Dynamic simulation and optimal operation of district cooling networks via 2D orthogonal collocation

Abstract

Due to the increasing demand for cooling worldwide and the need for reliable and energy-efficient alternatives to provide it, the analysis of district cooling (DC) networks has become a focus of interest in recent years. In DC networks, the temperature of the cooling utility returning to the production site must be close to the design temperature of the installed technology to ensure proper efficiency and avoid the technical issue known as low ΔT syndrome. Via dynamic optimisation, it is possible to compute the mass flow profiles in the network that lead to an operation which overcomes this problem. In this paper, we propose a methodology that provides a simultaneous (equation- oriented) solution to this dynamic optimisation problem using 2D Orthogonal Collocation on Finite Elements (OCFE). We apply this methodology to a medium-sized cooling system serving 20 consumers of different categories with fluctuating cooling demands subject to variable external conditions. The dynamic simulation and optimisation were performed using insulated and non-insulated piping. The proposed methodology exhibits low computational cost, demonstrating its potential use for developing applications for operating and forecasting these systems.