Optimal Design of District Heating System with Gas-Fired Peak Load Regulating Boiler in the Secondary Network

Heat output from district heating(DH) varied significantly to match the heat load variation caused by outdoor temperature,resulting in the decrease in energy efficiency of the heat source and waste of energy.In DH system with gas-fired peak load regulating boiler in the secondary network,by extending run time of base load boiler under rated condition,the mean energy efficiency was increased.To optimize this kind of system,the problem was formulated as a mathematical model,which was a monovariant nonlinear constraint programming with one objective to minimize the operational cost,and a real case was discussed as an example to obtain the optimal ratio of base load to total load,starting temperature and run time of gas-fired peak load regulating boiler.The present work can provide theoretical basis for optimal design and operation of this kind of DH system.