Energy consumption of existing projects.

This paper sorts out, analyzes, optimizes and classifies the data of ground source heat pump projects in Beijing, and makes full use of the actual data to quantitatively analyze the operating energy consumption of different ground source heat pump systems.

In the analysis of energy consumption, the first-hand data obtained are verified and some abnormal data are selected for analysis. The analysis involves 30 projects, of which 27 projects have refrigeration data and 29 projects have heating data.

1. Statistical analysis of energy consumption

When analyzing the completed projects, the total cooling and heating time of each project is quite different, and the unit electricity price of different projects is also different. When comparing the operating costs of cold season and heating season with "yuan/square meter quarter", there is a great difference. Considering that buildings mainly consume electricity when using ground source heat pump for cooling and heating, in the analysis of energy consumption, it is unified as the daily electricity consumption per square meter of the building, that is, the daily average electricity consumption per unit area KW h/(m2 d). Because most of the energy consumption of the terminal fan-coil unit or fresh air unit is not measured separately, their energy consumption is not calculated in the following analysis. In actual operation, the power of the terminal fan coil unit is small, but the number is large, and its power consumption can not be ignored.

Statistical software uses SPSS, that is, social science statistical software package. Using its descriptive statistical function in the statistical analysis process, the daily average power consumption per unit area of cooling and heating of ground source heat pump projects is statistically analyzed with one-dimensional frequency distribution, and statistical descriptive indicators such as Mean, Median and standard deviation (Std) are calculated. Deviation (standard deviation), variance (variance) and extreme range (extreme range). Using the drawing system of SPSS, the daily average power consumption histogram of ground source heat pump project is drawn. SPSS is the abbreviation of English Statistical Package for the Social Science, and its name is social science statistical Package, in order to emphasize its application in social science, because many phenomena in social science research are random and need to be studied by statistics, but in fact it is widely used in economics, sociology, biology, education, psychology, medicine, sports, industry, agriculture, forestry, commerce and finance, and it is the most influential in the world.

1) statistical frequency table

Scientific grouping and summary of the obtained data will make the original data systematic and orderly, which is beneficial to the calculation and analysis of statistical indicators in the next step. The daily average power consumption per unit area of ground source heat pump in summer and winter is grouped by the interval of 0.05 kW h/(m2 d), and its frequency distribution and frequency distribution are calculated, as shown in Table 7- 1 and Table 7-2. The number of times each group contains data is called frequency, and the ratio of the number of times each group contains data to the total number of times is called frequency. Frequency distribution is the number of times that data is distributed in each group according to its grouping flag, which consists of two elements: grouping flag sequence and distribution times corresponding to each group, and frequency distribution consists of grouping flag sequence and frequency corresponding to each group.

As can be seen from the above two frequency distribution tables, the average daily power consumption per unit area of ground source heat pump in summer is concentrated in the area of 0.10 ~ 0.25 kw h/(m2 d), accounting for 74. 1% of 27 projects. The average daily power consumption per unit area of ground source heat pump in winter is concentrated in the area of 0. 18 ~ 0.38 kw h/(m2 d), accounting for18 projects, accounting for 62% of 29 projects.

Table 7- 1 ground source heat pump refrigeration frequency distribution table

Table 7-2 Frequency Distribution of Ground Source Heat Pump Heating

Table 7-3 Statistical Description Index Table of Cooling Power Consumption of Ground Source Heat Pump

2) Statistical description indicators

Input the daily average power consumption per unit area of ground source heat pump in summer and winter into SPSS, and use its descriptive statistical function to carry out one-dimensional frequency distribution statistics, calculate statistical descriptive indicators and draw histograms in the statistical analysis process.

Table 7-4 Statistical Description Index Table of Heating Energy Consumption of Ground Source Heat Pump

Figure 7- 1 histogram of frequency analysis of ground source heat pump refrigeration.

Through statistical description index table and frequency analysis histogram, it can be seen that the daily average power consumption per unit area of ground source heat pump project in cooling season is 0.38 kW h/(m2 d), the lowest is 0.07 kW h/(m2 d), and the range is 0.31kW h/(m2 d). The average daily electricity consumption per unit area in heating season is 0.53 kW h/(m2 d), the lowest is 0.11kW h/(m2 d), and the range is 0.42 kW h/(m2 d), which shows that the data is scattered. Therefore, we should consider the common values for calculating power consumption.

The data dispersion is large, and the mean value is greatly affected by the extreme value. When calculating common values, the median is used for calculation. Because the median is the value in the middle after data sorting. The median divides the data into two halves, half of which is larger than the median and the other half is smaller than the median. Using the median to represent the approximate level of the overall mark value can avoid the influence of extreme values in the series and has better stability. Taking the distance between 0.6 times the median, the corresponding power consumption range is the range of common values. The common value of daily average electricity consumption per unit area of ground source heat pump project in cold season is 0.11~ 0.20 kw h/(m2 d), and the common value of daily average electricity consumption per unit area of ground source heat pump project in heating season is 0.17 ~ 0.32 kw h/(m2 d).

