Living without owning an internal combustion engine

General cycling advice ( NOT technical ! )
Mike Sales
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Re: Living without owning an internal combustion engine

Postby Mike Sales » 14 Aug 2019, 3:50pm

NetworkMan wrote:Don't know about the young ones - aren't the stag parties in Prague still popular?


The young are not an homogenous group, no more than cyclists.
I do not imagine the school strikers are going to Prague.
Are these stag parties still popular, I wouldn't know?

mattheus
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Re: Living without owning an internal combustion engine

Postby mattheus » 14 Aug 2019, 4:06pm

Mike Sales wrote:
NetworkMan wrote:Don't know about the young ones - aren't the stag parties in Prague still popular?


The young are not an homogenous group, no more than cyclists.
I do not imagine the school strikers are going to Prague.
Are these stag parties still popular, I wouldn't know?


Greater Tunaberg (for one) has better things to do with her time.

perhaps others will be inspired by her?

Bmblbzzz
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Re: Living without owning an internal combustion engine

Postby Bmblbzzz » 14 Aug 2019, 10:55pm

Vorpal wrote:As for other combustion engines... most of them have electric substitutes. Felling a large tree needs a petrol chain saw, but the other stuff can be done with electrics, unless you have a large lawn. Of course, that's not necessarily ideal. If your power comes from coal plants, for example the combustion engine is probably a better choice, as it's more efficient and less polluting.

That's not usually true. The efficiency of an internal combustion engine is around 30%. The efficiency of a steam turbine as used in a power station is around 60%. And the efficiency of an electric motor is about 90%. So converting coal to electricity is actually more efficient, in most cases, than burning petrol or diesel (which, of course, both consume electricity in the refinery).

Vorpal
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Re: Living without owning an internal combustion engine

Postby Vorpal » 15 Aug 2019, 9:33am

Bmblbzzz wrote:
Vorpal wrote:As for other combustion engines... most of them have electric substitutes. Felling a large tree needs a petrol chain saw, but the other stuff can be done with electrics, unless you have a large lawn. Of course, that's not necessarily ideal. If your power comes from coal plants, for example the combustion engine is probably a better choice, as it's more efficient and less polluting.

That's not usually true. The efficiency of an internal combustion engine is around 30%. The efficiency of a steam turbine as used in a power station is around 60%. And the efficiency of an electric motor is about 90%. So converting coal to electricity is actually more efficient, in most cases, than burning petrol or diesel (which, of course, both consume electricity in the refinery).

A few things...
First, thermal efficiency (use of heat energy) in a turbine is not the same thing as mechanical (work) efficiency; transferring quantities of stuff into work such as cutting grass, trimming trees, etc.

Secondly, there are many losses in the system outside of a turbine that make the process of coal energy to something useful at a house somewhat less efficient than doing the same thing with a combustion engine held in my hand. Most electricity generation in the UK comes from combined cycle plants, which are rather more efficient than the few aging coal power plants still running.

If we were comparing an electric car to a combined cycle power plant, I would agree (although 60% is still a bit high)

However, a two cycle engine (the small petrol engines used for chain saws, lawn mowers, etc) are very much more efficient than large IC engines, like those used in cars. The thermal efficiency is double (2 cycle versus 4 cycle engine) and the mechanical efficiency is typically 60 or 70% better.

That said, if we compare everything in the system from O&G /coal extraction & refining, emissions, etc. to work done in my garden, they are probably fairly comparable.

The solution is not to do it at all. :wink:
“In some ways, it is easier to be a dissident, for then one is without responsibility.”
― Nelson Mandela, Long Walk to Freedom

Bmblbzzz
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Re: Living without owning an internal combustion engine

Postby Bmblbzzz » 15 Aug 2019, 9:59am

Vorpal wrote:...

The solution is not to do it at all. :wink:

True!

