spark plug operating temperature – were all tested. The tests were carried out using a CNG burner (with an excess air ratio of lambda = 1) and four spark plugs. As a result of the ionization signal research, the following relationships were obtained: regarding the impact of the sensor position on the amount of generated voltage (the smaller the distance the greater the value of the signal), the effect of temperature on the sensor resistance (non-linear relationship: increase in temperature decreases resistance, with R2 = 0.9997) effect of system voltage on the ionization signal (linear relationship: voltage increase increases the ionization current signal with a determination coefficient of R2 = 0.9803). In addition, it was found that using an iridium electrode candle had the best effects on the ionization current, regardless of the electrode’s geometrical parameters.

Use of the gas ionization signal for combustion process diagnostics in the cylinder of a spark ignition engine

The running diagnostics of the combustion process in an internal combustion engine is essential for increasing its efficiency and to improving its performance indicators. The modern diagnostics of this process no longer concerns only measurements of fast-changing thermodynamic variables, but also measurements of other parameters allowing for its evaluation. The use of electrical or optical methods in diagnostics enables the evaluation of local process parameters, such as occurrence of the flame and its temperature distribution. Actually, there are some new methods under investigation which are proposed for this kind of diagnostic. This article focuses on demonstrating the potential for using an electric signal from the gas ionization to estimate the maximum combustion pressure in a cylinder of an SI engine. This is a comparative analysis of the gas ionization current signal in the cylinder and the fast-changing pressure at fixed operating points of a 4-stroke natural gas powered engine. The study was carried out on a one-cylinder 4-stroke SI engine equipped with a cylinder pressure recording system and monitoring of the cylinder ionization current using appropriate measuring systems. The influence of engine operating conditions on the ability to determine cylinder pressure based on the ionization current signal was analyzed. This impact assessment was analyzed statistically and a strong correlation was found between the analyzed signals. The obtained results point in the potential direction of development of this type of measuring system.