Enhanced Energy Saving Performance in Composite Trigeneration Systems

Small-scale cogeneration prime movers (below 1 MWJ such as microturbines and internal combustion engines can be effectively coupled to absorption chillers fed by cogenerated heat and/or electric heat pumps fed by cogenerated electricity. Such trigeneration or Combined Cooling Heat and Power (CCHP) systems potentially boast significant energy saving characteristics with respect to the traditional separate generation of electricity (from large power plants), heat (in boilers) and cooling power (in electric chillers). In this paper, a specific high-efficiency composite scheme, in which a cogeneration prime mover, an absorption chiller, and an electrical heat pump are combined all together, is illustrated and discussed. The performance of this system is assessed through the Trigeneration Primary Energy Saving (TPES) indicator, previously introduced by the authors. Performance maps for equipment available on the market are drawn, through which it is possible to evaluate the plant energy performance at every operating point. Sensitivity studies are provided to point out the influence of the different variables and parameters on the plant performance characteristics.