Performance evaluation of CHP with heat storage in buildings

Abstract

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.Combined heat and power (CHP) production gains more and more attention. Offices and public buildings often have a large thermal power demand in combination with a fairly large electrical power demand. On the other hand they are seldom occupied by night and in weekends, reducing the actual operational time of the heating system. This in turn brings down the financial benefits of investing in CHP. A second problem is that electrical and thermal demands are often shifted in time. The running time of the engine is again limited this way, as it is often not allowed to deliver electricity to the power grid. A possible solution is using heat storage. This way the CHP-engine can run when the electricity demand is high. In the paper a simulation model of CHP with gas engine and heat storage by means of a hot water vessel is developed. The model is validated through experiments on an engine and a vessel. This model is used to analyze the design, control and performance of cogeneration plants. It is shown that storage is marginal beneficial and the design has to be done with great care.