From the hand-operated folding fans in the 1940s, to the electric fans in the 1960s, to the split air conditioners and central air conditioners in the 1980s and 1990s, my country's household refrigeration equipment has undergone many upgrades. Nowadays, ground source heat pumps have become the latest choice to enter our lives. So, what is a geothermal heat pump? What is the principle of ground source heat pump? What are the construction steps of a ground source heat pump? Let’s take a look with the editor below.
1. What is a ground source heat pump?
Ground source heat pump is a brand new heating and cooling technology. Its emergence has changed the original cooling and heating situation. At present, the maturity of my country's ground source heat pump technology is still very low, and there is a big gap with Europe and the United States and other countries. Therefore, understanding ground source heat pumps is a necessary condition for promoting this technology.
Ground source heat pumps are mainly divided into three forms: underground water system, surface water system and underground pipe system. Compared with the first two ground source heat pump systems, the underground pipe system is commonly known as ground source heat pump. This system uses the shallow soil on the surface as the heat source and exchanges heat with the water circulation system through a geothermal heat exchanger composed of underground pipes. It is also the most widely used ground source heat pump system so far.
Soil source heat pump air-conditioning technology takes advantage of the relatively stable temperature characteristics of warm winters and cool summers deep in the earth. It exchanges heat through closed circulating water in underground pipes and relies on consuming a small amount of electricity to drive the heat pump unit to complete cooling or Heating cycle, thereby exchanging heat between air-conditioned rooms and soil, surface water, etc. to achieve cooling and heating or hot water preparation requirements.
2. Principle of ground source heat pump
Ground source heat pump can integrate heating, air conditioning, refrigeration and domestic hot water. A set of ground source heat pump can replace the original heating Three sets of devices or systems including boiler, refrigeration, air conditioning and domestic hot water heating, thereby also increasing the economy. Below, we will comprehensively analyze the working principle of ground source heat pumps from three aspects: summer, transition season, and winter.
Ground source heat pumps provide air conditioning, refrigeration and domestic hot water in summer
Summer: The ground source heat pump air conditioning unit buries the heat exchanger underground, and passes the water through the high-strength plastic The pipes (PE pipes) circulate in a closed loop to achieve the purpose of heat and cold exchange with the soil and realize indoor fan coil cooling. At the same time, the waste heat generated by the unit is used to produce domestic hot water for free on the one hand, and the other is On the one hand, it transfers heat underground to cool down the room and at the same time stores heat for winter use.
Ground source heat pump provides domestic hot water in the transition season
Transition season: When the ground source heat pump unit is running, it absorbs low energy from the underground vertical buried pipe loop through the soil heat exchanger in winter. High-grade heat energy, and then use the compressor system to upgrade low-grade energy into high-grade energy, producing continuous domestic hot water at 45-50°C.
The ground source heat pump provides floor heating and domestic hot water in winter
Winter: The underground heat pump system transfers the heat in the soil to the room through closed pipes buried underground, and uses The higher temperature is released into the room through the end of the indoor heating and air conditioning. Facilities such as floor heating and fan coil units can be used for heating and domestic hot water can be provided. At the same time, cold energy is stored for summer use. The earth's soil provides a good A source of free energy storage, thus realizing the seasonal conversion of energy.
3. Ground source heat pump construction steps
1. Drilling
1) Before construction, you should understand the existing underground pipelines and underground structures in the buried pipe site. function and its accurate location. Before drilling each vertical hole, an exploration pit should be manually dug. The diameter of the exploration pit should not be less than 300mm and the depth should not be less than 1.2m;
2) Ensure that the drill pipe is ensured when drilling vertical to ensure that each vertical hole is parallel to prevent channeling;
3) This project is located in Daxing, with a lot of sand layers. In order to prevent the vertical holes from collapsing and water seepage, drilling holes should be drilled in time during drilling. Clay is injected into the hole to improve the hole-forming quality and shorten the hole-forming time.
2. Vertically lowering the pipe
1) Before lowering the pipe, all pipes must be pressure tested, not less than 0.6MPa, and the pressure should be stabilized for 15 minutes. The pressure will not drop, and there will be no leakage or leakage. If it leaks, it is considered qualified;
2) After the pipe is lowered and before backfilling, the pressure of the PE pipe should be tested in time. Only after it passes the test can the next hole be drilled;
3) In order to prevent holes The sediment inside will reduce the effective depth of the hole. After drilling is completed, the pipe should be lowered in time, and fixing measures should be taken to prevent the PE pipe from floating up;
4) After passing the pressure test, seal the U-shaped pipe in time The four open ends of the U-shaped pipes are tied separately in each pair to facilitate future pipe connections.
3. Horizontal pipe laying and pipe connection
1) Horizontal buried pipes do not need to have a slope. The top of the uppermost buried pipe should be 0.4m below the frozen soil layer and not far from the ground. Less than 0.8m, and the spacing between supply and return loop headers should not be less than 0.6m;
2) Pipeline connections currently often use special equipment for electric fusion welding and hot fusion welding. Electrofusion welding has special instruments to control the time, and the welding process is good, but the price of electrofusion welding parts is higher; pay special attention to hot-melt welding and master the time to avoid shrinkage holes after welding, or even blockage of pipes.
4. Backfilling
1) The vertical hole grouting material should be a mixed slurry of bentonite and spun yarn or special materials. The mud sediment generated during the drilling process can also be used to ensure that the drilling The grout is dense with no cavities. Otherwise, the heat transfer effect will be reduced and the quality of the project will be affected;
2) The backfill soil of the horizontal joint pipe should be fine, loose, uniform, and free of stones and soil. The backfill compaction process should be uniform and must not be used. The pipeline is overhead;
3) The connection between the external pipeline and the equipment in the computer room. When the external pipeline enters the computer room, a wall-penetrating casing should be installed and the casing should protrude from the outer wall by no less than 50mm. The casing and the external wall, the casing and All exterior pipe spaces should be waterproofed, and then exterior backfilling should be carried out.
5. Machine room and terminals
1) The machine room is located in the basement and does not occupy effective space; the heat pump unit adopts a ground source heat pump unit specially designed by Yongyuan Heat Pump Company for underground pipe systems. The unit is compact as a whole, and the machine room area is small. The entire machine room area is less than 5_;
2) Fan coils are used to supply air at the end, and radiators are used in some functional rooms;
3) Construction precautions Matters: The construction of villa projects mostly involves individual owners. As the decoration progresses, the owners will inevitably have new ideas. Therefore, in the final construction, you cannot just rely on the drawings. You must cooperate with the decoration and communicate with the owners in a timely manner.