Dynamic error of heat measurement in transient

Abstract

According to EN1434 (European Standard) and OIML R-75(International Organization of Legal Metrology), there are two methods in heat measurement, and they are all steady-state methods of test, using them in transient, obvious error will be produced, so some accurately measuring functions should be seeking. In a previous published paper of the author, a transient function relationship of heat quantity and time is deduced, and the validity of this function is proved through experimentation, also it is simplified reasonably, so it can be used in variable now rate heating system. In this study, a comparison with steady-state method and dynamic method is presented, the errors exist in the steady state method are analyzed. A conclusion is improved that the steady-state methods used in variable flow heating system will result in appreciable errors, the errors only exist in transient, when system reach steady state, the errors disappear, moreover, the transient time is long in heating system, it is at least 30 minutes, so it is necessary to take some measures to correct them, however, study showed that the error can be ignored when the flow rate step change is less than 5kg/h. © Springer-Verlag Berlin Heidelberg 2007.