Preface 1.General Considerations 2.Basic Processes in Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.Atomizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index

Atomization and Sprays

Over the past decade, a range of sensor technologies became available on the market, enabling a revolutionary shift in air pollution monitoring and assessment. With their cost of up to three orders of magnitude lower than standard/reference instruments, many avenues for applications have opened up. In particular, broader participation in air quality discussion and utilisation of information on air pollution by communities has become possible. However, many questions have been also asked about the actual benefits of these technologies. To address this issue, we conducted a comprehensive literature search including both the scientific and grey literature. We focused upon two questions: (1) Are these technologies fit for the various purposes envisaged? and (2) How far have these technologies and their applications progressed to provide answers and solutions? Regarding the former, we concluded that there is no clear answer to the question, due to a lack of: sensor/monitor manufacturers' quantitative specifications of performance, consensus regarding recommended end-use and associated minimal performance targets of these technologies, and the ability of the prospective users to formulate the requirements for their applications, or conditions of the intended use. Numerous studies have assessed and reported sensor/monitor performance under a range of specific conditions, and in many cases the performance was concluded to be satisfactory. The specific use cases for sensors/monitors included outdoor in a stationary mode, outdoor in a mobile mode, indoor environments and personal monitoring. Under certain conditions of application, project goals, and monitoring environments, some sensors/monitors were fit for a specific purpose. Based on analysis of 17 large projects, which reached applied outcome stage, and typically conducted by consortia of organizations, we observed that a sizable fraction of them (~ 30%) were commercial and/or crowd-funded. This fact by itself signals a paradigm change in air quality monitoring, which previously had been primarily implemented by government organizations. An additional paradigm-shift indicator is the growing use of machine learning or other advanced data processing approaches to improve sensor/monitor agreement with reference monitors. There is still some way to go in enhancing application of the technologies for source apportionment, which is of particular necessity and urgency in developing countries. Also, there has been somewhat less progress in wide-scale monitoring of personal exposures. However, it can be argued that with a significant future expansion of monitoring networks, including indoor environments, there may be less need for wearable or portable sensors/monitors to assess personal exposure. Traditional personal monitoring would still be valuable where spatial variability of pollutants of interest is at a finer resolution than the monitoring network can resolve.

Applications of low-cost sensing technologies for air quality monitoring and exposure assessment: How far have they gone?

A cycle simulation model for predicting the performance of a diesel engine fuelled by diesel and biodiesel blends

From low-cost sensors to high-quality data: A summary of challenges and best practices for effectively calibrating low-cost particulate matter mass sensors

Calibration of low-cost PurpleAir outdoor monitors using an improved method of calculating PM2.5

. In this paper we evaluate characteristics of three optical particulate matter sensors/sizers (OPS): high-end spectrometer
11-D (Grimm, Germany), low-cost sensor OPC-N2 (Alphasense, United Kingdom) and in-house developed MAQS
(Mobile Air Quality System), which is based on another
low-cost sensor – PMS5003 (Plantower, China), under realistic conditions of strong and mild urban pollution. Results were compared against a reference
gravimetric system, based on a Gemini (Dadolab, Italy), 2.3 m 3  h −1 air sampler, with two channels (simultaneously measuring PM 2.5 and PM 10 concentrations).
The measurements were performed in Sarajevo, the capital of Bosnia-Herzegovina, from December 2019 until May 2020.
This interval is divided into period 1 – strong pollution – and period 2 – mild pollution. The city of Sarajevo is one of the most polluted cities in Europe in terms of particulate matter: the average concentration of PM 2.5 
during the period 1 was 83  µ g m −3 , with
daily average values exceeding 500  µ g m −3 . During period 2, the average concentration of
PM 2.5 was 20  µ g m −3 . These conditions represent a good opportunity to test optical devices against the reference instrument in a wide range of ambient particulate matter (PM) concentrations. The effect of an in-house developed diffusion dryer for 11-D is discussed as well. In order to analyse the mass distribution of particles, a scanning mobility particle sizer (SMPS), which together with the 11-D spectrometer gives the full spectrum from nanoparticles of diameter 10 nm to coarse particles of diameter 35  µ m, was used.
All tested devices showed excellent correlation with the
reference instrument in period 1, with R2 values between 0.90 and 0.99 for daily average PM concentrations. However, in period 2, where the range of concentrations was much narrower,
 R2 values decreased significantly, to values from 0.28 to 0.92. We have also included results of a 13.5-month long-term comparison of our MAQS sensor with a nearby beta attenuation monitor (BAM) 1020 (Met One Instruments, USA) operated by the United States Environmental Protection Agency (US EPA), which showed similar correlation and no observable change in performance over time.

