What is Exhaust: Definition and 132 Discussions

An exhaust system is used to guide reaction exhaust gases away from a controlled combustion inside an engine or stove. The entire system conveys burnt gases from the engine and includes one or more exhaust pipes. Depending on the overall system design, the exhaust gas may flow through one or more of:

Cylinder head and exhaust manifold
A turbocharger to increase engine power.
A catalytic converter to reduce air pollution.
A muffler (North America) / silencer (UK/India), to reduce noise.Aftermarket exhaust parts can increase peak power by reducing the back pressure of the exhaust system. These parts sometimes can void factory warranties, however the European Union Block Exemption Regulations 1400/2002 prevents manufacturers from rejecting warranty claims if the aftermarket parts are of matching quality and specifications to the original parts.

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  1. A

    I Is there a way to calculate how rocket exhaust gas spreads out in empty space after leaving the rocket?

    I haven't found anything obvious about how rocket thrust gas particles would expand once they leave the thruster of the ship from which it is ejected. Inside the rocket would be the exploding gas, but outside the rocket the temperature would be ~ 3 Kelvin and zero pressure since outer space...
  2. S P

    As much steam as possible from engine exhaust gas + warm water?

    Hi all, The idea is to generate as much as possible water steam from heat of internal combustion engine exhaust gas. The so called steam generation device is a simple sloped engine exhaust pipe where water from engine cooling and hot gas is fed at the top and all the mix is exiting at the...
  3. Optymista93

    Cleaning of the finned tubes on gas cooler without disassembling

    Hi, I've been thinking about the solution for cleaning a water-cooled gas cooler and would love to hear some advice from the smarter people with more experience. Description - I will try to roughly explain the concept. Gas Cooler is used to decrease exhaust gas temperature. The exhaust gas...
  4. B

    The Traditional Bernoulli Eqn Derivation of Rocket Exhaust Velocity

    If you've seen it, they chose one point in the combustion chamber and the other in the exhaust nozzle. I think they're assuming that we have a gas both places. They say that the pressure in the nozzle is atmospheric pressure, or it you're in outer space, zero. That makes perfect sense...
  5. M

    I Making a heat shield for my car's exhaust

    Hello, I'm just wanting to make sure I remember this correctly. I have a hot exhaust pipe I want to shield from fuel lines. So I have a shield (stainless) that is going 1/2 way around the exhaust, with an air gap of about 1". I want to sand blast the side facing the heat and polish the side...
  6. theycallmevirgo

    CNC Laser Exhaust: Need Complete Enclosure?

    I want to set up exhaust to take up fumes for my cnc laser. Do I need to cmpletely enclose it, or can I just put some suction near the cutting head? Thanks so much Joe
  7. V

    Does the exhaust of a truck match the velocity of the truck?

    My doubt is whether its correct to assume that the exhaust is having the velocity of truck when it comes out of the exhaust pipe. So, I am not sure if Ve = Vt. Should not the exhaust come out in a south direction from exhaust pipe since truck is moving in north direction? If yes, then it cannot...
  8. A

    Motion of a rocket with propellant exhaust gas speed = constant

    Now this is how I've tried to solve this $$ v_e = u0 \cdot ln \frac {M} {M- μ \cdot t} $$ After putting in the values I get this; $$ v_e = 200 * ln 0,36 $$ $$ v_e = 73,54 \frac m s $$ Now I'd say that this is the correct way to do it, but this part is confusing me "What is the speed of the...
  9. D

    Automotive Diesel engine parts for post-treatment of diesel engine gas exhaust

    Hi folks, Any idea about what is it? I am required to find parts like these items which are made of stainless steel 304 and used on the post-treatment of diesel engine gas.
  10. D

    DV Calculation clarification (rocket booster)

    When calculating the dV available from a rocket booster, the below calculation is used: (ISP . g) . ln(Mass when full/Mass when empty) Is 'g' always equal to 9.81 in this equation, or do you use the actual gravitational acceleration that the booster will experience, at it's given altitude, to...
  11. G

