Questions tagged [compressors]
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43
questions
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2answers
65 views
why not put the compressor right next to the evaporator?
the cold line from evaporator to compressor will gain tons of heat on a super hot day even with insulation. if they put the compressor right outside the evaporator, both of the long lines will be hot ...
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0answers
16 views
Ignoring Mechanical Material Properties and Design Implications, in a Compressor, does the Thermal Density of the Blades Affect Efficiency?
Consider an ideal adiabatic compressor, ignoring the remainder of the thermodynamic cycle. In this case, the heat flow q into and out of the compressor itself is zero, by definition of adiabatic ...
2
votes
1answer
142 views
What is diffusion in the context of compressor?
When studying about the axial compressor, I came across the term 'diffusion' being used to explain the conversion of kinetic energy to pressure, also terms like 'diffusion factor'. What is being ...
1
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2answers
27 views
Is there a way to calculate mass flow rate of an axial compressor?
Is there a rule of a thumb equation for the mass flow rate of a stationary axial compressor at sea level, using intake area and RPM? Or do other factors like blade geometry make too much of a ...
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2answers
26 views
Compressing gas with liquid
This question, in short, is: Can a gas be compressed with high pressure liquid?
As a scenario, imagine a tank full of atmospheric gas at STP. Could something like a pressure washer pump (in this case ...
0
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0answers
20 views
In a throttling process do we consider static pressure or stagnation pressure and is there a reverse throttling process?
In a throttling process, the 'pressures' decreases whereas the enthalpy and so the 'temperature' remains constant. Are these pressures and temperatures static values or the stagnation values?
I am ...
0
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1answer
92 views
Why stagnation temperature doesn't change in stator
I was going through a review of rotary compressor and i understood that the stagnation pressure and stagnation temperature both change in the rotor stage (as energy is being added).I also read that in ...
0
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0answers
41 views
Force of Jet from Air Compressor
I want to use a compressor to create a jet of air. At discharge from compressor how much CFM (Cubic Feet per Minute) are enough to create a force that can turn a heavy object (say 40 kg) at 3 rev per ...
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0answers
52 views
Could I define an isothermal efficiency?
There's an adiabatic efficiency because real processes can't be adiabatic.
I want an isothermal compression (yes, I know an adiabatic compression consumes less work, but my pressure differential is ...
4
votes
1answer
140 views
Is Scrooge's giant glass dome feasible in real life?
In an Uncle Scrooge (or Scrooge McDuck, not sure of the translation here) comic named "Treasure Under Glass", Scrooge orders a giant glass dome to be manufactured in order to aid his endeavours ...
0
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1answer
24 views
Pressure delivered to an object under a pneumatic press
I'm hoping some kind person can tell me if I have this right or not. I swear this isn't a homework problem.
I'll be using a heated pneumatic press to heat seal lidding to plastic containers (...
0
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2answers
68 views
If the turbine drives the compressor, then what limits the engine speed?
My understanding of a typical jet engine is that when running, the turbine extracts energy from the hot exhaust gases. This drives the turbine, which is coupled to the compressor at the front of the ...
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2answers
10k views
Define Free Air Delivery for an air compressor
Free Air Delivery (FAD) is a common measure of the capacity of an air compressor. I have a question that comes at the end here. My question is a little different from what you might be expecting. So ...
2
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1answer
68 views
Recommended compressed air source and location for separate air compression system
I am investigating what would be the most appropriate compressed air source (fan/blower/compressor) for designing a separate air compressor system.
The information is as follows:
the compressed air ...
1
vote
1answer
154 views
Force to compress flexible elastic tubing
How would one work out the force required to compress flat, using a flat bar on top pressing down, a thick walled (15mm OD 10mm ID) piece of flexible plastic (PVC) tubing i.e. so reducing the x-...
0
votes
1answer
837 views
What is the reason for a reduction in entropy in a compressor
I was under the impression that the entropy reduction in a system only works with either mass or heat transfer.
While I was researching intercooling of compressors I stumbled across a peculiar ...
1
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0answers
86 views
Adjusting the pressure of the condenser and the evaporator
The picture below shows a refrigeration unit
I was reading the operation manual of this unit. It is written that the pressure of the condenser is controlled by the water flow rate. Reducing water ...
1
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1answer
69 views
can we run rotary compressor of Air conditioner with different frequency level?
I am working on split type AC compressor. I actually want to know, if i changed the frequency of the compressor to run on different power level, will it affect the life of the compressor. My actual ...
1
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1answer
55 views
What will remain constant during the circulation of working substance in a refrigerating machine? [closed]
For Example, the pressure of evaporator can be changed, also the pressure of condenser and many more parameters. What is that parameter which remain constant while others keep changing ?
-1
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2answers
79 views
Good or bad (AC Split compressor input with cold freon)
Hermetic Compressor is used by split Air Conditioning unit. The compressor compressed freon gas coming from indoor unit. The gas is usually quite cold (about 2 deg.C lower than inside room temperature)...
0
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1answer
28 views
Compression and check valves
Pressure pumps are used to apply pressure to a system. What would happen if someone attempted to fill, for example, a bicycle tire (with a check valve) to 2 ATM of pressure using a pressure pump that ...
0
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1answer
60 views
Axial compressor - change of temperature not proportional to number of blades and their geometrical properties?
