Techno-economic Optimization Algorithm of the Combined Cooling, Heating and Power System by Internal Combustion Engine for a Residential Apartment

In this study, the cooling, heating and electrical energy demands of a sample residential apartment in Mashhad region (Iran) has been estimated hourly during a year. By employing a CCHP system for this apartment compared to the separate production system, hourly and monthly amounts of optimal consumption of NG as prime fuel and electrical energy imported from/sold back to grid during a year and cost saving ratio and payback ratio has been investigated. For this purpose an optimization algorithm was proposed to find the best optimized operation of the cogeneration system based on operation of the power generation unit (PGU) according to nonlinear relationship of electrical efficiency of the engine (Prime Mover) so that the cost of the energy in CCHP system, as an objective function, be least amount in each time step during a year. The results of proposed algorithm, specifying the best operation, show that PGU with 12 kW capacities has the lowest payback ratio of 3.3 years and that PGU with 5 kW capacities has the lowest energy cost saving ratio of 57%.