PDQ Mobile
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Re: Living without owning an internal combustion engine

Postby PDQ Mobile » 15 Aug 2019, 10:58am

Vorpal wrote:
Bmblbzzz wrote:
Vorpal wrote:However, a two cycle engine (the small petrol engines used for chain saws, lawn mowers, etc) are very much more efficient than large IC engines, like those used in cars. The thermal efficiency is double (2 cycle versus 4 cycle engine) and the mechanical efficiency is typically 60 or 70% better.


I am going to question this statement.
The more incomplete combustion of the two stroke results in more wasted fuel than a valved engine that combusts and scours itself more completely.

The power to weight ratio of the two stroke is high and hence it's suitability for small (often hand held) machinery.
But for example a 50cc moped could typically achieve 120 mpg; a modern diesel lugging perhaps twenty times the weight at twice or three times the speed could achieve half (or is that double? You know what I mean) the fuel consumption of the moped.
It would seem the diesel is far more efficient?
There are example of 2t vehicles. The Trabant! not noted for it's fuel efficiency.

Then there's the partially unburnt smoky fumes from the 2t. Even one small moped can be a real source of the stinking blue haze. En mass in a city simply dreadful.

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Re: Living without owning an internal combustion engine

Postby Vorpal » 15 Aug 2019, 11:52am

PDQ Mobile wrote:I am going to question this statement.
The more incomplete combustion of the two stroke results in more wasted fuel than a valved engine that combusts and scours itself more completely.

The power to weight ratio of the two stroke is high and hence it's suitability for small (often hand held) machinery.
But for example a 50cc moped could typically achieve 120 mpg; a modern diesel lugging perhaps twenty times the weight at twice or three times the speed could achieve half the fuel consumption of the moped.
It would seem the diesel is far more efficient?
There are example of 2t vehicles. The Trabant! not noted for it's fuel efficiency.

Then there's the partially unburnt smoky fumes from the 2t. Even one small moped can be a real source of the stinking blue haze. En mass in a city simply dreadful.


I suppose it's possible that some changes have occurred since I calculated this stuff in engineering school, but in principle, a 2 stroke engine does it's work in 2 cycles, where a 4 stoke engine does it in 4 cycles, which means a potential to be 2X as efficient. As you say, the fuel is not used as effectively, hence the mechanical efficiency is somewhat less than 2X as good.

It's not reasonable to compare a 200 hP diesel engine to a 2 stroke engine. They are designed for different things, and work better in different applications. It would be silly to design a diesel engine for a hedge trimmer. A 2 cycle engine on a large tractor is slightly more feasible, but not much more sensible (yes I know people have done it in the past, and there are still tractors around with single and double stroke engines).

Two cycle engines do produce worse pollution. They have relatively little control for emissions, and many require oil & petrol mixed which is worse from an emissions perspective.
“In some ways, it is easier to be a dissident, for then one is without responsibility.”
― Nelson Mandela, Long Walk to Freedom

PDQ Mobile
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Re: Living without owning an internal combustion engine

Postby PDQ Mobile » 15 Aug 2019, 12:02pm

The test has to be the amount of energy delivered at the flywheel per litre (or any measure) of fuel consumed.

As you say horses for courses.
Broadly that is what we have developed in response to those factors.
2t where engine weight is a major factor but diesel wins hands down for the amount of work done.
Petrol agricultural tractors and lorries are like hens teeth. 2t ones extinct, though they did exist.

Bmblbzzz
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Re: Living without owning an internal combustion engine

Postby Bmblbzzz » 15 Aug 2019, 12:08pm

The most efficient production internal combustion engine is supposedly a 2-stroke diesel used in marine applications. I'll try and look up the details.

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Re: Living without owning an internal combustion engine

Postby Bmblbzzz » 15 Aug 2019, 12:19pm

Can't find reference to a particular engine atm, but:
The two stroke Diesel engine does not mix fuel or oil with the combustion air. The crankshaft bearings are lubricated from pressurised oil in the same way as a four stroke engine.

and
When a ship is being constructed in a shipyard, the most important machinery that is to be selected is the main propulsion machinery. Both 2 stroke and 4 stroke engines are widely available in the market but for a large ocean-going merchant vessel, a 2 stroke engine is more commonly used as the main engine and has a much better market.

