I. Calculation of Utilizable Resources
According to the aforementioned calculation methods and parameters, the utilizable resources of shallow geothermal energy in suitable areas for groundwater source heat pumps in the study area are calculated; and the total area that can be heated in winter and the total area that can be cooled in summer are discounted according to the average winter heating load of 50W/m2 and the average summer cooling load of 75W/m2 in each city. The total heating area in winter and cooling area in summer were calculated. The results are shown in Table 7-8.
Table 7-8 Calculation results of shallow geothermal energy available resources in suitable areas for groundwater source heat pumps
II. Evaluation of groundwater quality for water source heat pumps
1 . Evaluation standards
The reference standards of groundwater quality for water source heat pump are shown in Table 7-9.
Table 7-9 Groundwater ground source heat pump water quality requirements
The impact of various water quality indicators on the operation of groundwater source heat pump and service life is as follows:
1) sand content and turbidity: some water sources contain sediment, organic matter and colloidal suspensions, so that the water becomes turbid. High sand content of the water source on the unit and the pipe valve will cause wear and tear, and in serious cases will cause pipeline blockage. Moreover, water with high sand content and turbidity used for underground recharge will cause aquifer clogging.
2) Scaling tendency: you can analyze the water hardness, that is, the total amount of Ca2 +, Mg2 + in the water. Hardness, easy to scale.
3) mineralization: the mineralization of water is usually 1L of water containing a variety of salts in the total number of grams to indicate (g / L). Underground groundwater mineralization level, directly affecting the salt content of the soil. Groundwater suitable for groundwater source heat pumps are generally freshwater and weakly saline water.
4) pH: the pH value of water is less than 7, acidic, and vice versa is alkaline. Groundwater pH value is too high or too low will cause corrosion of the unit, seriously affecting the service life of the system. Groundwater source heat pump water pH value should generally be 6.5 ~ 8.5.
5) Cl-, CO2, water content: Cl- to a large extent to promote the corrosion of carbon. CO2 dissolved in the water, accelerate the oxidation and corrosion of high-strength low alloy steel. Mainly on the cement corrosion.
2. Evaluation of water quality suitability
According to the table of water quality requirements for groundwater ground source heat pump, combined with the water quality of each city, the suitability of water quality in each city is evaluated as follows.
Overall, the groundwater basically meets the water quality needs of water source heat pump except for hardness, and individual elements locally exceed the standard.
In the 22 water samples of Zhengzhou City, hardness exceeded the standard, and Cl-, and free CO2 exceeded the standard locally.
Kaifeng City, 10 water samples, hardness exceeded all standards, total alkalinity, Cl-, and free CO2 localized exceedance.
Luoyang city, 10 water samples, hardness all exceeded the standard, Cl-, and free CO2 local exceeded the standard.
Pingdingshan City, 94 water samples, 87 hardness exceeded the standard, Cl-, localized exceedance.
Jiaozuo City, 10 water samples, hardness exceeded all standards, total alkalinity, Cl-, and free CO2 localized exceedance.
Hebi City, 48 water samples, 46 hardness exceeded the standard, total alkalinity, Cl-, and free CO2 local exceeded the standard.
Xinxiang City, 77 water samples, hardness all exceeded the standard, total alkalinity, Cl-, , mineralization and free CO2 local exceeded the standard.
Anyang city, 33 water samples, hardness all exceeded the standard, Cl- and partial exceeded the standard.
Puyang city, 31 water samples, hardness exceeded all standards, total alkalinity, Cl- and localized exceedance.
Xuchang city, 36 water samples, hardness exceeded all standards, total alkalinity, Cl-, and free CO2 localized exceedance.
Luohe City, 32 water samples, hardness exceeded all standards, total alkalinity, Cl-, and mineralization exceeded the local standards.
Sanmenxia City, 48 water samples, 44 hardness exceeded the standard, Cl-, and free CO2 local exceeded the standard.
Nanyang city, according to the information collected, the hardness and Cl- localized exceeded in the groundwater of Nanyang city
Zhoukou city, eight water samples, hardness and free CO2 exceeded in all, and the total alkalinity, Cl- and localized exceeded.
Jiyuan City, 33 water samples, hardness and free CO2 all exceeded, free CO2 most exceeded, Cl- and localized exceeded.