Inlet conditions

Inlet conditions for pressure and velocity at the inlet to the flow channels are given in terms of total constant inlet pressure and average inlet reactant gas 

The average inlet gas velocity is computed from the reactant gas consumption rate as 

In a fuel cell, the reactant gas mass flow rate at the inlet to the gas flow channels is assumed to be ideally equal to the gas consumption rate at the electrode-membrane interface, which depends on the operating cell current density and given as 

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Heat flow required from the turbine exhaust = 21.9 MW From steam tables, inlet conditions at T, = 300°C and Pi = 41 bar are /ii = 2959kJkg ... 

Cost of 10-barg steam. Here, 41-barg steam is now expanded to 10 barg in a steam turbine. Details of steam turbine calculations were gpven in Sec. 6.7. From steam tables, inlet conditions at 41 barg and 400 C are... 

The above example is a simple one, and it can be seen that the individual items form part of the chain in the production system, in which the items are dependent on each other. For example, the operating pressure and temperature of the separators will determine the inlet conditions for the export pump. System modelling may be performed to determine the impact of a change of conditions in one part of the process to the overall system performance. This involves linking together the mathematical simulation of the components, e.g. the reservoir simulation, tubing performance, process simulation, and pipeline behaviour programmes. In this way the dependencies can be modelled, and sensitivities can be performed as calculations prior to implementation. 

BOUNDARY CONDITIONS IN POLYMER PROCESSING MODELS 95 Inlet conditions... 

Fig. 17. Comparison of the predictions of k-Q model with experimental data for a turbulent jet inside a 5° conical duct, (a) Flow geometry and inlet conditions, where geometry =1.6 cm, = 16 cm, L = 64 cm, 0 = 5°-, flow conditions, p = 0.998 g/mc, p = 0.01 g/cm-s, Uj = 40 cm/s,...

The importance of equations 37—39 is that once the heat-exchanger effectiveness, S, is known for a given heat exchanger, one can compute the actual heat-transfer rate and outlet stream temperatures from specified inlet conditions. This process is known as rating a given heat exchanger. 

For most cooling towers in the United Kingdom, the exit air is saturated at a temperature close to the mean water temperature in the tower. Hence, if the water temperatures and the air inlet conditions are known, AH, AT, and AT can all be calculated, and Tcan be deterrnined. It was found that the quantity C was approximately constant for these towers, ca 0.4—0.5 (34). If the value of C is known for a given tower, then the left side of equation 49 can be computed and, setting this equal to Z9, the allowable Hquid flow rate can be found. Alternatively, when and air-inlet conditions are given, the... 

Natural-draft cooling towers are extremely sensitive to air-inlet conditions owing to the effects on draft. It can rapidly be estabUshed from these approximate equations that as the air-inlet temperature approaches the water-inlet temperature, the allowable heat load decreases rapidly. For this reason, natural-draft towers are unsuitable in many regions of the United States. Figure 10 shows the effect of air-inlet temperature on the allowable heat load of a natural-draft tower for some arbitrary numerical values and inlet rh of 50%. The trend is typical. 

Vacuum pump capacity is conventionally based on the total cycle and expressed as mVh-m" (cfi7i/ft ) of filter area measured at pump inlet conditions. Thus, the gas volumes per unit area passing during each dry period in the cycle are totaled and divided by the cycle time to arrive at the design air rate. Since air rate measurements in the test program are based on pressure drop across the cake and filter medium only, allowance must be made For additional expansion due to pressure drop within the filter and auxiliary piping system in arriving at vacuum pump inlet conditions. 

In most processes involving the absorption of a gaseous pollutant from an effluent gas stream, the gas stream is the processed fluid hence, its inlet condition (flow rate, composition, and temperature) are usually known. The temperature and composition of the inlet liq-... 

