Entropy generation minimization of one and two-stage tube in tube ammonia evaporators cooling high pressure gaseous hydrogen for vehicle refuelling
Gaseous hydrogen as an automotive fuel is reaching the point of commercial introduction.To facilitate this coming fleet of hydrogen vehicles,refuelling stations must be implemented.To ensure a costumer acceptable refuelling duration without overheating the vehicles hydrogen tank,hydrogen must be supplied at a temperature of-40XC.This paper presents a study on the design of coaxial tube in tube ammonia evaporators for three different concepts of hydrogen cooling,one one-stage and two two-stage.A multi objective optimization has been imposed to minimize the entropy generation rate and evaporator size.For the two-stage concepts,the optimal intermediate temperatures have been found by minimizing the thermally driven entropy generation rate.A zero-dimensional numerical heat transfer model of the tube in tube evaporator is developed in Engineer Equation Solver using heat transfer and pressure drop correlations from the open literature.With this heat transfer model the optimal choice of tube sizes and circuit number is found for all three concepts.The results showed that cooling with a two-stage evaporator after the pressure reduction of hydrogen yields the lowest entropy generation rate,49%lower than the highest,which was encountered with an one-stage evaporator after the pressure reduction.This entropy generation reduction requires an increase in evaporator size of 59%compared to the one-stage cooling.Two-stage cooling with the high-stage before the pressure reduction and the low-stage after,resulted in a 42%reduction of entropy generation but equally 59%of evaporator size increase.
Entropy generation minimization Evaporator design Heat transfer modelling Hydrogen refuelling Refrigeration
Jonas K.Jensen Erasmus D.Rothuizen Wiebke B.Markussen
Technical University of Denmark,Kgs.Lyngby,Denmark
国际会议
桂林
英文
1-12
2013-07-16（万方平台首次上网日期，不代表论文的发表时间）