Inlet correction

COMPRESSOR INLET CORRECTION FACTORS FOR VARIOUS PIPING ARRANGEMENTS... 

Performance tables are based on standard dry air at 70°F at sea level (barometric pressure 29.92 in. Hg) with a density of 0.075 lb per fp. When the fans are required to handle gases at other conditions at the inlet, corrections must be made for temperature, altitude, and air or gas density. 

As SR decreases, 1 must be decreased too (and thereby also the inlet pressure loss/total pressure ratio is decreased). This is what is really observed when dispersed fillers are added to polymer [182,190,193,194], The rubber phase in heat resistant polystyrene behaves much like a dispersed filler it also diminishes the inlet correction [195]. For polystyrene with different fillers the following relationship was found to be valid [196] ... 

When the Inlet correction and the Kinetic Energy Correction are incorporated, the above equation takes the form... 

The velocity distribution across the tube (capillary or jet) diameter does not become uniform immediately as an element of liquid enters the tube. A correction factor to minimise the error due to this drawback is known as Inlet Correction . The magnitude of the correction factor decreases with increase in the length of the tube and with decrease in its diameter. 

Investigators of tower packings normally report kcCi values measured at very low inlet-gas concentrations, so that yBM = 1, and at total pressures close to 100 kPa (1 atm). Thus, the correct rate coefficient For use in packed-tower designs involving the use of the driving force y — y /yBM is obtained by multiplying the reported k co values oy the value of pf employed in the actual test unit (e.g., 100 kPa) and not the total pressure of the system to be designed. 

For gas-absorption systems in which the inlet gas is concentrated, the correct equation is... 

Another instance in which the constant-temperature method is used involves the direc t application of experimental KcO values obtained at the desired conditions of inlet temperatures, operating pressure, flow rates, and feed-stream compositions. The assumption here is that, regardless of any temperature profiles that may exist within the actu tower, the procedure of working the problem in reverse will yield a correct result. One should be cautious about extrapolating such data veiy far from the original basis and be carebil to use compatible equilibrium data. 

As long as the volume flow is kept near design point, both the deflection angle and pressure drop can be corrected. Temperature differential increase is limited by metallurgy, so it is neglected in analytical calculations. This evaluation is based on inlet pressure changes. The new volume at a different pressure is calculated by the ideal gas equation ... 

The actual mass flow rates and speeds are corrected by factor ( /0/ ) and (l/ /0) respectively, reflecting variations in inlet temperature and pressure. The surge line joins different speed lines where the compressor s operation becomes unstable. A compressor is in surge when the main flow through a compressor reverses direction for short time intervals, during which the back... 

Since aerothermal performance of compressors and turbines is very sensitive to inlet temperature and pressure variations, it is essential to normalize the aerothermal performance parameters such as flow, speed, horsepower, etc., to standard-day conditions. When these corrections to standard conditions are not applied, a performance degradation may appear to occur when in fact it was a performance change resulting merely from ambient pressure and temperature changes. Some of the equations for obtaining correction to standard-day conditions are given in Table 19-3. 

These refer to hot and cold fluid terminal temperatures, inlet of one fluid versus outlet of the other. For a cross exchanger with no phase change, the ATm gives exact results for true countercurrent flow. Most heat exehang-ers, how ever, deviate from true countercurrent so a correction factor, F, is needed. 

To assist the engineer in making estimates, the curve in Figure 3-6 gives values of efficiency plotted against pressure ratios. The values on the curve include a 95% mechanical efficiency and a valve velocity of 3,000 feet per minute. Table 3-1 and Table 3-2 are included to permit a correction to be made to the compressor horsepower for specific gravity and low inlet pressure. They are included to help illustrate the influence of these factors to the power required. The application of these factors to... 

The temperature at the entrance to the impeller is increased because of the hot leakage. Calculate the corrected impeller inlet temperature using Equation 5.20. 

If the mobile phase is a liquid, and can be considered incompressible, then the volume of the mobile phase eluted from the column, between the injection and the peak maximum, can be easily obtained from the product of the flow rate and the retention time. For more precise measurements, the volume of eluent can be directly measured volumetrically by means of a burette or other suitable volume measuring vessel that is placed at the end of the column. If the mobile phase is compressible, however, the volume of mobile phase that passes through the column, measured at the exit, will no longer represent the true retention volume, as the volume flow will increase continuously along the column as the pressure falls. This problem was solved by James and Martin [3], who derived a correction factor that allowed the actual retention volume to be calculated from the retention volume measured at the column outlet at atmospheric pressure, and a function of the inlet/outlet pressure ratio. This correction factor can be derived as follows. 

Consequently, as the inlet pressure increases, the mean flow rate will be reduced according to the pressure correction function and the expected decrease in elution rate will not be realized. Consider an open tubular column. 

Atwood and Goldstein [16] examined the effect of pressure on solute diffusivity and an example of some of their results is shown in Figure 7. It is seen that the diffusivity of the solutes appears to fall linearly with inlet pressure up to 40 MPa and the slopes of all the curves appear to be closely similar. This might mean that, in column design, diffusivities measured or calculated at atmospheric pressure might be used after they have been appropriately corrected for pressure using correction factors obtained from results such as those reported by Atwood and Goldstein [16]. It is also seen that the... 

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. 

---