Transducer apparatus as well as measuring system formed therewith

A transducer apparatus, comprising:

• a transducer housing exhibiting a cavity encased by a wall;
• a tube exhibiting a lumen surrounded by a wall, said tube is arranged within the cavity of said transducer housing in such a manner that between an inner surface of the wall of said transducer housing facing the cavity and an outer surface of the wall of said tube facing the cavity an intermediate space is formed, and
• said tube is adapted to guide in its lumen a fluid, in such a manner that said inner surface of the wall of said tube facing the lumen is contacted by the fluid guided in the lumen in order to form a first interface of a first type, wherein the first interface of the first type is an interface between the fluid guided in the lumen of the tube and the wall of said tube;
• a first temperature sensor including a first temperature detector arranged within said intermediate space and a first coupling body coupling said first temperature detector thermally conductively with the wall of said tube, said first temperature sensor being adapted to register a first measurement location temperature, wherein a temperature at a first temperature measurement location is formed by means of said first temperature detector, and to transduce said first measurement location temperature into a first temperature measurement signal, said first temperature measurement signal is a first electrical measurement signal representing the first measurement location temperature;
• a second temperature sensor including a second temperature detector spaced from said first temperature detector and arranged within said intermediate space and a second coupling body coupling said second temperature detector thermally conductively with the wall of said tube, said second temperature sensor being adapted to register a second measurement location temperature, wherein a temperature at a second temperature measurement location is formed by means of said second temperature detector, and to transduce said second measurement location temperature into a second temperature measurement signal, said second temperature measurement signal is a second electrical measurement signal representing the second measurement location temperature;
• wherein:
• said transducer housing and said tube are adapted to hold a fluid in said intermediate space in order to form a fluid volume surrounding said tube, in such a manner that said outer surface of the wall of said tube facing said intermediate space is contacted by the fluid held in said intermediate space in order to form a second interface of the first type, wherein the second interface of the first type is an interface between the fluid held in said intermediate space and the wall of said tube;
• said first temperature sensor contacts by means of said first coupling body the outer surface of the wall of said tube forming a first interface of a second type, wherein the first interface of the second type is an interface between the first coupling body and the wall of said tube and said second temperature sensor contacts by means of said second coupling body the outer surface of the wall of said tube forming a second interface of the second type, wherein the second interface of the second type is an interface between the second coupling body and the wall of said tube, in such a manner that:
• a first thermal resistance, R1, opposes a first heat flux, resulting from a temperature difference between said first interface of the second type and said first temperature measurement location, totally passing through the first interface of the second type and flowing further to the first temperature measurement location;
• a second thermal resistance, R2, opposes a second heat flux, resulting from a temperature difference between said second interface of the second type and the second temperature measurement location, totally passing through the second interface of the second type and flowing further to the second temperature measurement location;
• and
• the fluid volume surrounding said tube contacts said first temperature sensor to form a third interface of the first type as well as contacts said second temperature sensor to form a fourth interface of the first type, in such a manner that:
• a third thermal resistance, R3, opposes a third heat flux, resulting from a temperature difference between said third interface of the first type and the first temperature measurement location, flowing from the first temperature measurement location totally to said third interface of the first type, equally as well totally passing through said third interface of the first type;
• and
• a fourth thermal resistance, R4, opposes a fourth heat flux, resulting from a temperature difference between said fourth interface of the first type and the second temperature measurement location, flowing from the second temperature measurement location totally to said fourth interface of the first type, equally as well totally passing through said fourth interface of the first type;
• and
• said first thermal resistance, R1, said second thermal resistance, R2, said third thermal resistance, R3, as well as said fourth thermal resistance, R4, are so dimensioned that a condition
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• is fulfilled.