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A reciprocating compressor or piston compressor is a positive-displacement compressor that uses pistons driven by a crankshaft to deliver gases at high pressure. [ 1 ] [ 2 ] Pressures of up to 5,000 psig are commonly produced by multistage reciprocating compressors.
The industrial compressor overload is a capacity limit and requires high power levels to pass the high flow rates required. [31] Excess power is available to inadvertently take the compressor beyond the overload limit to a hazardous condition on cold days if it is driven by a gas turbine.
Centrifugal compressors are the largest available compressors, offer higher efficiencies under partial loads, may be oil-free when using air or magnetic bearings which increases the heat transfer coefficient in evaporators and condensers, weigh up to 90% less and occupy 50% less space than reciprocating compressors, are reliable and cost less ...
In all, the higher heating value of hydrogen is 18.2% above its lower heating value (142 MJ/kg vs. 120 MJ/kg). For hydrocarbons, the difference depends on the hydrogen content of the fuel. For gasoline and diesel the higher heating value exceeds the lower heating value by about 10% and 7%, respectively, and for natural gas about 11%.
The most efficient cycle is the Atkinson Cycle, but most gasoline engine makers use the Otto Cycle for higher power and torque. Some engine design, such as Mazda's Skyactiv-G and some hybrid engines designed by Toyota utilize the Atkinson and Otto cycles together with an electric motor/generator and a traction storage battery.
Surging takes place when compressor is operated off the design point and it affects the whole machine and this is aerodynamically and mechanically undesirable. It can damage the rotor bearings, rotor seals, compressor driver and affect the whole cycle operation. It results in high temperature, high vibration and leads to flow reversal. [4] [11 ...
Absolute cylinder pressure is used to calculate the dynamic compression ratio, using the following formula: = where is a polytropic value for the ratio of specific heats for the combustion gases at the temperatures present (this compensates for the temperature rise caused by compression, as well as heat lost to the cylinder)
In a reciprocating compressor, this can be achieved by using a finned piston [10] and low cycle speeds. [11] Current [when?] challenges in effective heat exchangers mean that they are only practical for low power levels. The theoretical efficiency of isothermal energy storage approaches 100% for perfect heat transfer to the environment.