Even with a wide variety of advantages that 4 stroke engine offers like the compact size of the plant, much more RPM or speed etc, a 2 stroke engine outshines with few but vital advantages.

2-stroke Engines

Some of the important reasons why 2 stroke engines are more popular than 4 stroke engines as main propulsion engine on ships

Fuel Selection: The fuel prices have gone sky high and better grade fuel is adding higher costs to vessel operation. A two-stroke engine can burn low-grade fuel oil and hence reduce the running cost of the ship.
Efficiency: The thermal and engine efficiency of 2 stroke engine is much better than that of a 4 stroke engine.
Power: Most of the 2 stroke engines are now large stroke engines that produce more power. Hence they have high power to weight ration as compared to 4 stroke engine.
More Cargo: Ship can carry more weight and hence more cargo with 2 stroke engines because of high power to weight ratio.
Reliability: Two stroke engines are more reliable in operation as compare to 4 stroke engine.
Less Maintenance: The maintenance requirement of the two-stroke engine is much lesser than 4 stroke engine.
Direction control: Direct starting and reversing is easier with two stroke engine.
No reduction attachments: As two stroke engines are low speed engine, there is no requirement of reduction gear or speed reduction arrangement as required for high speed four stroke engine.
However, the ease-of-manoeuvring a two stroke engine is less than that of a four stroke engine and the initial cost of installation of a two stroke propulsion plant is also much higher than running and maintenance cost of a 4 stroke engine. In 2 stroke engine, the amount saved on high grade fuel can compensate all other disadvantages and also reduce the whole operating cost of a ship.


http://www.marinediesels.info/Basics/th ... nation.htm
https://www.marineinsight.com/main-engi ... -on-ships/

None of which, of course, is directly applicable to land vehicles. At least, I'm not aware of any 2-stroke diesel road vehicles, some railway locomotives might use them.

PDQ Mobile
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Re: Living without owning an internal combustion engine

Postby PDQ Mobile » 15 Aug 2019, 12:40pm

^^
Yes I am aware of the 2t diesel marine engines.
Certainly power to wieght ratio is very high.
Some run on low grade (and hence cheaper) oil fuels. And some emit lots of black smoke. Channel ferries!
As the article states maintenance costs are favourable too.

Whether they do that much more work per unit of fuel than a well designed 4stroke conventional diesel I really could not say.

Bmblbzzz
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Re: Living without owning an internal combustion engine

Postby Bmblbzzz » 15 Aug 2019, 2:01pm

I think all marine engines run on low grade fuels. The Channel ferries will be running on something higher grade than the deep ocean ships due to EU regs. Fuel used on deep ocean shipping needs to be heated and filtered on board the ship in order to make it usable.

Grandad
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Re: Living without owning an internal combustion engine

Postby Grandad » 15 Aug 2019, 2:21pm

Looks at thread title , thinks

Fuel used on deep ocean shipping needs to be heated and filtered on board the ship in order to make it usable.


I am living without one of these internal combusion engines :)

Barks
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Re: Living without owning an internal combustion engine

Postby Barks » 15 Aug 2019, 2:47pm

Grandad wrote:Looks at thread title , thinks

Fuel used on deep ocean shipping needs to be heated and filtered on board the ship in order to make it usable.


I am living without one of these internal combusion engines :)


You are living with them if you buy any imported goods.

Debs
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Re: Living without owning an internal combustion engine

Postby Debs » 15 Aug 2019, 3:07pm

It would be appropriate, and not before time, to legislate the complete ban of two-stoke vehicles from UK roads.
This would mainly force those horrid stink-wheeler scooters and motorcycles off the roads which would be an immediate improvement in air quality. Still too many old classic two-strokes around from the 60s and 70s which should be consigned to the wheeley-bin of really bad ideas :evil:
Last edited by Debs on 15 Aug 2019, 3:08pm, edited 1 time in total.