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What are the boundary condition to simulate flow through vent mast?

Dear all, I am currently working on modeling compressible flows that occur when hydrogen needs to be evacuated (for purging, in case of fire, etc.). I am endeavoring to determine the appropriate ...
Dam's user avatar
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1 answer
49 views

Explanation of phases of fridge cycle from power draw (power factor, reactive and active power)

I've got this power draw graph of my fridge during a couple of cycles. The power factor axis is on the left, active and reactive power axis in watts/VAr on the right. I'd like to understand the phases ...
JavierG's user avatar
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1 vote
2 answers
74 views

What is this hole in some gas related threads

What are those holes for? (Those are for CO2.) Here are a few examples :
Camion's user avatar
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1 answer
91 views

Why are double-acting reciproating compressors more efficient than single-acting ones?

On many websites, I read that double-acting reciprocating compressors are more efficient than single-acting compressors. These sources say it's because they complete two compression cycles on each ...
Daniel's user avatar
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0 answers
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Can rubber be used as the membrane in a diaphragm compressor with a 1:10 or higher compression ratio?

I've been investing time learning about diaphragm compressors and I can't understand how this particular type of compressor can have a 20:1 compression ratio, and what material could stretch that much ...
Boolean's user avatar
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28 views

How do I purchase cylinders of Hydrogen (H2) gas for person use?

I'm interested in building small model airships, and I would like to purchase a cylinder of H2 gas to fill the envelopes with as is far cheaper and more effective than helium. I've contacted some ...
Person Person's user avatar
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0 answers
29 views

What is the optimum layout for a hydrogen compressor, that would have least wear and tear on the compressor?

I have been investing time in understanding the layout/schematic of a compressor that would be used for compressing hydrogen to high pressure ratings. It's not clear to me what is the best design - ...
Boolean's user avatar
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Opposing orientation of multi-stage particulate filter in Nitrogen separation/purification system

I recently purchased an assortment of parts taken out of a Nano Purifications Nitrogen Generator, one of the parts included was a two stage filter for removing particulates from the air stream. The ...
J H's user avatar
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2 answers
157 views

How to calculate the required power to pump out (to vacuum) a container?

Consider I have a cubic container with its volume is 1m cubic as in the simple picture above. It is sealed nicely, it is air proof, no air leaking. I would like to pump out (to vacuum) the container ...
AirCraft Lover's user avatar
0 votes
3 answers
326 views

Can a compressor give the same discharge pressure even if suction pressure varies?

The task is to maintain compressor discharge pressure at 200 bars. The inlet pressure varies with time from 200 bars to 10 bars (emptying a compressed air tank and compressing to transfer it to ...
Aron PE's user avatar
1 vote
2 answers
91 views

Driving an air cylinder with ignited hydrogen/oxygen gas mixture from fuel cell?

Summary: I need to build a linear actuator that has a very fast actuating speed but fits in a very small space. My Question/Idea: Electric gearmotors, c02, and air pressure, are all ideas that come to ...
dutenh's user avatar
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1 answer
102 views

How to transfer high pressure hydrogen using flexible pipes?

The task is to transfer hydrogen (high pressure gas > 400 bars) from offshore platform to land. To do so we have to use flexible pipes but for high pressure and high flow rate I'm afraid we can't ...
Aron PE's user avatar
1 vote
0 answers
35 views

A 40L compressed air cylinder at 100 bar is emptied in pulses at the rate of 41kg/s. How many such cycles would it take to empty the cylinder? [closed]

I am constructing a blowback gas system where clogged debris needs to be removed with compressed air using compressed air cylinder. 40L compressed air cylinder at 100bar pressure is available as ...
Yadunandan's user avatar
-1 votes
3 answers
78 views

How to transfer compressed gas GH2 from one tank to another at the same pressure?

The problem is to transfer all the compressed hydrogen from one tank on a ship at 400 bars to fill another tank on earth (also to fill it at 400 bars). What are the common technologies and equipment (...
Aron PE's user avatar
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0 answers
122 views

How to calculate the gas flow rate?

I am using a Venturi burner fed using a lpg cylinder. I need to calculate the gas flow rate? I am thinking of filling the gas in a balloon/fixed container can take the weight before and after to get ...
Amit Agarwal's user avatar
1 vote
1 answer
80 views

If you shut down a gas pipeline for a few months would you fill it with gas at full pressure?

This is of course inspired by the Nordstream gas pipelines in the Baltic Sea. When it was decided that Nordstream 2 would not start operating after construction finished they still filled it with ...
quarague's user avatar
  • 113
4 votes
3 answers
578 views

What is the maximum possible compression with fuel injection in a gasoline combustion engine?

Maximum possible compression in a gasoline engine was originally determined by knocking in engines with carburetor. With fuel injection the fuel could be injected after compression and thus eliminate ...
David Jonsson's user avatar
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What contributes to the energy cost of multistage compression at high discharge pressures?

