Airconditioning

[Marc1]

Beauty?
Interesting, and good to know, tho, so thanks.
Sounds to me like they had to figure out a way to hang it in limited space, and settled for less-than-ideal.
Do the math. All things being equal, what's more efficient: Burning fuel to drive a flywheel that powers a belt that drives a compressor, or burning fuel to drive a flywheel that powers a belt that drives a generator that generates electricity that powers a motor that drives a compressor?

 

[Marc1]

Sorry about the above post. About 'efficiency'. I must disagree with the last post. Electric fans are inefficient in theory compared to mechanically driven yet they have a place in most modern cars. If CAT engeneers have built an all electric system, I am sure they are aware that a mechanical systemn would use a few grams of fuel less per week. They have probably written off a fraction of fuel in favour of a lighter systme easier to fit anywhere. Not everything comes down to fuel consumption and efficiency is a much broader concept that grams of fuel /HP/Hour. Just an example... what is more efficient, a Detroit Diesel 6 71 or a Cummis of comparable power? The Cummis will use less fuel yet brake down more frequently and end up needing a full rebuild by the time the DD needs a bit of a clean up. A $15,000 bill goes a long way to buy fuel!

 

[thetool]

Sorry about the above post. About 'efficiency'. I must disagree with the last post. Electric fans are inefficient in theory compared to mechanically driven yet they have a place in most modern cars. If CAT engeneers have built an all electric system, I am sure they are aware that a mechanical systemn would use a few grams of fuel less per week. They have probably written off a fraction of fuel in favour of a lighter systme easier to fit anywhere. Not everything comes down to fuel consumption and efficiency is a much broader concept that grams of fuel /HP/Hour. Just an example... what is more efficient, a Detroit Diesel 6 71 or a Cummis of comparable power? The Cummis will use less fuel yet brake down more frequently and end up needing a full rebuild by the time the DD needs a bit of a clean up. A $15,000 bill goes a long way to buy fuel!

Is there a place where they could have mounted a belt-driven compressor on your CAT?
I'm not quite sure what it is that you're disagreeing with me on.
Fans and A/C compressors are different animals.

 

[bobcat_ron]

Is there a place where they could have mounted a belt-driven compressor on your CAT?
I'm not quite sure what it is that you're disagreeing with me on.
Fans and A/C compressors are different animals.

There is adequate room on Cat for them to use a belt driven A/C system, but it would hinder the rear door, they have less than 1/4" of room between the door and the belt cover, I know, I dented my door in 1/4" and the plastic cover is rubbing on the door! The only place on the medium frames is on the right side above the battery and next to the electric motor for the quick change pump, the large frames would be on the left side, so the fuel filters would be in the way.

 

[Marc1]

Is there a place where they could have mounted a belt-driven compressor on your CAT?
I'm not quite sure what it is that you're disagreeing with me on.
Fans and A/C compressors are different animals.

Do the math. All things being equal, what's more efficient: Burning fuel to drive a flywheel that powers a belt that drives a compressor, or burning fuel to drive a flywheel that powers a belt that drives a generator that generates electricity that powers a motor that drives a compressor?

I answered this comment that addresses one theoretical issue with electricity driven accessories, regardless of what they are, A/C or fan, fuel pump or winch, same thing. Not everything ....actually....hardly much at all has to do with fuel consumption in machinery really. It may be the popular thing to look at, but if you compare the overall cost of running machinery the cost of fuel is negligible.

 

[Tazza]

I answered this comment that addresses one theoretical issue with electricity driven accessories, regardless of what they are, A/C or fan, fuel pump or winch, same thing. Not everything ....actually....hardly much at all has to do with fuel consumption in machinery really. It may be the popular thing to look at, but if you compare the overall cost of running machinery the cost of fuel is negligible.

