6._Process_variables__P__T__and_dimensio

6._Process_variables__P__T__and_dimensio - dimensionless...

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January 28. Process variables (P, T) and dimensional homogeneity Felder and Rousseau, Sections 3.4-3.5 and Section 2.6 Pressure = force per area N/m 2 (=Pa), lb f /in 2 Hydrostatic pressure: P = P o + ρ gh Manometer Temperature = a measure of the average kinetic energy possessed by the substance molecules Dimensional homogeneity Every valid equation must be dimensionally homogenous. Æ all additive terms on both sides of the equation must have the same dimensions. only quantities with the same dimensions may be added / subtracted. exponents, transcendental functions, and arguments of transcendental functions must be
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Unformatted text preview: dimensionless quantities. Examples: (1) pressure measurement with a manometer h g P = (2) working with temperature (Example 3.5-3, p63) January 30: Problem solving practice Conversion of temperature (T) Conversion factors for temp. difference ( T) Dimensionless form: 15 . 273 + = C T K T o C K 67 . 459 + = F T R T o F R = 32 8 . 1 1 F T C T o F o C K C o 1 1 R F o 1 1 K R 1 8 . 1 C F o o 1 8 . 1 With proper dimensions: 15 . 273 ) ( ) ( + = C T K T o 67 . 459 ) ( ) ( + = F T R T o ( ) 32 ) ( 8 . 1 1 ) ( = F T C T o o...
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