Ice storage technology and water source heat pump combination

Ice storage and water source heat pump technology originated in Europe and the United States and other developed countries, ice storage technology is mainly in order to balance the power grid day and night peak and valley difference in the nighttime power storage ice storage device capacity, during peak daytime release of its storage The cooling capacity, reduce power consumption of refrigeration equipment during peak power is the best way for the power sector to "cut the peak and fill the valley." Since the 90s of last century, China started to promote this technology. At present, some completed projects have been completed. Due to the power part of the implementation of the power peak-valley spread, allowing users to get a certain amount of operating costs. Due to the increasing peak-valley difference in China's power grid, the peak-valley difference in North China has reached 40%, and there is a tendency to further increase. As a result, the management of power load side is also increasingly difficult. In recent years, this situation is particularly prominent in the hot summer months of late July and early August. In order to solve this problem, it is imperative to promote ice storage technology vigorously.

Water source heat pump technology is a renewable energy development and utilization technology that can move low-level energy to high-energy technologies. It can make full use of renewable energy in nature such as groundwater, geothermal water, soil, rivers and lakes, industrial waste water, etc. A large amount of stored low energy is converted to high energy by a small amount of electric energy for us to use, and its energy conversion ratio can reach 4: 1, which means that 1KW of electric energy can generate 4KW of heat, and the other 3KW of heat comes from Free energy. The use of water source heat pump technology, users can greatly reduce the cost of energy use, but also a substantial replacement of coal-fired boilers, to solve the environmental pressure.

In the past few decades, these two technologies have been thriving and have been widely applied in Europe, the United States and other countries. In recent years, our country has also developed rapidly and is in the ascendant.

However, these two relatively independent technologies have their own limitations. Ice storage technology can only be applied to the summer air-conditioning season, which can be used to reduce the peak load. However, ice storage technology can not provide winter heating, which is powerless to users who have heating needs. Similarly, although water source heat pump technology can provide both winter heating and summer cooling, it can not accumulate cold power during nighttime power-down periods and thus serve to reduce the peak load and fill the valley.

For ordinary buildings, especially large commercial buildings, the cooling load is often greater than the heating load, and a combination of these two technologies, you can use water source heat pump technology to meet both cooling and heating needs, but also the use of ice storage technology for power grid Clipping peak filling. Even if users use cheap heating methods, but also solve the pollution problem, but also made a contribution to the power grid day and night, can serve multiple purposes.

In drawing a large number of foreign advanced technology at the same time, China's first water source heat pump and ice storage technology combined project ---- Genesis edge has been in September 2002 in Beijing successfully completed. The success of Sky Genesis symbolizes that the two technologies have been successfully grafted together and is the first joint operation system in China. It has played an important exemplary role in the blue sky project of the capital and the load side management of North China Power Grid.

Day Shiyuan Datun Road, Chaoyang District, Beijing, with a total construction area of 170,000 m ^2, which is Deshang building large commercial facilities, air-conditioned area of 40,000 m ^2, need to install central air-conditioning system to meet winter heating and summer cooling Requirements, the use of water source heat pump and ice storage technology, you can meet the above requirements, but also allows the entire air-conditioning system to maximize energy and operating costs savings.

Days Genocidal summer air conditioning maximum design cooling load of 6050KW, winter air conditioning maximum design heat load of 4000KW. The system first considers the use of constant-temperature groundwater from mining aquifers to cool the condensing ends of water-to-water heat pump units in the summer and cooling through water-to-water heat pump units. In the meantime, low temperature heat source can be provided by the constant temperature of groundwater in the underground aquifer in winter, and then the water heat pump equipment can be elevated to high energy for heating. In winter, due to the use of a large amount of free energy in groundwater, operating costs are greatly reduced.

In addition, according to the characteristics of day genocidal summer cooling load conditions, the summer cooling load is much larger than the winter heating load, so if simply using the water heat pump system, will make the required amount of groundwater larger, the need to mine 11 wells , 5 pumping 7 recharge, it is subject to specific drilling conditions. Taking into account the nature of the business at Tin Chi Mansion, air conditioning is not required during the post-night electricity downturn. Considering the ice-storage air conditioning scheme, the system utilizes night trough power storage for cold storage. During peak daytime hours, the required cooling capacity Co-operation with water-heat heat pump units to provide cooling capacity to the end of air conditioning. Making groundwater evenly distributed and used throughout the day. Therefore, it is only necessary to drill seven water wells and three pumping wells, greatly saving the amount of wells drilled. In the meantime, summer operating costs have also been significantly reduced due to the extensive use of late-night trough electricity instead of electricity consumption during peak daytime hours.

The technology takes full advantage of the constant, renewable energy of groundwater and provides two functions of heating in winter and cooling in summer through the clean power of electricity. The well water after being used is fully recharged back to the ground without pollution to well water and no waste. The entire water source heat pump and ice storage air conditioning system in winter maximum power consumption of 1407KW, to meet the needs of winter heating; Summer day maximum power consumption of 1125KW, night maximum power consumption of 815KW. Day ice storage system enabled, to meet the needs of daytime air conditioning, the entire system obvious peak load effect.

