UF software Park heat pump and storage of central air conditioning technology

Abstract: This article mainly introduces the design plan of a ground source heat pump and ice storage central air conditioning system project of Beijing UF Software Park Phase I, with emphasis on the underground soil heat exchanger and ice storage system. Key words: Ground source heat pump soil heat exchanger ice storage First, the project overview UF Software Park is located in the Zhongguancun Industrial Park, southwest of Yongfeng, Yongfeng Road to the east, south of Yongfeng Nanhuan Road, west of West Riverside Road, North and North Clear road bordering. The entire software park covers an area of ​​45.52 hectares, with a total construction area of ​​296,000 square meters, construction in two phases: a # R & D center, 2 # R & D center, 5 # R & D center, food center, exchange center, staff Canteens, exhibition centers and test buildings, a total construction area of ​​184,000 square meters, total heating and air conditioning area of ​​nearly 160,000 square meters, the total heat load of 13391kw, the total cooling load of 15784kw, heat consumption hour heat 1722kw. Second, the design ideas UF Software Park's goal is to build world-class eco-environmental software park. Buildings, cold, warm air-conditioning system is one of the important facilities in the park, but also affect the ecological environment of the park an important factor. So clean, low energy consumption is the software park planning needs. The combination of heat pump technology and energy storage technology can not only utilize the heat pump technology to satisfy the characteristics of cooling and heating at the same time, but also use the energy storage technology to cut the peak load of the power grid. Even if users use cheap heating and air-conditioning methods, Solve the pollution problem, but also make a contribution to the day and night balance of the power grid, can greatly reduce the air conditioning system daytime peak load of electricity. Therefore, the system uses a combination of heat pump technology and energy storage technology, making the system not only has the function of cutting peak filling, but also a machine with three (three conditions heat pump heating conditions, cooling conditions and system Ice conditions), the use of clean electric energy and underground free renewable energy not only provide stable cold and heat sources to the system, but also solve the problems of coal pollution and high energy consumption of fuel oil and gas. Not only in line with national environmental protection policies, but also in the fundamental interests of users. The main equipment of the system includes: three working condition heat pump units, gas boilers, water cooled centrifugal chillers, ice storage equipment, cooling towers, plate heat exchangers and shielded pumps, etc. In system design, starting from the system functions, Complement each other in the summer by the cooling tower and underground soil heat exchanger alternate each other in winter by the gas boiler and heat pump units alternate each other to protect the system's safety and reliability. Third, the system design 3.1 Winter Heating Program According to the software park in winter air conditioning design heat load total 13391kw, according to the composite system design ideas and design principles, a planning winter design day 60% of the maximum heat load as a standard selection France CIAT three conditions of ground-source heat pump unit 4, a single unit heating capacity of 1676kw, while the selection of 4 gas-fired boilers, a single system heat 2100kw, to meet the design requirements of thermal load peak regulation. Ground source heat pump circulating fluid through the soil heat exchanger system, get low-grade heat from the soil. Continuation of winter heat load Figure 3.2, summer air conditioning program 3.2.1, program discussion Summer design maximum cooling load of 15784kw (4489RT). The entire software park exists in various forms of construction, use different functions, room equipment, running a large number of thermal energy distribution and other factors, more complex air-conditioning cooling load. The load distribution in each time period is shown in the following figure: According to the load distribution map, the load structure of the project can be seen as follows: The load is mainly concentrated in 8: 00-21: 00, and the power peak is 6 hours , Power cut off for 7 hours. Overall, there is an extremely clear change in the load throughout the day. The air conditioning system is quite suitable for the design of a cold storage system. According to the characteristics of this project, in order to save the initial investment, the ice storage system of this project chooses part of the load-balanced ice storage. Because of the partial cooling load at night, the air-cooled cooler (centrifugal chiller) is set separately. The ice storage system uses a series system with a large temperature difference upstream of the host, and at the same time, the ice storage device manufactured by CIAT of France is selected as the ice storage device. Due to the lower temperature of the ethylene glycol aqueous solution, it is guaranteed that the plate heat exchanger provides the system with 5 ° C effluent water while having higher efficiency and lower initial investment. On the typical design day, the air-conditioning cooling load is shared by the three-condition heat pump unit, the air-cooled unit and the ice storage unit. The non-typical design day meets the cooling load requirement through optimized control and reduces the system power consumption to a minimum. When the system is co-cooled with heat storage unit and ice storage equipment, the ethylene glycol solution first passes through the heat pump unit to cool down in the air-conditioning condition to maintain a more efficient work, and then cooled by the ice bath to make the temperature of the glycol solution Further reduce the inlet and outlet ethylene glycol solution so plate heat exchanger can reach a larger temperature difference, so that under the same load conditions, the flow of ethylene glycol solution in series system smaller, so under the same conditions The ethylene glycol circulation pump in the series system is smaller than the parallel system, which makes the equipment investment and operation cost of the series system superior to the parallel system. In addition, the simple and reliable pipeline in series mode is reliable. 3.2.2 Main Equipment Configuration According to the above actual demand of summer cooling in Software Park, the centrifugal chiller will bear the load of base load, the combined heat pump and ice storage equipment of the three conditions will be used to cool the air conditioners in summer, and 2 sets of McQuay Produced by the centrifugal chiller WSC126MBGN2F / E4212 / C4212, a single cooling capacity of 1200RT, cooling tower system with its own set of independent cooling; configuration 4 France CIAT company's three conditions LWP4200 three conditions heat pump unit + Ice storage equipment, to bear the main cooling load, three conditions heat pump ice storage at night, during the day air conditioning conditions and ice storage equipment co-cooling, the part of the air conditioning cooling heat energy through the underground soil heat exchanger circulating fluid system, Transported to the ground by the radial flow of groundwater and heat conduction cooling formation, configuration 440m3 France CIAT company produced high efficiency AC.00 type storage ball, the total storage capacity of 7040RTH. 3.2.3 Typical Day Load Balancing Strategy Typical day of air conditioning design load (100% load) Load distribution: Due to the large hourly cooling load on design day, in order to fully utilize the cooling capacity of ice storage equipment and heat pump units, the maximum Reduce system operating costs, air-conditioning cooling load by the three conditions of heat pump units, airborne host and ice storage equipment shared. Combined with the electricity price policy in Beijing, the three working condition heat pump units store ice at 23: 00-7: 00 during the nighttime trough of electricity. In order to rationalize the operation and save operating costs as much as possible, the ice storage equipment needs to be used as much as possible in the peak section. Under this operating strategy, air-conditioners can be optimally allocated for cooling while minimizing operating costs. 100% load distribution diagram as shown in the following figure: 100% load distribution diagram 3.2.4, non-typical design day load balancing strategy Load distribution at 70% load segment: 70% load segment in Beijing during the air conditioning period appears relatively long How to allocate the load more reasonably and adjust the cooling load of the heat pump unit, airborne unit and ice storage equipment in the third working condition is the key to decide how much the running cost is saved in this period. The hourly cooling load in this period is still relatively large. However, the efficiency of air conditioners in the three working condition heat pump units is relatively low. In principle, the cooling capacity of the ice storage equipment should be fully used to reduce the workload of the three working conditions. Time, only in the maximum load 8: 00-21: 00 a total of 13 hours to open the heat pump unit, which can reduce the system to run the greatest electricity. Combined with the electricity price policy of Beijing, the three working condition heat pump units are also operated at full capacity for storing ice during nighttime electricity trough period 23: 00-07: 00, at 8: 00-10: 00 and 18: 00-2