Parameters Estimation of Hydraulic Circuit Head Losses for Virtual Sensor Design

This paper presents the procedure used to design a so-called virtual sensor (VS) that is able to estimate fluid flow rates (FRs) in the elements of a complex hydraulic closed network, only knowing the total FR imposed by the circulator pump and the open/closed state of the valves that section off each subnet. The VS is based on a mathematical model representing the relationship between FR and head loss (HL). An identification procedure is developed to estimate the numerical values of the parameters of the FR/HL relationship. Once the mathematical model is completely known, in terms of its topological representation and the numerical values of all the model parameters, a flow-solver algorithm is used to estimate the FR in each branch of the hydraulic circuit. The importance of such a mathematical device is evidenced by the necessity to compute the heating power, directly depending on the hydraulic FR, that each single heating body releases, in order to give a new solution going beyond the current technologies to many problems, such as, for example, the optimization of the central heat generator efficiency or the fair cost allocation in the management of old centralized heating plants. The good results obtained from different tests, carried on a reference mock-up, are presented to prove the reliability and the efficiency of the proposed approach.