Abstract
This paper presents an investigation on the optimum design for a plate-fin heat exchanger (PFHE) of a gas and supercritical carbon dioxide combined cycle which uses thermal oil as intermediate heat-transfer fluid. This may promote the heat transfer from low heat-flux exhaust to a high heat-flux supercritical carbon dioxide stream. The number of fin layers, plate width and geometrical parameters of fins on both sides of PFHE are selected as variables to be optimized by a non-dominated sorting genetic algorithm-II (NSGA-II), which is a multi-objective genetic algorithm. For the confliction of heat transfer area and pressure drop on the exhaust side, which are the objective indexes, the result of NSGA-II is a Pareto frontier. The technique for order of preference by similarity to ideal solution (TOPSIS) approach is applied to choose the optimum solution from the Pareto frontier. Finally, further simulation is performed to analyze the effect of each parameter to objective indexes and confirm the rationality of optimization results.
Highlights
Gas turbines have a strategic position in the field of energy utilization, with the advantages of high-efficiency, flexible operation and a wide range of fuel applications
Medium–high temperature waste heat is often carried by the low-pressure exhaust of gas turbines
In order to make full use of exhaust heat from gas turbines, this paper presents an investigation on the multi-objective optimum design for plate-fin heat exchangers of a gas and supercritical carbon dioxide combined cycle using thermal oil as an intermediate heat-transfer fluid
Summary
Gas turbines have a strategic position in the field of energy utilization, with the advantages of high-efficiency, flexible operation and a wide range of fuel applications. The development of flexible and high-efficient gas turbine power generation technology is an inevitable demand for creating a low-carbon and high-efficiency energy system [1]. Medium–high temperature waste heat is often carried by the low-pressure exhaust of gas turbines. The waste heat of gas turbines is of a lower heat flux density compared with solar energy, nuclear energy and other medium–high temperature heat sources, and a higher grade than low-temperature heat sources, which indicates that it is valuable to be recovered. According to the principle of energy cascade utilization, combined power cycles can be used for the recovery and utilization of gas residual heat energy
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