Optimal Operation Of Ice Storage System For HVAC In Consideration Of Cooling Load Behavior

Because of its advantages in shifting peak load and saving operation cost, ice-storage systems have been welcome by both power plants and AC users. thus air-conditioning systems with ice-storage are adopted more and more widely. Many demonstrating projects with ice-storage system have been constructed in recent years at home , which accumulated a lot of experience for new projects. Most researches concentrate on optimal design of the system, analysis of the dynamic characteristic of ice tanks, economic analysis and evaluating of projects However, research on the auto control systems as a whole is insufficient. Running costs and energy consume can be decreased by efficiency running mode. The major work of this thesis is to study the optimal operation of ice storage system considering influence of cooling load on existing projects.This thesis takes the ice harvester system in Donghua University as the experimental object. The optimization control is related to the cooling load characteristic and the forecast of air-conditioning load is the precondition of optimal operation for ice storage system. Since this thesis doesn't conclude the load forecasting, it replaces the forecasted load with a set of system's exact load curve of air-conditioning season. The optimal operation model and solve method and computer program derived from the load curve are applicable to all the air-conditioning system of this thesis, then the research outcome can be taken into practice if the air-conditioning load is forecasted successfully. In order to get the load curve and continue characteristic of air-conditioning season, a cooling load mathematical model is established firstly according to some cooling load data about the ice-storage system and the standard year meteorological data. On the basis of above analyses, with the operation costs of the whole air-conditioning season as the objective function, combined with the characteristics of borneol-sliding dynamic ice storage system, an optimal mathematic model is built. And the way of the optimization control has been analyzed: the load distribution of refrigerating engine and ice-storage tank under different electrical price; the time and quantity of the refrigerating engine to be turned on when daily total load greater than the maximum content of the ice-storage tank. It is necessary to keep the refrigerating engine work under high efficiency and avoid turning off the refrigerating engine frequently. In order to give prominence to the advantage of optimal operation, a refrigerating engine running first strategy of ice storage system was built, additionally, ice storage system was not suitable to adopt ice-storage tank running first strategy when ender the ice harvester system.By using the object orientation program design technology and Visual Basic language to develop the optimization control software of ice-storage air-conditioning in Windows environment, in this thesis. This software introduces the load of total air-conditioning season and the refrigerating engine running first model and optimal operation model. The software can calculate the whole system; obtain the load distribution results of refrigerating engine and ice-storage tank under those two models in any time, additionally, the time and quantity of the refrigerating engine to be turned on; calculate the charge of every equipments and the total charge of every day or whole air-conditioning season under those two models in any time.Finally, according to the result of the software, the advantage of optimal operation is not obvious when daily load is higher, but obvious when running under partial load. The running charge of optimal operation model is less than refrigerating engine running first model by 189085.96 yuan in whole air-conditioning season, which reduce almost 16.2% of the total running charge. In a word, it is very economical.