The significance of energy conservation and environmental protection is constantly reinforced in our minds whenever we face the consequences of environmental damage. As a result, the adoption of energy-efficient and eco-friendly equipment has become a growing trend among many people. Among these technologies, ground-source heat pumps have gained widespread recognition due to their energy efficiency and stability, making them a popular choice across various industries.
Ground-source heat pump systems utilize the natural thermal properties of the earth by tapping into shallow low-temperature geothermal energy. The system works by using the ground as a heat exchanger, where heat is absorbed from the soil and then elevated through the heat pump before being distributed for use. This process not only reduces energy consumption but also minimizes environmental impact.
**Thermal Characteristics**
The thermal behavior of soil plays a crucial role in the performance of ground-source heat pump systems. Key factors include thermal conductivity, volumetric heat capacity, and thermal diffusivity. Thermal conductivity measures how effectively heat moves through the soil, typically expressed in Kcal/m·h·°C. Volumetric heat capacity reflects the soil’s ability to store heat, while thermal diffusivity indicates how quickly temperature changes propagate through the ground.
These properties vary depending on the soil's composition, structure, density, and moisture content, and can differ between regions and seasons. In general, the heat stored in the soil accounts for about 80% of the heat it absorbs, highlighting its importance in geothermal applications.
**Earth Temperature**
Understanding the subsurface temperature is essential because the temperature difference between the ground and the circulating fluid drives heat exchange. The underground temperature remains relatively stable and close to the annual average surface temperature. At a depth of 10 meters, the temperature is almost unaffected by seasonal changes.
As depth increases, temperature fluctuations decrease significantly. For example, at 0.3 meters, the temperature fluctuation is around ±15°C, while at 3 meters, it narrows to ±5°C, and at 6 meters, it further reduces to ±1.5°C. Below 60 meters, the temperature is considered constant, making deeper installations more efficient for heat pump operation. In this project, the drilling depth is set at 100 meters to ensure optimal performance.
**Moisture Content**
Soil moisture is a critical factor affecting heat transfer. When water replaces air between soil particles, it reduces contact resistance and enhances heat transfer. However, once the moisture content exceeds a certain threshold—known as the critical moisture content—the thermal conductivity stabilizes. Below this level, thermal conductivity decreases, which can negatively affect heat exchange.
During summer cooling, heat is transferred from the heat exchanger to the surrounding soil, causing moisture to be expelled. If the soil is at or near the critical moisture level, reduced water content can lead to a decline in heat transfer efficiency, creating a cycle that further dries the soil. This can result in greater heat absorption losses than heat release, especially in dry, high-temperature areas. Therefore, careful consideration must be given to thermal stability when installing geothermal systems in such regions.
In practice, soil moisture can be increased artificially by adding water. In northern China, where groundwater levels are high and cooling demand is low, soil moisture often remains above the critical point, ensuring consistent performance over time.
**Groundwater Flow**
The movement of groundwater significantly influences heat transfer in the subsurface. The Earth’s geological structure includes layers of clay, sand, sedimentary rock, and water. Tectonic activity creates fractures and voids, allowing rainwater to seep into deeper layers and form groundwater flow. This movement not only conducts heat but also enhances convective heat transfer.
If the groundwater flow rate exceeds 8 mm/h, the heat transfer can be calculated based on the movement of water itself. Understanding these dynamics is crucial for optimizing the design and performance of ground-source heat pump systems.
With increasing awareness of sustainability, more energy-saving products are entering the market, and more users are adopting them to protect the planet and secure a better future for generations to come.
*Concerned about surprises*
**Label:** Analysis of characteristics of ground source heat pump buried pipe
**Previous:** Application of linear motor on high speed machine tool
**Next:** Four ways of joint operation of wooden door hardware
High Speed Doors,High Speed Roll Up Doors,Rapid Roller Doors,Rapid Roll Up Door
SHANGHAI KENVO DOOR CO.,LTD , https://www.kenvodoor.com