Energy flow definitions

The massecuite circulates in a loop within the evaporating crystallizing vessel. The massecuite flows upwards through the heating tubes. In the room above the calandria the massecuite flow changes its direction to radial inwards and then to vertical downwards. An impeller in the central tube forces the circulation. Below the calandria the main direction of flow is radially outwards until threads of the massecuite stream enter the heating tubes in upwards direction. Within the tubes heat is transferred to the massecuite. At low temperature differences between heating steam and massecuite and higher levels of the massecuite in the crystallizer vapor bubbles are not found in the tubes. Vapor bubbles can be formed at a massecuite level in the crystallizer where the temperature of the massecuite is higher than the local boiling temperature of water, which depends on the local pressure (including the static pressure of the massecuite at this point) and the boiling point elevation of the mother liquor. The surface tension of the liquid is a resistance against the bubble formation, which has to be overcome by the local superheating i.e. the part of the enthalpy of the massecuite exceeding the local boiling temperature. The formation and the flow of the bubbles change the density of the massecuite/bubbles mixture and has an influence on the massecuite flow. The formation of a vapour bubble is connected with a local drop of the massecuite temperature which changes the local supersaturation. Today the heat transfer into the magma is quite well known but the process of bubble formation is quite unknown. Some basic considerations about the formation of bubbles and its influence on local supersaturation based on calculation of heat and mass balances and models of bubble formation are be given and discussed. Experiments for basic investigations are proposed.

Download Full-text

Energy flow analysis of straw-return agricultural modes in the Central Shaanxi Plain

CHINESE JOURNAL OF ECO-AGRICULTURE ◽

10.3724/sp.j.1011.2012.01388 ◽

2013 ◽

Vol 20 (10) ◽

pp. 1388-1393

Author(s):

Bi JIANG ◽

Fa-Qi WU ◽

Xi-Hui WU ◽

Ming LI ◽

Xiao-Gang TONG

Keyword(s):

Energy Flow ◽

Flow Analysis ◽

Energy Flow Analysis ◽

Straw Return

Download Full-text

Nutrient Cycling and Energy Flow in Grasslands

10.1093/oso/9780198744511.003.0004 ◽

2018 ◽

Author(s):

Brian J. Wilsey

Keyword(s):

Energy Flow ◽

Animal Species ◽

Net Primary Productivity ◽

Growing Season ◽

C4 Plant ◽

Geographic Scale ◽

Organic C ◽

Natural Forms ◽

Belowground Productivity ◽

Remote Sensing Techniques

Net primary productivity (NPP) is the amount of C or biomass that accumulates over time and is photosynthesis—autotroph respiration. Annual NPP is estimated by summing positive biomass increments across time periods during the growing season, including offtake to herbivores, which can be high in grasslands. Remote sensing techniques that are used to assess NPP are discussed by the author. Belowground productivity can be high in grasslands, and it is important to carbon storage. Across grasslands on a geographic scale, NPP, N mineralization, and soil organic C all increase with annual precipitation. Within regions, NPP can be strongly affected by the proportion of C4 plant species and animal species composition and diversity. Humans are adding more N to the environment than all the natural forms of addition (fixation and lightning) combined. Animals, especially herbivores, can have strong effects on how plants respond to changes in changes in resource availability.

Download Full-text