CN-122015172-A - Underground heat exchanger with medium-shallow combined variable flow and control method

CN122015172ACN 122015172 ACN122015172 ACN 122015172ACN-122015172-A

Abstract

The invention discloses a buried pipe type underground heat exchanger with a medium-shallow combined variable flow and a control method, and relates to the technical field of ground source heat pumps. The heat exchanger comprises a ground switching unit, a heat collecting unit and a heat exchange unit buried underground, wherein the heat exchange unit comprises a U-shaped buried pipe assembly, two ends of the U-shaped buried pipe assembly are connected to the ground switching unit, a communication pipe used for communicating two ends of the U-shaped buried pipe assembly at a preset depth position, the heat exchange unit further comprises a first one-way valve and a second one-way valve which are respectively arranged on the communication pipe and the U-shaped buried pipe assembly, the first one-way valve and the second one-way valve are reversely arranged to be matched with a four-way reversing valve of the ground switching unit to switch a fluid conduction path, an input end and an output end of the heat collecting unit are respectively connected to two ends of the U-shaped buried pipe assembly, and when the heat collecting unit operates, the first one-way valve is closed, and the second one-way valve is conducted. The heat-collecting unit can adapt to stratum temperature requirements of different working conditions, and the overall energy efficiency ratio of the heat exchanger is improved through the heat-collecting unit and the real-time monitoring of the ground temperature.

Inventors

LU KE
PENG FAN
YIN KUI
WEN JIANGTAO
LIU LI
LIU WEIWEI
SUN JINGYU
KE WENMING
WANG XINGPO
WANG WENTAN

Assignees

中建三局集团有限公司

Dates

Publication Date: 20260512
Application Date: 20260228

Claims (10)

1. The underground heat exchanger is characterized by comprising a heat collection unit, a ground switching unit and a heat exchange unit buried underground; The heat exchange unit comprises a U-shaped buried pipe assembly with two ends connected to the ground switching unit and a communication pipe for communicating the preset depth positions of the two ends of the U-shaped buried pipe assembly; The heat exchange unit also comprises a first one-way valve arranged on the communication pipe and a second one-way valve arranged at the bottom of the lower end of the U-shaped buried pipe assembly, wherein the first one-way valve and the second one-way valve are reversely arranged to be matched with a four-way reversing valve of the ground switching unit to switch a fluid conduction path; the input end and the output end of the heat collection unit are respectively connected to two ends of the U-shaped buried pipe assembly, and the first one-way valve is closed and the second one-way valve is conducted when the heat collection unit operates.
2. The underground heat exchanger with the medium-shallow combined variable flow according to claim 1, wherein the heat collecting unit comprises a heat collector and a heat storage water tank, wherein the input end of the heat collector is connected with the first output end of the heat storage water tank, the output end of the heat collector is connected with the first input end of the heat storage water tank, and the second input end and the second output end of the heat storage water tank are respectively connected with two ends of the U-shaped underground pipe assembly; The heat collector comprises a heat storage water tank, a heat collector, a U-shaped buried pipe assembly, a heat storage water tank and a heat storage water tank.
3. The underground heat exchanger with the medium-shallow combined variable flow according to claim 1, wherein the U-shaped underground pipe assembly comprises a rising pipe and a falling pipe, and a second one-way valve is connected between the rising pipe and the falling pipe; and two ends of the communication pipe are respectively connected to preset depth positions of the down pipe and the up pipe.
4. The underground heat exchanger of claim 1, wherein the depth of burial of the heat exchange unit is determined based on a combination of formation thermophysical parameters, thermal load requirements, and cost of burial.
5. A variable flow medium and shallow buried pipe type downhole heat exchanger according to claim 4, wherein the buried depth of the U-shaped buried pipe assembly is set to 500 m according to the thermal property parameters of the stratum, the thermal load requirement and the buried cost.
6. The underground heat exchanger of the middle-shallow combined variable flow according to claim 5, wherein the preset depth of burying the communicating pipe is set to 120 m according to the thermal property parameter of the stratum, the thermal load requirement and the depth of burying the U-shaped underground pipe assembly.
7. A buried pipe type downhole heat exchanger with a medium-shallow combined variable flow according to claim 3, wherein when taking cold in summer, fluid enters the communication pipe from the four-way reversing valve through the down pipe, and flows through the up pipe and the four-way reversing valve in sequence through the first one-way valve to refrigerate the building.
8. The underground heat exchanger with the middle and shallow combined variable flow according to claim 3, wherein the underground heat exchanger comprises a first winter heating mode and a second winter heating mode when heating in winter, wherein when heating in winter, the underground heat exchanger is switched to the second winter heating mode after the shallow ground temperature of the ground surface is recovered to a preset ground temperature threshold value from a preset depth through the first winter heating mode; when the first winter heating mode is adopted, fluid enters the communication pipe from the four-way reversing valve through the descending pipe, and flows through the ascending pipe and the four-way reversing valve in sequence through the first one-way valve to heat the building; When the second winter heating mode is adopted, fluid enters the ascending pipe from the four-way reversing valve, passes through the second one-way valve and then sequentially flows through the descending pipe and the four-way reversing valve to heat the building.
9. A shallow and medium combined variable flow underground heat exchanger according to claim 3 wherein when heat is collected in the transition season, fluid enters the riser from the input end of the heat collection unit and flows out of the downcomer to the input end of the heat collection unit after passing through the second one-way valve.
10. A method of controlling a buried tubular downhole heat exchanger according to any one of claims 1 to 9, comprising: deciding a working mode of the heat exchanger based on the acquired seasonal parameter information; controlling a fluid conduction path of the heat exchange unit through the ground switching unit based on the working mode of the heat exchanger; Based on the obtained ground temperature data, adjusting control parameters of a water pump in a ground switching unit or a heat collecting unit until the ground temperature is within a preset error range; based on the water pump control parameters when the ground temperature is within a preset error range, heat exchange is carried out through a heat exchange unit; The heat exchanger working modes comprise a summer cooling mode, a winter heating mode and a transitional season heat collecting mode, wherein the winter heating mode comprises a first winter heating mode and a second winter heating mode.

