【 Weak current College 】 geological conditions on the economic impact of ground source heat pumps---Power By 【 China power house network 】

1. economical characteristics of the ground source heat pump system

1. economical ground source heat pump system is suitable for small, scattered, insulation of low-rise and low investment, low running costs of the heating system.

2. the appropriate ground heat exchanger:

(1) decentralized buried pipe

(2) set for backwater, decentralized setting unit

2. impact on underground pipe heat pump system of geological, hydrogeological elements

1. underground tube heat exchanger system principles and mechanisms of heat transfer mechanism of heat transfer:

(1) soil body, wall of Thermophysical properties

Heat transfer in solids (thermal conductivity) and groundwater heat convection (aquifer thickness, groundwater flow).

(2) heat temperature difference

The average temperature in formation and fluid temperature (by unit operating decisions) the temperature difference between.

(3) heat exchanger for heat transfer area

Tube, pipe Groove dimensions, diameter, length, heat exchanger packing.

2. the economic effects of heat, geological and hydrological factors

(1) soil layer thickness, decided to use the space that is boring depth

(2) groundwater aquifers thickness, water levels, flow speed

(3) decision to reverse soil temperature temperature difference of size to take advantage of

(4) unfavourable geological body, low thermal conductivity (drainage layer) and drillability (gravel) formation

Third, Beijing plain geological, hydrogeological characteristics
Topography, drainage
Quaternary system
Strata
Groundwater system
Quaternary system in the pore water supplies, runoff and excretion
Recent groundwater
Shallow geothermal
1 topography

Beijing area apart from missing the late Ordovician-Carboniferous out of dew.

Beijing underground pipe heat pump systems mainly in the implementation of the Quaternary period.
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Quaternary (Q): lithology is mainly clay, sand, gravel, plain area, widely distributed, thickness variation, exposing the maximum thickness of up to 1000m above.

Hydrogeological profile example

4, groundwater systems Division

Juma River alluvial fan of the pore water system (Ⅰ district)

Yongding River alluvial fan system (Ⅱ)

Chaobai-Jiyun alluvial fan of the pore water system (Ⅲ)

Nankou alluvial fan and mountain rivers flood alluvial subsystem (North canal water) (Ⅲ 1 district)

Chaobai River alluvial fan system (Ⅲ zone 2)

Jiyun alluvial fan system (Ⅲ 3 district)

5. fourth line of the pore water recharge, runoff and excretion

Beijing usually shallow geothermal plain 13 ~ 15 degree, partial exception with geothermal 15 ~ 18 degrees.

Fourth, the buried pipe heat pump systems for suitability
Basic constraints
Vertical-type underground tube heat exchanger system partition index
Preliminary results

Initial investment is buried pipe heat pump system economics major constraints. Consists of the following conditions reflect the suitability of differences.

(1) soil layer thickness

(2) aquifer cumulative thickness

(3) gravel and drainage layer thickness

Quaternary alluvium thickness 30 ~ 60 m;

Pebble thickness > 10 m;

Aquifer cumulative thickness < 10 m;


5. conclusions and recommendations

1. conclusions

(1) underground tube heat exchanger system is small, scattered buildings with more economical heat.

(2) buried pipe heat pump system in Beijing, but in most areas available in Shijingshan Piedmont, Piedmont region, Haidian, Fengtai District subtotal, Fangshan district of South-East and West, Daxing District, because of the alluvial fan of the top, due to sediment is bulky, the vertical tube into a hole is difficult, the high initial investment, you can use horizontal tube.

(3) rational design oftube, burial depth and hole spacing is affected economical operation of the system.

2. recommends that the

(1) in view of the different geological conditions, should be carried out exploration work in the region, through drilling and field heat test for thermal physical properties of rock and soil, providing heat exchanger system to provide a basis of reasonable design.

(2) due to the vertical tube heat exchanger system covers small, high heat transfer efficiency, practical projects should use.

(3) local conditions, and other renewable sources of energy, comprehensive utilization.