Feasibility and operating costs of an air cycle for CCHP in a fast food restaurant

• A power, heating and cooling Brayton cycle to serve fast food restaurants is presented.
• The numerical cycle model relies on existing correlations to calculate compressor/turbine performance.
• The power, heating and cooling loads for fast food restaurants are calculated for “mixed-humid” and “cold/very cold” climates.
• The model shows that the loads can be met.
• Capital costs are relatively low, but operational costs are high for the Brayton cycle.

This work considers the possibilities of an air-based Brayton cycle to provide the power, heating and cooling needs of fast-food restaurants. A model of the cycle based on conventional turbomachinery loss coefficients is formulated. The heating, cooling and power capabilities of the cycle are extracted from simulation results. Power and thermal loads for restaurants in Knoxville, TN and in International Falls, MN, are considered. It is found that the cycle can meet the loads by setting speed and mass flow-rate apportionment between the power and cooling functional sections. The associated energy costs appear elevated when compared to the cost of operating individual components or a more conventional, absorption-based CHP system. A first-order estimate of capital investments is provided. Suggestions for future work whereby the operational costs could be reduced are given in the conclusions.