    A rocket and its gas exhaust velocity

    This isn't right, is it? -\dfrac{GM}{R}+\dfrac12 v^2=-\dfrac{GM}{R+h} v=\sqrt{\dfrac{GM}{R}}\left( 1-\sqrt{\dfrac{R}{R+h}}\right) He's doing energy conservation. The mechanical energy at the Earth's surface is equal to the energy when the speed is 0.
  12. L

    Calculating heat recovery from engine exhaust gases

    Hello, I am doing a study for my final years Uni project, which includes waste heat recovery from gas fuelled engine exhaust. I am using a data sheet for a Jenbacher J620 engine-. In the data sheet it is stated that; exhaust gas mass flow (wet) = 17325 kg hr ( not sure about the wet part?)...
  13. Anon_Miner

    Where do I put this Server Room's air exhaust?

    Hey guys. I have a room which i want to use as a server room. the devices need to work 24/7 and they get pretty hot. so it is imperative to keep the room cool otherwise the devices will be damaged. I have an air vent to bring cold air into the room for the devices so their fans can suck in cold...
  14. P

    HVAC Exhaust flow for the chimney design on a custom boiler

    Hi all 😁 Hopefully it's ok to ask this question here. Ok so my project is a little bit redneck as opposed to being engineered science. I have been experimenting with burning waste oil in my oil furnace in my garage. It is an average house oil furnace with Beckett burner. ( burner has electric...
  15. K

    A Exploring Rocket Exhaust Plume Molecules in the Upper Atmosphere

    I'm pondering the behavior and persistence of rocket exhaust plume molecules far above the atmosphere. For example, the plume from an apogee circularization thrust from GTO (Geosynchronous Transfer Orbit) to GEO (Geosynchronous orbit). CO₂ and H₂O are among the molecular species emitted by a...
  16. D

    Venturi pipe in engine exhaust flow

    I would appreciate opinions on this...on which setup would create the best vacuum in an exhaust gas stream? The #1 drawing is a pipe that has a birds eye cut in it. These are sold for engine crankcase exhaust ventilation. There are some that say they work, then others that say they don't work...
  17. J

    Can I Verify the Flow Rate of an Exhaust Fan Based on Specifications?

    I've been given some specifications by a company for an exhaust fan that I am looking at purchasing for my company. They tell me it is 10,900 cfm. Then given some specs on the electrical requirements. I am wondering with the information given could I check their given flow rate? I imagine that...
  18. Stephen Ryan

    Auto/Motor Exhaust baffle modification

    Hi everyone. I don't have much knowledge in physics but I am trying to take a scientific approach to silencing my motorcycle exhaust. The muffler is a basically a perforated straight-through tube with fiberglass packing (too loud). The baffle (only knocks one decibel off) came as just an...
  19. J

    Water sometimes drips from the exhaust of a running car....

    Homework Statement You may have noticed that water sometimes drips from the exhaust of a car as it is running. Is this evidence that there is at least a small amount of water originally present in the gasoline? Homework Equations not sure if there is one. The Attempt at a Solution I'm not...
  20. H

    Automotive Exhaust brake for gasoline engines

    Everything I've read about them has said they would be ineffective or have very minimal benefit due to lower compression on non-diesel engines and other factors. Yet I am aware of one that sold well in the '80's and '90's and was tremendously effective as a "mountain tamer" in the RV industry...
  21. R

    The diameter of the exhaust nozzle of jet engines

    Hello, Can anybody please tell me the typical diameter of the exhaust nozzle of a jet engine? I know, there are different types of engines and nozzle types also vary. For instance, I am interested to know the typical diameter of the nozzle of a turbofan engine. Thanks
  22. L

    Relative velocity of exhaust in Ideal Rocket Equation

    In this derivation of the Ideal Rocket Equation (https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation#Most_popular_derivation), they use the fact that ##V_e = V - v_e##, or that the velocity of the exhaust in the observer frame ##V_e## is the velocity of the rocket ##V## minus the speed of...
  23. E

    Air motor: temperature of exhaust

    I have an industrial application where 20kW of heat is being wasted, which is painful to watch. I have learned already that low temperature turbines just don't work, so would like to check some ideas and better understand how air motors/turbines work. I have also learned so far that...
  24. T

