Water source heat pump system design and security of the key issues

Ground source and water source heat pump system is mainly composed of underground heat exchange device, heat pump unit and end system. The heat pump unit and the terminal system are quite mature. The underground heat exchange device absorbs energy from the underground through the heat exchange. Due to the ever-changing and complex underground conditions, it is the largest inhomogeneous body in the world. Therefore, the underground heat exchange device How to adapt to local conditions, long-term and stable access to underground heat pump energy required, while not affecting the environment as much as possible, is the installation of water, ground source heat pump system, the key technology.

Site survey:
The site survey mainly includes site investigation, surface water survey and hydrogeological survey. Among them, hydrogeological survey is highly specialized and is the focal point of investigation. It must be completed by a hydrogeological expert. The hydrogeological survey is a survey of the occurrence conditions, movement rules and water chemistry of groundwater in an area. Calculating the amount of resources by collecting relevant parameters, and then putting forward the plan of groundwater supply, which provides the basis for the next system design.


Results of Hydrogeological Survey: Hydrogeological Profile Reveals the Results of Hydrogeological Survey of Aquifer Structures: Hydrogeological maps reveal regional
Rich water, water level, flow direction and other hydrogeological conditions
system design:
System design is mainly the design of underground heat exchangers. The water source heat pump system is divided into surface water system and groundwater system. Which system should be adopted after the feasibility analysis of the water supply plan proposed by the site investigation is determined.
The surface water system collecting device includes two parts: water intake structure and heat exchanger. The water intake structure generally includes a water inlet pipe, a water conduit (or a horizontal water collecting pipe) and a water collecting well, which are greatly influenced by the amount of water, the flow velocity and the water level of the water source. Attention should be paid to the relationship between elevation and changes in the water level during the season. Heat exchanger design is the focus of heat exchanger selection. The length of the heat exchanger depends on the maximum cooling capacity of the water loop in the cooling condition or the maximum heat absorption of the water loop under the heating condition. In the design of the structure and process of the heat exchange coil, the coil should be connected in groups To the loop header, at the same time, arrange the loop header according to the water body and make the loop header the shortest.

Groundwater system underground heat transfer devices are mainly water supply wells and recharge wells. The designer arranges well location, well depth and well structure according to local hydrogeological conditions and construction load requirements.
In general, both the water supply well and the recharge well should be arranged in areas with good water-richness, at least the water requirements of water source heat pump units should be met. The well depth is determined according to the formation conditions and the demand of water discharge. Take more aquifers; well structure generally includes wellhead, casing, filters, sinking pipe and several other parts, of which the filter is the key to the design. In order to increase the amount of water outflow and to prevent grit blasting, a gravel filter is usually used in loose formations, and the bedrock formation does not leave the filter if the rock is stable. Fill gravel filter is composed of filter tubes and gravel, sometimes wrapped around the filter tube galvanized lead wire or copper wire, nylon mesh.
Filtration tube is divided into round and strip type, usually made of steel or cast iron, the porosity of 30% to 50%. Gravel to round, oval is good, prohibited the use of angular crumbs, rock composition should adopt quartzite, limestone, pebbles, can not use the soft rock components such as marl. Gravel size and landfill thickness should be based on the type of aquifer to determine, in the powder, fine, medium, coarse sand gravel, 6-8 times the size of gravel, and try to increase the gravel thickness; gravel Pebble aquifer, particle size 6-10 times the gravel, gravel thickness can be properly reduced.

System installation:

System installation should be strictly in accordance with the design requirements, of which the installation of surface water systems are basically on the ground operation, easy construction, and groundwater system of water supply well and recharge wells hidden concealed strong, we must find a qualified construction team to complete The specific construction steps include drilling, logging, down pipe, gravel, well closure, well washing, pumping test and water quality analysis. Among them, down pipe, gravel, seal well and wash are the key links. Under the pipe according to cuttings cataloging and logging interpretation of the stratigraphy do not under the aquifer strainer, under the aqueduct casing; gravel selected gravel and aquifer particle size to match, and uniform clean Fill the outer side of the drainage pipe; seal wells are filled evenly in the gravel layer of clay to avoid contamination of the aquifer; flushing wells are commonly used carbon dioxide and pressure blower combined washing well, pump pumping well and other methods, according to the actual drilling Of the strata to choose.

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