Questions tagged [combustion]

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Fastest possible mean (peak?) piston speed on a Diesel engine

On a Diesel engine running distillate fuel (the kind you run in cars, SUV's, trucks, trains, boats, and smaller ships), what are the theoretical and practical limits to maximum mean piston speed you ...
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73 views

What methods should I use to calculate the size of a moving grate incinerator

I have been tasked with calculating the size of a moving grate incinerator for a college project. I have calculated the mass and energy balances for the waste to be burned on the grate, but I am ...
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52 views

How to calculate the amount of fuel required and time to preheat a furnace's combustion air to 850 C

I am designing an incinerator to combust MSW producing a flue gas of 1000 °C. A requirement of the furnace is that the air inside must be preheated to 850 °C through the use of auxiliary fuel burners ...
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2 answers
84 views

Why this engine can work without a timing belt? [closed]

Is it possible that this tiny engine work without timing belt? I have seen the schematics of it and it pretty much rely on holes in the middle of piston to get the hot gas out whereas the ignition is ...
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2 votes
1 answer
110 views

Out of the three types of Stirling Engines, which one is the most efficient and delivers the most amount of power?

I was thinking that the beta Stirling engine would be the most efficient as it has a displacer to block heat transfer from the hot to cold regions in between thermodynamic cycles. However, I heard ...
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2 votes
4 answers
464 views

Is high pressure combustion hotter than atmospheric pressure combustion

let's say i have the same quantity of coal and air. Will the combustion achieve higher temperature if the air is under pressure?
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5 votes
1 answer
190 views

How do I choose a blower design for an induced draft brick kiln?

I am responsible for a brick kiln in the Punjab province of Pakistan. My government requires all brick kilns to be upgraded to match recent new standards, which include the addition of a blower near ...
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Comparing EPA emission limits between wood stoves and wood furnaces

Emission limits set by the EPA were updated in 2020. Currently, "Wood-burning stoves" are allowed 2.5 grams/hour of smoke emission [1]. On the other hand, "Wood-burning forced-air ...
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1 answer
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Theoretical maximum pressure from combusting LPG

I am curious how to find or estimate the theoretical maximum pressure that the combustion of a LP gas, such as propane, can produce inside of a constant volume, such as in a cylinder. I know what the ...
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1 vote
0 answers
77 views

A Variable Valve Timing (VVT) engine with exhaust GT added, with and without Turbo Charger applied to the crankshaft?

This topic is the follow-up to the original topic: Why are turbo compound engines not more widely used? Why are turbo compound engines not more widely used? Please, do understand that I am a pure ...
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2 votes
1 answer
67 views

Ash size particle dependency of initial coal particle size in fluidized bed combustors

I'm looking for information on coal ash size in fluidized beds. How dependent is it on the initial coal particle size? Would I expect ash from 5mm coal particles to be significantly larger than ash ...
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1 vote
2 answers
64 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 ...
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1 vote
1 answer
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Can I increase the range of a howitzer by using more propellant?

The muzzle velocity of a firearm can, all else equal, be increased by lengthening the barrel of the weapon which can theoretically be extended up to the point that friction and air resistance would ...
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3 votes
1 answer
84 views

Can we currently achieve 55 MPG on Non-Hybrid vehicles using internal combustion engines?

With recent debates, one frequently hears that it's currently not possible for car manufacturers to meet the 55 MPG energy efficiency rating required by 2025. So, is there something physically ...
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3 votes
1 answer
37 views

Recovering mechanical energy from natural gas water boiler

Is there any heat energy lost to the mechanical force of pushing a piston in a combustion engine? In other words, would a natural gas burning as a flame produce more heat than the same amount of ...
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1 vote
1 answer
386 views

Trouble with Valveless PulseJet

My friend and I are working on building a valveless pulsejet out of sheet metal. We initially built a small one (a few feet in length) using the below dimensions: The issue was that we were unable to ...
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-1 votes
1 answer
548 views

Calculating Mass Fractions of a Hydrogen and Oxygen Gas Mixture Pre Ignition

I am trying to calculate mass fractions of a Hydrogen Oxygen gas mixture as a function of equivalence ratio before ignition. My work is the following: Equivalence Ratio: $$\phi=\frac{FA}{FA_s}=\frac{\...
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2 votes
1 answer
75 views

