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# Test Lab Time Signal Calculator: Calculating Heat Transfer Rate

Creator

Starting with a single time history (CH1) that represents the change in temperature across a system in C°

1. what would the formula be
2. how to create a watt/second unit

Where:

The resulting time history = Heat Transfer Rate (watt/second)

3 REPLIES

# Re: Test Lab Time Signal Calculator: Calculating Heat Transfer Rate

Siemens Phenom

Hello,  We don't have enough information to calculate the Heat Transfer Rate from temperature alone.

If you were to differentiate the Temperature data that would give your the rate of temperature change.

based on the following link, to calculate the heat transfer rate you need information on the thermal conductivity of the material along with the area and the thickness of the material.

Rate = k•A•(T1 - T2)/d

# Re: Test Lab Time Signal Calculator: Calculating Heat Transfer Rate

Creator

Thank you for the response:

When I differentiate ⁰C it becomes KHz seems like it should be ⁰C/s see the attached

With respects to calculating heat transfer rate using the time signal calculator

thermal conductivity of the material : Iron, cast 55[W∙m^-1∙K^-1]   https://en.wikipedia.org/wiki/List_of_thermal_conductivities

Area: 2207657.925 mm^2

Thickness of the material: It is a complex shape (Casting)

# Re: Test Lab Time Signal Calculator: Calculating Heat Transfer Rate

Siemens Phenom

Hello,

Similar to your other question, you need to provide the unit to use or the desired resulting unit in square brackets. In addition to this, (⁰C)/s or (deg C)/s or whichever unit you wish to use needs to exist in your unit system. It is not in our default unit system so resolves to (deg C)Hz as you have found out.

Open your Units Editor (currently LMS Configuration and Unit System 2.2). Highlight one your Temperate units and then press Add Unit. I added the following:

Save your unit system, then start (or restart) Test.Lab.  You can then use that unit in your formulas:

CH1 GENERATE_CONSTANT(1.0[⁰C];0;10;12800;0)
CH2 DIFFERENTIATE(CH1) [(⁰C)/s]

or

CH1 GENERATE_CONSTANT(1.0[deg C];0;10;12800;0)
CH2 DIFFERENTIATE(CH1) [(deg C)/s]