| Distributed energy system with its high energy efficiency and environmental protectionadvantages become one of the preferred technology for energy conservation and emissionreduction. Off-design performance was poor, and waste heat of low grade temperature cannotbe efficiently recycled, it leads to thermal performance and economy of CCHP systemdeteriorated. Therefore, the control methods of off-design performance and dehumidificationcycle driven by waste heat of CCHP system have been investigated in this paper, it is greatsignificance to to improve distributed CCHP system energy efficiency.According to the off-design model of each unit, the model of combined cooling heatingand power cogeneration system with specific features has been explored. The control methodsof improving the system off-design performance were proposed. The influence factors ofCCHP system have been analyzed. The optimization model of CCHP system established. Theoperation modes of all kinds need adopting of cold, heat and power load was investigated.The evaluation criterias of primary energy rate and relative energy saving ratio were adopted.The impact of cooling to power ratio, the efficiency of power generation and power on theCCHP system was analyzed. The performance of CCHP system was controlled by energystorage, electric compression refrigeration or afterburning. The results showed that, thecooling to power ratio was the main factor affecting performance of CCHP system. With thecooling to power ratio increasing, the primary energy rate increased, and relative energysaving ratio increased firstly and then decreased following the cooling load mode, there wasoptimal cooling to power ratio. With the cooling to power ratio increasing, the primary energyrate and relative energy saving ratio increased firstly and then decreased following the powerload mode, there was optimal running point.Combined the off-design model and the experimental platform, the theoretical andexperimental performance of the internal combustion engine CCHP system has beeninvestigated.based on dynamic characteristic of user’s need and each unit. The resons of poorperformance was investigated. The best working state of CCHP system had been explored,when power of combustion engine was40kW. In order to further study the available energyutilization of internal combustion engine CCHP system. Exergy analysis for CCHP systemhad been researched adopting the "black box" model. The distribution and reasons of exergyloss were analyzed. The exergy loss of combustion engine was the largest, and the exergy lossof heat exchange was the least. With output power increasing, the exergy loss of each unitincreased. Since low grade heat would not to be efficiently recovered and the damp climaticcharacteristics of southern China area, low grade waste heat effective utilization mechanismof CCHP system were studied. LiCl solution absorption dehumidification unit was driven bylow grade heat. The experiment platform of dehumidification unit driven by low grade heat ofinternal combustion engine cylinder jacket water was built. The low grade heatdehumidification mechanism and experimental research had been carried out. The off-designperformance of LiCl solution absorption dehumidification unit was investigated in thispaper.The results show that, compared to conventional CCHP system, the primary energy rateof CCHP system with dehumidification increased by about15%, relative energy saving ratioincreased by20%.All kinds of integrated schemes of industrial park1200kW CCHP system wereresearched, which combined internal combustion engine, absorption refrigeration, absoptiondehumidification, energy storage and other integration technologies. Considering thetechnology and economy, the scheme with ice storage had obvious advantages. As therecommended scheme, its primary energy utilization rate was81.7%, relative primaryenergysaving rate was34.7%. According to the actual test data of CCHP system, thermalperformance of CCHP system was analyzed. The primary energy rate was77.6%, and relativeprimary energy saving rate was25.3%. It verified control theory and method correctness ofsystem integration and performance. |
PDF Full Text Request