Optimization of a D-CHP System Based on Monthly Power-to-Heat Ratio

In this paper, a combined heat and power (CHP) system utilizing two power generation units operating simultaneously with differing operational strategies (D-CHP) is analyzed on the basis of operational cost savings. An operating cost optimization metric, based on the facility monthly power-to-heat-ratio (PHR), is presented. The PHR is defined as the ratio between the electric load and the thermal load required by the facility. Previous work in this field has suggested that D-CHP system performance may be improved by limiting operation of the system to months in which the PHR is relatively low. The focus of this paper is to illustrate how the facility PHR can be used to determine the potential of a D-CHP system to reduce operational cost. This paper analyzed the relationship between the PHR and the operational cost savings of six different benchmark buildings, including buildings that are traditionally poor candidates for CHP or D-CHP systems, due to high cost of operation as compared with conventional systems with separate heating and power (SHP). Achieving operational costs savings through optimal operation based on monthly PHR for these building types can enhance the practical implementation potential of D-CHP and CHP systems.