A geothermal well underground direct evaporation heat pump system and heat exchange method

Abstract

The present invention discloses a direct evaporative heat pump system for a geothermal well, belonging to the field of heating and ventilation technology. The system comprises a downhole heat exchange device, a compressor, an above-ground heat exchange device, a throttling device, a circulating water pump, and a circulating water pipe. The downhole heat exchange device is installed in the geothermal well water and is used to directly exchange heat with the geothermal well water. The downhole heat exchange device comprises a liquid supply pipe, an air intake pipe, an upper cavity, and a lower cavity. The heat exchange capillary tube is used for initial heat exchange between the refrigerant therein and the geothermal well water outside. The lower cavity is used for secondary heat exchange between the refrigerant therein and the geothermal well water outside. The circulating water pump is installed on the circulating water pipe, which is located around the downhole heat exchange device. The circulating water pump and the circulating water pipe are used to circulate the geothermal well water within. The direct evaporative heat pump system for a geothermal well of the present invention is simple to manufacture and install, and has significant cost advantages.

Description

Technical Field

[0001] The present invention relates to the field of HVAC technology, and in particular to a geothermal well underground direct evaporation heat pump system and a heat exchange method. Background Art

[0002] At present, there are two main types of heat exchange methods for geothermal wells: "extracting heat without consuming water" and "extracting heat without taking water". The "extracting heat without consuming water" type of geothermal well heat exchange system has the problem of re-injection. The "extracting heat without taking water" type includes coaxial shell and tube heat exchange system and gravity heat exchange system. The conventional gravity heat exchange system and coaxial shell and tube heat exchange system currently available on the market require the heat exchange pipe to be installed at the bottom of the geothermal well. The heat exchange pipe is long, the pipe air tightness requirement is high, the investment is high, and the transportation energy consumption is large.

[0003] Therefore, there is a need for a geothermal heat exchange system that can eliminate the problem of reinjection, reduce system energy consumption, reduce heat exchange losses, reduce system construction difficulty, and reduce investment. Summary of the Invention

[0004] The purpose of the present invention is to provide an efficient underground direct evaporation heat pump system and heat exchange method for geothermal wells, which can eliminate the problem of reinjection, reduce system energy consumption, reduce heat exchange losses, reduce system construction difficulty, and reduce investment.

[0005] In order to solve the above technical problems, the present invention provides a geothermal well underground direct evaporation heat pump system, comprising an underground heat exchange device, a compressor, an above-ground heat exchange device, a throttling device, a circulating water pump and a circulating water pipe;

[0006] The downhole heat exchange device, the compressor, the ground heat exchange device and the throttling device are connected in a circular manner in sequence;

[0007] The downhole heat exchange device is installed in the geothermal well water, and the downhole heat exchange device is used to directly exchange heat with the geothermal well water;

[0008] The downhole heat exchange device includes a liquid supply pipe, an air suction pipe, an upper cavity and a lower cavity;

[0009] The head end of the liquid supply pipe is connected to the outlet of the throttling device, and the tail end of the liquid supply pipe is connected to the upper hollow cavity;

[0010] The upper cavity is located directly above the lower cavity and is connected to the lower cavity via a plurality of heat exchange tubes. The heat exchange tubes are used for preliminary heat exchange between the refrigerant therein and the geothermal well water outside. The lower cavity is used for secondary heat exchange between the refrigerant therein and the geothermal well water outside.

[0011] The head end of the suction pipe is connected to the lower cavity, and the tail end of the suction pipe passes through the upper cavity and is connected to the inlet of the compressor;

[0012] The circulating water pump is installed on a circulating water pipe, and the circulating water pipe is located around the downhole heat exchange device. The circulating water pump and the circulating water pipe are used for internal circulation of geothermal well water.

[0013] Preferably, the liquid supply pipe is arranged vertically;

[0014] The tail end of the liquid supply pipe is communicated with the top center of the upper hollow cavity.

