THE PERFORMANCE OPTIMIZATION OF A GAS-TURBINE COGENERATION HEAT-PUMP FACILITY WITH THERMAL STORAGE

with the push for greater energy conservation, the need or heating and /or power production is being filled by cogeneration facilities. Thus, the search for the best performance at the least cost for such multip urpose plants is made much more difficult by the fact that such facili ties must meet differing goals or demands. Such a facility exists at t he Ecole Polytechnique Federale de Lausanne (EPFL) and has been studie d in order to find the optimum modes of operation as a function of tim e for variations in both the heating and electrical demands this facil ity must meet. The results of this study are presented here. The plant itself provides heat and electricity for both the EPFL and the Univer sity of Lausanne and is projected to supply electricity to the exterio r utility grid provided it can be shown to be economically viable. The plant's primary components include two gas turbines, a heat recovery system, two heat pumps, a set of heat storage tanks, and both medium a nd low-temperature district heating networks. In order to find the opt imum mode of operation, a mixed-integer linear programming approach wa s used, which balances the competing costs of operation and minimizes these costs subject to the operational constraints placed on the syste m. The effects of both the cost of the fuel and the costs of electrici ty sold and bought on the best performance of the system are evaluated . In addition, the important features of the modeling process are disc ussed, in particular the heat storage tanks, which complicate the opti mization of the series of steady-state models used to model the overal l quasi-steady-state behavior of the system.