Modelling of cogeneration systems Part 3: Application of steam turbine cogeneration analysis to Auckland Hospital cogeneration utility system

Abstract

Steam turbine cogeneration analysis (STuCA) is a quasi-static steam cogneration plant modelling tool, which has been developed and applied to the Auckland Hospital energy centre at Auckland, New Zealand. The STuCA code consists of four submodels, namely a load, a system, a plant and an economic model. The load model was developed using historical data and drove the system model, which consisted of heat exchangers. The system model output was then used to drive the plant model that modelled the turbine and boiler and predicted the primary energy flows and cash flows at the site. Economic analysis tools including thermodynamic, thermoeconomic and economic performance measures such as the payback period and the net present value used these data to analyse the economic performance measures such as the payback period and the net present value used these data to analyse the economic performance of the site. The STuCA model output correlated to site data to within 10 per cent and provided data that could be used by the economic analysis tools. The application of the STuCA model to the hospital site proved that it could be used to design cogeneration plants, to analyse retrofit, to upgrade proposals and to study the effects of changing site loads on plant performance.