[0015] Preferably, the diameter of the air intake pipe is smaller than the diameter of the liquid supply pipe;

[0016] The air suction pipe passes through the middle of the liquid supply pipe.

[0017] Preferably, the heat exchange tubes are evenly arranged around the intake pipe.

[0018] Preferably, the downhole heat exchange device further comprises a middle partition;

[0019] The air intake pipe and the heat exchange tube are both fixed through the middle partition.

[0020] Preferably, the upper cavity and the lower cavity are hemispherical and arranged oppositely.

[0021] Preferably, the upper hollow cavity is composed of an upper spherical shell and an upper partition;

[0022] The lower hollow cavity is composed of a lower partition plate and a lower spherical shell.

[0023] Preferably, the two ends of the circulating water pipe are respectively an inlet pipe and an outlet pipe;

[0024] The outlet pipe of the circulating water pipe is higher than the upper cavity;

[0025] The water inlet pipe of the circulating water pipe is at a level lower than the lower cavity.

[0026] The present invention also provides a heat exchange method for a geothermal well downhole direct evaporation heat pump system, comprising the following steps:

[0027] The low-pressure and low-temperature refrigerant liquid in the throttling device enters the upper cavity through the liquid supply pipe;

[0028] The low-pressure, low-temperature refrigerant liquid in the upper cavity flows through the heat exchange tube to perform a preliminary heat exchange with the geothermal well water. Part of the low-pressure, low-temperature refrigerant liquid turns into gaseous state, and then enters the lower cavity to exchange heat with the geothermal well water again. The remaining part of the low-pressure, low-temperature refrigerant liquid turns into gaseous state to obtain refrigerant gas, which can prevent the appearance of liquid in the lower cavity and cause liquid hammer in the compressor.

[0029] The refrigerant gas in the lower cavity enters the compressor through the suction pipe;

[0030] The compressor pressurizes and heats the refrigerant gas to obtain high-pressure and high-temperature refrigerant gas, which then enters the ground heat exchange device;

[0031] The high-pressure and high-temperature refrigerant gas in the ground heat exchange device releases heat to the user end, obtaining high-pressure and high-temperature refrigerant liquid and entering the throttling device;

[0032] The throttling device throttles, reduces pressure and cools the high-pressure, high-temperature refrigerant liquid to obtain a low-pressure, low-temperature refrigerant liquid that enters the liquid supply pipe;

[0033] The circulating water pump circulates the geothermal well water internally through the circulating water pipe. The system resistance is small, energy consumption is saved, and there is no need to set up a separate reinjection well, eliminating the problem of geothermal well water reinjection.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention's direct-evaporation geothermal well heat pump system utilizes a downhole heat exchanger installed tens of meters below the geothermal well's dynamic water level. The downhole heat exchanger directly exchanges heat with the well water, eliminating the need for an intermediate heat exchanger. This reduces heat exchange losses and increases the system's energy efficiency. The internal circulation resistance of the well water is low, allowing a low-power submersible pump to transport water from the bottom of the well to the top of the downhole heat exchanger, creating an internal circulation system. This reduces energy consumption for geothermal water transportation.

[0036] In addition, compared with the currently common gravity heat exchange system, the geothermal well underground direct evaporation heat pump system of the present invention is simple to manufacture, easy to install, and has obvious cost advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0038] Figure 1 This is a diagram of a direct evaporation heat pump system for a geothermal well according to the present invention;

[0039] Figure 2 A top view of the downhole heat exchange device of the present invention;

[0040] Figure 3 AA sectional view of the downhole heat exchange device of the present invention;

[0041] Figure 4 It is a BB cross-sectional view of the downhole heat exchange device of the present invention;

[0042] Figure 5 It is a CC cross-sectional view of the downhole heat exchange device in the present invention.

