Design and off-design operating characteristics analysis of Brayton cycle cold end air-cooled heat exchanger
The gas cooler,as an essential heat exchange device in Brayton cycle system,has a significant influence on structural compactness and operational efficiency of the cycle system.The performance and influencing factors of a cross flow printed circuit heat exchanger(PCHE)-plate-fin gas cooler are analyzed.A calculation model is established for this type of heat exchanger,and a MATLAB program is written to verify its reliability.Based on this,the coolers are designed,and the power density is above 1 MW/m3,indicating the cooler is compact heat exchanger.Moreover,the design and performance analysis of the heat exchanger are carried out under varying working conditions,and the change law of the pressure drop and heat transfer performance of the gas cooler with the inlet state of the circulating working medium and cooling air is given.The pressure drop and heat transfer performance are compared when the working medium of the Brayton cycle is supercritical carbon dioxide,nitrogen and air.The results show that,the change of cold and hot fluid mass flow has the most obvious influence on the heat transfer performance.The research has reference significance for the design and operation of Brayton circulating air cooling heat exchangers.
Brayton cycleair-cooled heat exchangeroff-design condition calculationheat transfer performancepressure drop performance