Effect of Pressure on Combustion efficiency (of hydrogen) in excess air

Can somebody explain relation between combustion efficiency and pressure in lean mixtures using any kind of chart or mathematical equations? At first glance I thought, combustion efficiency increases ...
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1 answer
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Engine Combustion Cylinder Wall Thickness

Been referencing this website for some time but now need to seek specific help. I am not an engineering student but rather a DIY hack who loves engineering and machining neither of which I am ...
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1 vote
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Search for comprehensive term for plants with heat generation with heat storage and operating states

My master thesis deals with systems with several operating states that generate heat and store it in a heat storage. Thereby I analyze combined heat and power plants with combustion engines, but also ...
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0 votes
1 answer
73 views

What are the non-practical features of a sterling engine that cause the internal combustion engine to be used instead?

What are the non-practical features of a sterling engine that cause the internal combustion engine to be used instead (in a car)? (e.g. price, size, the power to weight ratio, etc.) Can you name any ...
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2 answers
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Where the Water Have Gone from Engine from a Combustion Process (C8H18+12.5O2==>8CO2+9H2O)?

During studying engine's exhaust as I asked here, I have to go far. The thing I though is quite simple, the fact is complicated. Thence I knew that there is water produced in combustion process. The ...
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1 vote
0 answers
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What is the principle behind controlling thermoacoustic combustion instability with a speaker?

From "ThermoAcoustics and the Rijke Tube: Experiments, Identification, and Modeling", thermoacoustic instability can be subsided using an amplifier and a speaker. It says in page 4, The microphone ...
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1 vote
1 answer
52 views

Why to compress the hydrogen + air mixture in Hydrogen ICE engines when combustion efficiency of hydrogen at 1 atm is already high?

ICE Engines are designed to burn the fuel and air mixtures at high pressures to increase the combustion efficiency. But hydrogen combustion efficiency is already high at 1 atm and at constant Volume ...
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1 vote
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Measurement of ICE torque

I'm seeking a precise description of engine torque. We talk about torque in terms of the twisting force that the piston exerts on the crankshaft with a radius equivalent of the rod throw. Assume these ...
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Heat of Combustion, Vaporization tables

It's my first time posting on this specific forum. I hope I'm doing this right. I am currently modeling fire spreading through different buildings via FDS, but I lack the properties of the materials ...
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3 votes
3 answers
3k views

Preheating Diesel before injection?

Significant amount of heat is lost from an engine by various means, so to recoup the energy, is it possible to increase efficiency via heating of diesel fuel prior to injection using waste engine heat ...
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7 votes
2 answers
247 views

Why afterburners are needed instead of burning more fuel inside the turbine?

I'm reading this article on afterburners: https://www.airspacemag.com/flight-today/how-things-work-afterburners-18481403/ It says in the article: A typical jet engine uses only about half the ...
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5 votes
2 answers
184 views

How to calculate the pressure loading of a vented silo explosion?

I would like to independently check a vendor's silo design for proper explosion venting. Worst case, it is essentially cylinder filled with a stoichiometric mixture atomized sugar dust and atmospheric ...
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3 votes
3 answers
61 views

Advice on simple spark ignition system

I'm looking for any tips on a simple and cheap means of generating a regular spark for ignition of propane in air, could be electrical or other but needs to be simple and fairly reliable. Criteria ...
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0 votes
1 answer
85 views

Can a water pressure switch be used as a low-water cutoff means for a steam boiler?

Steam boilers obviously need to be protected from the catastrophe of running out of water -- you then either get a meltdown if the boiler is fired unwatered for an extended period of time or a boiler ...
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0 votes
1 answer
55 views

Magnetohydrodynamics, ionizing combustion exhaust then converting its kinetic energy to electricity

I am trying to understand how to make generation of electrical power more efficient by using Faraday's law to directly convert the kinetic energy of the ionized or easily ionizable exhaust gases of ...
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-1 votes
1 answer
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What is the real CO2 emission for cars? 1g/km or >100g/km?

If one searches for the different levels of CO2 emissions in cars, one can find two very different levels. For instance: 1: Here it is written that: The law requires that the new cars registered ...
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9 votes
5 answers
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Why is "regular" gasoline standard instead of something more knock-resistant?