For sure, fuel is nothing in the scheme of things.
I do agree about the losses though. Say driving the compressor direct from the engine would pull say 5hp. It would be say 5.5 if you run it electrically. It all goes to the laws of physics. The engine spins the alternator that generates power, it also generates heat, the heat is a loss of good power. This power then goes to the compressor that converts the power to motion energy while compressing gas, it also produces heat, another loss. I won't also include sound energy here. So running it direct would cut out some of the losses, so I'm sure you won't loose 1/2 a hp here but you get the idea, there is still a loss.
Its convenient being able to place the compressor away from the engine though. Just not as efficient, but if you have a turbo machine you probably won't notice the difference.

 

[thetool]

For sure, fuel is nothing in the scheme of things.
I do agree about the losses though. Say driving the compressor direct from the engine would pull say 5hp. It would be say 5.5 if you run it electrically. It all goes to the laws of physics. The engine spins the alternator that generates power, it also generates heat, the heat is a loss of good power. This power then goes to the compressor that converts the power to motion energy while compressing gas, it also produces heat, another loss. I won't also include sound energy here. So running it direct would cut out some of the losses, so I'm sure you won't loose 1/2 a hp here but you get the idea, there is still a loss.
Its convenient being able to place the compressor away from the engine though. Just not as efficient, but if you have a turbo machine you probably won't notice the difference.

About fuel-the cost of fuel is a LOT of smaller payments spread over a longer time, where a hefty repair bill comes all at once. Don't let that mislead you.
If a machine burns 5 gallons an hour, and you run it for 3000 hours, that's 15000 gallons. Multiply that by the price of fuel and it definitley becomes an issue.
Do the math again......The numbers are in the ballpark of the purchase price of a new machine, at current fuel prices.

 

[Marc1]

About fuel-the cost of fuel is a LOT of smaller payments spread over a longer time, where a hefty repair bill comes all at once. Don't let that mislead you.
If a machine burns 5 gallons an hour, and you run it for 3000 hours, that's 15000 gallons. Multiply that by the price of fuel and it definitley becomes an issue.
Do the math again......The numbers are in the ballpark of the purchase price of a new machine, at current fuel prices.

Hum... Lets see... A) Unless I un-click the editor from my profile, I can not type in the message box. B) Electric driven accessories use up more fuel than mechanically driven. Correct. However they have also some advantages, one of them being that they do not draw power directly from the engine but indirectly. First from the battery who in times demands more charge from the engine. The end result is that if you need a burst of power to get unstuck from a sticky place, your A/C will not increase the load instantly because of the increase in revs, and rob you from all the power needed to drive the compressor, something that could be a problem in extreme cases. The alternator will increase its demand on the engine to replenish the battery but it will be a gentle increase spread along some time and the sudden surge due to your acceleration will be taken care of by the battery. However I don't want to appear to say that Cat is "right" and Bob is wrong. Each system has its merits and reasons to be. As for costs, I am aware of the costs of running machines and I have it clear that fuel plays it's role, however small. Yet to debate the difference in real money to be paid for a job if your A/C is mechanically driven, as opposed to if it is electrically driven, I challenge you to quantify this in dollars and cents and itemise it in your next quote. I don't think you will be able to pay for your coffees with it.

 

[thetool]

Hum... Lets see... A) Unless I un-click the editor from my profile, I can not type in the message box. B) Electric driven accessories use up more fuel than mechanically driven. Correct. However they have also some advantages, one of them being that they do not draw power directly from the engine but indirectly. First from the battery who in times demands more charge from the engine. The end result is that if you need a burst of power to get unstuck from a sticky place, your A/C will not increase the load instantly because of the increase in revs, and rob you from all the power needed to drive the compressor, something that could be a problem in extreme cases. The alternator will increase its demand on the engine to replenish the battery but it will be a gentle increase spread along some time and the sudden surge due to your acceleration will be taken care of by the battery. However I don't want to appear to say that Cat is "right" and Bob is wrong. Each system has its merits and reasons to be. As for costs, I am aware of the costs of running machines and I have it clear that fuel plays it's role, however small. Yet to debate the difference in real money to be paid for a job if your A/C is mechanically driven, as opposed to if it is electrically driven, I challenge you to quantify this in dollars and cents and itemise it in your next quote. I don't think you will be able to pay for your coffees with it.

