Optimal Sizing for a Gas-Fired Grid-Connected Cogeneration System Planning

Abstract

This paper presents an optimization approach to determine the optimal sizing for a gas-fired grid-connected cogeneration system planning. An absorption chiller and a thermal storage system are included as part of the cogeneration system configuration. The optimization uses a mixed-integer nonlinear optimization technique to size the system. The search for the minimum operational cost uses a Newton-Raphson and conjugate method with tangent estimates and forward derivatives. In certain cases, the approach uses dynamic programming principle to decide on the best feasible practical solution. The electrical and thermal outputs from the turbogenerator are modeled by taking into account partial loading. The annual facility load is represented by a week of hourly load. The optimization variables used are the one week of hourly electrical energy output from the turbogenerator and the optimum solution is determined by minimizing the total operational cost. The paper evaluates three case studies of different types of load characteristic (hospital, university campus, and paper mill) to demonstrate the capabilities of the proposed model. The optimum size of the whole system will be presented. The paper will also present the financial analysis of the optimum system. Electrical load.L H Heating load. r 1 Fuel cost. r 2Top-up peak energy rate. r 3Top-up off-peak energy rate. r 4Water rate. r 5Top-up peak demand rate. r 6Standby peak demand rate. r 7Electricity selling rate (feed in). W Water consumption. X C Excess cooling energy from absorption chiller. X E Excess electrical energy. X T Excess thermal energy.

Energy Applications and Studies for Healthcare Facilities- A Systematic Review

“…For example, Li et al used a MINLP model that includes three aspects of energy demands that they are x (design variables = facility capacities, maximum purchased gas and electricity) y and z (continuous and integer operation variables) [51]. In the same manner, Azit et al [52], tried to define the optimal capacity of a CHP system using the MINLP method. In another study, Jing R. et al proposed to optimize system design and operation simultaneously for solid oxide fuel cells (SOFCs) based combined cooling, heating and power system (CCHP) with MINLP because there are two unknown parameters are the installed capacities and dispatch strategy of the proposed system [53].…”