The Use of Ultrasound in the Treatment Process of Wastewater. A review

In this paper, different types of ultrasound devices for the treatment process of wastewater are presented. The use of ultrasound in treatment processes is a method of perspective, an alternative to conventional methods. This technique is based  in the cavitation phenomenon that occurs in liquids at ultrasonic irradiation and it is used to enhance or ensure the processes of heat and mass transfer. Some of the main advantages of using ultrasound, namely low consumption of additional material or energy, are presented in this paper. The categories of the ultrasonic transmitters distinguished on the basis of the principle underlying the generation of acoustic waves are described

Treatment of Ammonia Wastewater by Ultrasound. Part I: The Influence of the Ultrasound Energy on the Ultrasound Bath Temperature

The industrial ammonia water decontamination depending on the sample temperature is monitored by this study. The treatment was conducted by the UP100S ultrasound generator (Hielscher Ultrasound Technology, Germany), operating at 30 kHz frequency and acoustic power densities of 90 W/cm2 and 460 W/cm2 respectively. The effect of sonication both on the bath temperature and ammonia removal, based on treatment time, is presented in this paper. Experiments were carried out according to different parameters, so as the sample temperature variation by ultrasonic treatment to be determined. Studied parameters were: the operating mode variation (continuous or intermittent), the additional aeration and the application of a cooling water serpentine. Based on the results, the ammonia removal efficiency is improved by the heating produced by the ultrasonic energy

Water-in-Diesel Emulsions as an Alternative Fuel for Diesel Engines. Part II: Performance of Diesel Engines Fueled with Water-in-Diesel Emulsions. A Literature Review

This paper presents the recent advances of water-in-diesel emulsion fuel studies, especially the impact of using this emulsion fuel to the performance and emissions of diesel engine. Studies revealed that the onset and the strength of micro-explosion process give strong effect with regard to the combustion efficiency inside the combustion chamber. Most of the researchers tested emulsions with water content of 5-40% in diesel fuel. Some studies concluded that 20% water in the emulsion fuel gives the optimum engine performance. Many researchers and experts agree that the reason why there is a slight drop in brake power and torque is the fact that water-in-diesel emulsion fuel has a lower heating value than a neat diesel fuel, thus less energy is released during combustion. In general, the results suggest that the water emulsification has a potential to slightly improve the brake efficiency and to significantly reduce the formation of NOx, soot, hydrocarbons and PM in the diesel engine. Some factors may affect the experimental results that need to be considered, such as the effect of volatility of the base fuel, the water content of the emulsion, emulsion stability, ambient temperature, pressure, type of surfactant and engine test conditions: engine load, speed, injection timing and compression ratio

A Test for Rapid Tribological Characterization of Bearing Steels

In this paper is a study the influence of the material and heat treatment on the changes of the fine structure parameters of the superficial layer of triboelements during the first cycles of rolling contact process. The tests were conducted by using a four-roller testing machine. The specimens (rollers) were made of case-hardening, through hardening and high frequency hardening steels. In order to induce different stress distributions in the superficial layer of the specimen specific treatments were applied. Using X-ray diffractometry can be appreciated that the durability of rolling tribosystems can be determined by an optimal relationship between studied parameters. The observed correlation can be used as a fast method to estimate the fatigue life of rolling bearing materials

Environmental Benefits of Rapeseed Methyl Ester Use as Fuel for Diesel Engines

The continuously increasing number of auto vehicles that determine a substantial growth of greenhouse gas emissions, along with the decrease of fossil fuel supply and the increase of its price, make necessary the intensification of research for less polluting, alternative fuels for car engines. Through the laws adopted by governments around the world and the huge funds allocated, biofuels receive growing attention as they are considered the number one substitute for fossil fuels. This paper focuses on some aspects concerning the use of biodiesel with regard to its environmental benefits. Even if vegetable oils as fuel for diesel engines are principally considered to be CO2 neutral, yet there are significant carbon dioxide emissions from the cultivation and conversion processes. The Life Cycle Assessment is used to evaluate and compare the environmental effects when using rapeseed oil (RO), rapeseed oil methyl ester (RME) or diesel fuel. The results show benefits first in favor of RO then RME compared to diesel fuel; this indicates the potential to reduce greenhouse gas emissions and finite energy consumption through the substitution of conventional petro diesel with RO and RME

Use of Alternative Fuels in Road Transport and its Environmental Effects. A Literature Review

This paper presents a literature review on use of alternative fuels in road transport, in respect of their performance and emission in diesel engines/vehicles. The major limitations of vegetable oils as fuel in diesel engines are their high viscosity and poor volatility, which lead to severe engine deposits, injector coking, and piston ring sticking. Transesterification reaction reduces the viscosity of vegetable oils, and the result of this reaction is biodiesel. In general, engine power dropped due to the lower heating value of biodiesel. A proper injection timing, by advancing the start of fuel injection by 1-2°BTDC, determined that all changes in engine emission are according to chemical and physical properties of the tested fuels

Water-in-Diesel Emulsions as Alternative Fuel for Diesel Engines. Part I: Water-in-Diesel Emulsions. A Literature Review

Although emulsions have found numerous and various applications in chemical, pharmaceutical and food industries, emulsions of water in diesel fuel are applicable alternative fuels for the existing diesel engines. Water-in-diesel emulsion fuel can improve the combustion efficiency of a diesel engine and reduce harmful exhaust emission, especially nitrogen oxides and particulate matter. In general, due to the lower heating values of water-in-diesel emulsion fuels, torque and power produced by diesel engines fueled with emulsified fuels are lower as compared to the neat diesel fuel. The heterogeneous results regarding the use of water-in-diesel emulsions as fuel for diesel engines suggest that more experimental work for optimizing the emulsion formulation is recommended