Evaluation of combined cooling, heating and power (CCHP) systems with energy storage units at different locations

• Show expressions of ESRs of CCHP systems with ESUs at different locations.
• Discuss the trend of ESR changing with a single variable (COP or χ).
• Demonstrate the existence of χ boundaries and show the upper and lower limit values.
• Summarize ESU merits at different locations in two situations.

Incorporating energy storage units (ESUs) enables components of Combined Cooling, Heating and Power (CCHP) systems to operate stably as well as to decrease the system scales. In the premise of “priority of providing cooling” regime, two potential locations of ESUs which individually represent different energy storage technologies were involved to study their location and performance impacts on energy saving rates (ESRs) of CCHP systems. Detailed discussions were undertaken to study how critical parameters (Efficiency of Energy Utilization and Coefficient of Performance) affect ESRs of CCHP systems. Theoretical analysis has indicated that how the electrical demand is satisfied will have distinct influence on the final results. When CCHP systems can solely satisfy the electrical demand, a cooling storage system is recommended to be installed between absorption refrigerator and the CCHP user. If supplementary electricity from the grid is required to meet the electrical demand, the selections of ESU locations will depend on efficiencies of both the grid and the power generation unit of the CCHP system. Furthermore, the authors also demonstrate the existence of boundaries of Efficiency of Energy Utilization and show the upper and lower limit values.