Ground water source heat pumps has been a hot spot of energy saving in the industry, and its system has high energy saving. For the sake of energy saving, many users choose water source heat pump in spite of local geological and hydrological characteristics and system design. After running for 3 ~ 5 years, the effect becomes worse. Instead of achieving the expected energy saving effect, it is difficult to maintain due to frequent failures.
The Intermediate People’s Court of Tongliao City, Inner Mongolia originally used the ground water source heat pump system for heating. After 7 years’ operation, the heating effect was poor and the energy consumption was high. Later, it was changed to the air source heat pumps heating system with low cost, strong heating effect and outstanding energy saving effect.
Firstly，Failure analysis after 7 years of operation
The office building of Tongliao Intermediate People’s Court in Inner Mongolia is located in Horqin District, Tongliao City, Inner Mongolia. The heating area of the project is nearly 20,000 ㎡. The screw unit of groundwater source heat pump was used as the system heat source, and the geothermal energy in groundwater was absorbed as the low-level heat source.
After 7 years of operation, the system has an irreversible fault. There is a large amount of heat exchanger cleaning work and some heat exchangers need to be replaced; The main compressor is noisy and inefficient. Insufficient groundwater recharge leads to poor heat exchange capacity of the unit.
- the efficiency decreases year by year, and the maintenance cost is high
- Irrational recharge and poor heating effect
- System rectification is difficult
Second, change the relevant details of the air source heat pumps.
- The transformation needs and forms are determined.
Tongliao Intermediate People’s Court has 149 police officers at the same level, handling about 2,400 cases of various types every year. In addition, it is in charge of case judgments in one place, has jurisdiction over 8 grassroots people’s courts, and has sent 31 people’s courts, handling about 22,000 cases every year. The poor heating capacity of the original system has seriously affected the normal legal work in one place. After multi-party comparison, in order to meet the cold and hot needs of office workers in time and make the best use of the original terminal system, the air source heat pumps is used for heat source reconstruction project, and the original water source heat pump is abandoned and replaced by an air source heat pump that does not rely on underground heat source but absorbs outdoor air low-level heat source.
2.Choose 10 sets of 150KW cryogenic machines
The annual average temperature in Tongliao City is 6.6℃, the outdoor calculated temperature for heating in winter is -19℃, and the heating period is as long as 166 days. The heat load in winter is relatively large. By re-calculating the heat load of the project, 10 sets of 60P ultra-low temperature air source heat pump units are configured. Under the working conditions of ambient temperature -20℃ and unit outlet temperature of 55℃, the heating capacity of a single unit is 102.4kW, and the total heating capacity of the system is 1024kW, which fully meets the heating demand of the project.
3.Use the original terminal and pipeline system
In order to reduce the initial investment of users and recover the loss of the original system transformation, the technicians carried out on-the-spot investigation on the original terminal and pipe network system to meet the needs of warm and comfortable office area and quiet and warm trial court, so the original terminal and pipeline system were used.
Third, the cost is lower and the effect is good
After a heating season, the superiority of the system has been fully reflected.
During the day, the high-efficiency operation mode is started, and the outlet water temperature of the unit is set at 50℃, which fully guarantees the warmth and comfort of the room. During the night rest period, when the outside air temperature is low and the unit operation efficiency is low, the low energy consumption operation mode is started, and the outlet water temperature is set at 30℃ to ensure the basic needs of buildings and achieve the purpose of energy saving. Finally, according to statistics, the heating cost is greatly reduced, the heating effect is far better than before, and the system performance greatly exceeds the user’s expectation.
