![]() ![]() ![]() ![]() Dezhen Chen, in Design and Operation of Heat Exchangers and their Networks, 2020 Abstract The multiplier 4 / D in this term arises from the fact that the ratio of the inside pipe surface area to the internal pipe volume is π D / ( π D 2 / 4 ) = 4 / D. The final term, − q A 4 / D, represents the loss of heat from the pipeline through conduction and/or convection from the pipe surface, where q represents the heat flux (heat flow rate per unit surface area) at the inner pipe surface. Ρ A f / 2 D | v 3 | represents the work of friction on the fluid. Inherent in these two terms is the work in the fluid element as it expands or contracts and the Joule-Thomson effect. The first two RHS terms, − T ( ∂ p / ∂ T ) ρ ( A t + ( v A ) x ) + p A t, include a thermodynamic derivative ( ∂ p / ∂ T ) ρ that can be computed with the assistance of an equation of state. The spatial component represents the convection of thermal energy with the fluid as it moves through the pipeline. There is a time component and a spatial component because the fluid element under consideration is moving. The left side represents the rate of change of internal energy of a fluid element. 4.3) represents conservation of energy of a fluid element.
0 Comments
Leave a Reply. |