Process and device for the determination of the thermal resistance of

Abstract

The process consists in that two comparison tube sections (3; 4), which originate from a single condenser tube and of which one (3) is left in the corroded condition and/or the condition encrusted by mineral deposits and the other (4) is brought into the new condition by etching or other cleaning procedures, are conductively connected in series, and cooling water flows through them and they are heated from the outside in a condenser chamber in each case (1 and 2 respectively) by steam flows of equal power. The temperatures (t.sub.1, t.sub.2 and t.sub.3, t.sub.4 respectively) measured at the inlet and outlet positions of the comparison tube sections (3; 4), the measured values of the mass flow of cooling water (M.sub.w) and the steam temperatures (t.sub.f ; t.sub.b) and the heat flows (Q.sub.kf =Q.sub.kb) in the two condenser chambers (1 and 2 respectively) permit the determination of the thermal resistance (R.sub.f) of the incrustation layer of the tube drawn for the purposes of investigation from the condenser. A device for carrying out the process exhibits two condenser chambers (1; 2) to receive the comparison tube sections (3; 4) and a degassing vessel 11, which communicates with the condenser chambers (1; 2). In a cooling water duct (15+5+16) there are provided, before and after the condenser chambers (1; 2), measurement chambers (17 and 19, 18 respectively) with thermo-elements for the measurement of the differences of the said cooling water and steam temperatures. Precision wattmeters preferably serve for the measurement of the heat flows (Q.sub.kf =Q.sub.kb). The heat flows can also be calculated from the difference in enthalpy of the mass flow of the cooling water (M.sub.w) before and after the condenser chambers (1; 2). The measurement of the mass flow of cooling water (M.sub.w) preferably takes place by weighing the quantity of cooling water which has flowed out in unit time.