ODE45: ODE Error using odearguments must return a column vector

Hi, I have the following equation and I am trying to solve this for Tm. The size of Qinj_t is 10525X1. I have 10525 different data points and I want to get the Tm value for each point/timestep. All other parameters are constant except the Qinj_t . By using the following code I am getting error. Can anyone please help me out?

%% Auusmptions &constant parameters

n = 1.3581 % Capacity exponent for the unit

Tsu = 75; % [C] inlet temperature of the radiator

Tair = 21; % [C] Air temperature

C_rad = 5.7770e+04; % Total thermal capacity of radiator

C=10;

%% Time series data for Qinj

tQin = (0:0.0022805:24)';

step = 10524; %

tspan =[0 0.0022805];

t0 = 0; % Start time

t1 = 24; % Final time

t = linspace(t0 , t1 , (step+1));

%% Reading data from Excel sheet

[num txt raw] = xlsread('Radiator_sweep190.xlsx');

Qinj_t = num(:,4); (10525X1)

Qinj_td = interp1(tQin, Qinj_t, t, 'linear');

Tmo = 20 ;

[t,Tm] = ode45(@(t,Tm) rad_h(t, Tm, tQin, C_rad, Qinj_td, C, Tair, n ),tspan,Tmo);

Following function is used:

function dtmdt = rad_h(t, Tm, tQin, C_rad, Qinj_td, C, Tair, n )

dtmdt = 1/C_rad*((Qinj_td)- (C*(Tm-Tair).^n))

end

[Star Strider]

I cannot run your code. However the problem is likely that you are passing ‘Qinj_td’ as a row vector rather than as individual elements in a loop. The same would also apply to the other vectors you are passing as arguments.

[Haseeb]

Hi, Thanks for your response. I am not expert in matlab. I will try this way. This is the continuous data for 24 hours.

[Star Strider]

My pleasure.

It might help to know what you want to do.

[Haseeb]

Well, I will try to explain.

I have the following equation and I want to solve this equation for 10525 timestep (for a day) to get the "Tm" values.

This is actually a simple energy balance:

Qstore = Qinj - Qemitted

Hence;

dTm/dt = 1/C_rad * ((Qinj)- (C*(Tm-Tair).^n))

In the above equation all other parameters are constant except ''Qinj''. Qinj is actually the heat injected to the radiator and it has a step change. I am using ODE45 to solve this. The purpose is to observe the change in Tm by changing the Qinj.

So I want to solve the above equation for 10525 different timesteps to get the Tm for each data point. Since this is the continuous data so the initial value for Tm (Tm0) for the next timestep will be equal to the Tm value for the previous timestep (Becuase this is the time-series data).