He he-I am unable and unwilling to rise to your challenge, but in reading all your post, I don't think we have any grounds upon which to debate.
I heard "fuel is nothing" asnd "fuel in negligable" and I laughed, but in the context of EXTRA fuel to run A/C, it is relatively little, so yes, I'll concede that point.
Electrically driven stuff is not necessarily less efficient than mechanical. Ron's example of electric-drive D7 and even the big haul trucks they use here at the mine, super-giant excavators and drag-lines-all electric powered by on-board diesel generators. All good and more efficient than hanging huge hydrostatic drive systems-and past a certain size, cheaper as well.
I had two points when getting into this, which I now regret.
1. Taking a stab at Ron
2. The more stuff between the actual burning of fuel and the desired result, the less efficient the system. It may be a necessaary evil, depending on overall design.
The first was unnecessary, and the second is of course mostly common knowlege......=).

 

[Marc1]

He he-I am unable and unwilling to rise to your challenge, but in reading all your post, I don't think we have any grounds upon which to debate.
I heard "fuel is nothing" asnd "fuel in negligable" and I laughed, but in the context of EXTRA fuel to run A/C, it is relatively little, so yes, I'll concede that point.
Electrically driven stuff is not necessarily less efficient than mechanical. Ron's example of electric-drive D7 and even the big haul trucks they use here at the mine, super-giant excavators and drag-lines-all electric powered by on-board diesel generators. All good and more efficient than hanging huge hydrostatic drive systems-and past a certain size, cheaper as well.
I had two points when getting into this, which I now regret.
1. Taking a stab at Ron
2. The more stuff between the actual burning of fuel and the desired result, the less efficient the system. It may be a necessaary evil, depending on overall design.
The first was unnecessary, and the second is of course mostly common knowlege......=).

On the subject of electric driven, there is a new trend in boats that started with large one and is now getting into the smaller one, and that is diesel-electric. What served us for generations on the rails, the DD12-71 and similar who could not possibly have a gearbox for such massive engine, is now turning up on boats. Multi engine boats with multi gear boxes and additional genset have clearly a maintenance cost challenge. A single engine genset with 2 or more electric motors directly coupled to the shaft solve most of the problems. At a cost, yes, more expensive for now because of the novelty but clearly more efficient in this case despite the theories to the contrary. Diesel engines are the best in converting fuel into enegry providing they are at optimal load. And usualy this means flogging it. Some commercial fishing boats and all recreational boats live most of their life idling around with glazed cylinders and carbon filled chambers. If the main engine can be made to run at optimal load most of the time, regardless of the speed of the shaft, the system is more efficient most of the time.

 

[bobcat_ron]

On the subject of electric driven, there is a new trend in boats that started with large one and is now getting into the smaller one, and that is diesel-electric. What served us for generations on the rails, the DD12-71 and similar who could not possibly have a gearbox for such massive engine, is now turning up on boats. Multi engine boats with multi gear boxes and additional genset have clearly a maintenance cost challenge. A single engine genset with 2 or more electric motors directly coupled to the shaft solve most of the problems. At a cost, yes, more expensive for now because of the novelty but clearly more efficient in this case despite the theories to the contrary. Diesel engines are the best in converting fuel into enegry providing they are at optimal load. And usualy this means flogging it. Some commercial fishing boats and all recreational boats live most of their life idling around with glazed cylinders and carbon filled chambers. If the main engine can be made to run at optimal load most of the time, regardless of the speed of the shaft, the system is more efficient most of the time.

Here's a good stab, some people complain that their A/C systems perform well and poor under certain engine RPM's, this might be due to at higher engine RPM's the air from the hot rads is warming the A/C rad thus creating warmer refrigerant, or it doesn't get cool enough at lower (idle) RPM's due to insufficient air flow, with and all electric powered system, since the electric motor is already running at peak RPM's, the system is proving sufficient chilled air to keep the operator happy, and any complaints would be from the windows being directly exposed to the sun causing the inner cab temps to rise.