China
Africa
Explore chapters and articles related to this topic
Petroleum Geochemical Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
The presence of water vapors in the atmosphere is due to the evaporation of water. Evaporation occurs from different water sources, namely oceans, rivers and lakes, etc. Water vapor is also introduced in the atmosphere by the perspiration of animals and transpiration of plants. The rate of evaporation of water depends on many factors such as temperature, relative humidity, surface area and the concentration of dissolved solids. Higher temperatures and less humidity accelerate evaporation. The rate of evaporation from sea water is about 2- -3% less than the fresh water rate, because of higher salinity in the ocean. The amount of evaporated water from the ocean is far greater than the small quantity of evaporated fresh water. The contribution from ocean water to the atmospheric water vapor is around 85% of the total, whereas fresh water sources provide 15% of the vapor in the atmospheric pool.
Vacuum and Gas Kinetics
Published in Eiichi Kondoh, Micro- and Nanofabrication for Beginners, 2021
Evaporation in an ideal liquid occurs at the surface below the boiling point, when the liquid changes to gas. When this process occurs at a solid surface, it is called sublimation, and the phenomenon of sublimation is included in evaporation in vacuum technologies. Condensation is the counter process that occurs at a surface when gas molecules get captured. The pressure at which the rates of evaporation and condensation are balanced (equilibrium) is called equilibrium vapor pressure.
Energy Basics/Foundation for Understanding
Published in Dale R. Patrick, Stephen W. Fardo, Ray E. Richardson, Brian W. Fardo, Energy Conservation Guidebook, 2020
Dale R. Patrick, Stephen W. Fardo, Ray E. Richardson, Brian W. Fardo
Evaporation is quite different from boiling. Evaporation can take place to a greater or lesser degree at any temperature. Boiling is much more restricting and takes place at only one temperature for a specific material. Also, evaporation takes place only from the surface of a liquid, whereas boiling occurs throughout the liquid.
Process conditions sensitive (PCS) thin-layer mathematical model of hot air convective drying
Published in Chemical Engineering Communications, 2023
Juma Haydary, Mohammad Jafar Royen, Abdul Wasim Noori
Figure 5 shows the model sensitivity to the change of air velocity (Figure 5(a)), air temperature (Figure 5(b)), initial air relative humidity (Figure 5(c)), and layer thickness (Figure 5(d)). This figure shows sensitivity analysis results for apple slices; however, using the model parameters given in Table 3, similar data can be generated for all other material types. By increasing air temperature, air relative humidity decreases resulting in increased drying force for moisture evaporation and increased drying rate. Increase of the air velocity near the drying surface leads to more intensive convective heat and mass transfer from the material surface, which then results in increased drying rate. Higher initial air relative humidity means higher air moisture content and higher relative air humidity also in the drying chamber and thus lower driving force and consequently lower drying rate. The effect of layer thickness is significant, the higher the layer thickness, the lower the drying rate. After the critical moisture content is reached (all free moisture from the material surface is evaporated), the drying rate is limited by the diffusion of the moisture from the material structure to its surface; the higher the sample thickness, the slower the drying.
Spray-dried almond milk powder containing microencapsulated flaxseed oil
Published in Drying Technology, 2022
Federico Bueno, Alexander Chouljenko, Vondel Reyes, Subramaniam Sathivel
The evaporation rate of 0AMFO was 0.54 ± 0.00 kg water/h, which was significantly higher than 0.51 ± 0.00 kg water/h for 4AMFO. Although, the evaporation rate for 2AMFO was not significantly different from either 0AMFO or 4AMFO. The evaporation rate may be affected by emulsion composition since 4AMFO had more solids added to the formulation and thus a lower moisture content (86.0 ± 0.1%) compared to 0AMFO (90.2 ± 0.1%). The increase in solid content of 2AMFO and 4AMFO emulsions caused a decrease in the evaporation rate (average diffusion coefficient smaller), resulting from a bigger temperature difference (driving force) between the particle and surrounding air. Two factors that have an effect on the evaporation rate are the inlet temperature and the humidity in the air.[21] Since these factors were comparable at the time of drying, the evaporation rates were not very dissimilar from each other. The temperature used for spray drying in this study was kept stable at 150 °C. Drying at higher temperatures would cause a greater evaporation rate.
Algal biomass harvesting using low-grade waste heat: the effect of waste heat temperature and air speed on dewatering algal suspension
Published in Biofuels, 2022
Ramin E. Yazdi, Temesgen Garoma
Figure 6 shows the decrease in temperature of the air at 10 mm above the interface (Figure 6A) and in the liquid at 10 mm below the interface (Figure 6B) within the length of the evaporation tank. Figure 6A clearly shows that in the case of natural convection with an air speed of zero, the temperature of the air decreased gradually from the outlet to the inlet, but as the air speed increases from 0.5 to 3 m/s the decrease in air temperature occurred more rapidly and over shorter distances from the air outlet. This agreed with the work of Raimundu et al. [33] who found that in forced convection the effect of advection is dominant over the effect of thermal driving potential. This effect also causes more difference in the temperature of liquid and air, hence enhancing evaporation. Figure 6B shows the temperature drop in the liquid domain within the length of the evaporation tank. It can be seen that at an air speed of zero the temperature drops rapidly in an area 200 to 300 mm from the liquid inlet. This area is located right after the area of maximum evaporation. For air speeds of 0.5 to 3 m/s, the decrease in temperature is smaller due to the mixing effect of high-speed air flow over the shallow liquid, and this decrease is minimal at an air speed of 3 m/s.