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1. A cylinder contains a fluid at a gauge pressure of 360 KN/m 2. Express this pressure in terms of a head of (a) water, and (b) mercury of sp gr = 13.6 What would be the absolute pressure in the cylinder if atmospheric pressure is 760mm Hg. Solution: Pressure (P) = 360 KN/m 2 = 360x10 3 N/m 2 Head (h) = ? where ρ = Density of fluid a) Head in terms of water (ρ = 1000 kg/m 3) = 36.7m b) Head in terms of mercury ρ = sp gr x density of water = 13.6x1000 = 13600 kg/m 3 = 2.7m Atmospheric pressure (h) = 760mmhg = 0.76m hg Atmospheric pressure () = 101396N/m 2 = 101.3KN/m 2 Absolute pressure (Pabs) = ? Pabs = Pgauge + Patm = 360+101.3 = 461.3KN/m 2 2. What would the pressure in kN/m 2 be if the equivalent head is measured as 400mm of (a) mercury (sp gr 13.6) (b) water (c) oil specific weight 7.9 kN/m 3 (d) a liquid of density 520 kg/m 3 ? Solution: Head (h) = 400mm = 0.4m Pressure (P) =? where ρ = Density of fluid a) In terms of mercury, ρ = sp gr x density of water = 13.6x1000 = 13600 kg/m 3 = 13600x9.81x0.4 = 53366 N/m 2 = 53.366 KN/m 2 b) In terms of water, ρ = 1000 kg/m 3 = 1000x9.81x0.4 = 3924 N/m 2 = 3.924 KN/m 2 c) In terms of oil of sp. wt. () = 7.9 kN/m 3
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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright a b s t r a c t This article is the second part of a two-part paper, dealing with an experimental study of convective condensation of R134a at a saturation temperature of 40 °C in an 8.38 mm inner diameter smooth tube in inclined orientations. The first part concentrates on the flow pattern and the heat transfer coefficients. This second part presents the pressures drops in the test condenser for different mass fluxes and different vapour qualities for the whole range of inclination angles (downwards and upwards). Pressures drops in a horizontal orientation were compared with correlations available in literature. In a vertical orientation, the experimental results were compared with pressure drop correlations associated with void fraction correlations available in literature. A good agreement was found for vertical upward flows but no correlation predicted correctly the measurements for downward flows. An apparent gravitational pressure drop and an apparent void fraction were defined in order to study the inclination effect on the flow. For upward flows, it seems as if the void fraction and the frictional pressure drop are independent of the inclination angle. Apparent void fractions were successfully compared with correlations in literature. This was not the case for downward flows. The experimental results for stratified downward flows were also successfully compared with the model of Taitel and Dukler.
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