Process dynamics modelling for heated tank, differential equations

Click For Summary

Discussion Overview

The discussion revolves around modeling the dynamics of a heated tank using differential equations. Participants explore the relationship between incoming and outgoing temperatures, the control of heat flux, and the formulation of the necessary equations for effective temperature regulation.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant presents a differential equation for the tank's temperature dynamics: ρ*cp*vdT/dt = q + m*cp*(T-Ti), but expresses difficulty in formulating the equation for heat flux q.
  • Another participant seeks clarification on the modeling approach, suggesting that the inlet temperature may vary over time and that the goal is to control the outlet temperature based on measurements.
  • A later reply indicates that the initial differential equation is correct but emphasizes the need to define how the heat flux q is controlled to maintain the desired temperature set point.
  • It is proposed that if a proportional controller is used, then q could be expressed as q = k(Ts-T), where k is a constant and Ts is the set point temperature.

Areas of Agreement / Disagreement

Participants generally agree on the formulation of the differential equation but have not reached consensus on how to define and control the heat flux q for temperature regulation.

Contextual Notes

The discussion includes assumptions about the system being a well-mixed continuous stirred tank (CST) and the potential variability of the inlet temperature, which may affect the modeling approach.

Who May Find This Useful

This discussion may be of interest to individuals involved in process dynamics, control systems, and thermal engineering, particularly those exploring temperature regulation in fluid systems.

maistral
Messages
235
Reaction score
17
I can't seem to model this properly. This isn't an assignment, I'm just curious how this will go, lol.
So I have this tank with an incoming feed stream with temperature Ti, and an output stream T. It has a jacket where q would be modified depending on the desired output stream T.

So I assembled this:

ρ*cp*vdT/dt = q + m*cp*(T-Ti)


I can't seem to assemble the differential equation required for q.

Thanks!
 
Physics news on Phys.org
maistral said:
I can't seem to model this properly. This isn't an assignment, I'm just curious how this will go, lol.
So I have this tank with an incoming feed stream with temperature Ti, and an output stream T. It has a jacket where q would be modified depending on the desired output stream T.

So I assembled this:

ρ*cp*vdT/dt = q + m*cp*(T-Ti)


I can't seem to assemble the differential equation required for q.

Thanks!

Hey maistral. Let me understand what you are trying to do. You are looking as a well-mixed CST. The inlet temperature may be a function of time, and you are trying to control the outlet temperature. You measure the outlet temperature as a function of time, and compare it to the desired set point. The question is, based on these measurements, what strategy do you use to control q to minimize the deviation from the desired set point. Correct?

Chet
 
Yes. That's what I'm after, and I can't seem to set the differential equations for it :|
 
maistral said:
Yes. That's what I'm after, and I can't seem to set the differential equations for it :|

You already have the differential equation. The only thing you are missing is how the heat flux is controlled to try to maintain the set point. For example, if it is a proportional controller, then q = k(Ts-T), where k is a constant of proportionality and Ts is the set point temperature.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
Replies
12
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 11 ·
Replies
11
Views
9K
Replies
2
Views
5K
Replies
8
Views
6K
  • · Replies 5 ·
Replies
5
Views
3K