Low compression ratio

Low specific volume of vapor Low compression ratio Low viscosity... 

Poppet valves are typically used for low compression ratio applications, such as pipeline booster compressors. As the pressure differential increases across each of the individual poppets, they lift and allow gas to pass through the flow openings in the stop plate. 

Figure 12-2M. For low compression ratios, designed for 1,000 psi discharge pressure equipped with hand-operated crank and head-end fixed clearance pockets for capacity control. Air-cooled, cast semisteel, double-acting. (Used by permission Dresser-Rand Company.)...

The booster (blower or Roots) pumps are high-throughput pumps with a low compression ratio. A booster pump is schematically shown in Fig. 1.8. The gap between the two counter-rotating rotors is of the order of 0.1 mm. The rotation (about 50rps) of the rotors,... 

Low compression rate and low compression ratio Splay and air entrapment 11.12.4... 

The injection-molding press was producing a part and runner system that had a mass of 2.15 kg. The mass was plasticated using a 120 mm diameter, 8L/D screw. The screw used for the process had a barrier melting section that extended to the end of the screw, as shown by the specifications in Table 11.9. That is, the screw did not have a metering channel. Instead, the last sections of the barrier section were required to produce the pressure that was needed to flow the resin through the nonreturn valve and into the front of the screw. The specific rotational flow rate for the screw for the IRPS resin was calculated at 9.3 kg/(h-rpm) based on the depth of the channel at the end of the transition section. The screw was built with an extremely low compression ratio and compression rate of 1.5 and 0.0013, respectively. For IRPS resins and other PS resins, screws with low compression ratios and compression rates tend to operate partially filled. The compression ratio and compression rate for the screw are preferred to be around 3.0 and 0.0035, respectively. The flight radii on the screw were extremely small at about 0.2 times the channel depth. For IRPS resin, the ratio of the radii to the channel depth should be about 1. 

For recruitment compensation, on the other hand, longer release times are desired to minimize any deleterious effects of the compression on the speech envelope[Plomp, 1988] [Boothroyd et al., 1988] or in modulating the background noise[Cole, 1993] [Neuman et al., 1995], Low compression ratios are often chosen to match the dynamic range of the impaired ear to that of a normal ear, and a low compression threshold is often chosen so that speech sounds at any level of presentation can be perceived above the impaired auditory threshold [Waldhauer and Villchur, 1988][Killion, 1993],... 

Fig. 21 shows the PSNR (Eq. (8)) versus the compression ratio of the 3-D and 2-D methods. We only show the results for one of the test volumes here. The results for the second volume are very similar. The compression ratio of the 3-D wavelet method is much higher than that of the 2-D wavelet method at comparable PSNR. For a very low compression ratio the JPEG algorithm yields a slightly higher PSNR, but for higher compression ratios 3-D wavelet compression easily outperforms both 2-D methods. 

The thermodynamic performance is usually poorer than that of the light and medium machines. This is partly due to the need for low compression ratios in the compressor. 

When the black box is a compressor, it is mechanical energy that makes the vapor more valuable, and the technique is referred to as mechanical vapor recompression (MVR). The steam temperature in the heating element of the evaporator must give a reasonable AT for heat transfer. This sets the condensing pressure, and the vapor from the evaporator must be compressed at least to that pressure. There is an economic balance to be struck between energy cost and evaporator surface area. Low compression ratios reduce compressor energy consumption but provide smaller temperature differentials and therefore require more heat-transfer surface. 

From Eq. 7.159 it can be seen that the length of the transition section has to increase with the channel depth of the feed section H, with the compression ratio X with the throughput p Vj KiWi, and with the helix angle cp. The maximum possible compression ratio is directly determined by Lj,. A short transition section requires a low compression ratio to avoid plugging. 

Compression could be lossless if it achieves exact reconstruction of the original image and lossy when it includes quantization. In general, lossless compression is preferred in medical applications in order to maintain the data integrity and to expedite accurate diagnosis. However, lossless compression provides relatively low compression ratios when compared to lossy methods. Therefore, certain applications such as telemedicine suffer from this limitation [18]. 

Different types of MCFC-gas turbine (GT) integration are possible. The configuration proposed by Ansaldo Fuel Cells (AFCo) uses the compressor to pressurize the air fed to the FC the FC exhaust is burnt with additional methane in the turbine burner and expanded. This configuration couples the Brayton cycle top pressure and the MCFC pressure, and is most suited for integration with microturbines or in any case with low compression ratios. 

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