[0043] In the picture:

[0044] 1-downhole heat exchange device; 2-compressor; 3-ground heat exchange device; 4-throttling device; 5-water pump; 6-circulating water pipe; 61-water inlet pipe; 62-water outlet pipe; 11-liquid supply pipe; 12-air suction pipe; 13-upper spherical shell; 14-upper partition; 15-heat exchange tube; 16-middle partition; 17-lower partition; 18-lower spherical shell; 101-upper cavity; 102-lower cavity. DETAILED DESCRIPTION

[0045] The following description sets forth numerous specific details to facilitate a thorough understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific implementations disclosed below.

[0046] The terms used in one or more embodiments of this specification are for the purpose of describing specific embodiments only and are not intended to limit one or more embodiments of this specification. The singular forms "a," "the," and "the" used in one or more embodiments of this specification and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used in one or more embodiments of this specification refers to and includes any or all possible combinations of one or more associated listed items.

[0047] It should be understood that although the terms first, second, etc. may be used to describe various information in one or more embodiments of this specification, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of one or more embodiments of this specification, the first may also be referred to as the second, and similarly, the second may also be referred to as the first. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0048] The present invention is described in further detail below with reference to the accompanying drawings:

[0049] The present invention provides a geothermal well underground direct evaporation heat pump system, comprising an underground heat exchange device 1, a compressor 2, an above-ground heat exchange device 3, a throttling device 4, a circulating water pump 5 and a circulating water pipe 6;

[0050] The downhole heat exchange device 1, the compressor 2, the ground heat exchange device 3 and the throttling device 4 are connected in a circular manner in sequence;

[0051] The downhole heat exchange device 1 is installed in the geothermal well water, and the downhole heat exchange device 1 is used to directly exchange heat with the geothermal well water;

[0052] The downhole heat exchange device 1 includes a liquid supply pipe 11, an air intake pipe 12, an upper cavity 101 and a lower cavity 102;

[0053] The head end of the liquid supply pipe 11 is connected to the outlet of the throttling device 4, and the tail end of the liquid supply pipe 11 is connected to the upper hollow cavity 101;

[0054] The upper cavity 101 is located directly above the lower cavity 102. The upper cavity 101 is connected to the lower cavity 102 via a plurality of heat exchange tubes 15. The heat exchange tubes 15 are used for preliminary heat exchange between the refrigerant therein and the geothermal well water outside. The lower cavity 102 is used for secondary heat exchange between the refrigerant therein and the geothermal well water outside.

[0055] The head end of the suction pipe 12 is connected to the lower cavity 102, and the tail end of the suction pipe 12 passes through the upper cavity 101 and is connected to the inlet of the compressor 2;

[0056] The circulating water pump 5 is installed on the circulating water pipe 6, and the circulating water pipe 6 is located around the downhole heat exchange device 1. The circulating water pump 5 and the circulating water pipe 6 are used for internal circulation of geothermal well water.

[0057] Preferably, the liquid supply pipe 11 is arranged vertically;

[0058] The tail end of the liquid supply pipe 11 is connected to the top center of the upper hollow cavity 101 .

[0059] Preferably, the diameter of the air intake pipe 12 is smaller than the diameter of the liquid supply pipe 11;

[0060] The air intake pipe 12 passes through the middle of the liquid supply pipe 11 .

[0061] Preferably, the heat exchange tubes 15 are evenly arranged around the intake pipe 12 .

[0062] Preferably, the downhole heat exchange device 1 further includes a middle partition 16;

[0063] The air intake pipe 12 and the heat exchange tube 15 are both fixed through the middle partition plate 16.

[0064] Preferably, the upper hollow cavity 101 and the lower hollow cavity 102 are hemispherical and arranged opposite to each other.

[0065] Preferably, the upper hollow cavity 101 is composed of an upper spherical shell 13 and an upper partition 14;

[0066] The lower hollow cavity 102 is composed of a lower partition 17 and a lower spherical shell 18 .

[0067] Preferably, the two ends of the circulating water pipe 6 are respectively an inlet pipe 61 and an outlet pipe 62;

[0068] The outlet pipe 62 of the circulating water pipe 6 is at a level higher than the upper cavity 101;

[0069] The water inlet pipe 61 of the circulating water pipe 6 is at a level lower than the lower hollow cavity 102 .