I'm getting into hydrogen compression from a theoretical point of view and am looking for a model to describe the energy requirements. I've gathered, that hydrogen is often compressed with piston ...
Eike's user avatar
  • 101
1 vote
1 answer
66 views

Is it feasible to compress cleaned Biogas?

Biogas generated from anaerobic digestion mainly contains around 50-60% $CH_4$, 35-40% $CO_2$, small amount of $N_2$, saturated $H_2O$ and trace of $H_2S$. It's upgraded to automotive fuel grade by ...
Pandya's user avatar
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1 vote
2 answers
221 views

Constant Pressure Variable Volume Tanks

Do constant-pressure variable-volume tanks exist in industry? I've read about water-column and membrane-based designs, do either of these exist as OTS components, and where would one get them? Edit: ...
davedawave's user avatar
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0 answers
155 views

Calculating gas volume in a gas-liquid system/pressurized vessel

There is water in a tank and the tank is connected to a piece of piping that has a volume of 2.5L. The headspace above the water is pressurised by using air, to a pressure of 3 bar (a). What happens ...
Eng101's user avatar
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0 votes
3 answers
63 views

Is it possible to remove a split unit's head, and replace it by a false-ceiling head?

Normal split unit: Ducted split unit: I have: Outdoor split unit that compresses gas. Compressed gas moves down to some room where it connects to some wall-mounted indoor split unit. The indoor ...
caveman's user avatar
  • 123
-1 votes
2 answers
631 views

Energy required to liquify gaseous oxygen?

Does anyone know where I can find some documentation of a real-world liquification process, and the energy costs? I can calculate the heat that must be removed from O2 gas to get to liquid, but how ...
dlight's user avatar
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0 votes
1 answer
131 views

Recommended books for process engineering? [closed]

I made a career change from machine design to CNG processing. What I’m looking for are some good books/handbooks that cover the following topics. Something similar to Machinery’s Handbook. Piping, ...
LSUEngineer's user avatar
1 vote
1 answer
61 views

Replace Hydrogen in an air cylinder

Can we use a gas cylinder made of A6061, meant to carry air up to 300 bar, with Hydrogen up to the same pressure? If not, what is the maximum pressure that one can safely use hydrogen with?
AkhilMadem's user avatar
4 votes
2 answers
295 views

Time-rate of change of P and T in a pressurized rigid volume with a hole in it

I am trying to model the time-rate of change of pressure and temperature of a gas being held within a pressurized rigid volume as it escapes: an unsteady, open system with no heat transfer. Most ...
J. Day's user avatar
  • 49
1 vote
2 answers
106 views

What is the purpose of combustor in a gas turbine

I have read online that a gas turbine converts the chemical energy in the fuel gas to mechanical energy of the turbine blades. The way I see it, because of this hot air one would have to go for heat ...
user110565's user avatar
-1 votes
1 answer
150 views

Should pressure vessel head be thicker than wall [closed]

I wondering should the head of a rectangular pressure vessel cylinder be thicker than the wall ?
richardo tong's user avatar
-1 votes
1 answer
441 views

Relation between Inlet and Outlet mass flow rate for a turbocharger?

For the compressor maps for automotive turbochargers, the Corrected mass flow rate (at inlet) is given as abscissa. However, I wish to know the mass flow rate at the outlet. What is the relation in ...
afterburner77's user avatar
4 votes
4 answers
2k views

Is it possible to increase the heat output of a gas stove by connecting two gas supply canisters to it at the same time, and is it safe to do so?

Here's a typical outdoor gas stove: It is fed by a low-pressure gas supply in the form of a camping cartridge or via an LPG cylinder connected to a low-pressure regulator (around 30mbar) like this ...
WackGet's user avatar
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1 vote
0 answers
21 views

Skelet Theorie, can anyone help?

I am studying Gas dynamics and came across the lift angle approximation as based on Skelett Theorie (in german). I have done google searches on finding this theory but no luck on any information. Can ...
QUTADAH's user avatar
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1 vote
0 answers
65 views

Can any Air rotameter be used for refrigerant gas by using equation conversion?

Currently, I am trying to find rotameter calibrated for R134A gas flow. However, most companies only sell rotameter or variable area flowmeter for water/Air/Nitrogen flow. Is it possible to use any ...
HENG KIM RUI's user avatar
4 votes
1 answer
39 views

gas regulator exhaust gas during diaphragm adjustment?

On my air tool compressor or scuba gear you can see or hear a diaphragm regulator sloughing off a tiny amount of gas to the atmosphere when you adjust the regulator down. Does a natural gas regulator ...
Andyz Smith's user avatar
1 vote
1 answer
40 views

Real life example of motor/piston involving an isoterm process?

