h****o
发帖数: 49 | 1 I found that heat capacity=density*specific heat, then since
the density
has the unit of kg/m3, specific heat is J/kgk, then heat
capacity should
have the unit of J/m3k, right? (Holman, heat transfer, the
last
paragragh of page 4)
thermal expansion coefficient has the unit of ppm-k;
ppm=parts per million, who can find some explantion about
ppm? I can not understand it.
Thx. | c****u
发帖数: 584 | 2
1e-24m=ppm I guess.
【在 h****o 的大作中提到】
: I found that heat capacity=density*specific heat, then since
: the density
: has the unit of kg/m3, specific heat is J/kgk, then heat
: capacity should
: have the unit of J/m3k, right? (Holman, heat transfer, the
: last
: paragragh of page 4)
: thermal expansion coefficient has the unit of ppm-k;
: ppm=parts per million, who can find some explantion about
: ppm? I can not understand it.
| h****o
发帖数: 49 | 3 is ppm so small? I am sure.
is specific heat=specific heat capacity?
because some books regard heat capacity and heat specific
have the the same unit, that's J/kg*k, I was confused. I
think "specific" should not have unit, usually defined as
the ratio of something to that of wate. e.g., specific heat
is defined as :
The ratio of thermal energy required to raise the
temperature of a body 1c to the thermal energy required to
raise an equal mass of water 1c.
But here it has the unit of J/kg*k, real
【在 c****u 的大作中提到】
:
: 1e-24m=ppm I guess.
| s**********i
发帖数: 711 | 4
ppm is part per million.
both are correct since specific heat has
those two definitions.
【在 h****o 的大作中提到】
: is ppm so small? I am sure.
: is specific heat=specific heat capacity?
: because some books regard heat capacity and heat specific
: have the the same unit, that's J/kg*k, I was confused. I
: think "specific" should not have unit, usually defined as
: the ratio of something to that of wate. e.g., specific heat
: is defined as :
: The ratio of thermal energy required to raise the
: temperature of a body 1c to the thermal energy required to
: raise an equal mass of water 1c.
| h****o
发帖数: 49 | 5
no unit, just 1e-6.
why are there these two definitions? Historical reasons?
【在 s**********i 的大作中提到】
:
: ppm is part per million.
: both are correct since specific heat has
: those two definitions.
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