    Exhaust velocity of a fire extinguisher

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > Hey, For our project we have to think of an experiment that can kind of simulate a rocket. We decided to use a fire extinguisher on a kart, since its mass constantly changes (same with a rocket)...
  25. M

    EGR ratio from exhaust gas composition

    Homework Statement given:-fuel and air mass flow, measured mole ratios of exhaust composition y_i. Let's assume stoichiometric combustion so we have only CO2, H20 and N2 as products. Homework Equations Can EGR ratio be calculated from available data? The Attempt at a Solution I get result...
  26. R

    B Air movement in an exhaust systems

    Hello I'm trying to understand how exhaust systems work .In general I want to understand how air movement changes according to leight of vent tubes. Example I have made little vent system with in lane fan that sucks air out of room. As I understand air speed in tube that is pulling air from...
  27. BitWiz

    B Equation for Relativistic Exhaust Velocity (Ve): Help Needed

    Does anyone have an equation that -- given energy applied to a mass over a distance -- will give me an (ideal) final velocity of the mass? If I direct a gigajoule to accelerate a gram over a distance of a meter, I obviously get into real trouble with c using conventional equations. I've found...
  28. Jason Louison

    Automotive Exhaust Gas Pressure/Blowdown Calculations

    Hi! I am a bit confuzzled by these equations given by a highly referenced and cited paper I have been using to create a spreadsheet I have been working on. The equations are: PV=mRT Where P is the cylinder pressure, m is the mass of gasses in the cylinder, R universal gas constant of the gas...
  29. P

    Exhaust pipe diameter question

    Homework Statement The engine turns at 3000 rpm at this speed. The engine capacity has a displacement of 1.2 litres: this means that 1.2 litres of exhaust gas is expelled from the motor (into the exhaust manifold) every two* revolutions. Further assume that the gas leaves the exhaust pipe with...
  30. P

    What is the exhaust pipe diameter required for the given exhaust speed?

    Homework Statement The problem: Here is an approximate reaction for burning hydrocarbons in air: (CH2)n + 1.5*n O2 + 6n N2 -> n CO2 + n H2O + 6n N2 (n is an integer) The (CH2)n approximates the fuel, and everything on the right is the exhaust. The atomic masses of hydrogen, carbon, nitrogen...
  31. J

    Coal Exhaust Making a Solar Updraft Tower Work

    I was thinking of ways of making carbon cleaner for the environment. One of the ways I came up with is filling a solar updraft tower https://en.wikipedia.org/wiki/Solar_updraft_tower with the exhaust from a gas/coal plant. So you'd get a true greenhouse gas accumulation of heat going in the...
  32. K

    Automotive Can hot air replicate the sound effects of exhaust gases?

    Hey guys, is it possible to replicate the sounds produced by exhaust gases in a car by using only hot air? Thanks in advance for your responses.
  33. A

    Valve Exhaust Port Calculation

    Hi, I am following this particular article from machinedesign.com about properly sizing a pneumatic system - http://machinedesign.com/archive/right-sizing-pneumatic-motion-systems In the section Valve Exhaust Port, he does a calculation for the valve loss coefficient and arrives at 1.833 cfm...
  34. Ali Durrani

    Can Turbulence and Vibrations Affect Exhaust Gas Measurements?

    Hello i have done tests on Exhaust gas re circulation on my engine test bench and these are the results, i don't know what's wrong? but at 8% loading conditions i am getting some weird results the trendlines in the graph shows an increase in NOx with EGR is there any explanation for this ? thanks
  35. Chevreuil

    4 stroke engine exhaust fed to high air flow

    Hello, So say that I have a small four stroke engine that is designed to be kept static at ground level. I then take this engine and mount it to a small air plane, feeding the engine with either still air from inside the cabin (cargo) or the outside wind. The exhaust is fed out to the wind...
  36. C

    Mass of Particulate from fuel exhaust

    I'd like to know that apart from Gases coming out of tailpipe of a vehicle, how much is Solid particle mass exhausted per gallon of fuel? I tried to search but I couldn't get exact answer. e.g. After 1 gallon of fuel burnout, exhaust pipe emits 1 gm or 10 gm or 100 gm of solid particles (PM10...
  37. N

    I Methods to Prove Existence of Tritium in Fusor Exhaust

    I'm looking into a science fair project involving proving the existence of tritium in the exhaust of a Farnsworth fusor, and was wondering what the ideal method to prove it is. I've thought of three so far. The first is ionizing the gas and analyzing the spectra. The second is placing an alpha...
  38. y2j

    Automotive Temperature and mass flow rate of ICE exhaust gas

    Hi everyone I searched about the mass flow rates and temperatures of exhaust gases of light gasoline internal combustion engine at different condition but I don't fond anything yet . Anyone can guide me? .
  39. A

    Could Turbine Exhaust Temperatures Reach Below Zero Celsius?

