Conversion of kW to Btu

[jrrocks]

Hi,

I have seen over the internet that while converting kW to IP units, it appears like Btuh, while converting kWh to IP units, it appears Btu.

Why HOUR factor is considered while concerting kW to Btuh and why not when converting kWh to Btu.

 

[MintJulep]

Because power and energy are related by time.

 

[LittleInch]

It is considered.

As noted the power has to be defined as energy divided by time

Heat power in IP units is BTU per hour
Heat power in SI is Joules per second. Joules per second is more commonly know as Watts.

Energy on the other hand is exactly that.
A KWh is just a useful unit so that people can get a grasp on what energy is being used over a set period. This can and really should be just called Joules. So 1KWh is actually 3.6 million Joules. That sounds like a HUGE number and once you get into big heat power it can make it look too big and then people make errors as to whether it is MJ, GJ, TJ

Because heat power in IP is in BTU/hr, to equate a KWh simply means converting Joules to BTU
So 3.6 million Joules is 3,412 BTU.

So it is the same thing, but just common usage has replaced some of the correct technical definition.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[jrrocks]

Thanks...

 

[EngrPaper]

Also, as a clarification: Btu/hr is often written as Btuh. Hence your conversion from kW to Btuh (which is Btu/hr) is dimensionally consistent. kWh is actually kW*hr (analogous to Btu as a unit of energy), making the notation inconsistent with Btuh.

 

[rb1957]

Btu is a unit of energy, kW is a unit of power.

another day in paradise, or is paradise one day closer ?

 

[jrrocks]

Thanks to everyone....

 

[Tunalover]

I always remember that there is 3.413 Btu/hr per W. So there is 3413 Btu/hr per KW.

ElectroMechanical Product Development
(Electronics Packaging)
UMD 1984
UCF 1993