Research In Density Compensation Of The Flow Amount

The indemnify technique about temperature, pressure of the density is one of the most important research issues in measurement of the discharge. It is always hoped that the influence of the density is overcome by simple method in flow measuring by measuring mass flux of the fluid on-line, it is important to improve measure accuracy of flow by density compensation. This text mostly research the indemnify technique about temperature, pressure of the density and explore the development of the flow measuring technology, the measuring method of the mass flux, the mathematical model of the compensative density, the factor of the error influence and the intelligent flow instrument composed of compute on-chip.The measurement of volumetric flow rate will be errors when the parameters of the temperature and pressure change unceasingly. It is difficult to apply direct mass flow meter in high temperature and high pressure by reason of the medium's material and structure effect. Indirect mass flow meter was applied with difficulties too because of restricted by the applicable range about temperature and pressure of the density.The mass flow meter compensate by temperature and pressure were used wide-spread in industrial production. We can set-up the mathematical model which based on the relation of temperature, pressure and density. Most flow rate measurement instrument was detect the volumetric flow rate, if measure the massflux by differential pressure flow meter then the equation is is the coefficient in connection with dontrivance to control flow), if by linear flow instrument, the equation is qm = Kρf (K. is the coefficient of instrument). We canget the value of the mass flux by direct measuring differential pressure or frequency, temperature and pressure on-line. At the present time, the mass flow meter compensate by temperature and pressure is in practical application but it can not directly measure the density on-line in majority situation. When the parameter of the medium have wide range, the correct reparation are more difficult, so we must research further the density mathematical model which can suit the concrete media and apply in practical production. This text research the temperature, pressure of the density compensative equation of the gas which frequent use based on the mathematical model which raised by other scholar, and we did the error analysis.At last, on the basis of early researching, against the measure project how to amount mass flux of the liquid ammonia which was difficult to solve at the present time, this text has establishes the density and temperature reparation mathematicalmodel of the liquid ammonia ρ = ρ0(1 + βt+ λt2) by method of least squares andbring forward the measure project how to amount mass flux of the liquid ammonia on-line. By measure of principle-analysis and practice-application, we have a satisfactory result. The curvilinear of the mathematical model have a high fitting-accuracy. The density calculated value of the model with the error of the probe was < ?.05%. It satisfied the detection of mass flux on-line, and will bring well economic effect.