Description

Underground heat exchanger with medium-shallow combined variable flow and control method Technical Field The invention belongs to the technical field of ground source heat pumps, and particularly relates to a buried pipe type underground heat exchanger with a medium-shallow combined variable flow and a control method. Background Clean energy heating is used as the core direction of energy conservation and carbon reduction in the building field, so that the clean low-carbon heating such as heat pumps, fuel gas, biomass energy, geothermal energy and the like is the development target of the current building industry according to local conditions. From the market scale, the heating season in the northern severe cold and cold areas is 120-180 days, the building heat load is concentrated, the clean heating requirement is urgent, and the market space is wide. The gas heating has high running cost and heavy user load, and the rural area in cold areas has serious pollution or high heating cost. The prior art is faced with high initial investment of middle-deep geothermal heat, long recovery period, and takes a middle-deep geothermal well of 2000-3000 m as an example, the investment recovery period is as long as 13-25 years, and only the heating function can be realized, and the cooling cannot be performed in summer. The shallow geothermal heat pump is limited by land, and has insufficient heating capacity, namely, taking a 0-200 m shallow buried pipe as an example, a large amount of land is occupied, urban land is covered, project land red line limitation leads to low coverage rate of shallow geothermal heating, and the shallow geothermal heat pump has limited heat extraction quantity, so that the heat supply requirement of urban high-density buildings is difficult to meet. The efficiency of the air source heat pump in the low-temperature working condition is seriously attenuated, namely, in the extremely low-temperature environment below-15 ℃ in winter in the north, the heating efficiency of the air source heat pump is reduced by more than 50 percent compared with the heating efficiency of the air source heat pump in the normal-temperature working condition, and the heating requirement cannot be met stably. Disclosure of Invention The invention aims to provide a buried pipe type underground heat exchanger with a medium-shallow combined variable flow and a control method thereof, wherein the heat exchange unit structure is utilized to switch the heat taking position of a U-shaped buried pipe assembly by utilizing a four-way reversing valve, so that the requirements of adapting to stratum temperature under different working conditions in winter and summer are met, and the overall energy efficiency ratio of the heat exchanger is improved. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme. The invention provides a buried pipe type underground heat exchanger with a medium-shallow combined variable flow, which comprises a heat collecting unit, a ground switching unit and a heat exchanging unit buried underground; The heat exchange unit comprises a U-shaped buried pipe assembly with two ends connected to the ground switching unit and a communication pipe for communicating the preset depth positions of the two ends of the U-shaped buried pipe assembly; The heat exchange unit also comprises a first one-way valve arranged on the communication pipe and a second one-way valve arranged at the bottom of the lower end of the U-shaped buried pipe assembly, wherein the first one-way valve and the second one-way valve are reversely arranged to be matched with a four-way reversing valve of the ground switching unit to switch a fluid conduction path; the input end and the output end of the heat collection unit are respectively connected to two ends of the U-shaped buried pipe assembly, and the first one-way valve is closed and the second one-way valve is conducted when the heat collection unit operates. The heat collection unit comprises a heat collector and a heat storage water tank, wherein the input end of the heat collector is connected with the first output end of the heat storage water tank, the output end of the heat collector is connected with the first input end of the heat storage water tank, and the second input end and the second output end of the heat storage water tank are respectively connected with the two ends of the U-shaped buried pipe assembly; The heat collector comprises a heat storage water tank, a heat collector, a U-shaped buried pipe assembly, a heat storage water tank and a heat storage water tank. The heat collection unit realizes the resource storage in transition season, ensures the heat supply quantity in winter and improves the overall energy efficiency ratio of the heat exchanger. The heat collection unit is matched with the first one-way valve and the second one-way valve, so that heat is only supplied to the middle stratum in transition seaso