Equivalent Metric Sensible Heat Formula
Equivalent Metric Sensible Heat Formula
(OP)
Can anybody out there help me with a metric equivalent to the old tried and true formula of:
Q = 1.08 x CFM x delta T
where:
Q - Heat quantity (BTU/Hr)
CFM - Cubic Feet per Minute
Delta T - Change in temperature - Deg F
Thanks in advance.
Q = 1.08 x CFM x delta T
where:
Q - Heat quantity (BTU/Hr)
CFM - Cubic Feet per Minute
Delta T - Change in temperature - Deg F
Thanks in advance.
Quote:
I don't know much about statistics, but I do know that if something has a 50-50 chance of going wrong, 9 times out of 10 it will. Author unknown





RE: Equivalent Metric Sensible Heat Formula
The specific heat of air at 20°C is 1.05 kJ/kg.°C
At 20°C and 1 atm abs the density of air is 1.20 kg/m3
So the equivalent of your formula at 20°C and 1 atm abs would be
Q = 1.26 x m3/s x delta T
where:
Q - Heat quantity (kW or kJ/s)
m3/s - Cubic meters per second at 20°C and 1 atm abs
Delta T - Change in temperature - Deg C
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Equivalent Metric Sensible Heat Formula
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Equivalent Metric Sensible Heat Formula
Take the "V" out of HVAC and you are left with a HAC(k) job.
RE: Equivalent Metric Sensible Heat Formula
Is m^3/sec the preferred HVAC airflow units in metric?
During my searches on the internet and in ASHRAE the units I saw were liters/sec.
Any assistance on preferred units for all metric HVAC and plumbing/piping flows, pressures and heat values would be apprciated.
Once again, Thanks in advance.
RE: Equivalent Metric Sensible Heat Formula
Programs like Mathcad or TKSolver can handle these unit conversions transparently. For the problem stated, the exact same equation can be used with any of the terms applied in a different unit system, e.g., density in lbs/in^3, specific heat in BTU/gm-ºF, and flow in cubic furlongs/nanosecond, if desired.
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Equivalent Metric Sensible Heat Formula
Actually though, we do all of our calculations in imperial units then convert. The contractor's get our drawings, convert to imperial then bid. As a result we try to choose metric units that are 'close' to the imperial...
RE: Equivalent Metric Sensible Heat Formula
Take the "V" out of HVAC and you are left with a HAC(k) job.
RE: Equivalent Metric Sensible Heat Formula
To be fair to Canada, we do use kilometers, Celsius and litres... Just not in construction.
RE: Equivalent Metric Sensible Heat Formula
Specific heat of Air is generally accepted to be 1.005 kJ/kgK (another 0)
Which makes the formula:
Q = 1.206 x m3/s x dT
Cheers.
RE: Equivalent Metric Sensible Heat Formula
need a real metric stud spacing to match up with the size of a sheet is all.
I only saw metric on gov/public jobs
Take the "V" out of HVAC and you are left with a HAC(k) job.
RE: Equivalent Metric Sensible Heat Formula
regards
Harvey
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com