How do I convert kW to kWh for my project involving a heat exchanger?

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Discussion Overview

The discussion revolves around the conversion of power (kW) to energy (kWh) in the context of a project involving a heat exchanger. Participants explore the relationship between these units and their application in calculating energy usage and conversions to BTU.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about the relationship between watts and kilowatt-hours, questioning whether 216 kJ translates to 216 kWh.
  • Another participant clarifies that 60 W running for one hour equals 60 Wh, not 60 kWh, and emphasizes the correct conversion of power to energy.
  • It is noted that a 1 kW heater running for one hour equals 1 kWh, reinforcing the understanding of these units.
  • A participant mentions the need to convert kW to BTU, stating that 1 kW equals 3412 BTU/hr, while also pointing out that BTU is typically expressed as BTU/h.
  • One participant reflects on the relationship between kWh and kJ, suggesting that kWh needs to be converted by a factor of 3600 to align with kJ, and mentions that a Joule is a Watt-second.

Areas of Agreement / Disagreement

Participants generally agree on the conversion relationships between kW, kWh, and BTU, but there remains some confusion regarding the interpretation of these units and their applications in specific contexts.

Contextual Notes

There are unresolved aspects regarding the precise definitions and conversions between energy and power units, particularly in the context of practical applications in projects involving heat exchangers.

FQVBSina_Jesse
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Say I have a 60W device.

I know running for one hour it uses 60 W x 3600 s = 216 kJ of energy.

Does that mean it uses 216 kWh of energy?

Or does kWh means 60 W x 1 hour = 60 kWh?

I am confused because the units in 60 kWh is not in their simplified terms.

More specifically, this pertains to a project that I am working on.
From experimental values, I found that with X kg/s of water flowing through the heat exchanger and some temperature increase, I can find the power of the heat exchanger in kW.
I would like to provide the values in BTU since that is just what people still use in the States.
I realized BTU is an energy unit, not power, and 1 kWh = 3412 BTU.
So I need to convert kW to kWh.
 
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FQVBSina said:
Or does kWh means 60 W x 1 hour = 60 kWh?

you have a k in there that you shouldn't

60 W x 1 hour = 60 Wh

FQVBSina said:
So I need to convert kW to kWh.

so going from what I wrote above

a 1kW heater running for 1 hour = 1kWh
 
davenn said:
you have a k in there that you shouldn't

60 W x 1 hour = 60 Wh
so going from what I wrote above

a 1kW heater running for 1 hour = 1kWh
Alright, thanks! I thought kWh is basically kJ. I guess kWh needs to convert by a factor of 3600 before it becomes kJ then.
 
FQVBSina said:
More specifically, this pertains to a project that I am working on.
From experimental values, I found that with X kg/s of water flowing through the heat exchanger and some temperature increase, I can find the power of the heat exchanger in kW.

Yes that's possible/correct.

I would like to provide the values in BTU since that is just what people still use in the States.

I believe they actually use BTU/h (BTU per hour) but the "h" is sometimes omitted (bad practice).

So you just need to use..

1 kW = 3412 BTU/hr
 
FQVBSina said:
Alright, thanks! I thought kWh is basically kJ. I guess kWh needs to convert by a factor of 3600 before it becomes kJ then.
One thing worth remembering: a Joule is a Wattsecond.
So 3600 J = 3600 W s = 1 W h = 0.001 kW h .
 

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