HEY GRUMPYVETTE?
"I have a question about cooling and this cold weather we are having. ....Im wondering how wind chill will affect the coolant. It tested down to about -20. The day I go home the starting temp is forecast to be 0. How does hiway speeds affect the cooling system in this kind of conditions. Ive driven trucks but we would block the air flow to the radiator to keep temps up."
thats a good question that most guys never think about
this should help
http://www.springfrog.com/weather/wind-chill.htm
http://www.weatherimages.org/data/windchill.html
at 55mph the effective wind chill on the radiator fins will be about -30f so at least in theory youll want to increase the percentage of anti freeze,
but the anti freeze still only sees the true outside temperature, of the air, wind chill is related to how fast the heat on a warmer object is absorbed by the air ,not the true temperature, of the air passing over the fins, on the radiator, or put a different way the coolant in the radiator will loose, or transfer heat to the air flow faster at higher speeds but it won,t potentially drop below the true outside temperature , so your T-stat may spend more time being closed in each cycle, or your car will take longer to heat up, but if your coolant is fine for -20F and its only 0F even if the wind chill at 70 mph is significantly lower than -20f you've got nothing to worry about
Answer
In still air, as internal energy is conducted from a warmer body to the surrounding air, the air near the object is warmed. That increased air temperature reduces the temperature difference between the body and air, slowing the rate of heat loss. When the air surrounding a warm body is moving, the warmed air is replaced more quickly by cool air, keeping the temperature difference, and rate of energy transfer, higher.
It is the flow of energy to/from the skin that determines our sense of hot and cold. If the skin is cold, room temperature air feels warm. If the skin is warm, the same room temperature feels cool.
Wind chill temperature is based on a combination of air temperature and wind speed. As air temperature decreases and wind speed increases, the air feels colder because the temperature difference between skin and air is maximized as any warmed air is quickly replaced by cold air. That larger temperature difference increases heat flow, and our sense of coldness. Wind chill is calibrated to the human body's sense of coldness due to that effect.
Heat always flows from higher to lower temperature, so the temperature of human skin will not drop below that of the surrounding air, regardless of wind. Likewise, inanimate objects (like automobiles) will not drop below the temperature of surrounding air. So while a wind will reduce the time it takes for a warm object to cool down to air temperature, it can't result in a final temperature below that of the air itself. If air temperature is -10 degrees and the wind-chill temperature is -25 degrees, for example, automobiles and tractors only need antifreeze protection down to -10 degrees.
Answered by: Paul Walorski, B.A. Physics, Part-time
btw that cold air flowing over the outside of the oil pan and transmission cooler also tends to delay the engines getting up to operational temperatures, so wait until your oil temp hits 200F before running the car like you stole it or you might have lubrication issues result
"I have a question about cooling and this cold weather we are having. ....Im wondering how wind chill will affect the coolant. It tested down to about -20. The day I go home the starting temp is forecast to be 0. How does hiway speeds affect the cooling system in this kind of conditions. Ive driven trucks but we would block the air flow to the radiator to keep temps up."
thats a good question that most guys never think about
this should help
http://www.springfrog.com/weather/wind-chill.htm
http://www.weatherimages.org/data/windchill.html
at 55mph the effective wind chill on the radiator fins will be about -30f so at least in theory youll want to increase the percentage of anti freeze,
but the anti freeze still only sees the true outside temperature, of the air, wind chill is related to how fast the heat on a warmer object is absorbed by the air ,not the true temperature, of the air passing over the fins, on the radiator, or put a different way the coolant in the radiator will loose, or transfer heat to the air flow faster at higher speeds but it won,t potentially drop below the true outside temperature , so your T-stat may spend more time being closed in each cycle, or your car will take longer to heat up, but if your coolant is fine for -20F and its only 0F even if the wind chill at 70 mph is significantly lower than -20f you've got nothing to worry about
Answer
In still air, as internal energy is conducted from a warmer body to the surrounding air, the air near the object is warmed. That increased air temperature reduces the temperature difference between the body and air, slowing the rate of heat loss. When the air surrounding a warm body is moving, the warmed air is replaced more quickly by cool air, keeping the temperature difference, and rate of energy transfer, higher.
It is the flow of energy to/from the skin that determines our sense of hot and cold. If the skin is cold, room temperature air feels warm. If the skin is warm, the same room temperature feels cool.
Wind chill temperature is based on a combination of air temperature and wind speed. As air temperature decreases and wind speed increases, the air feels colder because the temperature difference between skin and air is maximized as any warmed air is quickly replaced by cold air. That larger temperature difference increases heat flow, and our sense of coldness. Wind chill is calibrated to the human body's sense of coldness due to that effect.
Heat always flows from higher to lower temperature, so the temperature of human skin will not drop below that of the surrounding air, regardless of wind. Likewise, inanimate objects (like automobiles) will not drop below the temperature of surrounding air. So while a wind will reduce the time it takes for a warm object to cool down to air temperature, it can't result in a final temperature below that of the air itself. If air temperature is -10 degrees and the wind-chill temperature is -25 degrees, for example, automobiles and tractors only need antifreeze protection down to -10 degrees.
Answered by: Paul Walorski, B.A. Physics, Part-time
btw that cold air flowing over the outside of the oil pan and transmission cooler also tends to delay the engines getting up to operational temperatures, so wait until your oil temp hits 200F before running the car like you stole it or you might have lubrication issues result