Concentric Tube Heat Exchanger - Clarification on Energy Balance

In summary, a concentric tube heat exchanger is a heat exchanger that uses two or more concentric tubes to transfer heat between two fluids without mixing them. It works by allowing one fluid to flow through the inner tube while the other flows through the annulus. The energy balance in a concentric tube heat exchanger involves the conservation of energy, which can be calculated using the equation Q = mCpΔT. This type of heat exchanger has advantages such as high efficiency, compact size, and easy maintenance.
  • #1
dweeegs
12
1
I'm trying to model a Transfer function for the response of the deviation in temperature of water coming out of the concentric tube heat exchanger in response to an input velocity of water function.


THE PROBLEM

I start the derivation with a couple equations in Seborg's Process Dynamics and Controls and then go off on deriving on my own since my application of the equations are different then what they were using them to show.

A short snippet before I started my derivation:

axyEGvn.png


rNCaXUH.png


Now I understand what A_s and A_L are (the area available for heat transfer for those two... the length times 2(pi)R for the outside and inside radii, respectively).

What the heck is Aw? Is that an average of the two areas or the total amount of area available for heat transfer?

I got my model into standard form for what I want, but I'm having trouble putting in actual numbers.

Any help is much appreciated!
 
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  • #2
It's not clear from the OP where Aw is used.
 
  • #3
SteamKing said:
It's not clear from the OP where Aw is used.

Feel dumb now, I was up awake for an extremely long stretch of time and read the equation wrong... in my mind somehow the variable subscripts were flipped.

I am not confused after a good night's rest :D
 

Related to Concentric Tube Heat Exchanger - Clarification on Energy Balance

1. What is a concentric tube heat exchanger?

A concentric tube heat exchanger is a type of heat exchanger that consists of two or more concentric tubes, with one fluid flowing through the inner tube and the other fluid flowing through the annulus between the inner and outer tubes. It is used to transfer heat between two fluids without mixing them.

2. How does a concentric tube heat exchanger work?

A concentric tube heat exchanger works by allowing one fluid to flow through the inner tube, while the other fluid flows through the annulus. The fluids are kept separate by the tube walls, but heat is transferred from the hotter fluid to the cooler fluid through the tube walls. This process continues until the two fluids reach an equilibrium temperature.

3. What is the energy balance in a concentric tube heat exchanger?

The energy balance in a concentric tube heat exchanger involves the conservation of energy, where the amount of energy entering the system is equal to the amount of energy leaving the system. This means that the amount of heat gained by the cooler fluid is equal to the amount of heat lost by the hotter fluid.

4. How is the energy balance calculated in a concentric tube heat exchanger?

The energy balance in a concentric tube heat exchanger can be calculated using the equation Q = mCpΔT, where Q is the heat transferred, m is the mass flow rate, Cp is the specific heat capacity, and ΔT is the temperature difference between the two fluids. This equation takes into account the mass and specific heat of the fluids, as well as the temperature difference to determine the amount of heat transferred.

5. What are the advantages of using a concentric tube heat exchanger?

There are several advantages of using a concentric tube heat exchanger, including high heat transfer efficiency, compact size, and easy maintenance. The concentric design allows for a large surface area for heat transfer, while the compact size makes it suitable for a variety of applications. Additionally, the tubes can be easily removed for cleaning or maintenance, making it a cost-effective and efficient option for heat transfer.

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