buletinul institutului politehnic din iaşi - Universitatea Tehnică ...

156 Marius Receanu et al.
In Fig. 2 the functions of temperatures Tri and Tre tend to distinct values at
approach to steady states. In situation b) - radiator obturated, the speed of
increase of the temperatures at the approach to steady states (observed on
Laptop) is greater as the situation a).
The Eq. (4) can be written in the second transient phase for this situations
a) and b)
( Ch Ch) cl( Θ Θ)
Q q
' '
,
l r
− = − (6)
where: Θ and Θ’ are the mean of functions ”product”: qr(t)[Tri(t)–Tre],
respectively: q’r(t)[T’ri–T’re] in the second phases: [0, tr] or [0, t’r]
t op
= 1
q () t ⎡
ri() t re d
r T −T
⎤ t
top − ⎣ ⎦
tcltcl
Θ ∫ , (7)
t
'
op
' 1
' '
Θ = () () d
' ∫ q t ⎡
r T ri t −T
⎤
re t.
(8)
⎣ ⎦
top −tcl
t
cl
The function Θ and Θ’ – (7), (8), can be calculated with software in
LabVIEW, after experiments and the relations
'
Θ −Θ
'
C h C h cl Q l
− = ;
'
Θ −Θ
'
C h C h cl Q l
'
h
= − ,
and fuel economy, in percent : Ch
−C
ε = 100 , in MATLAB/Simulink.
Ch
For different position of the blind who obdurate the radiator: Fig. 3 (in
positions: 0 –radiator is not obturated; 1, 2 ,3 – radiator is obturated) and some
ambient temperatures