The standard light petroleum distillate for vehicle engines, "regular gasoline," is (or is equivalent to) some mix of heptane (C7) and octane (C8). Higher proportions of C8 are more knock-resistant, ...
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0 votes
1 answer
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IC engine where the piston is the spark plug

I recently had an idea about the design of an internal combustion engine. Normally, the spark must be timed using some kind of circuit, but if there was a "spike" on the piston: then would there be ...
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3 votes
2 answers
516 views

Why is soot produced in diesel exhaust, since diesel runs lean?

Since diesel runs lean, why is soot produced in diesel exhaust? Soot is carbon particles due to incomplete combustion. But, since diesel runs lean with plenty of oxygen, why does this happen?
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1 vote
2 answers
2k views

How do you prevent ignition of the gas-air mixture before it reaches the burner nozzle?

I believed that the flame propagates over the place where fuel contacts the oxygen. If it contacts a fule+O2 mixture, the mixture inflames as well, and so on and on and on until there is no more ...
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1 vote
2 answers
824 views

How can I estimate the rate of consumption of oxygen in a car engine?

I need some approximate figures for how many litres of oxygen per minute a typical car engine requires. How would I estimate this?
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2 votes
0 answers
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How is the reaction progress variable $c$ coupled with Temperature equation while solving the SIMPLE algorithm in CFD?

While solving the Navier-Stokes equation using SIMPLE algorithm, we solve the transport equation for additional scalar at the last step according to the SIMPLE's procedure. We need to add a new ...
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4 votes
2 answers
116 views

Viscosity of select species at atmospheric pressure for very large temperatures?

I'm dealing with hot combustion products flowing through heat exchangers and I'd like to perform some calculations regarding the flow properties (velocity, temperature, pressure and density) as it ...
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5 votes
3 answers
2k views

How to increase the speed of exhaust gas?

I have a tube, at the bottom of the tube is burning wood and an air inlet. How can i increase the speed of the exhaust gas coming out of the tube? I thought about "bottle-necking" the exhaust pipe to ...
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  • 417
5 votes
1 answer
918 views

Why does hydrogen fuel produce less horsepower than gasoline in internal combustion engines?

I was looking at hydrogen as alternative fuel and came across an article stating that although $\textrm{H}_2$ produces more energy than conventional fuel, it produces less horsepower in internal ...
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4 votes
2 answers
91 views

What surface temperature (rise) is required to (dis)qualify a combustion appliance from obtaining a "zero clearance to combustibles" rating?

How far must the surface temperature of a UL-listed combustion appliance rise to prohibit the manufacturer from specifying it for a zero clearance to combustibles installation? (I looked in UL 127 ...
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1 vote
3 answers
16k views

How to filter outside air during wildfire to safe breathable level?

I've had an experience of having outside air heavily polluted by wildfire smoke, and now I'm reading up on the wildfire happening in Southeast Asia. When the air outside got too polluted to breathe, I ...
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4 votes
3 answers
2k views

What metal material to use for stove exhaust pipe?

If biofuel is burnt, for example wood, and the stove I am building is made of metal, what is the most appropriate metal material I should use to avoid excessive corrosion in the exhaust pipe of the ...
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1 vote
1 answer
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Is it possible to store leftover pressure from burning a propellant in a pressure vessel?

Say, in a firearm, after giving off a shot, if the barrel were to be closed off, does there exist a way to store some of it in an external pressure vessel, without requiring a mainly-external source ...
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3 votes
1 answer
244 views

Derivation for the Formulas of the Approximate Ultimate Analysis of Coal

I've been given the following to memorize; But my head is so crammed with many others that I need to find another way; Are these formulas Empirical? I was hoping that if I derive it from a much more ...
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2 votes
0 answers
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What data do I need to plot a BSFC map

I have an 4 stroke spark ignition engine simulator which takes user inputs and outputs performance data. I need rpm, torque and brake specific fuel consumption (bsfc) to plot the bsfc map. I am able ...
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4 votes
2 answers
488 views

What relationship is there between mass of water vapour produced in combustion and the energy lost through producing this water?

I am performing a number of simple heat transfer experiments with the application of a magnetic field around the fuel line to evaluate the effects. To attempt to quantify some of the heat losses in ...
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1 vote
2 answers
1k views

How can I turn home gas (LPG) from liquid to gas?

"LPG" is the term used here for a mixture of Propane & Butane sold for public use. The exact ratio varies depending on where you buy it and I think also with the season and is not known to me. I ...
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