[0070] The present invention also provides a heat exchange method for a geothermal well downhole direct evaporation heat pump system, comprising the following steps:

[0071] The low-pressure and low-temperature refrigerant liquid in the throttling device 4 enters the upper cavity 101 through the liquid supply pipe 11;

[0072] The low-pressure, low-temperature refrigerant liquid in the upper cavity 101 flows through the heat exchange tube 15 to perform a preliminary heat exchange with the geothermal well water. Part of the low-pressure, low-temperature refrigerant liquid turns into a gaseous state, and then enters the lower cavity 102 to exchange heat with the geothermal well water again. The remaining part of the low-pressure, low-temperature refrigerant liquid turns into a gaseous state to obtain refrigerant gas, which can prevent the presence of liquid in the lower cavity and cause liquid hammer in the compressor.

[0073] The refrigerant gas in the lower cavity 102 enters the compressor 2 through the suction pipe 12;

[0074] Compressor 2 pressurizes and heats the refrigerant gas to obtain high-pressure and high-temperature refrigerant gas, which then enters the ground heat exchange device 3;

[0075] The high-pressure and high-temperature refrigerant gas in the ground heat exchange device 3 releases heat to the user end, obtaining high-pressure and high-temperature refrigerant liquid and entering the throttling device 4;

[0076] The throttling device 4 throttles, reduces pressure and cools the high-pressure, high-temperature refrigerant liquid to obtain a low-pressure, low-temperature refrigerant liquid which enters the liquid supply pipe 11;

[0077] The circulating water pump 5 circulates the geothermal well water internally through the circulating water pipe 6, which reduces the system resistance, saves energy, and eliminates the need for a separate reinjection well, eliminating the problem of geothermal well water reinjection.

[0078] In order to better illustrate the technical effects of the present invention, the present invention provides the following specific examples to illustrate the above technical process:

[0079] Example 1: A geothermal well direct evaporation heat pump system, such as Figures 1 to 5 As shown, it includes: a downhole heat exchange device 1, a compressor 2, a ground heat exchange device 3, a throttling device 4, a water pump 5, a circulating water pipe 6, a water inlet pipe 61, and a water outlet pipe 62.

[0080] The downhole heat exchange device 1 includes: a liquid supply pipe 11, an air intake pipe 12, an upper spherical shell 13, an upper partition 14, a heat exchange tube 15, a middle partition 16, a lower partition 17, a lower spherical shell 18, an upper hollow cavity 101 and a lower hollow cavity 102.

[0081] In this embodiment, the downhole heat exchange device 1 is installed tens of meters below the dynamic water level of the geothermal well (optionally below 30 meters). The downhole heat exchange device 1 is used to directly exchange heat with the geothermal well water;

[0082] In this embodiment, the downhole heat exchange device 1, the condenser 2, the ground heat exchange device 3, and the throttling device 4 are connected in sequence.

[0083] In this embodiment, an insulation layer is provided on the outside of the liquid supply pipe 11 above the water surface of the geothermal well to insulate the liquid supply pipe 11.

[0084] In this embodiment, the diameter of the air intake pipe 12 is smaller than the diameter of the liquid supply pipe 11 .

[0085] In this embodiment, the air intake pipe 12 passes through the liquid supply pipe 11 .

[0086] In this embodiment, the medium in the liquid supply pipe 11 is refrigerant liquid.

[0087] In this embodiment, the medium in the suction pipe 12 is refrigerant gas.

[0088] In this embodiment, the middle partition 16 fixes the heat exchange tubes and the air intake tube.

[0089] In this embodiment, the upper spherical shell 13 and the upper partition 14 are combined to form an upper hollow cavity 101 .

[0090] In this embodiment, the lower partition 17 and the lower spherical shell 18 are combined to form a lower hollow cavity 102 .

[0091] In this embodiment, the heat exchange tube 15 connects the upper hollow cavity 101 and the lower hollow cavity 102 to form a communication channel.

