PromLegion DX4085, Руководство пользователя

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Z-Meter DX4085/ User Guide PromLegion Ltd
Where
𝑈𝑈
𝛼𝛼
= 𝑁𝑁𝑈𝑈(𝑇𝑇
1
− 𝑇𝑇
0
)
- TEC Seebeck voltage,
𝑈𝑈
𝑅𝑅
= 𝑁𝑁𝐼𝐼𝑅𝑅
- TEC Ohmic component of the voltage.
The ratio of the voltages
𝑈𝑈
𝛼𝛼
and
𝑈𝑈
𝑅𝑅
in Eq. (5.3.1.5) must be averaged
for two directions of the current (the index
𝐴𝐴𝐴𝐴
=average), as it
eliminates expressions depending linearly on the current and allows
extracting the corrections
𝑏𝑏
𝑎𝑎ℎ
,
𝑏𝑏
𝑟𝑟
,
𝑏𝑏
𝑇𝑇
.
The value
𝑏𝑏
𝑎𝑎ℎ
is the correction for additional heat flux between the
pellets;
𝑏𝑏
𝑟𝑟
is the correction for leading wires electric resistance;
𝑏𝑏
𝑇𝑇
is
the correction allowing for inequality of the TE module average
temperature and the ambient temperature.
The values
𝑎𝑎
0
,
𝑎𝑎
1
are estimated with account of free convection in
the air and of thermal radiation:
𝑎𝑎
0,1
= (𝑈𝑈
𝑐𝑐𝑐𝑐𝑎𝑎𝑐𝑐
+ 𝑈𝑈
𝑟𝑟𝑚𝑚𝑟𝑟
)𝑆𝑆
0,1
, where
𝑈𝑈
𝑐𝑐𝑐𝑐𝑎𝑎𝑐𝑐
,
𝑈𝑈
𝑟𝑟𝑚𝑚𝑟𝑟
are thermal exchange coefficients of convection and of
heat emission calculated for each TE module individually,
𝑆𝑆
0
and
𝑆𝑆
1
are the surfaces of the cold and hot sides of the TE module tested.
Eq. (5.3.1.5) remains fair if inequalities (5.3.1.3) are modified as:
𝑎𝑎
0
𝑁𝑁 =≪ 𝑘𝑘
′
, 𝑎𝑎
0
≪ 𝑎𝑎
1
(5.3.1.6)
That means that the method allows finding the value
𝑍𝑍
of a TE
module when the heat exchange on one side of the module is
intensive enough. Therefore, the Z-Meter enables testing of a TE
sub-assembly: TEC mounted on a header. In this case the value a
1
is
the header thermal resistance (calculated by the Program).
The measured
𝑍𝑍
of a single-stage TE module allows estimating
∆𝑇𝑇
𝑚𝑚𝑚𝑚𝑚𝑚
of the module at the hot side temperature
𝑇𝑇
1
:
∆𝑇𝑇
𝑚𝑚𝑚𝑚𝑚𝑚
(𝑇𝑇
1
) = 𝑇𝑇
1
−
�1 − 2𝑍𝑍𝑇𝑇
1
− 1
𝑍𝑍
(5.3.1.7)
9.3.2. Two-stage TE Module
𝒁𝒁
For a two-stage TE module
𝑍𝑍
can be estimated with the help of the
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