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Quick clarification on convection

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  • chcoa
    Hi all, I m writing a report for BGT on the Women t ProLite I m testing. I m about to include a section on how it performed as bottom insluation in my hammock
    Message 1 of 5 , Apr 4, 2006
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      Hi all,

      I'm writing a report for BGT on the Women't ProLite I'm testing. I'm
      about to include a section on how it performed as bottom insluation in
      my hammock with a reference to heat loss via the wind. I was going to
      call this convection then I started second guessing myself and even
      though I looked it up, I'm not entirely sure convection is the right
      word to describe heat loss via wind.

      Will someone who knows clarify for me please?

      Thanks
      jamie d
    • Coy
      I think you are right Jamie, from wind it would be convection. if you are laying on the pad and heat is leaving the bottom of the pad then it would be a
      Message 2 of 5 , Apr 4, 2006
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        I think you are right Jamie, from wind it would be convection. if you
        are laying on the pad and heat is leaving the bottom of the pad then
        it would be a combination of convection and conduction. conduction
        would be the heat from your body the pad lets through for convection
        to then take on off. This of course assumes that the underside (air)
        is colder than you on the top side.

        Coy Boy

        --- In hammockcamping@yahoogroups.com, "chcoa" <jdeben@...> wrote:
        >
        > Hi all,
        >
        > I'm writing a report for BGT on the Women't ProLite I'm testing. I'm
        > about to include a section on how it performed as bottom insluation in
        > my hammock with a reference to heat loss via the wind. I was going to
        > call this convection then I started second guessing myself and even
        > though I looked it up, I'm not entirely sure convection is the right
        > word to describe heat loss via wind.
        >
        > Will someone who knows clarify for me please?
        >
        > Thanks
        > jamie d
        >
      • Dave Womble
        Choca, Heat transfer can get confusing and it is difficult at times to determine whether radiation, conduction or convection is the primary means. Convection
        Message 3 of 5 , Apr 4, 2006
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          Choca,

          Heat transfer can get confusing and it is difficult at times to
          determine whether radiation, conduction or convection is the primary
          means. Convection is fluid movement, with natural convection (in
          air) being warm air rising because it is lighter and being replaced
          by cooler, heavier air. This replaces your boundary layer of warm
          air at some rate that primarily depends on the temperatures
          involved. Wind is sometimes referred to as forced convection where
          wind currents rapidly replace your boundary layer of warm air. I'm
          calling the boundary layer of warm air as the layer of air on the
          outside of your insulation that you warm up some in still air.

          But, you may be talking of wind currents actually flushing warm air
          out of your insulation. Air mats are immune to that since they are
          air tight. Some types of highly breathable insulation, like most of
          the sleeping bags we use, are not immune to that and their
          susceptibility is inversely proportional to how breathable they are.
          I would call this how wind proof versus breathable it is rather than
          labeling it as some form of convective heat transfer. Wind proofness
          is a good thing in cooler, windy conditions while high breathability
          is a good thing in warmer, stagnant conditions... usually we are in
          the middle ground where it is six-of-one versus half-a-dozen of the
          other.

          Hope I didn't confuse you.

          Dave



          --- In hammockcamping@yahoogroups.com, "Coy" <starnescr@...> wrote:
          >
          > I think you are right Jamie, from wind it would be convection. if
          you
          > are laying on the pad and heat is leaving the bottom of the pad then
          > it would be a combination of convection and conduction. conduction
          > would be the heat from your body the pad lets through for convection
          > to then take on off. This of course assumes that the underside
          (air)
          > is colder than you on the top side.
          >
          > Coy Boy
          >
          > --- In hammockcamping@yahoogroups.com, "chcoa" <jdeben@> wrote:
          > >
          > > Hi all,
          > >
          > > I'm writing a report for BGT on the Women't ProLite I'm testing.
          I'm
          > > about to include a section on how it performed as bottom
          insluation in
          > > my hammock with a reference to heat loss via the wind. I was
          going to
          > > call this convection then I started second guessing myself and
          even
          > > though I looked it up, I'm not entirely sure convection is the
          right
          > > word to describe heat loss via wind.
          > >
          > > Will someone who knows clarify for me please?
          > >
          > > Thanks
          > > jamie d
          > >
          >
        • Dave Womble
          ... Some types of highly breathable insulation, like most of ... Opps! Should have said ...susceptibility is proportional to how breathable they are.
          Message 4 of 5 , Apr 4, 2006
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            --- In hammockcamping@yahoogroups.com, "Dave Womble" <dpwomble@...>
            wrote:
            >
            Some types of highly breathable insulation, like most of
            > the sleeping bags we use, are not immune to that and their
            > susceptibility is inversely proportional to how breathable they are.

            Opps! Should have said "...susceptibility is proportional to how
            breathable they are."
          • chcoa
            Thanks guys. I ll stick with convection so it s more simple for the readers of my report. I don t want anyones head to explode with all the complexities of
            Message 5 of 5 , Apr 4, 2006
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              Thanks guys. I'll stick with convection so it's more simple for the
              readers of my report. I don't want anyones head to explode with all
              the complexities of this stuff. :)

              jamie in az
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