Figure 7-2 Frequency Analysis Histogram of Ground Source Heat Pump Heating Power Consumption

2. Energy consumption comparison and benefit analysis

1) heating analysis

In order to facilitate the comparison of other heating methods, the electricity consumed by the ground source heat pump project is converted into standard coal according to the coal consumption method for power generation, as shown in Table 7-5. The conversion coefficient refers to the national average coal consumption of thermal power generation in 2004, that is,1kw h power is converted into 354g standard coal. The comparative data is "Research on Heating Mode in Beijing" made by China International Engineering Consulting Company 200 1. This report calculates the energy consumption and pollutant emissions converted into standard coal by various decentralized heating methods, as shown in Table 7-6.

Table 7-5 Calculation Table of Heating Energy Consumption of Ground Source Heat Pump

The common energy consumption range of ground source heat pump heating is 7.37 ~ 13.66 [kg standard coal/(m2 quarter)], which is lower than that of centralized boiler room, electric boiler, electrothermal film, wall-mounted gas stove and direct-fired machine. Compared with the central boiler room heating energy consumption of 2 1.73kg standard coal per square meter, it saves energy by 37% ~ 66%.

Table 7-6 Table of Energy Consumption and Pollutant Emissions of Various Heating Methods

According to the energy consumption data of ground source heat pump, 28 items are 2 1.73(kg standard coal /m2 quarter) lower than that of central boiler room, that is, 96.6%; There are 19 projects that are lower than the average heating energy consumption of groundwater heat pump (kg standard coal/m2 quarter), that is, 65.5%, so the heating energy saving effect of ground source heat pump system is obvious.

The ground source heat pump heating process does not produce pollutant discharge. Compared with the centralized boiler room, it can reduce 34.77g of smoke and dust, 326 g of sulfur dioxide (SO2) and 0/22.7 g of nitrogen oxides (nitrogen oxides) per square meter in each heating season. Compared with wall-mounted gas stoves, it can reduce 2.95g of sulfur dioxide and 43.37g of nitrogen oxides per square meter in each heating season. Compared with the direct-fired engine, it can reduce sulfur dioxide (SO2) by 2.77g and nitrogen oxides (nitrogen oxides) by 40.83g per square meter in each heating season. The ground source heat pump system reduces environmental pollution and has considerable environmental benefits.

2) refrigeration analysis

Compared with other forms of refrigeration, the cooling energy consumption of ground source heat pump buildings is calculated, and the cooling energy consumption is calculated according to the 90-day cooling season (Table 7-7), and compared with the conventional water chillers.

Table 7-7 Calculation Table of Refrigeration Energy Consumption of Ground Source Heat Pump

Electric refrigeration is the main form of central air conditioning refrigeration at present, and the energy it uses is single electric energy. The comparative data is "2008 Annual Development Research Report of Building Energy Efficiency in China" by Tsinghua University Building Energy Efficiency Research Center. This report provides the survey results of energy consumption of high-grade office buildings in Beijing, from which the power consumption of 10 chiller and circulating pump is calculated (Table 7-8), with an average calculation of 20kW h/(m2 quarter); At the same time, referring to the air-conditioning power consumption of central air-conditioned residential buildings with various advanced energy-saving technologies and measures measured in Beijing in 2006, the average of them, namely19.9 kW h/(m2 quarter), is taken as the cooling power consumption of conventional water chillers for comparison.

Table 7-8 Investigation Results of Air Conditioning Energy Consumption of High-grade Office Buildings in Beijing Unit: kW h/(m2 quarter)

The common energy consumption of ground source heat pump refrigeration is 9.72 ~18.09 kw h/(m2 quarter), which is lower than that of conventional water chillers. Compared with the energy consumption of conventional water chillers19.9 kw h/(m2 quarter), it can save energy by 9% ~ 5 1%. There are 23 items in the energy consumption data of ground source heat pump refrigeration that are lower than that of conventional water chillers19.9 kw h/(m2 quarter), that is, 85.2%. It can be seen that the energy-saving effect of ground source heat pump system refrigeration is obvious.

3) Cost analysis

The non-industrial electricity price in Beijing 1 ~ 10 kV is 0.6275 yuan/kw h, as shown in table 7-9. Considering the adjustment of peak and valley average electricity price, it is reasonable to calculate the average electricity price at 0.65 yuan/kW h, and at 12 1 day in heating season. The common value of heating cost is 13.53 ~ 25.09 yuan/(m2 quarter). If the cooling season is calculated as 90 days, the common value of cooling cost is 6.32 ~ 1 1.76 yuan /(m2 quarter); Compared with 22 yuan/(m2 quarter) for cooling water chillers and 30 ~ 50 yuan/(m2 quarter) for heating oil, gas and electric boilers, the operating cost of ground source heat pump system is much lower. For the convenience of comparison, the electricity price is uniformly calculated at 0.65 yuan/kW h. For different types of projects, it can be calculated according to their specific electricity price charges, which can be high or low. Because the actual heating and cooling energy consumption of the building is related to many factors such as the use conditions, occupancy rate, equipment efficiency attenuation, etc., and it is also closely related to the operation adjustment mode. In addition, the cold and heat sources of the ground source heat pump system, that is, the water intake and recharge conditions of the well, have a great influence on the operating efficiency of the host system and directly affect the operating energy consumption.

Table 7-9 Beijing Sales Electricity Price Table