Automotive Rariator Simulation
I'm developing a code to simulate thermal performance of automotive
radiators.
My results are 40% underpredicted. But when I multiply them to 1.6, they
match completely.
This is the graph that compares the results of program and experimental work.
It should be noted that this number (1.6) differs when we use the other data
sets.
Procedure of the program is as following :
1- given air velocity, coolant flowrate, inlet air and coolant temperatures.
2- assume outlet air and water temperatures( It should be a logical
assumption).
3- calculate air and fluid properties.(using interpolation in existed tables
based on men temperatures)
4- calculate heat transfer coefficient of water according to flow
regime(using <PERSON> or <PERSON> equations)
5- calculate <PERSON> j factor (using <PERSON> and Wang empirical correlation)
6- calculate the total thermal resistance between air and coolant.
7- calculate NTU and effectiveness
8- Calculate heat rejection
9- Calculate outlet temps and compare them with assumed temps. 842
if it doesn't
meet the specified error , go to step 3 and repeat calculations.
clc;clear all
% _____Jung Experiment_______
% Air Velocity m/s
Va=4;
water_Flowrate=2e-3/3;% m3/s (40 L/min)
% Top tank and inlet air temperatures (deg C)
twih=85; t_ambient=25;
% Specifying the j-factor correlation (<PERSON> & <PERSON>)
cor='CW';
% Entering the Radiator characteristics
cas='C:\Users\Solid\Desktop\jung.xlsx';
% ___ Calculation ___
ITD=twih- t_ambient;
% Export Geometrical details from jung.xlsx file and calculate the needed
% Areas like AT(total heat transfer area etc).
[R,L,Afrt,Afrf,Ac,Afront,sigma,Af,Aw,AT...
Lp,Fp, Fl, Ll, alpha, Fd, Tp, deltaf, Nlb,Td,LH,af,Dh,NT,kf...
RH,RW,RD,N,Nct,Np,Nf,Yl,Dm,D_major,W,tt]=Area_Calc(cas);
% Radiator tubes are flat. So we need hydraulic diameter(dw).
[dw,A_cross,Perimeter]=hydro2(Dm,L);
% ___ Pre_Procssing ___
t_top_tank=twih;
twi= t_top_tank;
tai = t_ambient;
% defining an error;
error=.01;
% Assuming outlet temperatures of water(Two) and Air(Tao) logically.
Tao=50; Two=75;
Y=1;
% defining a counter;
ll=0;
while Y
Q=0;
ll=ll+1;
% At the end of the loop, calculated temperatures will be compared
% with the tepms of the past iteration.So we save the tepms of the
% past iteration here.
Two1=Two; Tao1=Tao;
% Calculating the properties like viscosity(uw(coolant),ua(air)),Prandtel
% Number (Pra(air) ,Prw(coolant)) etc.
[ uw,ua,rhow,rhoa,cw,ca,kw,ka,Prw,Pra,tam ]=...
phyprop2(twi ,tai,Two,Tao);
% Air side Reynolds number. ReLp is the reynolds number based on
% Louver pitch.
ReLp=rhoa*Va*Lp*1e-3/(ua);
ReDh=rhoa*Va*Dh*1e-3/(ua);
% Air mass flowrate
mair=Ac*rhoa*Va;
% --- Coolant side Reynolds number and mass flowrate ---
[Rew,mwater]=hydro(dw,A_cross,water_Flowrate,rhow,uw,...
NT,'I');
% coolant heat transfer coff.
[hw]=hc2(Yl,dw,Rew,kw,Prw,1);
% Air heat transfer coff. 33