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Integrity Testing
Published in Maik W. Jornitz, Filtration and Purification in the Biopharmaceutical Industry, 2019
Laplace’s Law is descriptive of pores with the shapes of ideal cylinders. Nevertheless, as applied here, it makes plain in equation form the inverse relationship of P, the bubble point pressure, and d, the pore’s diameter. The bubble point value is the applied differential pressure level just sufficient to expel the water from the largest pores. However, the value calculated by way of the Laplace equation is always lower than would be expected. The differences are ascribed to imperfect wetting of the pore surfaces. This increases theta, Θ, the angle of wetting, and affects the results. The differences also may be due to the irregular shapes of the pores, and the pore size distribution. As said, the bubble point equation applies to regular cylinders, not to the irregularly shaped pores of the microporous membranes.
The Fundamentals of Vapour Compression Refrigeration
Published in W.P. Jones, Air Conditioning Engineering, 2007
Butler (1998) discussed refrigerant mixtures with components that boil at different temperatures, giving changes in the boiling points (termed ‘glide’) as the mixture evaporates or condenses. ‘Bubble point’ is the temperature at which a refrigerant liquid just starts to evaporate and ‘dew point’ is the temperature at which the vapour starts to condense. With a single refrigerant these points coincide and an azeotropic mixture having liquid and vapour phases in equilibrium also has a constant boiling point. On the other hand, for a zeotropic mixture of refrigerants, the constituents have different boiling points and the difference is termed the glide value for the mixture. Glide may lead to differential frosting temperatures across an evaporator, and condensers and evaporators tend to be larger than for a single refrigerant. Changes in heat transfer characteristics and refrigerant handling difficulties are possible with glide. Note that a refrigerant and a lubricant is a zeotropic mixture requiring special consideration. Whereas hydrocarbon refrigerants are compatible with conventional mineral oils, HFC refrigerants (such as R134a) and mixtures of them are not and a polyester lubricant is required.
Separation Processes
Published in Arthur J. Kidnay, William R. Parrish, Daniel G. McCartney, Fundamentals of Natural Gas Processing, 2019
Arthur J. Kidnay, William R. Parrish, Daniel G. McCartney
Adding more feed increases the liquid volume and makes the liquid composition richer in the heavy component. To keep the pressure constant the temperature must be adjusted after each addition. Once enough liquid is added to almost completely fill the vessel, the liquid composition equals the feed composition. Figure 4.6 shows this point, which is called the “bubble point.” The bubble point pressure is also the true vapor pressure (TVP) of the mixture. Another way to think of the bubble point is to have the vessel full of liquid, and slowly raise the temperature at constant pressure until the first “bubble” is formed. This is the bubble point temperature for the liquid with composition xF at the given pressure.
Numerical investigation of flashing of propane (R-290) in a helical capillary tube
Published in Numerical Heat Transfer, Part A: Applications, 2023
Soumik Bose, Sofen Kumar Jena, Sewan Das Patle
The frictional resistance provided by the tube wall results in pressure reduction in the capillary tube. The liquid refrigerant flashes (evaporates) into a mixture of liquid and vapor as its pressure reduces. The density of the mixture gradually drops along the length of the tube because the vapor refrigerant is lighter than the liquid refrigerant. Flow velocity increases over the length of the tube to maintain the mass flow rate. The change in velocity and the creation of accelerating flow are brought about by the pressure drop. The abrupt phase shift from a liquid to a vapor state is caused by a drop in local pressure below the saturated vapor pressure. The phenomenon is known as flashing. Bubble point refers to the place along the tube where the first vapor bubble forms. Under nonequilibrium conditions with a nonlinear pressure drop, the two-phase flow of liquid and vapor refrigerant prevails post-bubble point. The onset of vapor formation significantly restricts the flow rate across the capillary tube, and thus it acts as a flow regulator.
Absorbency of synthetic urine by cotton nonwoven fabric
Published in The Journal of The Textile Institute, 2021
Rupali Dhiman, R. Chattopadhyay
The measurement of pore sizes by Porolux 100 is based on gas-liquid displacement principle. A sample (approximately 2.5 cm in diameter) was completely immersed in the porofil (surface tension of 16.0 dyne/cm) wetting liquid for 30 s. The sample was placed in the sample holder and the pressure was raised gradually so that the liquid is forced to move out from the larger pores initially, followed by the smaller pores of the wetted sample. Per cent flow versus diameter and air-flow versus air pressure graphs were obtained. The method was used to measure the bubble point, smallest pore (SP) diameter, mean flow pore (MFP), cumulative filter flow, and pore size distribution etc. MFP was calculated at a point where the wet curve and half of the dry curve converged. The maximum and minimum pore diameters were determined by the bubble point and from the pressure at which wet and dry curves converged, respectively. A bubble point is a pressure at which the first flow of gas across the wet membrane is observed.
Exsolving two-phase flow in oil wells
Published in Geophysical & Astrophysical Fluid Dynamics, 2020
Victoria E. Pereira, Andrew C. Fowler
It is well understood through Henry's law that the concentration of dissolved gas is dependent on the pressure in the system; where K is a function of temperature T and ν is an empirically calculated constant. In an isothermal flow, the value K is an assumed constant. A commonly used correlation for oil developed by Vazquez and Beggs (1977) gives . The equilibrium between the dissolved gas concentration and the liquid pressure is therefore assumed to be Recall that the pressure at which the dissolved gas starts to come out of solution is known as the bubble-point pressure . Thus at this pressure the concentration of dissolved gas is saturated and we have , where is the initial concentration of dissolved gas. If we assume the values for and to be known, we can calculate the value of the parameter K.