Located in Gucheng County, Hengshui City, Hebei Province, the Old City Zhengkou Middle School and its family building cover an area of 254 mu, 190 mu of teaching area and more than 95000 square meters of building area. The building area of the family building is about 45000 square meters. The original heating mode is gas-fired boiler, which has high operating costs and operates in different periods of time throughout the day. The heating is not continuous, and the room temperature in the heating season cannot meet the standard, which has caused great problems for teachers and students at school and residents in the family building.
In order to effectively solve the current heating situation of high energy consumption, high cost, poor effect and low comfort, and actively respond to China's 30 · 60 dual carbon strategic goal, Zhengkou Middle School introduced Kcalin STS efficient air source heat pump units to achieve clean energy centralized heating for the campus and family buildings.
The project is equipped with 51 Kcalin STS high-efficiency air source heat pump units with the model of KLKQ-STS/S-90/24 (I) R3, which will be completed and put into operation in November 2021 to achieve continuous and stable heat supply in winter, and the indoor temperature will not be lower than 18 ℃.
The building area of the family building is 44170 square meters: 1 # - 6 # family buildings are floor heating systems, with a building area of 30000 square meters. A set of heating system (heating system 1) is set up, and a total of 16 Kcalin STS air source heat pump units are set up; 7 #, 8 # and bungalow are radiator systems, with a building area of 14170 square meters. A set of heating system (heating system 2) is set, and a total of 8 Kcalin STS high-temperature air source heat pump units are set.
The heating building area of the campus is 62100 square meters, of which 1 # - 6 # dormitory buildings and the second teaching building (radiator part) are radiator systems, with a building area of about 34000 square meters. A set of heating system (heating system 3) is set, and a total of 14 Kcalin STS high-temperature air source heat pump units are set; 7 # - 9 # dormitory buildings, the second teaching building (floor heating part), the third teaching building, and the comprehensive building are floor heating systems, with a building area of about 28100 square meters. A set of heating system (heating system 4) is provided, with a total of 13 Kcalin STS air source heat pump units.
The system is equipped with 51 STS air source heat pumps to replace the original gas boilers as new heat source equipment, so as to realize the centralized heating of clean energy in the campus and family buildings.
This design mainly includes relevant national heating, air conditioning and ventilation design standards, as follows:
1．Code for Design of Heating Ventilation and Air Conditioning of Civil Buildings GB50736-2012;
2．Code for Design of Building Water Supply and Drainage (GB50015-2019);
3．Heat Pump Water Heaters for Commercial, Industrial and Similar Purposes (GB/T 21362-2008);
4.Technical Measures for National Civil Building Engineering Design (HVAC power water supply and drainage)
5.Design Standard for Energy Efficiency of Residential Buildings in Severe Cold and Cold Regions (JGJ 26-2010);
6.Code for Acceptance of Construction Quality of Ventilation and Air Conditioning Engineering (GB50243-2016);
7．Relevant specifications and technical standards of other countries.
After checking the outdoor meteorological parameters of the National Code for Design of Heating Ventilation and Air Conditioning of Civil Buildings, the meteorological parameters of Hengshui City are as follows:
| project | numerical value | |
| Outdoor heating calculation temperature（℃） | -7.9 | winter |
| Outdoor air conditioning calculation temperature （℃） | -10.4 | |
| Outdoor ventilation calculation relative humidity（%） | -0.9 | |
| Outdoor average wind speed（m/s） | 2 | |
| Atmospheric pressure （hPa） | 1024.9 |
According to the actual investigation and understanding of the site and the thermal insulation of the house, the thermal load is calculated as 36.7w/m2.
The calculation results are as follows: 105000x36.7 w/m2/1000=3854 kW
According to the load calculation, the equipment selection is as follows:
| Serial No | name | Aggregate demand | Unit model | parameter | Quantity (set) | remarks |
| 1 | STS air source heat pump unit | Total heat load 3854KW | KLKQ-STS/S-90/24(I)R3 |
Nominal heating capacity:98KW Electric power:24KW |
51 | |
| 2 | water circulating pump | CHP-1/2 | TD150-22G/4 |
Flow200t/h,lift22m， Power18.5kW,one for use and one for standby; |
2 | Heating system 1 |
| 3 | water circulating pump | CHP-3/4 | TD150-22G/4 |
Flow120t/h,lift24.9m, Power: 15kW; One for use and one for standby; |
2 | Heating system 2 |
| 4 | water circulating pump | CHP-7/8 | TD150-22G/4 |
Flow: 200t/h, lift: 22m, Power: 18.5kW, one for use and one for standby; |
2 | Heating system 3 |
| 5 | water circulating pump | CHP-5/6 | TD150-22G/4 |
Flow 120t/h, lift 24.9m, Power: 15kW; One for use and one for standby; |
2 | Heating system 4 |
| Serial No | Winter heating form | unit | Kcalin STS air source heat pump | Gas fired boiler | remarks |
| 1 | Energy type | - | electric energy | Electric energy+gas | |
| 2 | Total heating load | kW | 3854 | 3854 | |
| 3 | Annual heat consumption | 10000kWh | 675.6 | 675.6 | |
| 4 | Annual energy consumption | 10000kWh | 225.2 | 15.9 | Power consumption |
| 10000Nm3 | / | 83.9 | Air consumption | ||
| 5 | Annual operation cost | 10000元 | 112.6 | 301.6 | |
| 6 | Heating cost per unit area | yuan/㎡ | 10.7 | 28.7 | |
| 7 | Indirect CO2emissions | tCO2/year | 1308.5 | 1673.4 |
Note:
1. Energy price: 0.50 yuan/kWh; The gas price is 3.5 yuan/m3; The calorific value of gas is 35.1MJ/kg; Operation time in winter is 120 days;
2. According to the Accounting Methods and Reporting Guidelines for Greenhouse Gas Emissions of Enterprises Power Generation Facilities (HBQ [2021] No. 9), the emission factor of the national grid is 0.5810tCO2/MWh. 1.88kgCO2/Nm for natural gas ³。
1) Energy saving
The operating cost of the original gas-fired boiler heating system is 28.7 yuan/(m2 · heating season) (the natural gas price is 3.5 yuan/m ³）， After the transformation, the operating cost of the air source heat pump heating system is 10.7 yuan/(m2 · heating season) (the electricity price is 0.50 yuan/KWh). Compared with the original system, the annual operating cost is reduced by 18.0 yuan/(m2 · heating season), saving 62.7% of the operating cost.
2) Environmental protection and emission reduction
CO2 emissions are calculated based on the national average carbon emission coefficient of 0.592 kg CO2/kWh per kilowatt hour in 2018, which is 21.8% less than that before the transformation. Air pollutant emission: after the transformation, the air pollutant emission of the heat pump heating system on the site is zero, the indirect NOx emission is 70.4% less than that of the gas boiler before the transformation, and the PM2.5 emission is 11.7% less than that before the transformation.
Through the practical verification of the last complete heating season, Kcalin STS efficient air source heat pump has created a warm, comfortable, clean and environment-friendly working and living environment for users of Zhengkou Middle School and the family building, and has significantly reduced the operating costs of heating equipment, which confirms that the air source heat pump is an effective way to help the country achieve carbon reduction.
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