Steam Rate Enthalpy data can be obtained from Mollier diagrams or from steam tables (see Sec. 2), from which the theoretical steam rate can be calculated. For example, a throttle inlet condition of 4137 kPa (600 psig) and 399° C (750° F) gives an enthalpy of 3.2 MJ/kg (1380 Btu/lb), and if the end point is at 348 kPa (50 psig), then adiabatic expansion is to 2.69 MJ/kg (1157 Btu/lb). This gives 0.52 MJ/kg (223 Btu/lb) available, and the theoretical steam rate is calculated from the Btu equivalent per Idlowatthour or horsepower-hour ... 

Example 1 shows the expander inlet conditions typical of past FCC applications with an expander inlet pressure of 30 psia and inlet temperature of 1,200°F. Example 2 shows the conditions prevalent in more recent FCC regenerator technology, where most of the CO is... 

The surge protection described above is for a simple, single section, constant geometry compressor with constant inlet conditions and constant speed of rotation. Many compressor installations involve more complex configurations and applications. 

The invariant coordinate, qj., is used to determine the flow calculation independent of inlet conditions. To determine the reduced flow... 

Losses are complex phenomena and as discussed here are a function of many factors, including inlet conditions, pressure ratios, blade angles, and flow. Figure 6-35 shows the losses distributed in a typical centrifugal stage of pressure ratio below 2 1 with backward-curved blades. This figure is only a guideline. 

The actual mass flow rates and speeds are corrected by factors f6jb) and (l/ /0), respectively, to account for variation in the inlet conditions of temperature and pressure. The surge line joins the different speed lines where... 

Woodhouse, H., Inlet Conditions of Centrifugal Compressors for Aircraft Engine Superchargers and Gas Turbines, J. Inst. Aeron, Sc., Vol. 15, 1948, pp. 403. 

The plant overall power and the heat rate are very dependent on the inlet conditions as seen in Figure 20-8, which is based on a typical gas turbine plant. The effect of temperature is the most critical component in the ambient condition variations of temperature, pressure, and humidity. 

Step L Calculate volumetric efficiency using Equations 3.5 and 3.6. To complete the calculation for volumetric efficiency, the compressibilities are needed to evaluate the f term of Equation 3.6. Using Equations 2.11 and 2.12 for the inlet conditions,... 

Step 2. Eind the velocity of sound for air at the inlet conditions given, using Equation 2.32 from Chapter 2. 

To start, convert the flow to values estimated to be the compressor inlet conditions. Initially, the polytropic head equation (Equation 2.73) will be used with n as the polytropic compression exponent. If prior knowledge of the gas indicates a substantial nonlinear tendency, the real gas compression exponent (Equation 2.76) should be substituted. As discussed m Chapter 2, an approximation may be made by using the linear average ut the inlet and outlet k values as the exponent or for the determination of the polytropic exponent. If only the inlet value of k is known, don t be too concerned. The calculations will be repeated several times as knowledge of the process for the compression cycle is developed. After selecting the k value, u,se Equation 2.71 and an estimated stage efficiency of 15 / to de clop the polytropic compression exponent n. 

In the above equation, is the critical velocity (m/s), K is the ratio of specific heats (Cp/C ) at inlet conditions, P is the pressure in the restriction at critical flow conditions (KPa, absolute - Note that this term is known as the critical flow pressure ), and p, is the density of the fluid at the critical flow temperature and pressure (kg/m ). 

K = Specific heat ratio, at inlet conditions given for some substances in Table 1. Note Published values of K at 15 °C and one atmosphere may be used. If K is unknown, a conservative value of K = 1.001 may be used, in which case the factor C = 315. Note that a correction for non-ideal gases may be necessary. 

V, = Specific volume at inlet conditions, m /kg. Other nomenclature is as defined after Equation (4), above. 

S = Specific gravity at the inlet conditions, referenced to water at 15 °C. 

Sizing for Flashing Liquids - PR valves handling fluids which are liquid at inlet conditions but which flash wholly or partially to vapor at discharge conditions can be sized using the following procedure ... 

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