Suction temperature

The measuring of temperature rise permits monitoring efficiency for a fixed pressure ratio and suction temperature. Efficiencies should always exceed 0.6, and 1.00 is approachable in reciprocating devices. Their better efficiency needs to be balanced against their greater cost, greater maintenance, and lower capacity. 

TI = Suction temperature, °R P, Pi = Suction, discharge pressures, psia K = Adiabatic exponent. Cp/C,... 

Suction temperature Discharge temperature Suction pressure Discharge pressure Isentropic exponent Specific gravity Percent clearance ... 

To provide flexibility for an eventually higher suction temperature ... 

The minimum recommended saturated suction temperature on single-stage reciprocating applications, column (J), is based on a compression ratio of about 9 to 1. The refrigerants 114, 11 (soon to be replaced by R-123), and 113 are not included due to the large cfm/ton. 

The minimum recommended saturated suction temperature on series multistage reciprocating-centrifugal applications, column (K), represents an approximate reasonable limit on suction temperature. The temperatures shown correspond to suction pressures below atmospheric. 

One compressor has two different suction temperatures (stages) and a second compressor has one. Both compressors discharge to same condenser. 

Condition 1 Figure 12-12. Start of the compression stroke. The cylinder is full of gas at suction pressure and essentially suction temperature (neglecting valve loss). The piston moves during compression toward condition (2) with suction and discharge valves closed. 

If Perfect Intercooling between Stages,c Intercooler Pressure Suction Temperature after Interceding Saving due to Jacketing bp Cylinder Adiabatic Compression... 

Loss Factor. The loss factor is a correction fector for standard horsepower curves for high suction pressures at low ratios of compression. The bhp (brake horsepower) is obtained from the curves. Figures 12-21A-C. These curves are a plot of the n or k value of the gas versus the required brake horsepower (required to compress 1 million fti of gas at 14.4 psia and suction temperatures) for various ratios of compression. 

Note that actual capacity at 14.4 psia and suction temperature = (PD)(E )(Pi)(100). Therefore, the bhp value given previously is in the correct units for the curves of Figure 12-21. 

Figure 12-22 presents a convenient solution to this relation. The value of 5/ read from the chart times the absolute suction temperature gives the discharge temperature T,. Thus,... 

Because the cooling water temperature is low enough to allow good cooling, cool the gas to 95 °F. This will be the suction temperature to the second-stage cylinder. 

A mixture of 3,000 scfin, dry basis, (14.7 psia and 60°F), 60% methane and 40% nitrogen is to be compressed from 16 psig to 3500 psig. Suction temperature is 90°E Intercoolers will use 85°F water cooling gas to 90°F, and the installation is essentially at sea level. The gas is saturated with water vapor. Five lb pressure drop is to be allowed for the interstage coolers. 

Vapor pressure of water at cylinder suction temperature of 90°F is 0.6982 psia. 

Brake horsepower per 1 million ft /day measured at 14.7 psia and suction temperature using 75% overall compressor efficiency is given in Figure 12-68, and a volume correction factor is shown in Figure 12-69. 

Figure 12-69. Correction factor for compressor bhp/million ft per day at 14.7 psia and suction temperature versus suction volume. (Used by permission Dresser-Rand Company.)...

Material Capacity Suction pressure Suction temperature Discharge pressure Discharge temperature Compressor speed Single-cylinder, double-acting... 

Pv = the vapour pressure of the liquid at the pump suction, N/m2, p = the density of the liquid at the pump suction temperature, kg/m3. 

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