5441337448

M. Lazar et al.

Designing Low Gas Flow Meters Based on the Calometric Principle...

DISCUSSION

As follows from experimental findings constructed gas flow meter based on the calorimetric measuring principle has minor deficiencies. When considering the flow rangę a confidence interval from 3 to 40 ml.s*¹ flow equation constructed on the basis of measured data shows the value of R²= 0.895 of the polynomial function series 4. This function is used to automate the measurement for the subseąuent iterative calculation of gas flow.

Deviation of the measured values from the polynomial curve appears on account of the uncertainly rangę of scanning device due to the materiał properties of TC parts and structural irregularities in the laboratory prototype. Location of thermocouples at a distance of 10 mm from the heating coil, because of the heat transfer by radiation and free convection flows in less than 10 ml, increases the measurement uncertainly. At a flow ratę greater than 50 ml the temperaturę is not stabilized in the cross-section of location of the thermocouples.

The gas flow meter is suitable for measuring the stationary discharge is not changed when the heat storage and no ongoing transition phenomena in terms of heat transfer outer sensor. In the case of rapid changes of flow ratę the heat balance of the flow gas is affected by heat transfer between the inner walls of Pertinax tubę and the gas. Therefore it is necessary to obtain relevant values have to consolidate the heat flow across the sensor arrays.

The compensation for heat leakage is possible either by using other liquid -binding materiał in the production of that show better materiał properties corresponding to the required criteria and along with applying a reflective coating on the inner surface of Pertinax tubes along the length respectively at least in the heating coil.

Planned changes in the structure and related results will be published after reviewing the current proposal and the results will be continuously published.

CONCLUSION

Seems to be the fluids flow ratę by using the designed method in the area of low flow rates is very complicated because of the heat losses of the sensing element and low heat capacity of gaseous fluid. It is evident that indirect way of volumetric fluid flow rate's calculation demands measuring of a great number of physical magnitudes and determining of correction coefficient kr whose characteristics and dependence on flow ratę needs to be determined by experiments. Based on experimental findings by measuring the gas flow meter designed certainly require construction modifications. This fact doesn t deny the usefulness of the measurement methods and designed gas flow meter in area of smali flow rates.

We would like to express sincere appreciation to the agency ofMS SR for EU Structural Funds: Operational Programme “Research andDeve/opment”, the projects no. ITMS 26220220044.

The Holłstic Approach to Environment 1(2011)4,153-162 Page 161