Ground source heat pump explained
What is a ground source heat pump
- Ground source heat pump is a device that converts low-grade heat energy into high-grade heat energy by inputting a small amount of high-grade energy into shallow ground energy.
- The ground source heat pump is a heating central air conditioning system composed of a water ground source heat pump unit, a geothermal energy exchange system and a building system. According to the different forms of geothermal energy exchange systems, ground source heat pump systems are divided into buried pipe ground source heat pump systems, groundwater ground source heat pump systems and surface water ground source heat pump systems.
- Heating and air conditioning system composed of water source heat pump unit, geothermal energy exchange system and indoor system using rock and soil mass, groundwater or surface water as low temperature heat source.
- The ground source heat pump heating and air conditioning system is mainly divided into three parts: outdoor ground source heat exchange system, ground source heat pump host system and indoor terminal system.
How Ground Source Heat Pumps Work
- In nature, water always flows from high to low, and heat always transfers from high to low temperature. One can pump water from low to high so that water can flow from low to high. Heat pumps can also transfer heat from low temperature to high temperature.
- Therefore, a heat pump is essentially a heat riser. It consumes a small amount of electric energy when working, but can extract 4-7 times of electric energy from environmental media (water, air, soil, etc.), and increase the use temperature. This is also the reason why heat pumps save energy
- A ground source heat pump is a type of heat pump. It uses soil or water as a source of heat and cold to make buildings cool in winter and cool in summer. A ground source heat pump simply "transfers" energy between the earth and the room. Uses very little electricity to maintain the desired temperature in the room
- The ground source heat pump uses water and ground energy (groundwater, soil or surface water) to exchange cold and heat as the cold and heat source of the ground source heat pump. Ground energy is a "heat source"; in summer, the indoor heat is taken out and released to groundwater, soil or surface water, and the ground energy is a "cold source" at this time.
Classification of ground source heat pumps
- According to the different forms of geothermal energy exchange systems, ground source heat pump systems are divided into buried pipe ground source heat pump systems, groundwater ground source heat pump systems and surface water ground source heat pump systems.
- Buried ground source heat pump systems are divided into two types: open type and closed type.
- An open system refers to a system in which surface water is driven by a circulating pump and flows directly through the water source heat pump unit or through an intermediate heat exchanger for heat exchange.
- It is a closed system in which antifreeze is injected into closed plastic tubes buried deep in the ground and exchanges energy with water or soil through a heat exchanger. The closed system is not affected by factors such as groundwater level and water quality.
Types of Ground Source Heat Pump Systems
1. Buried ground source heat pump
Horizontal ground source heat pump
- It exchanges cold and heat with the soil through a closed heat exchange system buried 2-4M below the surface. This system is suitable for buildings with small cooling and heating areas such as villas and small single buildings. The initial investment and construction of the system are less difficult, but the area is large
Vertical ground source heat pump
- Through vertical drilling, the closed heat exchange system is embedded in the rock and soil at a depth of 50M to 400M to exchange cold and heat with the soil. This system is suitable for buildings with a large cooling and heating area and a certain open space around them, such as villas and office buildings. The initial investment of the system is high, the construction is difficult, but the area is small.
2. Surface water ground source heat pump
- The ground source heat pump unit exchanges cold and heat with rivers, lakes, seawater, etc. through a closed heat exchange system arranged at the bottom of the water. This type of system is suitable for small and medium-sized buildings in hot and cold areas and near water areas. It utilizes the stable temperature and significant heat dissipation of pool or lake water, eliminating the need for drilling and trenching, and with minimal initial investment. but requires a deeper and larger river or body of water around the building
3. Ground source heat pump
- The ground source heat pump unit exchanges cold and heat with the deep groundwater pumped out by the water pump through the closed circulation system in the unit through the heat exchanger. Groundwater is pumped back or injected into the groundwater layer by means of a pressurized pump. The system is suitable for large single buildings and small building communities with large building area and limited surrounding open space.
4: Hybrid system
- A system that uses a combination of ground sources and cooling towers or heating boilers as cold and heat sources. Hybrid systems are very similar to decentralized systems with the addition of a cooling tower or boiler to the cold and heat source system.
- Refrigeration principle
- In the cooling state, the compressor in the ground source heat pump unit performs work on the refrigerant to make it undergo a vapor-liquid conversion cycle. Through the evaporation of the refrigerant in the refrigerant/air heat exchanger, the heat carried by the indoor air circulation is absorbed into the refrigerant. While the refrigerant is circulating, the refrigerant in the refrigerant/water heat exchanger is condensed, and the water carried by the refrigerant is condensed. It is circulated by the water circuit. Heat is absorbed and eventually transferred to groundwater or soil through the water cycle. The room is cooled with cold air below 13°C through the refrigerant-air heat exchanger during the continuous transfer of heat from the room to the floor
- Heating principle
- In the heating state, the compressor in the ground source heat pump unit performs work on the refrigerant, and reverses the flow direction of the refrigerant through the four-way valve. The heat in the groundwater or soil is absorbed by the groundwater cycle, the heat in the water cycle is absorbed into the refrigerant by the evaporation of the refrigerant in the refrigerant/water heat exchanger, and then the heat is transferred through the refrigerant/air exchange during the refrigerant cycle device. During the condensation process of the refrigerant, the heat carried by the refrigerant is absorbed by the air circulation. The ground source heat pump continuously transfers the heat from the underground to the room, and heats the room in the form of hot air above 35°C.
