Equilibrium temperature of heat exchanger

In summary, in a closed loop with a heater and a fan cooled finned heat exchanger where water flows between the two, the system may reach an equilibrium state but not necessarily an equilibrium temperature. There is no specific equation to calculate the equilibrium temperature, but assuming constant specific heat and heat flux from the heater, the temperature rise of the water can be approximated as a constant. However, the efficiency of the heat exchanger may prevent the water from cooling back to ambient temperature, resulting in a continuous change in temperature.
  • #1
Escheresh
1
0
In a closed loop with a heater and a fan cooled finned heat exchanger where water flows between the two, is it right to assume that the water will reach an equilibrium temperature?
If so, is there an equation that can get the equilibrium temperature?
The power of the heater and cooler, the flow rate, volume of water and initial temperature are known.
 
Engineering news on Phys.org
  • #2
I don't think the system will reach an equilibrium temperature, but it can reach an equilibrium state.

If the water doesn't boil, we can assume it has a constant specific heat, and I don't know what your specifics are, but it might also be safe to assume that the heat flux from the heater is a constant. If this is true, then the temperature rise of the water between the inlet and outlet of the heater is a constant.

So, if everything is at ambient temperature before you "switch it on," the water will start to flow and the water leaving the heater will be at some elevated temperature (ambient temperature + some constant temperature rise). The efficiency of the heat exchanger depends on the difference in temperature between ambient air and the water, so it might not (probably will not) be cooled back to ambient temperature. After several passes, the water might be hot enough that the temperature drop at the heat exchanger is equal to the temperature rise at the heater, so now your system is at its equilibrium state. But the water is still changing temperature.

-Kerry
 
  • #3


Yes, it is reasonable to assume that the water will reach an equilibrium temperature in this closed loop system. This is because the heat transfer between the heater and cooler, as well as between the water and the finned heat exchanger, will eventually balance out and reach a steady state.

There is an equation that can be used to calculate the equilibrium temperature in this system, known as the energy balance equation:

Qin + Qheater = Qout + Qexchanger

Where Qin is the heat input from the heater, Qheater is the heat dissipated by the heater, Qout is the heat output from the heat exchanger, and Qexchanger is the heat absorbed by the heat exchanger.

The equilibrium temperature can then be calculated using the following equation:

Teq = (Qin - Qheater) / (m * Cp)

Where Teq is the equilibrium temperature, m is the mass flow rate of the water, and Cp is the specific heat capacity of water.

In order to accurately calculate the equilibrium temperature, it is important to have accurate values for the power of the heater and cooler, the flow rate of water, the volume of water, and the initial temperature. Additionally, factors such as the design and efficiency of the heat exchanger can also affect the equilibrium temperature.
 

What is the equilibrium temperature of a heat exchanger?

The equilibrium temperature of a heat exchanger is the temperature at which the heat transfer rate between the two fluids in the exchanger is equal. This means that the amount of heat transferred from one fluid to the other is the same as the amount of heat transferred in the opposite direction.

How is the equilibrium temperature determined for a heat exchanger?

The equilibrium temperature can be determined by solving the energy balance equation for the heat exchanger. This equation takes into account the heat transfer rates, fluid flow rates, and inlet temperatures of the two fluids in the exchanger.

What factors affect the equilibrium temperature of a heat exchanger?

The equilibrium temperature of a heat exchanger is affected by a few key factors, including the type of fluids being used, their flow rates, the design and size of the exchanger, and the thermal conductivity of the exchanger's material.

Why is it important to maintain the equilibrium temperature in a heat exchanger?

Maintaining the equilibrium temperature in a heat exchanger is important because it ensures optimal heat transfer between the two fluids. If the equilibrium temperature is not reached or maintained, it can lead to inefficient heat transfer and potentially cause damage to the exchanger.

Can the equilibrium temperature of a heat exchanger be changed?

Yes, the equilibrium temperature of a heat exchanger can be changed by adjusting the flow rate and/or temperature of the fluids, as well as by modifying the design or size of the exchanger. However, these changes should be carefully considered and calculated to ensure efficient and safe operation of the exchanger.

Similar threads

Replies
2
Views
2K
  • General Engineering
Replies
21
Views
2K
Replies
10
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
22
Views
1K
  • General Engineering
2
Replies
67
Views
4K
Replies
1
Views
1K
Replies
25
Views
2K
Replies
2
Views
334
  • General Engineering
Replies
34
Views
3K
  • General Engineering
Replies
15
Views
531
Back
Top