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This is an energy balance which defines the position of the moving interface. Note that this evolving boundary is an unknown (hyper-)surface; hence, Stefan problems are examples of free boundary problems. Analogous problems occur, for example, in the study of porous media flow, mathematical finance and crystal growth from monomer solutions. [1]
Energy balance, in terms of energy economics, is concerned with all processes within an organization that have a reference to energy. It derives from the ecobalance and has the ambition to analyze and verify the emergence, transformation and use of energy resources in an organization in detail. [ 1 ]
Energy balance (energy economics), verification and analysis of emergence, transformation and use of energy sources within an economic zone Energy economics , where the energy balance of a country is an aggregate presentation of all human activities related to energy, except for natural and biological processes
From this energy balance, it is clear that NTU relates the temperature change of the flow with the minimum heat capacitance rate to the log mean temperature difference (). Starting from the differential equations that describe heat transfer, several "simple" correlations between effectiveness and NTU can be made. [ 2 ]
This problem is solved by recourse to the principle of conservation of energy. This principle allows a composite isolated system to be derived from two other component non-interacting isolated systems, in such a way that the total energy of the composite isolated system is equal to the sum of the total energies of the two component isolated ...
Transfers of energy as work, or as heat, or of matter, between the system and the surroundings, take place through the walls, according to their respective permeabilities. Matter or energy that pass across the boundary so as to effect a change in the internal energy of the system need to be accounted for in the energy balance equation.
The three-body problem is a special case of the n-body problem. Historically, the first specific three-body problem to receive extended study was the one involving the Earth, the Moon, and the Sun. [2] In an extended modern sense, a three-body problem is any problem in classical mechanics or quantum mechanics that models the motion of three ...
Measuring energy output is a solved problem; measuring the input remains highly debated. EROI is calculated by dividing the energy output by the energy input. Measuring total energy output is often easy, especially in the case for an electrical output where some appropriate electricity meter can be used. However, researchers disagree on how to ...