block heater

[OkieDave]

Cooling of inanimate objects is accelerated by wind in the same way that cooling of people is accelerated by wind. Why does blowing on your soup helps it to cool faster? It is exposed to a greater volume of cool air in a given amount of time, it is able to give up more heat to the increased volume of air. Why do you think there is a fan on your radiator? It helps the inanimate water to cool faster than it would without one. The fan is "wind chilling" the radiator.

Yes and no. Wind chill on skin is related to evaporation of moisture in the skin--as water (liquid) evaporates, it removes heat. No matter how dry your skin feels, there is still water present to evaporate.

Your engine block has no water to evaporate into free space the way your skin does. Still, as the block warms, it warms the air around it. If the air is still, that "bubble" of warm(er) air will draw less heat from the engine than cold air (rate of heat exchange is proportional to the difference in temperature). Blow away that warmer air and replace it with cold and you'll lose heat faster, resulting in a lower block temperature and longer preheat times.

 

[flyingcow]

If i took 2 identical vehicles, and the temp is -10f with a 10mph "breeze". Parked one with it's nose into the wind, and parked the other tucked up close to a building, protected from the wind, the one in the open will start harder and take a little longer to throw heat from the defroster.

 

[7snakes]

What is difference between starting my gasoline vehicles without a block heater and the diesel tractor with? What is it about the diesel that the engine likes preheat?

 

[flyingcow]

just a guess...but gas motors fire with a spark, diesels' do it by compression, it's nice to plug in the engine for a little extra help.

 

[Mace Canute]

What is difference between starting my gasoline vehicles without a block heater and the diesel tractor with? What is it about the diesel that the engine likes preheat?

Diesels ignite the fuel strictly with heated air. Compressing the air in the cylinder quickly causes the temperature to rise and ignition will occur once the temperature has risen to the auto ignition point of diesel...about 410 F. If the low initial temperature of the air combined with the surrounding metal surfaces leeching heat out of the compressed air result in keeping it's temperature below 410 F, the engine won't start. Anything that increases either the initial air temperature or the metal temperature of the cylinder or both will help the diesel engine start.

A gas engine starts when a spark plug ignites a flammable mixture of air and gasoline. The flash point of a flammable liquid is the lowest temperature at which there will be enough flammable vapour to ignite when an ignition source is applied and since gasoline has a flash point of about -45 F, theoretically it should start at any temperature just above or higher than -45 F. It often happens that it doesn't. I believe it's because the gasoline vapour surrounding the spark at the spark plug tip isn't between its lower and upper limits of flammability.

 

[7snakes]

That'll explain it. Thanks.:thumbsup:

 

[brokenot]

Cooling of inanimate objects is accelerated by wind in the same way that cooling of people is accelerated by wind.

Cooling of inanimate objects is accelerated by wind, but those inanimate objects do not get "colder" than whatever the ambient temperature is. So if the weatherman tells you it's 10F outside, but with the "wind chill" it's -10F, go outside and attach the most accurate temperature measuring device you can find to whatever inanimate object you're talking about. The temperature you read will be whatever the actual ambient temperature is....assuming it's been sitting there long enough to cool off to that ambient temperature level.

Wind chill absolutely does not apply to inanimate objects. If you park a tractor or vehicle, wind will make it cool down faster, but under no circumstances will it get "colder" than whatever the ambient temperature is.

And the whole "wind chill factor" thing is all about the temperature feeling colder than it actually is.

On another forum, a guy dared me to do something after I posted up a wind chill chart. According to him, the wind chill factor is actual, and that inanimate objects very much do see/feel those actual temps. The chart I posted had a bunch of temperatures and wind speeds listed. At 35F and with a 60 mph wind, the wind chill "factor" is 17F. So basically the guy dared me to drive my truck down the road at that ambient temp going 60 mph. He was convinced that if I had straight water in the radiator, that 17F "factor" would turn it to ice......barring the thermostat opening and ruining his theory, of course.

I'm still giggling about that.

I'm in North Dakota. No stranger to cold or wind, or getting things started in the cold. We typically spend a hour or so per day when it's cold getting stuff up and running for customers.



;-)

 

[JDGreenGrass]

Cooling of inanimate objects is accelerated by wind, but those inanimate objects do not get "colder" than whatever the ambient temperature is. So if the weatherman tells you it's 10F outside, but with the "wind chill" it's -10F, go outside and attach the most accurate temperature measuring device you can find to whatever inanimate object you're talking about. The temperature you read will be whatever the actual ambient temperature is....assuming it's been sitting there long enough to cool off to that ambient temperature level.

Wind chill absolutely does not apply to inanimate objects. If you park a tractor or vehicle, wind will make it cool down faster, but under no circumstances will it get "colder" than whatever the ambient temperature is.

And the whole "wind chill factor" thing is all about the temperature feeling colder than it actually is.

On another forum, a guy dared me to do something after I posted up a wind chill chart. According to him, the wind chill factor is actual, and that inanimate objects very much do see/feel those actual temps. The chart I posted had a bunch of temperatures and wind speeds listed. At 35F and with a 60 mph wind, the wind chill "factor" is 17F. So basically the guy dared me to drive my truck down the road at that ambient temp going 60 mph. He was convinced that if I had straight water in the radiator, that 17F "factor" would turn it to ice......barring the thermostat opening and ruining his theory, of course.

I'm still giggling about that.

I'm in North Dakota. No stranger to cold or wind, or getting things started in the cold. We typically spend a hour or so per day when it's cold getting stuff up and running for customers.


I agree.



;-)

I agree with you.

 

[pitt_md]

Egon....You may or may not know this but, the wind has no effect on temperature. In other words, the iron on your tractor does not "feel" the cold wind chill. Only us humans do.

If the temp is zero and the wind is blowing 40mph, the temperature is still zero.

Not sure the point your trying to make. Yes the temp is still what ever it is with out the wind BUT - The more cold air you move across a warm surface the more heat is dissipated. If your trying to heat up your tractor it will take longer if the wind is blowing 40mph.

 

[D7E]

Not sure the point your trying to make. Yes the temp is still what ever it is with out the wind BUT - The more cold air you move across a warm surface the more heat is dissipated. If your trying to heat up your tractor it will take longer if the wind is blowing 40mph.

Absoluteley ...so harder to warm and start !