Differential temperature

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Dif­fer­en­tial tem­per­a­ture is al­so called tem­per­a­ture dif­fer­ence. The dif­fer­en­tial tem­per­a­ture is the dif­fer­ence in tem­per­a­ture be­tween two pre­vi­ous­ly de­fined mea­sur­ing points. The for­mu­la sym­bol for the dif­fer­en­tial tem­per­a­ture is ∆T and the unit of mea­sure­ment is de­grees Cel­sius (°C), de­grees Kelvin (°K) or de­grees Fahren­heit (°F).

Calculation of the differential temperature (∆T)

∆T = T2 – T1

Measuring the differential temperature in practice

To mea­sure the dif­fer­en­tial tem­per­a­ture, mea­sur­ing de­vices de­signed for this pur­pose are used. The de­vices are equipped with tem­per­a­ture sen­sors and can in­form the user about the dif­fer­ence in tem­per­a­ture when two de­vel­op­ments are measured:

  • The tem­per­a­ture at the sec­ond mea­sur­ing point is low­er than the val­ue at the first mea­sur­ing point. In this con­text we speak of tem­per­a­ture loss.
  • The tem­per­a­ture at the sec­ond mea­sur­ing point is greater than the val­ue at the first mea­sur­ing point. In this con­text we speak of tem­per­a­ture increase.

The mea­sur­ing de­vice does not out­put a dif­fer­en­tial tem­per­a­ture if the tem­per­a­ture at both mea­sur­ing points is unchanged. 

What is the differential temperature measured for anyway?

The dif­fer­en­tial tem­per­a­ture pro­vides the ob­serv­er with in­for­ma­tion about the dif­fer­ence be­tween the tem­per­a­ture at the in­let and the tem­per­a­ture at the out­let of a heat­ing el­e­ment, heat ex­chang­er, heat­ing sys­tem or so­lar sys­tem. It is al­so re­ferred to as the flow tem­per­a­ture and the re­turn tem­per­a­ture. When the tem­per­a­ture dif­fer­ence ex­ceeds or falls be­low a spec­i­fied val­ue, process­es are ac­ti­vat­ed in the work­ing sys­tem that coun­ter­act the de­vel­op­ment of the temperature. 

Not expected change in the differential temperature

The dif­fer­en­tial tem­per­a­ture is an im­por­tant in­di­ca­tor of tem­per­a­ture loss­es and en­er­gy ef­fi­cien­cy. For ex­am­ple, the lev­el of the tem­per­a­ture dif­fer­ence sig­nif­i­cant­ly af­fects the en­er­gy ef­fi­cien­cy of any equip­ment in use. An un­in­tend­ed in­crease or de­crease in the tem­per­a­ture dif­fer­en­tial in a sys­tem can have sev­er­al con­se­quences for the en­tire process. To min­i­mize the dan­ger, the de­vel­op­ment should al­ways be mon­i­tored in or­der to re­act at an ear­ly stage. To find tem­per­a­ture dif­fer­ences in a wa­ter cir­cuit di­rect­ly, one helps one­self with dif­fer­ent da­ta log­gers. They log the tem­per­a­ture val­ues at the two mea­sur­ing points over a de­sired pe­ri­od of time and thus en­able the pre­cise in­ves­ti­ga­tion of developments.

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