(Beijing Huaqing Group)
Ground source heat pump system is a typical energy-saving, environmental-friendly and efficient new energy technology, which gives full play to the cold storage and heat storage functions of shallow rocks (soil) and realizes the heating and cooling of buildings. This paper introduces the design and operation analysis of ground source heat pump system through an engineering example-the air conditioning system reconstruction project of the training base of Chinese People's Armed Police Force.
Ground source heat pump system is not limited by geographical and hydrogeological conditions, and can be used in almost all areas. However, due to the different formation structures in different places, the difficulty of drilling heat exchange holes is also different. As far as Beijing is concerned, the strata in the north of Haidian, Chaoyang District, Changping District, south of Shunyi, Tongzhou and south of Daxing are fine and not suitable for pumping groundwater. However, it is easy to build heat exchange holes in this area, and the corresponding hole-forming cost is low. It is more suitable for ground source heat pump system. However, in mountainous areas and piedmont areas, the use of ground source heat pump system is limited due to the relatively high drilling cost because the rock stratum or loose layer has coarse particles and water permeability without water.
1 project overview
China People's Armed Police Guard Training Base is located in Beiqijia Town, Changping District, with a total construction area of about 36,000m2. In winter, the original heating and domestic hot water are provided by three 1400kW gas-fired boilers (using liquefied gas as fuel), and in summer, three 150 cold-ton water chillers (two for use, 1 standby) provide cooling, and the air conditioning area in summer is 18345m2. The annual gas cost alone exceeds 2 million yuan. In order to solve the problem of expensive gas, it is decided to change the original gas-fired boiler system into ground source heat pump heating and air conditioning system, and at the same time, the system can also meet the needs of 1200 people's bathing water and swimming pool heating.
The project started in June 2005 and was completed and put into use in early June 2005.
2 system scheme introduction
This project adopts vertical ground source heat pump system to provide heating and refrigeration for all buildings in winter, and can also heat domestic hot water and swimming pool water all year round. In summer, the system can provide domestic hot water for free through heat recovery.
2. 1 Selection of heat pump unit in machine room
According to the actual situation of the training base and considering the characteristics of each load, this project selects two screw-type ground source heat pump units BH/ESRHH3903 from Clemente, Italy (in which 1 is the total heat recovery unit) and 1 screw-type ground source heat pump units from BE/SRHH4004. The total heating capacity of the system is 370 1kW, and the total cooling capacity is 3 197kW. The BH/ESRHH3903 heat pump unit is a high-temperature heat pump unit, mainly considering that there is a part of radiator system at the end of the base, which provides domestic hot water and swimming pool heating at the same time. BE/SRHH4004 heat pump unit provides winter heating for fan-coil system.
2.2 annual operation plan of computer room system
Winter: Three heat pump units operate in heating state, which can meet the demand of total heating load of training base in winter. Among them, the heating of domestic hot water is provided by the total heat recovery unit, which produces domestic hot water and also provides heating for buildings. In the case that domestic hot water and heating are running at the same time, domestic hot water is preferred.
Summer: Three heat pump units operate under refrigeration conditions to provide building refrigeration, which can meet the total cooling load demand of the training base of the Security Bureau. Among them, the total heat recovery unit generates domestic hot water by absorbing the waste heat in the air conditioning system while providing refrigeration.
Transition season in spring and autumn: in this season, buildings do not need heating and cooling, but need to heat domestic hot water and swimming pool. 1 Total heat recovery unit is equipped with water storage tank to provide domestic hot water. At the same time, because the unit is a double condenser total heat recovery unit, it can also be used for swimming pool heating.
2.3 Outdoor heat exchange hole design
In order to accurately understand the geological conditions of the heat exchange hole area, Huaqing Company drilled a heat exchange exploration test hole in the site in May 2005, conducted geological exploration in the project area, and tested the thermophysical properties of the soil. According to logging data and regional geological and hydrological conditions, outdoor heat exchange holes are designed. A total of 348 outdoor heat exchange holes were drilled in this project, all with a diameter of 150 mm and a single hole depth of150 m. Four 32mm heat exchange tubes (double U-shaped tubes) were placed in each hole, with a hole spacing of 5m and arranged in a square shape. The heat exchange holes are all arranged under the football field, with a total area of about 8000m2.
After drilling the heat exchange holes, run four 32mm heat exchange tubes. The pipe spacing is 40mm, and it is fixed with pipe clamps, and the pipe clamp spacing is 5 m. ..
The horizontal connecting pipes between heat exchange holes are directly buried, and the buried depth is 1.6m below the ground. The pipes are HDPE pipes, with the main pipe diameter of φ 1 10 mm, and the main pipes of heat exchangers are laid in the same way. Each group is about 15 holes. Finally, all the heat exchange tubes in the heat exchange holes are merged into D3 15mm main pipe (HDPE pipe), and then connected to the computer room through DN300mm outdoor main pipe (seamless steel pipe).
3. System operation
The ground source heat pump equipment renovation project of China People's Armed Police Guard Training Base was officially put into operation in June 5438+065438+1October 55438+May 2005. After a complete heating season in 2005-2006, the effect is good. The indoor temperature of each room can reach 20 ~ 24℃ (end fan coil), the domestic hot water supply temperature is about 48℃, and the water supply of air conditioning system reaches 48℃. The operation cost is much lower than that of the previous liquefied gas boiler.
The system has been in trial operation since the middle of 2005 10. The average daily total electricity consumption in heating season is about11000 kw h, and the actual electricity fee is 0.60 yuan/kw h, so the daily heating and sanitary hot water operation cost of the training base of the Security Bureau is about 6,000 yuan. The total cost of system operation in heating season 120 days is about 792,000 yuan (including domestic hot water for the whole year, about 1200 people take a bath). The direct operating cost of system heating (including sanitary hot water) per unit building area is 22.0 yuan /m2, of which the domestic hot water cost is about 7 yuan /m2.
4 conclusion
With the approach of the 2008 Beijing Olympic Games, the China Municipal Government has also accelerated the development and application of new energy technologies. Recently, nine municipal government departments, including the Beijing Municipal Development and Reform Commission Office, jointly issued the Guiding Opinions on the Development of Heat Pump System, which clearly pointed out that "heat pump system is a new energy utilization mode using low-temperature heat source for heating and cooling, which is cleaner, more efficient and more energy-saving than conventional energy sources such as coal, gas and oil. Developing a heat pump system according to local conditions is conducive to optimizing the energy structure of our city, promoting multi-energy complementarity and improving energy efficiency. "
GB50366-2005, which was officially promulgated and implemented on June 5438+1 October1June 2006, standardized the design, construction and installation of ground source heat pump system, and technically ensured the smooth implementation of ground source heat pump system.
Ground source heat pump system has been paid more and more attention by HVAC industry because of its advantages of environmental protection, high efficiency, energy saving and capital saving. In today's energy shortage, developing clean energy is the general trend and the only way to adjust the energy structure. In this environment, the ground source heat pump system will shine and play its important role.