Advantages of ground source heat pumps
- A ground source heat pump is a heating, cooling and air conditioning system that utilizes solar energy stored in the soil as a cold and heat source for energy conversion. Ground source heat pumps use a technology that uses clean and renewable energy. The surface soil and water body is a huge solar collector, which collects 47% of the solar radiation energy, which is more than 500 times the annual human use (the groundwater body receives solar radiation energy indirectly through the soil); it is also a huge dynamic energy In a balanced system, the soil and water bodies on the surface naturally maintain a relative balance of energy reception and emission. The success of ground source heat pump technology has made it a reality to utilize the nearly unlimited solar or ground energy stored in it. If used in winter and summer, the stability of the ground source heat pump system is higher (the deeper the soil, the lower the gas content in the middle, the less affected by the ground temperature), and the theoretical renewable energy can be achieved.
- The ground source heat pump unit utilizes the soil or water temperature of 12-22 ℃ in winter, which is higher than the ambient air temperature, which increases the evaporation temperature of the heat pump cycle and also improves the energy efficiency ratio; the soil or water temperature in summer is 18-32 ℃, which is higher than the ambient air temperature. The temperature is low, reducing the condensation temperature of the refrigeration system, so that the cooling effect is better than the air-cooled and cooling tower. Heat or cooling over 5KW
- Compared with boiler (electricity, fuel) heating system, boiler heating can only use more than 90% of electric energy or 70-90% of fuel internal energy as heat for users to use. Therefore, ground source heat pumps are more economical than electric boiler heating. Oil-fired boilers use about one-half of the energy to save more than two-thirds of electricity; because the heat source temperature of the ground source heat pump is relatively stable throughout the year, generally at 10~25℃, its cooling and heating coefficient can reach 3.5~4.4, which is higher than that of traditional air. The source heat pump is about 40% higher, and its operating cost is 50 to 60% of the ordinary central air conditioner. Therefore, in the past ten years, ground source heat pump air conditioning systems have achieved rapid development in North America such as the United States and Canada, and central and northern Europe such as Switzerland and Sweden, and the ground source heat pump market in China has become increasingly active. Technology will be the most efficient heating and cooling air conditioning technology in the 21st century
Significant environmental and economic benefits
- Ground source heat pump units do not consume or pollute water during operation, do not need boilers, do not need cooling towers, and do not need sites for stacking fuel waste, and the environmental protection benefits are significant. Compared with air source heat pump, the power consumption of ground source heat pump unit can be reduced by more than 40%; compared with electric heating, it can be reduced by more than 70%. 75% increase in boiler efficiency
One machine is multi-purpose, widely used
- Ground source heat pump systems can provide heating, air conditioning and cooling, as well as domestic hot water. One machine can be used for many purposes. One system can replace the original two or two sets of boilers and air conditioners, especially suitable for equipment that requires heating and cooling at the same time. put up. Ground source heat pumps have obvious advantages. Not only saves a lot of energy, but also a set of equipment can meet the requirements of heating, cooling and domestic water supply at the same time, reducing the initial investment of equipment. Ground source heat pumps can be used in hotels, residential quarters, apartments, factories, shopping malls, office buildings, schools and other buildings, and small ground source heat pumps are more suitable for heating and air conditioning in villas.
Low maintenance and unattended
- Compared to traditional systems, ground source heat pump systems have fewer moving parts, reducing maintenance efforts. The system is either buried in the ground or installed indoors, protected from wind and rain. The unit is compact, space-saving and also protected from damage. It is more reliable and lasts longer. .High degree of automation control, unattended, remote management, no need to hire someone to take care of it.
- Compared with the air source heat pump, the pollutant emission of the ground source heat pump is reduced by more than 38%, which is equivalent to a reduction of more than 70% compared with the electric heating. Realize energy saving and emission reduction.
Maintain ecological balance
- The ground source heat pump discharges indoor heat into the ground in summer, and extracts the underground heat for indoor use in winter. Relatively speaking, it emits less energy to the environment and maintains the balance of the ecological environment.
- The underground buried pipes of the ground source heat pump are made of polyethylene and polypropylene plastic pipes, and the service life can reach 50 years, which is 35 years longer than ordinary air conditioners.
- Ground source heat pump systems have fewer moving parts than conventional systems, so maintenance is reduced, the system is installed indoors, protected from wind and rain, and is also protected from damage, more reliable, and has a longer lifespan
- There are no cooling towers, boiler rooms and other equipment, which saves the precious area occupied by the boiler room, which is a cooling tower, generates additional economic benefits, and improves the external image of the environment.
- The energy of the ground source heat pump system comes from natural energy. It does not discharge any waste gas, waste water and waste residue to the outside world, which is an ideal "green air conditioner". Considered the most environmentally friendly and efficient heating and cooling system. The system can be used in cold and tropical regions. Can be widely used in office buildings, hotels, schools, dormitories, hospitals, restaurants, shopping malls, villas, residential and other fields.
Application places of different systems of ground source heat pump
- The application mode of ground source heat pump can be divided into two categories: household and commercial from the application of building objects, and can be divided into centralized system, decentralized system and hybrid system from the mode of cold and heat transportation
- Users use their own heat pump, ground source and waterway or air duct delivery system for cold and heat supply, mostly used for residential air conditioners such as small houses and villas.
- The heat pump is arranged in the machine room, and the cold and heat are concentrated to each room through the air duct or the water distribution system.
- The central water pump delivers water as a cold and heat source to each user through the water cycle, and the user individually uses his own heat pump unit to adjust the air. Generally used in office buildings, schools, commercial buildings, etc., this system can fully reflect the cold and heat of the user's electricity consumption, which is convenient for measurement and suitable for independent heat measurement needs.
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