Heat Transfer from Air to Dynamic Fluid in Pipe

In summary: The equation most commonly used to calculate the exit temperature of a fluid from an exposed length of pipe is the Clausius-Clapeyron equation. This equation is based on the principle that heat will be transferred to the pipe's outer surface by thermal radiation and natural convection (assuming no breezes in the room). Roughly this will occur at the rate of about (2 BTU per hour)*ft2*delta F, where ft2 is the surface area of the pipe in square feet and delta F is the temperature difference between the pipe and the room.
  • #1
chriskaselak
1
0
I need some help estimating the heat transfer of a system. If I have an exposed length of pipe with a dynamic fluid moving at a constant volumetric rate through a very hot room, what equation is most appropriate to calculate the exit temperature of the fluid?

Given:
Initial temperature of the fluid
Temperature of the room
Material properties of the pipe and fluid

Thanks,
 
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  • #2
Heat transfer calculations can get complicated, but if you need just a ball park estimate your problem can be made simple. The main resistance to heat transfer from your hot room to the pipe will be the interface between the air and the outside surface of the pipe. The thermal resistance of the pipe itself and the fluid interface to the pipe's interior is most likely to be small in comparison.

Heat will be transferred to the pipe's outer surface by thermal radiation and natural convection (assuming no breezes in the room). Roughly this will occur at the rate of about (2 BTU per hour )* ft2 * delta F, where ft2 is the surface area of the pipe in square feet and delta F is the temperature difference between the pipe and the room.

So, compute the heat added to the first foot of pipe, then compute the temperature rise of the fluid, temp rise = heat input/(cp * mass flow)

where:
heat input is BTU/hour
cp is the thermal capacity of the fluid BTU/F/lb (for example, Cp of water = 1 btu/F/lb)
mass flow is lb/hour


Continue computing the heat rise for addition foot sections of pipe and adding them up until you've done the pipe's entire length (this is a numeric solution procedure to a differential equation).

Good luck!

Jay


chriskaselak said:
I need some help estimating the heat transfer of a system. If I have an exposed length of pipe with a dynamic fluid moving at a constant volumetric rate through a very hot room, what equation is most appropriate to calculate the exit temperature of the fluid?

Given:
Initial temperature of the fluid
Temperature of the room
Material properties of the pipe and fluid

Thanks,
 

What is "heat transfer"?

"Heat transfer" refers to the process of transferring thermal energy from one object or substance to another. This can occur through conduction, convection, or radiation.

How does heat transfer from air to dynamic fluid in a pipe work?

In this process, thermal energy is transferred from the air surrounding the pipe to the fluid flowing through it. This can happen through convection, where the air directly contacts the pipe and transfers heat, or through radiation, where thermal energy is emitted from the pipe and absorbed by the fluid.

What factors affect heat transfer in this scenario?

The rate of heat transfer from air to dynamic fluid in a pipe can be influenced by several factors, including the temperature difference between the air and the fluid, the surface area of the pipe, the flow rate of the fluid, and the properties of the materials involved.

What is the equation for calculating heat transfer in this situation?

The equation commonly used for calculating heat transfer in this scenario is known as the convective heat transfer equation: Q = hA(T1-T2), where Q is the heat transferred, h is the convective heat transfer coefficient, A is the surface area, and T1 and T2 are the temperatures of the air and fluid, respectively.

How can heat transfer from air to dynamic fluid in a pipe be optimized?

To optimize heat transfer in this situation, factors such as increasing the surface area of the pipe, increasing the flow rate of the fluid, and using materials with higher thermal conductivity can be considered. Additionally, proper insulation or heat transfer enhancement techniques can also be utilized to improve the efficiency of heat transfer.

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