Ground temperature（ground temperature）, refers to the ground surface and the following different depthssoil temperature The general name of.Unit:centigrade(℃)。The ground temperature refers to the temperature of the thermometer set on the ground at the ventilated and dry place of the brewing workshop in order to grasp the temperature of the next curve and kiln entry.Ground temperature is one of the meteorological observation items, which is very usefulclimateresources.
Ground temperature, the general term of soil temperature on the ground surface and at different depths below, is the temperature condition at the junction of atmosphere and surface.The unit refers to the depth of the water in the evaporator with a certain diameter reduced by evaporation.Unit: ℃.[4]
The temperature of the surface soil on the ground is called the ground temperature, and the temperature of the soil below the ground is calledGround temperature。The ground temperature shall be specially madeGeothermometerTo measure.[1]
To facilitate reading and accurate measurement of a certain depthsoil temperature , the underground temperature is usually specially madeCurved tube geothermal meterTo measure.The sensing sphere of the curved tube geothermal meter is connected with the surface body at an angle of 135 degrees. When installing, the surface body and the ground are buried in the soil at an angle of 45 degrees.The meteorological station generally observes the ground temperature at the depth of 5 cm, 10 cm, 15 cm, 20 cm, 40 cm, 80 cm, 160 cm and 320 cm on the ground and below the ground, as well as the daily maximum and minimum temperature on the ground.
During the day, the sun shines, and the ground temperature gradually rises after the earth receives heat.After sunset, near groundair temperatureGradually, the temperature of the earth's surface begins to drop.At sunrise and sunset, the ground temperature shows obvious diurnal variation.With the change of four seasons, there are also obviousInterannual changeThese changes generally decrease with the increase of depth.The occurrence time of the highest and lowest ground temperature is delayed with the increase of depth.The influence of ground temperature on the temperature near the ground and the germination and growth of plant seeds,microorganismThe reproduction and its activities have a great impact.The data of ground temperature is of great significance to the regional planning of agriculture, forestry and animal husbandry.In addition, plateaufrozen soilWith the construction of railways, underground minerals andGeothermal resourcesMany years of geothermal data are needed for mining.
Geothermal map
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Geothermal profile
stayGeological ProfileOn the basis of, add an isotherm, which is delineated according to the measured temperature data of boreholes on or adjacent to the profile.
Isotherm plan
Although we say that the ground temperature of a mining area is mainly related to the depth, the ground temperature gradient is roughly the same.But in fact, the temperature of underground rock mass is controlled by many other factors. The underground thermal field determines the temperature field, and the underground isothermal surface is very complex.The temperature of a certain underground point is not only related to the geothermal background, but also related to the carrier lithology, the heat conduction (structure), the radioactive material type and radiation intensity of the carrier lithology, the groundwater movement, and other factors.All these will lead to different temperatures at the same elevation. The underground isothermal surface is not a simple plane at all, but a complex surface approximating a plane.In order to correctly express the condition of this isothermal surface, it is necessary to draw various isothermal line plans.In essence, the isotherm plan is the intersection line between the isotherm surface and the space plane, which simplifies the complex isotherm surface into a two-dimensional isotherm.[2]
Various isotherm plans mainly include:
Underground isotherm plan of a certain elevation: is the projection of the intersection line of an elevation plane and a series of isothermal planes on the horizontal plane.Specific method: take the horizontal section map as the base map, obtain the intersection points of the elevation plane and each isotherm from a series of geothermal profiles, transfer these intersections to the horizontal section map, and connect the isotherm points to form an isotherm.
Isotherm plan of an ore bed: It is the projection of the intersection line of the floor or roof of a seam and a series of isothermal surfaces on the horizontal plane.Specific practice: take the contour map of the ore floor or roof as the base map, obtain the intersection points of the ore floor or roof and each isotherm from a series of geothermal profiles, turn these intersection points to the bottom map, and connect the isotherm points to form an isotherm.
It can be seen from this that in order to make a geothermal profile or isotherm plan, sufficient geothermal point data is required, that is, a large number of geothermal data of many boreholes need to be measured within the map range
Related terms
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（1）Geothermal gradient: The increment of ground temperature per 100 meters in the warming zone.
