Best Answer

In discussing adiabatic efficiency, it is best to first define efficiency. In its broadest terms, efficiency can be defined as the ratio of work output to work input normally expressed as a percentage. With regard to a compression application, one measure of the efficiency of a compressor is the adaibatic efficiency (Volumetric Efficiency being the other). Adiabatic Efficiency is the ratio of the amount of horsepower required just to compress a particular gas (Adiabatic Horsepower) divided by the total brake horsepower required for a praticular type of compressor to accomplish the desired compression. Note that Adiabatic Power is the same regardless of the type of compressor used because it is a function of the physical properties of the gas being compressed, and not the type of compressor doing the work. In other words, it takes a specifc amount of energy to compress a specific volume of gas to a particular pressure and this energy is the same no matter what technology you use to accomplish the compression. Adiabatic HP is the numerator of the equation and is the same no matter what kind of compressor is used.

The denominator of the equation is total brake horsepower (BHP) and it is the total power required for a compressor to accomplish the desirder compression. This will be a larger number as BHP includes adiabatic power plus all the other energy required by the compressor to overcome other losses requiring energy such as drive losses, mechanical friction losses, intake/discharge valve losses, heat exchanger losses, lubrication system power, etc.

Therefore, to answer the question specifically would require information on the specific gas being compressed, flow, pressure, atmospheric conditions, etc. To answer the question in general terms, the rotary vane type compressor will typically have a higher adiabatic efficiency than screw compressors and reciprocating compressors by virtue of the fact that other losses from friction, lube systems, valves, etc. which tend to be significant with screws and recips are not substantial and sometimes not present at all with vane technology. As such, vane compressor total BHP is normally lower than other technologies resulting in higher adiabatic efficiency. Another reason vane machines often have higher adiabatic efficiency is that they are limited to a maximum compression ratio of approximately 4.5 to 1, (depending on the type of gas and the application requirements). As is documented in Marks' Standard Handbook for Mechanical Engineering, as compression ratio increases, both adiabatic efficiency and volumetric efficiency decrease on screws and recips. Therefore, for discharge pressures up to approximately 125 psig, the vane technology, even in a two stage system, will likely be more energy efficient than other compression technologies.

The above is a broad answer to a specific question and the degree to which the efficiency is greater (or not) will vary with the specifics of the application. Adiabatic efficiency is however, a good measure of efficiency and a good indicator of how energy efficient equipment will be once in operation. All the compression technologies mentioned are viable and proven and some are better suited than others depending upon the specifics of the application. For example, as noted above, the vane machine is well suited for relatively high flows and for compression up to about 125 psig. For processes requiring compression above 125 psig discharge pressure, the vane technology is not suitable and screws or recips are likely the more appropriate technologies. Finally, in addition to power cost, buyers should also other factors that impact the cost of ownership such as parts, service, and maintenance requirments when considering compression equipment.

User Avatar

Wiki User

โˆ™ 2011-09-15 11:07:37
This answer is:
User Avatar

Add your answer:

Earn +20 pts
Q: What is the typical thermal adiabatic efficiency of a sliding vane compressor?
Write your answer...
Related questions

How inefficiencies of compressor and turbine affect back work ratio and efficiency of gas turbine?

Inefficiencies in the compressor of a gas turbine cycle increase the back-work ratio and decrease the thermal efficiency of the gas turbine cycle, since they increase the compressor work.

Is it true that thermal efficiency of a diesel engine equals indicated thermal efficiency - brake thermal efficiency?


What is the poly tropic efficiency of the air compressor?

it is the eff of thermal and volumetric efforts done on compressor. the bore stroke volume and the clearance volume is isential in this. to run it most ifficiantly one should have knoladge about all

What are the four thermal processes?

A thermal process refers to any process that uses heat. The four thermal processes are isobaric, isochoric, isothermal and adiabatic.

What is the effect or reheater in the gas turbine?

1.Turbine output is increased for same compressor work. 2.As more heat is supplied,thermal efficiency decreases.

What is the rate of heat output of a Carnot engine?

Power Output / [(1/Thermal Efficiency) - 1], where Thermal Efficiency = 1 - Tc/Th

What is thermal efficiency of petrol engine?

The maximum Thermal Efficiency of Petrol Engine or Gasoline Engine or Otto Cycle Engine is about 25-30%.

What is the thermal efficiency of diesel engine?


Which power plant has maximum efficiency?


What is adiabatic calorimetry?

Adiabatic calorimetry is used primarily for the study of thermal hazards and the consequences of a maloperationduring a process, for instance a misfeedor loss of cooling. This is because on larger scales the effective natural cooling rates are negligible in comparison to heat generation, and many large process vessels can therefore be considered to be adiabatic.An adiabatic calorimeter is designed to simulate the thermal behaviour of larger scale chemical reactors, especially when studying uncontrolled and run-awayreactions.

What is the definition of thermal efficiency?

the efficiency of a heat engine measured by the ratio of the work done by it to the heat supplied to it.

What is the efficiency of an engine that gives off 70 percent thermal energy?

It is not a good efficiency engine.

What is thermal efficiency of a engine?

About 17% if I recall from thermodyanimcs lecture.

If efficiency of converting chemical to thermal energy was 90 percent what would the overall efficiency be?

In saying what the overall efficiency would be, I suppose you mean for other processes, creating the chemical energy for example, and using the thermal energy. This is impossible to answer, not knowing what these processes are.

What is adabatic calorimetric?

The studies focused on uncontrolled and runaway reactions and designed to simulate the larger chemical reactors thermal behavior is called adiabatic calorimetry. It is used primarily for the study of thermal hazards.

What is the formula for thermal efficiency?

Thermal Eff = (mechanical heat produced/electrical heat produced) x 100%

What is the efficiency of an engine that gives off thermal energy?

anal probes

What does it mean to have high thermal energy?

It mean, it had high temperature difference to the surrounding. Quality of thermal energy is upon the temperature due to thermodynamics efficiency. At same thermal energy of 100 kJ refer to 0 oC ambient, a hot bath of 100 oC may have maximum theoretical thermal efficiency of 27% or 27 kJ usable but a hot steam of 200 oC may have maximum theoretical thermal efficiency of 42% or 42 kJ usable.

Friction reduces efficiency because energy is lost as what?

Mainly as heat (thermal).

What is brake thermal efficiency?

The ratio of brake power output to power input

Is it safe to use the unit even if your compressor is over heat?

Compressors have a thermal overload built inside that will shut down the compressor if the conditions are critical.

How does a contracting protostar convert gravitational energy into thermal energy?

Sliding friction tends to convert kinetic energy into thermal energy, thermal energy being heat, kinetic energy being movement.

Efficiency of nuclear power plant?

PWR's and BWR's have thermal efficiencies around 33%, that is the generated power as opposed to the reactor thermal power.

What is the efficiency of thermal power plant?

A modern combined cycle gas turbine/ steam turbine power plant can reach almost 60% efficiency.

Why are heat engines intentionally run at high operating temperatures?

better thermal efficiency.