Virtual flow meter for chilled and condenser water for chillers: Estimates versus measurements

Abstract

This article presents a virtual flow meter that estimates the chilled and condenser water mass flow rates for chillers using trend data commonly found in a building automation system. The quasi-steady-state thermodynamic mathematical model uses six different scenarios of available sensors that could be available in a building automation system. Two case studies of chillers installed in an ice rink and an institutional campus are used to demonstrate the use of the virtual flow meter tool. The estimates of virtual flow meter compared well with measurements, as the coefficient of variance of the root mean squared error and the normal mean bias error, two goodness-of-fit statistics of virtual flow meter models, are between 3.3% and 9.8% and between –6.9% and 7.8%, respectively, depending on the number of sensors available. The article also presents a discussion on the uncertainty of estimates and measurements.