    Could turbine exhaust temperature be negative Celcius? My calculations yield 176 K. Is that possible? Inlet conditions are 7.8 MPa and 625 K. Exit pressure is 1 atm. (100 kPa.)
  40. David Gin

    Internally Heated Dessicant Air Dryer Exhaust Pipe

    Hi all, Is there a correlation between an Air Dryer capacity and the exhaust pipe diameter? How would a small exhaust pipe diameter (not able to exhaust air enough) affects the capacity of an air dryer? If it does, could you expand on this? Thank you
  41. J

    Quick question about exhaust velocity

    I'm working on some propulsion homework for rockets. Basically combustion happens, and the gas velocity increases. sometimes we use: exhaust velocity = sqrt ( 2*Cp*exit temp) other times we use exhaust velocity = sqrt (2*Cp*(initial temp - final temp)) so the difference is, sometimes exit temp...
  42. T

    Why don't we just block off the exhaust pipe to prevent CO2

    If you were to put a cap on your exhaust pipe your emissions will reduce thus you would solve the whole paranoia of climate shenanigans.
  43. S

    Need help with exhaust system (acoustic/valves/pulse)

    Hi Need some advice regarding my exhaust, I am building a dragbike. Info: Vtwin Engine 45degrees (Harley Shovelhead) I whant to build a 2-1 (both cylinder connected to one pipe) I´ve learned that the primary should be at same length (driveabilty and performance) , If I don't do this, what's...
  44. DaveC426913

    Rocket exhaust and atmosphere

    This is perhaps a somewhat naive question about rocket exhaust. If I understand correctly, one of the challenges in designing a rocket nozzle - say, the main thrusters for the Saturn V - is that it needs to operate efficiently at sea level as well as at altitude. The difference in air pressure...
  45. Basimalasi

    Calculation of the exhaust velocity of a Hot Water Rocket

    inb4 "google it", I did. There aren't a lot of information about this topic. Can a Hot Water Rocket or a Steam rocket ever succeed to reach outer space? I can calculate the exhaust velocity by determining the change in enthalpy I guess but I don't in which state will it exist in and how can I...
  46. T

    Is there a limit on rocket engine exhaust velocity?

    I've been trying to figure this out for days. I'm told that atmospheric pressure imposes a limit on maximum possible exhaust velocity in the Earth's atmosphere, and that under STP conditions that limit is approximately 15,000 feet per second. But that doesn't make any sense. Suppose you had...
  47. K

    Exhaust Header design in 4-2-1

    In exhaust tuning it is well established that a 4-1 header provides the greatest Hp but only at peak rpm. For a more street efficient system a 4-2-1 give more gain at low rpm and moderates the peaks. Conventional design criteria says to tune the primary tubes to reinforce the rpm you want...
  48. David Morgan

    Can exhaust heat be used to reduce automotive drag?

    I was reading a BBC article about the automotive challenges of building a 300 MPH capable, street-legal vehicle and had a the following thought/question: Could one dissipate enough of the considerable exhaust heat generated by these supercars into the front bumper/air-splitter, so that the air...
  49. A

    Determining dimension of exhaust pipe from an air duct

    Hello. I need to determine the diameter of an exhaust pipe coming out of a 14" air duct. The exhaust would be perpendicular to the duct and connect to a vertical stack which exhausts to atmosphere. Supply air is 5000scfm at 2.5psi and 120F going into a gas heater which adds 400scfm air to the...
  50. P

    How can I remove steam from exhaust gases?

    hello I have hot gases with steam (water) inside how do I separate it ? without cooling it magnetic field can help? ultrasound? something else? thanks!
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