[0092] In this embodiment, the circulating water pump 5 is installed on the circulating water pipe 6. One end of the circulating water pipe 6 is a water inlet pipe 61, and the other end of the circulating water pipe 6 is a water outlet pipe 62.

[0093] In this embodiment, the circulating water pipe 6 is made of PE pipe.

[0094] During heating, the refrigerant liquid is heated up and converted into refrigerant gas by utilizing the characteristic that the temperature of the refrigerant liquid is lower than that of the geothermal well water. The heat of the geothermal well water is transferred to the user end through the downhole heat exchange device 1, the compressor 2, and the ground heat exchange device 3 in sequence for heating the user. The refrigerant liquid after releasing heat is sent back to the downhole heat exchange device 1 through the throttling device 4 for the next round of heat exchange. The specific implementation is as follows: low-pressure refrigerant liquid enters the upper cavity 101 through the liquid supply pipe 11 in the downhole heat exchange device 1, the refrigerant in the upper cavity 101 flows through the heat exchange tube 15 to exchange heat with the geothermal well water, and part of it becomes refrigerant gas and enters the lower cavity 102. The refrigerant in the lower cavity 102 further exchanges heat with the geothermal well water through the lower spherical shell 18, and all of it becomes refrigerant gas; the refrigerant gas in the lower cavity 102 is sent to the compressor 2 through the suction pipe 12, and becomes high-pressure and high-temperature refrigerant gas after passing through the compressor 2. It releases heat to the user end through the ground heat exchange device 3 and becomes high-pressure and high-temperature refrigerant liquid. It passes through the throttling device 4 and becomes low-pressure and low-temperature refrigerant liquid and enters the downhole heat exchange device 1 to continue to exchange heat with the geothermal well water.

[0095] In this embodiment, the upper hollow cavity 101 gathers the refrigerant liquid so that the refrigerant liquid flows evenly into the heat exchange tubes 15 .

[0096] In this embodiment, the lower hollow cavity 102 serves as a “transfer station” for the refrigerant gas, gathering the refrigerant gas in the heat exchange tubes 15 and delivering the refrigerant gas to the intake pipe 12 .

[0097] In this embodiment, channels are left between the heat exchange tubes 15 to increase the contact area between the tube walls of the heat exchange tubes 15 and the geothermal well water, so that the refrigerant in the heat exchange tubes 15 and the geothermal well water can fully exchange heat, thereby enhancing the heat exchange effect.

[0098] In this embodiment, the circulating water pump 5 serves as the power source for the circulation of geothermal well water, transporting the well water at the bottom of the geothermal well to the upper part of the downhole heat exchange device to form an internal circulation of the geothermal well water, thereby ensuring that the well water temperature at the location of the downhole heat exchange device of the geothermal well meets the heat exchange requirements of the downhole direct evaporation heat pump system.

[0099] The geothermal well downhole direct evaporation heat pump system in this embodiment is a system in which a downhole heat exchange device is installed tens of meters below the dynamic water level of the geothermal well. The downhole heat exchange device directly exchanges heat with the geothermal well water without the intervention of an intermediate heat exchange device, reducing heat exchange losses and increasing the system's energy efficiency. The internal circulation resistance of the geothermal well water is relatively low, and a low-power submersible pump alone can be used to transport the well water from the bottom of the geothermal well to the top of the downhole heat exchange device, forming an internal circulation of the geothermal well water, thereby reducing the energy consumption of geothermal well water transportation. In addition, compared to the currently common gravity-type heat exchange system, the geothermal well downhole direct evaporation heat pump system of the present invention is simple to manufacture and easy to install, with significant cost advantages.