I'm learning theory of axial compressors for my summer internship and I find some of the equations puzzling, although I do understand the way they were derived.
The equation bellow is for temperature ...
0
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1answer
34 views
Help me find a paper/textbook on axial compressor in turboshaft engine [closed]
I'm trying to calculate the values of pressure, temp, speed and density of air going through an axial compressor (12-stage) a helicopter. I've read a few bachelors' thesis and papers but wasn't able ...
0
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2answers
114 views
What is a good non-combustible oil to be used in air compression regenerative braking/energy storage system for cars, buses, and trucks?
An important energy storage method that is being given very little consideration is gas compression. The kinetic energy of the vehicle can drive an air pump or compressor that would compress air into ...
1
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1answer
2k views
Air Conditioners: Compressor Explosions?
In this piece of news it is said that an Engineer and Blogger named Utpal Chakrabarti has died after explosion of air conditioner compressor.
My question is, how dangerous air conditioners are? Which ...
1
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4answers
179 views
What type of air blower/compressor to use?
I need a way to move air which is somewhere in between a compressor and a fan: something along the lines of 20-40 cfm at 2-3 psi (500-1000 liters/minute at 10-20 kPa).
Typical small compressors (of ...
6
votes
1answer
612 views
Is a 3 Hz beat frequency from my neighbor's HVAC a sign of a malfunction?
I'm being annoyed by a pulsating hum which comes from my neighbor's HVAC system. I read up a little on the design of HVAC systems and I came to a tentative conclusion that what I'm hearing is a ...
1
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3answers
2k views
Could an air compressor be used to compress steam?
Could an air compressor be used to compress steam? What would be practical problems if any?
Say I have saturated steam at 1 barg and I need to compress it to 2 barg. In theory could I just pipe to ...
1
vote
1answer
112 views
Is the efficiency of a reciprocating air compressor constant for all allowable values of Pressure?
Efficiency = Actual Mass displaced by the compressor divided by the theoretical mass displaced.
If we continuously increase the pressure in the compressor tank, will the efficiency stay roughly ...
1
vote
3answers
2k views
What is the difference between a piston and a plunger compressor/pump?
My research has found a Quora link and another source giving two different, albeit not contrasting, definitions. Also, as far as I have seen, looking up "plunger compressor" also refers me to pumps.
...
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4answers
508 views
How does a stator convert velocity into pressure?
I'm looking for, hopefully, a qualitative answer to how a compressor increases pressure. I understand the equations that predict this result but I can't picture it in my head.
A rotor spins, ...
3
votes
1answer
604 views
Volumetric efficiency versus pressure ratio for rotary compressor
I am trying to plot the efficiency graph of a rotary compressor.
I already calculated the volumetric & polytropic efficiencies and the graph versus evaporating temperature is as follows:
Now i ...
0
votes
2answers
28k views
How does loading and unloading work in an air compressor?
I am looking at an ammonia refrigeration unit and trying to understand how loading and unloading solenoid valves work? and also how to modulate the compressor motor over a period of time.
2
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2answers
496 views
Why no hydraulic piston gas compressors?
I've been looking at solutions to compress gases and getting stunned by the cost and maintenance requirements of existing systems to fill cylinders (whether for SCBA or chemical storage) to 2000-...
4
votes
2answers
271 views
What are these bent shapes on this elbow in a compressor suction pipe?
See here are the shapes which are made on the suction head of compressor,
What are these, and why are they on the suction head pipe?
2
votes
1answer
205 views
Air tool to compressor backflow
As I was reorganizing my air tool arsenal, a theoretical question popped in my mind I'd like to know the answer to. In designing air flow between an air compressor and a tool (such as a nailer or an ...
2
votes
1answer
66 views
Lightweight Air Compressor
I need a small air compressor for a robotics application. I currently have one of those 12V tire inflators (200 psi, 1 CFM or so) that is sized well for this purpose (sample image below).
However, in ...
2
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0answers
56 views
How are small refrigerator compressors started?
Small refrigerator compressors in the US generally all have exactly the same design and I am trying to understand their starting mechanism better. How exactly does it work?
What I generally ...
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2answers
801 views
How can flow in a centrifugal compressor at fixed conditions vary?
Consider a centrifugal compressor. The compressor map usually plots the adiabatic head vs volumetric inlet flow for rated conditions of pressure, molecular weight and temperature at a given speed. But ...
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votes
1answer
1k views
Finding the mass in the tank of an air compressor from gage pressure
I am solving the following problem:
The tank of an air compressor has a volume of 3 cubic feet and is
filled with air at a temperature of 40 °F. If a gauge on the tank
reads 150 psig, what is ...
5
votes
2answers
571 views
Gigapascal pressures in a small package
How small/compact can a pump or other mechanism be, that would allow compressing gas (or liquid) to pressures of excess of 10GPa, continuously?
Throughput may be minuscule, of order of milligrams per ...
7
votes
2answers
857 views
How does a compressor know to lower condensing pressure in chiller?
I am working on an indirect ammonia chiller that is used to cool the ice in an arena. The system consists of 3 reciprocating compressors, an evaporative condenser with a vfd on the fan, a float ...
2
votes
2answers
2k views
Typical power consumption of large compressor
This one should be easy to answer by looking at the thermodynamics, but I find it not to be. Say we have a natural gas stream, ~700 N∙m3/h, that we want to compress from 16 bar to 250 bar. What will ...
