Compressor efficiency parallel compressors

Calculation of the specific work and the arbitrary overall efficiency may now be made parallel to the method used for the a/s cycle. The maximum and minimum temperatures are specified, together with compressor and turbine efficiencies. A compressor pressure ratio (r) is selected, and with the pressure loss coefficients specified, the corresponding turbine pressure ratio is obtained. With the compressor exit temperature T2 known and Tt, specified, the temperature change in combustion is also known, and the fuel-air ratio / may then be obtained. Approximate mean values of specific heats are then obtained from Fig. 3.12. Either they may be employed directly, or n and n may be obtained and used. 

Offer standby (cold) redundancy, so as to reduce the potential for full pressure leaks from the parallel compressors—this would have an adverse but tolerable effect on the production efficiency... 

This result requires some explanation. An argument was given by Denton [6], who pointed out that the expansion of the mixed gas (I + ip) from to may be considered as a combination of unit flow through the turbine from T3 to T4, and an expansion of a flow of (/(from T2 to 7), through a reversed compressor (Fig. 4.2). The cycle [1,2,3,5,6,1] of Fig. 4.2a is equivalent to two parallel cycles as indicated in Fig. 4.2b a cycle [1,2,3,4,1] with unit circulation plus another cycle passing through the state points [1,2,2,1] with a circulation tp. The second cycle has the same efficiency as the first (but vanishingly small work output) so that the combined cooled cycle has the same efficiency as each of the two... 

Figure 12-46D, Part 1. View toward inlet of 4 Vj-in. diameter brazed aluminum impeller. Note Regardless of the metal of manufacture, enclosed impellers with back-leaning blades are extremely useful in applications requiring a steep head-volume characteristic and the highest attainable efficiency. Applications include parallel operation with other compressors or boosting of another compressor s output. The power-volume curve will show a self-limiting feature at higher volumes. This feature is very beneficial when the driver has limited power available but operation throughout the full capacity range is required. (Used by permission A C Compressor Corporation.)...

A greater difficulty arises where the compressor may go down to 33% or 25% capacity and the thermostatic expansion valve is called upon to control a much reduced flow Under such conditions, the thermostatic expansion valve maybe unstable and hunt , with slight loss of evaporator efficiency Since the required duty is less, this is of no great importance. It is possible to fit two expansion valves in parallel, one for the minimum load and both for the full load, but this arrangement is not usually necessary... 

Which is more efficient—my beat-up, old centrifugal compressor, or my brand-new reciprocating compressor Both machines are working in parallel, but which has a better adiabatic compression efficiency ... 

Let us assume that a reciprocating compressor has two cylinders working in parallel. Each cylinder has both a crank-end section and a head-end suction, where gas is compressed. In effect, we have four small compressors working in parallel. The inlet and outlet pressures, and hence the compression ratio, for each of these four minicompressors, is the same. The relative efficiency for each minicompressor is then... 

The improvement in availability and production flow from introduction of parallel redundancy to the compressors is of 3.7% resulting in 99.7% production efficiency. 

In this study we saw that a plant modification involving introduction of parallel redundancy to gas compressors provided a 3.5% increase in production efficiency, but a 30% increase in individual risk to a sensitive location. 

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