| Wan Kuifang (Engineering Thermophysics)Directed by Xiao Yunhan and Zhang ShijieHumid air turbine (HAT) cycle,an advanced,efficient and clean dynamic cycle,haspotential of highest electrical efficiency and a spacious foreground in medium-small powerrange.As the development of decentralized energy system (DES),small HAT has beenpaid more and more attention and industrial test has begun.However,seldom studies aboutsmall HAT cycle focused on performace enhancement by configuration adjustment so far.Therefore,performance of small HAT cycle with different configurations and integratingwith IBC ( inverted Brayton cycle) bottom cycle was studied respectively in the thesis toseek for reasonable system configuration to improve performance.Finally,application totypical heat (cooling) and electrical load of cogeneration system based on HAT cycle wereinvestigated primarily by taking consideration of part-load,environment temperature andrunning mode.The main works and conclusions are as follows:1.Parameters optimization of HAT cycle with different water circuits,exhaustdischarging methods and part-flow air humidification shows that small HAT cycle withpart-flow air humidification and makeup water entering economizer can obtain highestelectrical efficiency and slightly higher than that of full-flow air HAT cycle.The optimalpart-flow ratio is about 0.46 to 0.65 as the turbine inlet temperature (TIT) increases from950℃to 1350℃.The optimal pressure ratio grows as the TIT increases,which makes itpossible to realize intercooling in small HAT cycle and at Ieast 2 percentage pointsenhancement of electrical efficiency can be achieved if intercooling was adopted.2.The electrical efficiency of the complex cycle (so-called BAHAT in the thesis) byintegrating the small HAT cycle with IBC (Inverted Brayton Cycle) is 0.4～0.6 percentagepoints higher than that of HAT with intercooling and the working pressure of aftercooler,humidification tower and hot section of turbine is 2～3 times lower than that of the later,which is much important to life-span and safety of the unit.Reduction of relativecompression work due to low exhaust temperature and increase of turbine output becauseof the high pressure ratio are the main factors of the performance enhancement.3.Performances of HAT cycle with different exhaust discharging methods show that electrical efficiency of HAT cycle with induced draft fan (IDF) or exhaust compressor is 1to 1.5 percentage points higher than that of exhaust discharging directly and exhaustrecuperate since the former takes advantage of low exhaust temperature after waterrecovery to reduce compression work.The optimal pressure ratio of IDF is about 1.5～1.6and it's better to put another condenser after the IDF to hold water recovery ratio.4.Comparing with recuperative cycle,high electrical efficiency can be obtained atpart load because of the heat recovery.The increase of humid rate makes the cycleunsensitive to environmental temperature rising.5.HAT cycle can run as recuperative cycle or water injected cycle in summer tosupply flexible electrical and heat load and,at the same time,hold exhaust temperaturehigh enough to drive absorption chiller.The problem of heat in pure HAT cycle's exhaustcan't supply cooling is overcomed.6.Applying to typical buildings,cogeneration system based on small HAT cycle cansupply heat and power in winter and cooling and power in summer by changing runningmode.The system has strong adaptability to user's load and has advantage in runningcharge and primary efficiency comparing with cogeneration system based on simple cycle.These conclusions provide references not only for small HAT cycle design but forplan and operation of cogeneration system with HAT cycle.
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