MechaEngBryan.github.io

California State University, Chico

Mecahanical and Mechatronic Engineering

MECA 482 Controls - Temperature Control System - Group Project Website

MECA 440 Engineerinig Capstone - SLAC Reservoir Cooling System Modeling



Project Description


Leveraging our Senior Capstone Project’s problem, we are creating a mathematical model that will programmatically capture the temperature control system. Our project is being tasked with controlling the temperature of a 4” in length x 0.5” in diameter 316 Stainless Steel cylinder – this cylinder is used as a holding reservoir for samples used during experimentation. Initial conditions for the cylinder are standard laboratory conditions e.g. 24°C and 50% RH. The final condition for the cylinder is 4 +/- 0.25°C after 5 minutes i.e. must achieve an average -5°C/minute ramp rate




Testing setup
The power supplies were used to power the Peltiers(x3) and the 80mm x 80mm Fans (x2)
MATLAB and an Arduino were used to supply PWM signal to Fans for Fan Speed

Device Under Test (DUT)



Parts list (not capturing clam shell)



Performing Test



DMM with K-Type Thermocouple Displaying Temperature




The input step command can be ignored on this plot, because this was not a closed loop test
Test initial Temperature was 24 degrees Centigrade - it took ~2 minutes to achieve 4 degrees Centigrade
Sampling was performed using a stopwatch at 10 second intervals

Results Plotted with exponential curve fit






The trend line equation was then taken from above collected data and converted to s domain



### MATLAB Script used to analyze Transfer Function Response 


%MECA 482 - Thermal Response
%12/4/2019

clc; close all; clear all;

%% raw data from testing, sampled at .1Hz
temp = [22.2 21.7 20.2 17.9 15.4 13.2 11.1 8.9 7.2 6 4.5 3.2 2.7];

time = [10 20 30 40 50 60 70 80 90 100 110 120 130];

%% Transfer Function and step response
s = tf('s');
%init temperature from exp trend line at t = 0
t = 0;
To = 34.701*exp(-.018*t);
K = -34.701;            % DC gain
tau = .018^-1;
TF = K/(tau*s+1);        % model transfer function
[y,t] = step(TF,130);    % model step response

%% plot generation
plot(time,temp,'rx',t,y+To,'b')
xlabel('Time [sec]')
ylabel('Temperature [C]')
title('SLAC Reservoir Clamshell Temperature Step Response')
legend('Raw data','Model','Location','NorthEast')



The results from the above MATLAB script plotted




The below captures the implemented Closed Loop Temperature Contoller using Simulink



Data collected during testing of the system



Unfortunately because of hardware limitations within the Arduino Uno we were using (32kb Flash memory) we were not able to compile and execute the simulink model on the microcontroller in a standalone configuration. Alternative microcontrollers have since been identified.


Link to prototype testing below

Prototype Testing