So I am involved in an introductory course in mathematics for pilots. I have the following problem I would like to give them, as it can be a practical application of integration However, does there ...
N3buchadnezzar's user avatar
2 votes
1 answer
108 views

Do pressurised cans still pose a risk to bursting in normal conditions, but after being exposed to heat?

We're planning on shipping some items from the US to Australia as you cannot get them here, that being: https://www.chewy.com/sentry-stop-that-noise-pheromone-dog/dp/56486 I have been in contact ...
Brett's user avatar
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1 vote
0 answers
68 views

Injecting CO$_2$ into water: how does injection work?

I've been wanting to design my own water carbonation device for a while. For reference, I've been looking at devices like the Sodastream, which injects pure CO$_2$ into water to dissolve it with up to ...
asoftbird's user avatar
0 votes
2 answers
127 views

Ideal gas law, theory vs reality

I am trying to get an idea of the amount of hydrogen that I can store in some pressurized steel tanks underground. Based on the ideal gas law PV=nRT I did a simple calculation pressure = 200bar ...
sean's user avatar
  • 13
0 votes
1 answer
34 views

hydrostatic storage of gasses

This question is a bit general but hopefully someone can point me in the right direction. If you have a metal container, welded shut that's fitted into a hole that is say 10 meters wide and 30 meters ...
sean's user avatar
  • 13
2 votes
0 answers
19 views

Parts needed for controlling vacuum line pressure with pressurized nitrogen

I'm trying to assemble a simple setup where a line which is typically under vacuum can be pressurized by an external nitrogen supply, with this pressure regulated to less than 1 bar absolute (let's ...
Gino's user avatar
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0 votes
2 answers
7k views

Calculating mass of gas in container

Given pressure is directly proportional to density, my understanding is that you can use the pressure of gas in a container to calculate the mass of the gas in the container. My reasoning being; $p=k\...
PhysicsGuy123's user avatar
1 vote
2 answers
363 views

Cheapest way to measure gas flow (mass)?

I understand that there are quite a few fairly simple and cheap methods to measure the flow of gas in terms of volume, allowing you to get a flow rate in terms of litres per minute for example. ...
PhysicsGuy123's user avatar
1 vote
1 answer
150 views

Do you adjust gas flow rate (SCCM) to volume of chamber?

If I am carrying out a reaction by flowing 200 SCCM of a gas in a 20mm diameter pipe at 100mm length, if I change the pipe diameter to 10mm: Do I adjust the mass flow rate of the gases? If so, how do ...
Luck's user avatar
  • 13
2 votes
0 answers
68 views

How to balance flow and pressure in nitrogen purged chambers?

I have an instrument that is technically a humidity controlled chamber. It measures how much moisture is picked up by the sample through a microbalance(Zone 1). Nitrogen gas flows from zone 3 and ...
Zaid assaf's user avatar
0 votes
2 answers
1k views

Is it standard practice to use a pressure relief valve as a pressure regulator?

I'm attempting to understand the difference between a pressure relief valve and a pressure regulating valve. From my research far, I've come to the following conclusion: Pressure relief valves are ...
Izzo's user avatar
  • 189
2 votes
2 answers
1k views

Lpg cylinder to compressed air tank

I am building a small robot having pneumatic system. I am using 12v car tyre inflator as my compressor.But i didn't find any 3ltr to 6ltr standardrd air tank. Can i convert my old 3ltr lpg tank into ...
Suman Ponmathan's user avatar
0 votes
1 answer
2k views

compare l/min output of CO2 pressure reducer to bar (compressed air)

I have a pressure reducer calibrated for Argon and CO$_2$ output. If I connected it to a gas tank with compressed air, how can I convert the output information "liters of Argon / CO$_2$ per minute" to ...
muffel's user avatar
  • 123
2 votes
1 answer
562 views

volume comparison of compressed air and gas duster

I'm currently using 400ml Dust Off 67 gas dusters and want to replace them with compressed air and a blow-out gun. In order to select the right equipment and get a better understanding I would like ...
muffel's user avatar
  • 123
12 votes
1 answer
3k views

Why was Freon used in spray cans before it was declared a threat to ozone?

I've heard that in the past, spray cans (aerosol cans) contained Freon. I found that the Montreal Protocol made the usage of Freon illegal due to its effect on the ozone layer, but I can't find the ...
Physther's user avatar
  • 614
0 votes
0 answers
69 views

Roskam Book equation of dry air density is not clear. I need explanation

Preface: Roskam in book "Airplane Aerodynamics and Performance" explains (in paragraph "1.1 ATMOSPHERIC FUNDAMENTALS"): To determne how water vapor affects air density, consider a given volume ...
p.pensopositivo's user avatar
2 votes
1 answer
1k views

Isentropic flow equation derivation

I am trying to derive the isentropic flow equations for a compressible gas by myself and at the end, I have different formulation than the one in the literature. Can you please tell me what am I doing ...
Physther's user avatar
  • 614