/pdf/evaluation-of-optical-particulate-matter-sensors-under-43a3yi8ndf.pdf

Evaluation of optical particulate matter sensors under realistic conditions of strong and mild urban pollution

An ignition delay is a very complex process which depends on a great number of parameters. In practice, definition of the ignition delay is based on the use of correlation expressions. However, the correlation expressions have very often limited application field. This paper presents a new correlation which has been developed during the research project on the direct injection M-type diesel engine using both the diesel and biodiesel fuel, as well as different values of a static injection timing. A dynamic start of injection, as well as the ignition delay, is defined in two ways. The first approach is based on measurement of a needle lift, while the second is based on measurement of a fuel pressure before the injector. The latter approach requires calculation of pressure signals delay through the fuel injection system and the variation of a static advance injection angle changing. The start of a combustion and the end of the ignition delay is defined on the basis of measurements of an in-cylinder pressure and its point of separation from a skip-fire pressure trace. The developed correlation gives better prediction of the ignition delay definition for the M-type direct injection diesel engine in the case of diesel and biodiesel fuel use when compared with the classic expression by the other authors available in the literature.

/pdf/investigation-into-the-effect-of-different-fuels-on-ignition-3nxu2ckx31.pdf

Investigation into the effect of different fuels on ignition delay of M-type diesel combustion process

/pdf/mobile-measurements-of-particulate-matter-concentrations-in-1i67t2xzcz.pdf

Mobile Measurements of Particulate Matter Concentrations in Urban Area

/pdf/new-approach-of-measuring-toxic-gases-concentrations-2qbybcc887.pdf

New Approach of Measuring Toxic Gases Concentrations: Principle of Operation

The main role in air/fuel mixture formation at the IC Diesel engines has the energy introduced by fuel into the IC engine that is the characteristics of spraying fuel into the combustion chamber. The characteristic can be defined by the spray length, the spray cone angle, and the physical and chemical structure of fuel spray by different sections. Having in mind very complex experimental set-ups for researching in this field, the mentioned characteristics are mostly analyzed by calculations. There are two methods in the literature. The first based on use of the semi-empirical expressions (correlations) and the second, the calculations of spray characteristics by use of very complex mathematical methods. The second method is dominant in the modern literature. The main disadvantage of the calculation methods is a correct definition of real state at the end of the nozzle orifice (real boundary conditions). The majority of the researchers in this field use most frequently the coefficient of total losses inside the injector. This coefficient depends on injector design, as well as depends on the level of fuel energy and fuel energy transformation along the injector. Having in mind the importance of the real boundary conditions, the complex methods for calculation of the fuel spray characteristics should have the calculation of fuel flows inside the injector and the calculation of spray characteristics together. This approach is a very complex numerical problem and there are no existing computer programs with satisfactory calculation results. Analysis of spray characteristics by use of the semi-empirical expressions (correlations) is presented in this paper. The special attention is dedicated to the analysis of the constant in the semi-empirical expressions and influence parameters on this constant. Also, the method for definition of realistic boundary condition at the end of the nozzle orifice is presented in the paper. By use of this method completely avoid a use of the coefficient of total losses inside the injector. At the same time, semi-empirical expressions have the universal constant that does not depend on the injector design.

/pdf/influence-of-geometric-and-hydro-dynamic-parameters-of-13cz5u7ioo.pdf

Dzevad Bibic

Papers

Evaluation of optical particulate matter sensors under realistic conditions of strong and mild urban pollution

Investigation into the effect of different fuels on ignition delay of M-type diesel combustion process

Mobile Measurements of Particulate Matter Concentrations in Urban Area

New Approach of Measuring Toxic Gases Concentrations: Principle of Operation

Influence of geometric and hydro-dynamic parameters of injector on calculation of spray characteristics of diesel engines