Experimental Study on the Effect of Humidification on the Pollution Characteristics of Particulate Matter in the Office

Indoor air quality has a direct impact on human health. Indoor air quality has aroused great concern. This experimental study compares the effects of different water humidification on the indoor particulate pollution characteristics, and analyzes the mass concentration and the particulate number concentration distribution of different sizes of particulates with time under each condition of the purified water humidification, the tap water humidification and the cold boiled water humidification in the office. The results show that under the three kinds of wetting conditions, the concentration of the fine particulates is higher. More minerals are contained in the tap water and the cold boiled water, so the two kinds of humidification have more significant impact on indoor particulate matter. But the purified water humidification has nearly no significant effect on it. The calcium and magnesium ionic compounds are partly removed after the water boiled, so the cold boiled water humidification has less impact on the indoor particulate matter than the tap water humidification. The mass concentration and particulate number concentration of the particle may also be affected due to the frequency of ultrasonic vibration.

Investigation on combustion and emission characteristics of diesel polyoxymethylene dimethyl ethers blend fuels with exhaust gas recirculation and double injection strategy

As a kind of renewable and high oxygen content fuel,polyoxymethylene dimethyl ether(PODE)can be added in diesel to realize energy saving and emissions reduction.To evaluate the combustion and emission characteristics of a diesel engine fueled with diesel and diesel/PODE mixtures,exhaust gas recirculation(EGR)and main-pilot injection strategies with various injection timings were applied.PODE was blended with diesel by volume to form mixtures which were marked as D100(pure diesel),D90P10(90%diesel+10%PODE),and D80P20(80%diesel+20%PODE).The results showed that the ignition delay(ID)and combustion duration(CD)of D80P20 were the shortest because of the highest cetane number(CN)and high oxygen content of PODE,indicating more concentrated heat release.At low and medium loads,D80P20 achieved the highest peak heat release ratio(PHRR)and peak combustion temperature(PCT)among the three fuels,and it was 14.3%and 3.6%higher than those of D100.PODE blending with diesel can significantly reduce particulate matter(PM)and D80P20 has the lowest PM emissions at all loads.Compared with D100,both PM and nitrogen oxide(NO_(x))emissions of PODE blends decreased simultaneously with 20%EGR at all loads.With the increase of pilot-main interval,the ID and CD of all test fuels increased,while the NO_(x)and PM emissions decreased.The conclusions of the present research provide a state of the application in light-duty engines fueled with diesel/PODE blends in future work.