Revisiting the estimation indicator for HONO emissions from light-duty vehicles
These videos have been matched automatically. Contact us if they are not relevant.
These videos have been matched automatically. Contact us if they are not relevant.
View abstract on PubMed
Summary
This summary is machine-generated.Vehicular emissions are a key source of nitrous acid (HONO), a precursor to hydroxyl radicals. This study reveals updated emission standards significantly reduce HONO, and a new estimation method improves accuracy.
Area Of Science
- Atmospheric Chemistry
- Environmental Science
- Automotive Engineering
Background
- Gaseous nitrous acid (HONO) is critical for hydroxyl (OH) radical formation and secondary pollution.
- Vehicular emissions are a major HONO source, traditionally estimated using a fixed ratio (RHONO/NOx = 0.8%).
- Recent measurements show wide variations in vehicular HONO emissions, necessitating refined estimation methods.
Purpose Of The Study
- To investigate the impact of evolving emission standards on HONO emission factors from light-duty gasoline vehicles.
- To identify key factors influencing HONO generation in vehicle exhaust.
- To develop and validate a modified estimation indicator for vehicular HONO emissions.
Main Methods
- Conducted chassis dynamometer driving tests on ten light-duty gasoline vehicles representing different emission standards (China IV, V, VI).
- Analyzed the influence of water content and exhaust temperature on HONO generation.
- Developed a modified estimation indicator by integrating NOx emissions and combustion efficiency.
- Created a dynamic inventory of vehicular HONO emissions for a specific urban district (Jinniu District, Chengdu).
Main Results
- HONO emission factors decreased significantly with stricter standards: 0.40 mg/km (China IV), 0.13 mg/km (China V), and 0.06 mg/km (China VI).
- Water content and exhaust temperature were identified as crucial factors for HONO formation.
- The modified estimation indicator demonstrated improved accuracy compared to the traditional method.
- The traditional indicator overestimated HONO emissions by approximately 17% in the study area.
Conclusions
- Modern emission standards substantially reduce HONO emissions from light-duty gasoline vehicles.
- A refined estimation approach, considering NOx and combustion efficiency, is crucial for accurate HONO budgeting.
- This research improves understanding of vehicular HONO sources and aids in reducing uncertainties in atmospheric models.
These videos have been matched automatically. Contact us if they are not relevant.
These videos have been matched automatically. Contact us if they are not relevant.
Related Concept Videos
There are two ways to determine the amount of heat involved in a chemical change: measure it experimentally, or calculate it from other experimentally determined enthalpy changes. Some reactions are difficult, if not impossible, to investigate and make accurate measurements for experimentally. And even when a reaction is not hard to perform or measure, it is convenient to be able to determine the heat involved in a reaction without having to perform an experiment.
This type of calculation...
Air content measurement in concrete is critical for ensuring structural integrity and durability of concrete structures, especially in environments prone to severe weather conditions. Accurate air content analysis optimizes concrete's resistance to freeze-thaw cycles and enhances its workability and strength. Several methods are standardized under ASTM guidelines to measure the air content in fresh concrete, each suitable for different concrete types and conditions.
The pressure method,...
It isn't easy to measure a parameter such as the mean height or the mean weight of a population. So, we draw samples from the population and calculate the mean height or mean weight of the individuals in the sample. This sample data acts as a representative measure of the population parameter. These sample statistics are known as estimates.
The estimate for the mean of a sample is denoted by ͞x, whereas the mean of the population is designated as μ. Further, parameters such...
On many occasions, physicists, other scientists, and engineers need to make estimates of a particular quantity. These are sometimes referred to as guesstimates, order-of-magnitude approximations, back-of-the-envelope calculations, or Fermi calculations. The physicist Enrico Fermi was famous for his ability to estimate various kinds of data with surprising precision. Estimating does not mean guessing a number or a formula at random. Instead, estimation means using prior experience and sound...
Enthalpy changes are typically tabulated for reactions in which both the reactants and products are at the same conditions. A standard state is a commonly accepted set of conditions used as a reference point for the determination of properties under other different conditions. For chemists, the IUPAC standard state refers to materials under a pressure of 1 bar and solutions at 1 M and does not specify a temperature. Many thermochemical tables list values with a standard state of 1 atm. Because...
A battery is a galvanic cell that is used as a source of electrical power for specific applications. Modern batteries exist in a multitude of forms to accommodate various applications, from tiny button batteries such as those that power wristwatches to the very large batteries used to supply backup energy to municipal power grids. Some batteries are designed for single-use applications and cannot be recharged (primary cells), while others are based on conveniently reversible cell reactions that...