Study of the off-design performance of a micro gas turbine-based combined cooling, heating and power (CCHP) cogeneration system

A micro gas turbine-based combined cooling, heating and power (CCHP) cogeneration system has been designed and a model for analyzing the off-design performance of the system, established. In combination with specific calculation cases, an analytic computation has been performed of the thermodynamic performance of the system in question operating at an off-design condition under the mode of 'determining power generation on the basis of heating (cooling) demand', thus revealing the off-design operating performance of the system under various regulating methods. It has been found that a recuperation adjustment can accommodate a relatively wide range of cooling and heating load regulation. Therefore, the micro gas turbine-based cogeneration system is particularly suitable for the occasion when the cooling and heating load undergoes a great change while the electric power load in the system is relatively stable. To keep a comparatively high performance of the system when operating at off-design conditions, in case of an increase of the cooling and heating load, the electric power regulation should be adopted as a first priority, followed by the recuperation regulation as a second choice and supplementary firing regulation as a last resort. When the cooling and heating load decreases, a reverse regulation order should be chosen. The research results can well provide useful reference and guidance for the design and operation of micro gas turbine-based CCHP cogeneration systems.