(2) Normal ground temperature gradient: gradient is less than or equal to 30C/hm
(4) High temperature area: the area where the ground temperature exceeds 400C.(The ground temperature of 31-37 degrees is the first level heat damage area, and the temperature above 37 degrees is the second level)
Development and utilization
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Ground energy heat pump
Shallow geothermal energy refers to the energy contained in soil, sand, gravel and groundwater within hundreds of meters of the earth's shallow surfaceLow temperature heat energy, widely existing in shallow strataConstant temperature bandMedium, less affected by the four seasons climate,soil temperature Relatively constant.AndDeep geothermalcomparison,Shallow geothermal energyIt is widely distributed, with huge reserves, rapid regeneration, low investment in development and utilization and high value, meeting the development needs of circular economy.
The annual low temperature that can be collected from soil within nearly 100 meters in ChinaenergyIt is 3750 times the installed power generation capacity of 400 million kilowatts in China, and 200 million kilowatts of low-temperature energy can be collected every year by 100 meters of inland water.As far as Beijing is concerned, the shallow layer can be mined every year based on 6900 square kilometersGeothermal energyIs equivalent to 140 million tonsStandard coal, 1.2 times of the 11 million tons of standard coal consumed by Beijing in 2003.
The water source heat pump technology draws ground water with the same temperature as the ground water, and exchanges heat with the extracted ground water through the unitquantity of heatTransfer to water source to realize refrigeration;In winter, energy is extracted from water sources andHeat pump technologyThe extracted energy is sent to the building to realize heating. The number of pumping wells and reinjection wells is designed according to the system load and water demand, the water production capacity and reinjection capacity of the formation. In fact, after the source water passes through the heat pump unit, only the heat is exchanged, and the water quality is almost unchanged. After reinjection to the formation or re discharge to the surface water,It will not pollute the original water source.ThereforeWater source heat pumpIn the process of technical utilization of groundwater and surface water sources, regional groundwater andSurface water pollution。
Ground source heat pump technologyUsing soil as heat source andHeat sinkThe heat exchanger filled with circulating liquid buried underground is used to exchange heat and cold with the soil, and the type, number and depth of heat exchange holes are designed according to the load of the system and the thermal conductivity of the stratum, which is different from the water source heat pump technology,Ground source heat pump systemNo need for extraction and reinjectiongroundwater, it uses a small amount ofelectric energyThrough the heat exchange between the circulating liquid in the closed PE heat exchange pipe buried in the soil and the stratum soil, the heat is absorbed in winter and dissipated in summer, which makeshydrologygeologyThe area with poor stripes can alsoGeothermal energyResources.
Use ground energyHeat pump technologyExploitation and utilization of shallow geothermal energy has obvious energy-saving effect, and only heating canenergy conservation30%-50%。The operation cost is also low, 63% of the projects are lower thanCoal burningCentral heatingThe heating prices of all the investigated projects are lower than those of fuel oil, gas and electric boilers, and can function locally, without transmission, without waste residue, and without discharging combustion waste into the atmosphere, indicating that it is highly practical and has broad application prospects.By the end of 2005Geothermal energyThe utilization area is about 8 million square meters, and the heating building area using shallow geothermal energy technology is growing at a rate of 15%~20% every year.
Shallow geothermal energy resources and environmental protection:
1. Zero pollution emission, directly improving the air quality in the applicable area
Shallow ground temperature can be clean and environmentally friendly.Shallow geothermal energy is a clean and renewable energy.After collecting shallow low temperature geothermal energy and slightly improving it, it can not only meet the demand for heating (cooling), but also achieve zero pollution emissions in heating (cooling) areas and directly improve the air quality in applicable areas.
2. Almost unaffected by environmental and climate changes, it regenerates rapidly
Shallow geothermal energy is widely distributed.Shallow geothermal energy widely exists in the huge constant temperature zone in the shallow layer of the earth (<200 meters). The soil temperature is relatively constant, almost unaffected by environmental and climate changes, and can be regenerated quickly and recycled.
3. Free from transportation and transmission, no waste residue
It is economical to use shallow geothermal energy.The investment of one square meter of building is about 250 to 380 yuan, which is 20 to 30% lower than that of gas and air conditioning systems that also meet the conditions of heating, cooling and domestic hot water. Its operating costs are significantly lower than other clean energy sources. In addition, it takes energy locally, avoids transportation and transmission, and has no waste residue, so its availability is strong.
Geothermal anomaly zone
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Naturalair temperatureThe change depends on the light and heat of the sun. When the distance between the earth and the sun is shortened,solar radiationThe heat energy to the earth will increase, making the earth hot and warm.In turn, the earth becomes cool.In this way, spring, summer, autumn and winter come into being.However, some lands have broken this natural law, and the phenomenon of warm winter and cool summer has appeared. Such zones are calledGeothermal anomaly zone。