24-hour summer building load curve is as follows:

According to Beijing Tian Chong Yuan 24 hours summer air conditioning load situation, the summer water source heat pump plus ice storage air conditioning program, the project selected six 580kw three conditions of water source heat pump host (evaporator chilled water supply, backwater conditions 6.8 / 10.5 ℃, and then cooled to 4 ℃ by the ice storage equipment, air conditioning system for the return water temperature of 7/12 ℃), night ice storage, day and ice storage equipment co-cooling. Calculated by the storage system selection software, come to the best configuration of the project system, the system energy distribution is as follows:

* Six sets of three conditions water source heat pump host daytime air conditioning conditions maximum energy output: 3480 kw

* Six sets of three conditions water source heat pump host night ice conditions energy output: 2262kw

* Storage capacity of the cold storage available at night: 18096 kwh

* Storage equipment during the day ice melting maximum output energy: 2570 kw

* Cold storage equipment to reduce peak load during refrigeration: 42.5%

Adopt water-heat pump and ice storage summer air-conditioning system operation strategy is as follows:

8:00 - 22:00: Liupanshui air-conditioned heat pump unit operating conditions.

8:00 - 20:00: Ice storage equipment ice output, combined with the water source heat pump cooling.

23:00 - 7:00: water source heat pump ice machine operating conditions, storage capacity of ice storage equipment 8 hours.

Six water source heat pump cooling water source provided by the groundwater, cooling towers can be replaced.

The use of water heat pump and ice storage winter air conditioning system operation strategy is as follows:

The six water source heat pump units operate in conjunction with the free natural renewable energy provided by groundwater to extract their heat for heating the entire building. The total heat supply of the six units is 4200kw.

According to the design of the project, six water-water heat pump units are selected, and a total of 330m ³ / h of groundwater at 15 ℃ is required. In summer, the groundwater is the cooling water source and the maximum recharge temperature is 15-26.3 ℃. In winter, For 15-7.2 ° C. Therefore, we need to make 3 wells, 4 wells for recharge, and the total water output is 330m ³ / h.

The system overall investment of 10.13 million yuan, compared with the conventional refrigeration system, an increase of about 560,000 investment, a total of drilling wells 7, and can meet the needs of winter and summer. The following is the investment comparison table:

Note: 1. All main equipments adopt joint ventures or imported products.

2, the pump is set to a pump corresponding to two hosts, and has a spare pump.

Note: 1, the conventional system all the major equipment used joint venture or domestic equipment.

2, due to the problem of disturbing the cooling water tower, can not be placed in the top of the podium, it is necessary to transform the original building to place the cooling towers, the owners review, the cost of the transformation of the building is about 1000000 yuan.

3, the pump for four with a prepared.

General system and water heat pump + ice storage system, the overall investment (equipment room and equipment room power distribution) Comparison:

Note: 1, the use of energy storage system can reduce the capacity of power equipment, including transformers, power distribution cabinets, the cost of not making statistics.

2. Since the electricity subsidy of this project has already been paid to the power supply bureau during the construction period, after the adoption of the ice storage system, it has been approved by the power sector to refund the electricity back-up fee to the owners for encouragement.

3, in the early stages of construction, such as considering the use of this program, you can also reduce the municipal heat investment.

In summer, due to the peak-valley electricity price policy adopted by the power grid in Beijing, the peak price and trough price have reached 4.3: 1. Therefore, the use of ice storage system, can greatly reduce the cost of air-conditioning system to run often.

At this stage, peak-valley timeshare electricity prices are as follows:

Comparing the annual operating cost of conventional system and ice storage system with 100% load, 80% load, 60% load and 40% load as the base, analysis and comparison: .

Conventional system and ice storage system room annual operating cost comparison

The annual running cost of ice storage system can save 400,000 yuan more than the conventional water-heat pump system.

In winter, the operation cost of water source heat pump is compared with that of conventional municipal heat. In winter, the operation cost is 120 days per day and 12 hours per day. The cost of municipal heat is 60 yuan /? (Storey storey is more than 4 meters) 2.4 million yuan, compared with the water source heat pump system, water and heat pump system in winter operating costs can be calculated separately in three stages, first and forenoon cold period, about 40 days, 12 hours a day, the load factor Is 0.6, the operating cost is about 320000 yuan; Then for the mid-cold period, about 60 days, 12 hours a day, the load factor of 0.8, the operating costs of about 650,000 yuan; Finally, the cold period, about 20 days running 12 hours a day, the load factor of 0.95, the operating costs of about 250,000 yuan; so the whole winter water source heat pump running costs 122 million. Than the average municipal heating system to save 1.18 million yuan.

The water source heat pump plus ice storage system compared with the conventional electric refrigeration heating system, the annual operating costs can save 1.58 million yuan. Although initial investment increased slightly, the increase in investment was quickly recuperated.

The project received the support of the power sector, the refund of 240 million yuan power paste, so the actual project total investment increased by only 560,000 yuan. If you do not consider this fee, the actual investment needs to increase 2.96 million yuan. However, the annual running cost savings of 1.58 million yuan, only two years to recover the initial investment increase.

At present, Beijing is in a phase of rapid economic development and environmental protection is particularly serious. It is a long way to go to eliminate the pollution caused by coal-fired boilers. The use of water source heat pump technology is an important measure to solve winter clean heating. The basic principle of water source heat pump technology can be understood as storing the heat energy in summer for underground use in winter and "cold" in winter to be stored underground for summer use. Is a "seasonal energy storage" system.

Ice storage technology is a "day energy storage" system. It can transfer a large amount of daytime peak power to be used during the night trough period, and make full use of the power grid night and day difference, so it is the best choice for users. Such as popularization of water source heat pump and ice storage air conditioning technology to Beijing's commercial buildings, will be the structural adjustment of the entire power grid in North China will play an important role; the same time can replace a large number of coal-fired boilers, environmental management in Beijing also Will play an important role. Therefore, the combination of water source heat pump technology and ice storage technology must have broad economic prospects and significant social benefits.