The same data with the vertical range of the graph set to show the equilibration process in detail. The range of cell holder temperatures indicated by ß| 1 |à includes the first full minute that the sample holder temperature stays within the range 37 ± 0.05 ⁰C; this is the criterion used by the temperature controller to determine that the cell holder temperature is stable. The range indicated by |ß 10 à| is an additional 10-minute period required for the sample temperature to stabilize.
Why are the final sample holder temperature and sample (probe) temperature different.
Consider the case when the Cell holder Temperature ( CT = 37 ⁰C) is greater than the surrounding Air Temperature ( AT = 25 ⁰C ).
The Rate of heat Gain ( RG ) of the sample is proportional to the temperature difference between CT and the Sample Temperature ( ST ).
RG = KG * ( CT ‑ ST ) where KG > 0
Similarly the Rate of heat Loss ( RL ) is proportional to the difference between AT and ST.
RL = KL * ( AT ‑ ST ) where KL < 0
The final sample temperature is reached when the two are equal.
KG * ( CT – ST ) = KL * ( AT – ST ) or ST = ( KG*CT ‑ KL*AT ) / ( KG ‑ KL )
|‑ KG / KL||ST||insulation value|
|2||33.00||worse than none|