Time for heating to equilibrium with constant heat flux

In summary, the conversation involves finding an equation to describe the heating process of a cylindrical metal with known dimensions and properties. The temperature of one side is kept constant while the other side is heated. The goal is to find an equation that can be used to obtain a temperature-time graph and determine how long it takes for the metal to reach equilibrium temperature. One suggestion is to use H=kA dt/dx=constant, which suggests that the temperature varies linearly with distance. However, this may not be the most helpful solution.
  • #1
Komakech
1
0
I have the following scenario and hope one of you can help me. I need to find an equation describing a heating process. A cylindrical metal of known dimensions and properties is heated from one side while the temperature of the other side is kept constant. I need to find the equation describing the temperature rise of the side being heated until it reaches equilibrium, so that from it, one can obtain a temperature time graph and know how long it takes to reach equilibrium.

Or rather does anyone know of an equation that can be used to describe how long a piece of metal being heated with constant heat flux takes to reach equilibrium temperature?
 
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  • #2
Ok. If a constant amount of heat is supplied, then H=kA dt/dx=constant. Hdx=kA dt. Integrating from 0 to x and 0 to t. kA (t)=H(x). This would make it seem like the temperature varies linearly... with distance? Dunno... sorry can't be of much help...
 
  • #3


I would suggest using the heat transfer equation, also known as Fourier's law, to describe the heating process. This equation states that the rate of heat transfer (Q) is equal to the product of the thermal conductivity (k), the cross-sectional area (A), and the temperature gradient (dT/dx). In this scenario, the temperature gradient would be the difference between the constant temperature on one side and the changing temperature on the other side.

To find the equation for the temperature rise over time, you can use the heat transfer equation in conjunction with the heat capacity equation (Q = mcΔT). This will give you an equation that relates the change in temperature over time (ΔT/Δt) to the heat flux, thermal conductivity, cross-sectional area, and heat capacity of the metal.

To determine the time it takes for the metal to reach equilibrium temperature, you can set the heat flux to zero (since the temperature on one side is being kept constant) and solve for the time at which the temperature rise reaches zero. This will give you the time it takes for the metal to reach equilibrium temperature.

I would also recommend considering any additional factors that may affect the heating process, such as the temperature of the surroundings, the material properties of the metal, and any heat losses due to convection or radiation. These can be incorporated into the equations to provide a more accurate description of the heating process.
 

1. What is meant by "Time for heating to equilibrium with constant heat flux?"

The time for heating to equilibrium with constant heat flux refers to the amount of time it takes for a substance or system to reach a stable temperature when heat is being constantly applied at a steady rate. This process is also known as thermal equilibrium, where the rate of heat loss is equal to the rate of heat gain.

2. How is the time for heating to equilibrium calculated?

The time for heating to equilibrium can be calculated using the following equation: t = (C x m x ΔT) / q, where t is the time in seconds, C is the specific heat capacity of the substance, m is the mass of the substance, ΔT is the change in temperature, and q is the constant heat flux.

3. What factors affect the time for heating to equilibrium?

The time for heating to equilibrium is affected by several factors, such as the specific heat capacity of the substance, the mass of the substance, the temperature difference between the initial and final states, and the constant heat flux. Other factors that may affect the time include the material and shape of the container, as well as any external factors that may influence the heating process.

4. Is the time for heating to equilibrium the same for all substances?

No, the time for heating to equilibrium can vary depending on the specific heat capacity and mass of the substance. Substances with a higher specific heat capacity will take longer to reach equilibrium compared to substances with a lower specific heat capacity. The mass of the substance also plays a role, as larger masses will take longer to heat up compared to smaller masses.

5. How can the time for heating to equilibrium be reduced?

To reduce the time for heating to equilibrium, the constant heat flux can be increased, or the mass of the substance can be decreased. Additionally, using materials with a higher thermal conductivity can help speed up the heating process. It is also important to ensure proper insulation and minimal heat loss during the heating process.

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