An environomic approach for the modeling and optimization of a district heating network based on centralized and decentralized heat pumps, cogeneration and/or gas furnace. Part I: Methodology

Although heat pump based district heating is often an obvious solution from an energy standpoint, adapting the delivery temperature to the most exigent users is detrimental to overall system performance. This pitfall can be avoided with a centralized plant of heat pumps, cogeneration units and an auxiliary furnace, supplemented by decentralized heat pumps. However, the problem of mixed energy production and delivery which this poses is complex and presents for the engineer the daunting if not impossible task of adequately, much less optimally, determining the best system for the job. In this first of a series of two articles, a general environomic methodology for aiding in this task is described, which includes models of the thermodynamic, economic, and environmental characteristics of the system considered. The system's environmental characteristics are introduced into the model through pollution damage cost terms and a new form of pollution penalty functions, which adapt to the system's changing emissions and to local and global pollutant conditions. The superstructure of a district heating system with cogeneration and heal pumps (centralized or not) is presented and discussed. Optimization results are presented in the accompanying article [1]. (C) 2000 Editions scientifiques et medicates Elsevier SAS.