Heterogeneous condensation of water vapor on coal-fired fine particles was investigated in a growth tube. The influence of operating parameters and wetting agent addition on vapor condensation enlargement for three coal-fired fine particles from different power plants were tested. The results show that all the three coal-fired fine particles induce heterogeneous condensation and the process is favored by increasing the water temperature and residence time and decreasing particles initial number concentration; wetting agent addition highly facilitates the effect of vapor condensation on fine particles and the performance is increased with the increase of wetting agent addition. It is also found that excessive addition encourages the performance of final mean size of particles but discourages the performance of finer particles enlargement. With wetting agent addition, the mean diameter of fine particles can be enlarged above 3 μm while the mean diameter can only be enlarged above 2 μm without wetting agent addition (the original mean diameter of particles is about 0.15 μm).

The supersaturation profiles in the one-/multi-section growth tube were predicted under the conditions of different carrier gases for two kinds of typical supersaturation-achieving methods. The results show that Lewis number (Le) of the carrier gas is an important factor affecting the supersaturation profiles. For the one-section growth tube, the carrier gas with a smaller Le is beneficial to a higher level and flatter trend of supersaturation profiles for method 1, where the supersaturated environment is achieved by a cool saturated flow into a warm-walled growth tube. However, for the carrier gas of a larger Le, the higher level but less stable supersaturation profiles are presented from method 2, with a warm saturated flow into a cold-walled growth tube. With the carrier gas of large Le (>1) from method 1 and the carrier gas of small Le (<0.5) from method 2, an efficient supersaturated environment cannot be achieved under the ordinary conditions. In the multi-section growth tube, the more minimum number of the sections is selected for stable supersaturation profiles with the carrier gas of larger Le. Additionally, the sections of a flatter supersaturated environment are closely related to the achieving methods of a supersaturation environment, the whole length of the growth tube, and radial positions.

No abstract

The suitability evaluation of agricultural land at the regional scale is of great significance for protecting land and water resources and building sustainable agricultural systems. Based on climate, soil, topographical, and surface water resources, land suitability index (LSI) data for maize, rice, and soybeans are established using an analytical hierarchy process and matter element analysis (AHP–MEA) model in Jilin Province, China. The results show that there is a significant positive linear correlation between the LSI and the measured yield, which indicates that the model has an ideal effect and certain reference and extension significance. The main limiting factors for maize and soybean planting are pH, total nitrogen (TN), available phosphorus (AP), and soil texture, while water shortage limits rice planting. Different spatial structure optimization schemes for planting are established using the LSI and measured yield, along with economic indices. This study shows that the scheme that integrates policy and cost can make full use of land and water resources and promote the economic growth of agriculture. After optimization, the planting areas of maize, rice, and soybeans were 7.22, 2.44, and 0.71 million ha, respectively, representing an increase of 15.71 billion yuan over the agricultural GDP for the existing planting structure. It is expected that this study will provide a basis for follow-up studies on crop cultivation suitability.