ENTHALPY MEASURING EQUIPMENT FOR MEASURING THE ENTHALPY OF A SUBSTANCE

摘要

An enthalpy measuring arrangement for measuring the heat content of a substance which may in the liquid phase, vapor phase or a mixed phase of liquid and vapor, comprises a first enthalpy calculating module for calculating the enthalpy of the substance when in a two-phase condition utilizing a plurality of discrete function blocks. The specific volumes of the overall mixture is calculated using a density transmitter which measures the density of the substance. Tables are utilized to obtain the specific volumes of the gas and vapor part of the substance on the basis of a measured temperature for the substance. These values are in turn used to obtain a quality value which is multiplied by a value representing the difference between the enthalpys of the vapor and liquid components of the substance to obtain the overall enthalpy of the mixture. Another module with a plurality of function blocks generates the enthalpy of the substance when it is superheated or entirely in the vapor phase. A selector module is connected to the mixed and vapor phase calculating modules to determine which of the modules should be utilized and to calculate the overall enthalpy of the substance regardless of its phase.