Flow rates of liquids

Nomenclature (Use consistent units.) A = heat-transfer surface C, c = specific heats of hot and cold fluids respectively Lq = flow rate of liquid added to tank M = mass of fluid in tank T, t = temperature of hot and cold fluids respectively Ti, ti = temperatures at beginning of heating or cooling period or at inlet To, to = temperature at end of period or at outlet To, to of liquid added to tank ... 

Zj, 2= Elevation at discharge and suction, respectively gpm = Flow rate of liquid being pumped, gal/min dj = Diameter of discharge pipe, in. d, = Diameter of suction pipe, in. 

The total heat conductance is considered constant and not influenced by the mass flow rate of liquid. 

W = Mass flow rate of liquid phase, pounds per hour per square foot of total pipe cross-section area... 

Wall-to-bed heat-transfer coefficients were also measured by Viswanathan et al. (V6). The bed diameter was 2 in. and the media used were air, water, and quartz particles of 0.649- and 0.928-mm mean diameter. All experiments were carried out with constant bed height, whereas the amount of solid particles as well as the gas and liquid flow rates were varied. The results are presented in that paper as plots of heat-transfer coefficient versus the ratio between mass flow rate of gas and mass flow rate of liquid. The heat-transfer coefficient increased sharply to a maximum value, which was reached for relatively low gas-liquid ratios, and further increase of the ratio led to a reduction of the heat-transfer coefficient. It was also observed that the maximum value of the heat-transfer coefficient depends on the amount of solid particles in the column. Thus, for 0.928-mm particles, the maximum value of the heat-transfer coefficient obtained in experiments with 750-gm solids was approximately 40% higher than those obtained in experiments with 250- and 1250-gm solids. 

Figure 5 illustrates the experimental technique developed by Hewitt et al. for measuring the flow rate of liquid in the wall film as applied to flow inside a heated tube. As can be seen, a short length of porous sinter tube is positioned a few diameters beyond the outlet of the heated tube. The internal diameter of the sinter and the heated tube are made identical so as to avoid any flow... 

The flow rate of liquid in the HPLC-electrospray system is paramount in determining performance both from chromatographic and mass spectrometric perspectives. The flow rate affects both the size and size distribution of the droplets formed during the electrospray process (not all droplets are the same size) and, consequently, the number of charges on each droplet. This, as we will see later, has an effect on the appearance of the mass spectrum which is generated. It should also be noted that the smaller the diameter of the spraying capillary, then... 

Here, p is density of liquid g is gravitational acceleration q is flow rate of liquid h is height which solution pumped up to, it was assumed 10 m high in this calculation and 77 is efficiency of a pump. 

It was also established that the distribution of the liquid phase in the reactor depends on the reactor start-up procedure. When the flow rate of liquid AMS is reduced from 1.47 x 10 1 g s 1 (Figure 5.4.6, images 43 and 45) down to 2.96 x 10-2 g s 1 (images 85 and 87), the distribution of the liquid phase hardly changes and the catalyst bed contains a substantial amount of liquid. At the same time, if... 

Q Volumetric flow-rate of liquid through a centrifuge l3t- ... 

Lm Molar flow-rate of liquid per unit area ML 2T ... 

The frictional pressure gradient in the liquid slug can be calculated using Eqs. (3-103) and (3-104), when the flow rates of liquid and gas are written in terms of the flow rate on the slug. Thus,... 

Consider an oil well drilled to a depth of 1000 ft and connected to the surface with 4-in (internal diameter) commercial steel pipe. If the pressure in the well reservoir is a constant 500 psig, what is the expected flow rate of liquid oil (in barrels per day) at the surface if the surface pipe is open to the atmosphere Assume 1000 ft of equivalent pipe and no gas flow with the oil. The specific gravity of the oil is 0.93, and its viscosity is 0.4 cen-tipoise. Make sure that you clearly state and justify any assumptions Remember, an oil barrel is 42 gal. 

The system Ah against Q curve shown in Figure 4.4 can be plotted using equation 4.12 to calculate the values of the system total head Ah at each volumetric flow rate of liquid or capacity Q. Equation 4.14 shows that for laminar flow the total head Ah increases linearly with capacity Q. Thus for laminar flow, the system Ah against Q curve is a straight line. 

In the above discussion it is assumed that the available NPSH in the system is adequate to support the flow rate of liquid into the suction side of the pump. If the available NPSH is less than that required by the pump, cavitation occurs and the normal curves do not apply. In cavitation, some of the liquid vaporizes as it flows into the pump. As the vapour bubbles are carried into higher pressure regions of the pump they collapse, resulting in noise and vibration. High speed pumps are more prone to cavitation than low speed pumps. 

Figure 4.5 shows a typical relationship between the available NPSH in the system and the NPSH required by the pump as the volumetric flow rate of liquid or capacity Q is varied. The NPSH required by a centrifugal pump increases approximately with the square of the liquid throughput. The available NPSH in a system can be calculated from equation 4.9 having substituted for hfs... 

Weirs are commonly used to measure the flow rate of liquids in open conduits. The theory is based on the Bernoulli equation for frictionless flow. From equation 1.13 with Ah = 0 and hf= 0... 

Gas adsorption into the liquid falling down a wetted wall column is of considerable interest. The flow of liquid down the surface of such a tube is essentially laminar if Re < 1200, where Re is defined as iu/vl, u being the volume flow rate of liquid, I the perimeter of the tube, and v the kinematic viscosity of the solvent. Under these conditions, if there are no surface forces acting, the velocity of the air-water surface of the... 

The flow rate of liquid chlorine through carbon steel pipelines is restricted to 2m/s to avoid removing the ferric chloride coating on... 

SC (simultaneous correction) method. The MESH equations are reduced to a set of N(2C +1) nonlinear equations in the mass flow rates of liquid components ltJ and vapor components and the temperatures 2J. The enthalpies and equilibrium constants Kg are determined by the primary variables lijt vtj, and Tf. The nonlinear equations are solved by the Newton-Raphson method. A convergence criterion is made up of deviations from material, equilibrium, and enthalpy balances simultaneously, and corrections for the next iterations are made automatically. The method is applicable to distillation, absorption and stripping in single and multiple columns. The calculation flowsketch is in Figure 13.19. A brief description of the method also will be given. The availability of computer programs in the open literature was cited earlier in this section. 

Norman and Binns (N3), 1960 Experimental determination of minimum flow rates of liquid to ensure wetting in wetted-wall columns, and effects of surface tension on same. 

Knowledge-based systems typically use qualitative methods rather than quantitative ones. For example, consider a simple tank system. The equation describing the flow rate of liquid out of the tank is given below, where C is the orifice coefficient, d is the diameter of the orifice, and h is the height of liquid in the tank. Based solely on the form of the equation, a human reasoner can infer that the flow rate F increases monotonically with the height h of liquid in the tank. 

Two factors must be known for downcomer flood calculation the flow rate of liquid on the subject tray and the downcomer area. We will assume that liquid flow is given in gallons per minute at the hot flow-... 

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