Optimization and validation of pumping system design and operation for water supply in high-rise buildings

Abstract

The application of mathematical optimization methods for water supply system design and operation provides the capacity to increase the energy efficiency and to lower the investment costs considerably. We present a system approach for the optimal design and operation of pumping systems in real-world high-rise buildings that is based on the usage of mixed-integer nonlinear and mixed-integer linear modeling approaches. In addition, we consider different booster station topologies, i.e. parallel and series-parallel central booster stations as well as decentral booster stations. To confirm the validity of the underlying optimization models with real-world system behavior, we additionally present validation results based on experiments conducted on a modularly constructed pumping test rig. Within the models we consider layout and control decisions for different load scenarios, leading to a Deterministic Equivalent of a two-stage stochastic optimization program. We use a piecewise linearization as well as a piecewise relaxation of the pumps’ characteristics to derive mixed-integer linear models. Besides the solution with off-the-shelf solvers, we present a problem specific exact solving algorithm to improve the computation time. Focusing on the efficient exploration of the solution space, we divide the problem into smaller subproblems, which partly can be cut off in the solution process. Furthermore, we discuss the performance and applicability of the solution approaches for real buildings and analyze the technical aspects of the solutions from an engineer’s point of view, keeping in mind the economically important trade-off between investment and operation costs.

OPTE special issue on technical operations research (TOR)

“…The application of mathematical optimization methods for water supply system design and operation provides the capacity to increase the energy efficiency and to lower the investment costs considerably. A system approach for the optimal design and operation of pumping systems in real-world high-rise buildings, is presented in Müller et al (2021). Here, different booster station topologies, i.e.…”

Validation of an Optimized Resilient Water Supply System

“…The test rig presented in [9], and shown schematically in Fig. 1a, represents a downscaled high rise building with five pressure zones on different height levels.…”

“…Its purpose is to supply each zone with a predefined volume flow and minimum pressure approximating the behavior a building with the same number of pressure zones. In [9] cost and energy optimal solutions have been computed based on different modeling and solution approaches, and the obtained results were validated on the test rig. These experiments do not consider resilience as it is done in this contribution.…”

“…Overall, multiple system layouts are possible. In [3] and [9] it was shown that a decentralized arrangement of pumps allows to achieve significant energy savings due to a reduction of throttling losses. The design and control of such sustainable systems, however, is highly complex and requires the usage of algorithmic approaches.…”

“…The main contribution of this paper is the experimental validation of resilience properties for topologies generated by the above mentioned algorithmic approach. For this, we use a modular test rig which was presented in [9] to validate the correctness of the underlying MINLP to model the physics of a high-rise water distribution system. The main point is that the computed optimal solution is not only valid for standard situations, but also if failures occurs.…”