Analysis of Low and High Temperature Heat Release in Dual-Fuel RCCI Engine and its Relationship with Particle Emissions

This study presents the influence of low-temperature heat release (LTHR) and high-temperature heat release (HTHR) on the combustion and particle number characteristics of the RCCI engine. The study investigates the relationship between the amount of LTHR, HTHR, and particle number emission characteristics. In this study, gasoline and methanol are used as low reactivity fuel (LRF), and diesel is used as a high reactivity fuel (HRF). The LRF is injected into the intake manifold using a port-fuel injection (PFI) strategy, and HRF is directly injected into the cylinder using a direct injection strategy. A particle sizer is used to measure particle emission in size ranging from 5 to 1000 nm. Firstly, the LTHR and HTHR are analyzed for different diesel injection timing (SOI) for RCCI operation. Later, the variation of particle emissions with LTHR and HTHR is characterized. Additionally, empirical correlations are developed to understand the relation between the LTHR and HTHR with particle emission. Two-staged auto-ignition of charge has been observed in RCCI combustion. Results depict that LTHR varies with diesel injection timing and the phasing of HTHR depends on the amount and location of LTHR. Results also showed that HTHR and LTHR significantly influence the formation of particle number concentration in RCCI combustion. The developed empirical correlation depicts a good correlation between diesel SOI and the ratio of HTHR to LTHR to estimate total particle number concentration.

On black hole area quantization and echoes

In this work we argue that black hole area quantization of Bekenstein and Mukhanov should not give rise to measurable effects in terms of so-called gravitational wave echoes during black hole mergers. We outline that the quantum spectrum of a black hole should be washed out during and after black hole mergers, and hence one should not expect echoes in this scenario. The extreme broadening of the spectrum is due to the large particle emission rate during ringdown. Our results question key assumptions being made in recent literature on this topic.

Threshold analysis of particulate matter emissions from biological soil crusts and their proportion in total wind erosion

The problem of farmland degradation and air pollution caused by wind erosion and particulate matter emissions is serious. Relying on biological soil crust coverage can effectively inhibit the production of wind erosion materials. However, recent studies have discussed the wind erosion and particulate matter emission processes separately and few studies analyzed both, clarifying the changes in the proportion of particulate matter emissions in the total wind erosion. Aiming at the typical farming-pastoral transition zone in the monsoon climate zone, this study used wind tunnels to analyze the wind erosion and particulate matter emissions of algae crusts and moss crusts for different wind speeds and coverage conditions. Results show that the effects of wind speed and coverage on the total wind erosion of biological soil crusts are similar. However, the emission of particulate matter is particularly sensitive to coverage of biological soil crusts. The proportion of particulate matter emissions in wind erosion decreases with increasing wind speed. According to the trend of the proportion with wind speed, the particle emission capacity of moss crust is directly proportional to the particle size and inversely proportional to the coverage. In contrast, the particle emission capacity of algae crust particles is proportional to the particle size, but the relationship with coverage is not regular. The results of this study can improve the knowledge of the relationship between wind erosion and particulate matter emissions and give relevant information for the management of wind erosion and particulate matter emissions.

Experimental Investigation on the DPF High-Temperature Filtration Performance under Different Particle Loadings and Particle Deposition Distributions

Based on DPF filtration and regeneration bench, the solid particle emission and high-temperature filtration characteristics of different carbon black particle loadings and particle deposition distributions are studied. The aerosol generator (PAlAS RGB 1000) is used to introduce carbon black particles into the inlet of a DPF, and the NanoMet3 particle meter is used to measure the solid particle concentration at the inlet and outlet of a DPF to obtain the filtration characteristics. Previous studies found that without inlet carbon black particles, there was an obvious solid particle emission peak at the outlet of the deposited DPF during the heating, and the concentration increased by 1–2 orders of magnitude. In this paper, the high-temperature filtration characteristics under steady-state temperature conditions are studied. It is found that a DPF can reduce the range of inlet fluctuating particles, and with the increase of temperature, the proportion of large solid particles in the outlet particles increases, and the size distribution range decreases. Particle loading has positive and negative effects on the DPF filtration, and the DPF has the optimal particle loading, which makes the comprehensive filtration efficiency improve the highest. The deposition transition section can make the deposition particles in the DPF uniform, but the filtration efficiency is reduced.