PromLegion DX4085, User Manual

Page: 51 / 64

Z-Meter DX4085/ User Guide PromLegion Ltd
𝜏𝜏 =
𝐿𝐿𝐶𝐶
1
𝐶𝐶
2
(𝐶𝐶
1
+ 𝐶𝐶
2
) �1 + 𝐿𝐿𝑈𝑈𝐿𝐿
𝑘𝑘
0
� 𝑠𝑠
0
𝑘𝑘
0
𝑁𝑁
(5.1.3)
Where
𝐶𝐶
1
,
𝐶𝐶
2
- TE module cold side and hot side heat capacities,
𝑈𝑈
- TE material Seebeck coefficient,
𝑘𝑘
0
- TE material thermal conductivity,
𝑁𝑁
- TE module pellets number,
𝐿𝐿
- pellets height,
𝑠𝑠
0
- pellets cross-section,
𝐿𝐿
- electric current density.
As Eq. (5.1.3) shows,
𝜏𝜏
calculation is stumbling because in practice
the values involved are never known with accuracy required. The Z-
meter allows measuring time constants of single-stage TE modules
and estimating those of more-stage ones.
9.2. Interpolation Results
The procedure of handling the time constant measurement data is as
follows.
The temporal behavior of a single-stage TE modules temperature
difference is measured via the Seebeck voltage that is a
corresponding proportional value:
𝑈𝑈
𝛼𝛼
~∆𝑇𝑇
(5.2.1)
For a two- or more-stage TE module this simple ratio is not
applicable. However the time constant can be estimated by the
temporal dependence of the Seebeck voltage and the approach for
obtaining the stationary voltage values is the same.
ver. 1.00 (2017) page 51 of 64