[0100] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention shall be covered by the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A geothermal well downhole direct evaporation heat pump system, characterized by: It comprises a downhole heat exchange device (1), a compressor (2), a ground heat exchange device (3), a throttling device (4), a circulating water pump (5) and a circulating water pipe (6); The downhole heat exchange device (1), the compressor (2), the ground heat exchange device (3) and the throttling device (4) are connected in a circular manner in sequence; The downhole heat exchange device (1) is installed below 30 meters of the dynamic water level of the geothermal well, and the downhole heat exchange device (1) is used to directly exchange heat with the water in the geothermal well; The downhole heat exchange device (1) comprises a liquid supply pipe (11), an air intake pipe (12), an upper cavity (101) and a lower cavity (102); The head end of the liquid supply pipe (11) is connected to the outlet of the throttling device (4), and the tail end of the liquid supply pipe (11) is connected to the upper hollow cavity (101); The upper cavity (101) is located directly above the lower cavity (102), and the upper cavity (101) is connected to the lower cavity (102) via a plurality of heat exchange tubes (15); the heat exchange tubes (15) are used for performing preliminary heat exchange between the refrigerant therein and the geothermal well water outside; the lower cavity (102) is used for performing secondary heat exchange between the refrigerant therein and the geothermal well water outside; The head end of the air intake pipe (12) is connected to the lower cavity (102), and the tail end of the air intake pipe (12) passes through the upper cavity (101) and is connected to the inlet of the compressor (2); The circulating water pump (5) is installed on a circulating water pipe (6), and the circulating water pipe (6) is located around the downhole heat exchange device (1). The circulating water pump (5) and the circulating water pipe (6) are used for internal circulation of geothermal well water; The two ends of the circulating water pipe (6) are respectively a water inlet pipe (61) and a water outlet pipe (62); The outlet pipe (62) of the circulating water pipe (6) is higher than the upper cavity (101); The water inlet pipe (61) of the circulating water pipe (6) is lower than the lower cavity (102); The medium in the liquid supply pipe (11) is a refrigerant liquid; The medium in the suction pipe (12) is refrigerant gas; the diameter of the suction pipe (12) is smaller than the diameter of the liquid supply pipe (11); the suction pipe (12) passes through the middle of the liquid supply pipe (11); The circulating water pipe (6) is made of PE pipe.

2. The geothermal well underground direct evaporation heat pump system according to claim 1, characterized in that: The liquid supply pipe (11) is arranged vertically; The tail end of the liquid supply pipe (11) is in communication with the top center of the upper hollow cavity (101).

3. The geothermal well underground direct evaporation heat pump system according to claim 1, characterized in that: The heat exchange tubes (15) are evenly arranged around the air intake pipe (12).

4. The underground direct evaporation heat pump system for geothermal wells according to claim 3, characterized in that: The downhole heat exchange device (1) further includes a middle partition (16); The air intake pipe (12) and the heat exchange tube (15) are both fixed through the middle partition (16).

5. The underground direct evaporation heat pump system for geothermal wells according to claim 4, characterized in that: The upper hollow cavity (101) and the lower hollow cavity (102) are hemispherical and arranged oppositely.

6. The underground direct evaporation heat pump system for geothermal wells according to claim 5, characterized in that: The upper hollow cavity (101) is composed of an upper spherical shell (13) and an upper partition (14); The lower hollow cavity (102) is composed of a lower partition (17) and a lower spherical shell (18).

7. A heat exchange method for a geothermal well underground direct evaporation heat pump system, wherein the heat pump system is the geothermal well underground direct evaporation heat pump system according to any one of claims 1 to 6, characterized in that: The following steps are involved: The low-pressure and low-temperature refrigerant liquid in the throttling device (4) enters the upper cavity (101) through the liquid supply pipe (11); The low-pressure and low-temperature refrigerant liquid in the upper cavity (101) flows through the heat exchange capillary (15) to perform preliminary heat exchange with the geothermal well water, and part of the low-pressure and low-temperature refrigerant liquid turns into gaseous state, and then enters the lower cavity (102) to perform heat exchange with the geothermal well water again, and the remaining part of the low-pressure and low-temperature refrigerant liquid turns into gaseous state to obtain refrigerant gas; The refrigerant gas in the lower cavity (102) enters the compressor (2) through the suction pipe (12); The compressor (2) pressurizes and heats the refrigerant gas to obtain high-pressure and high-temperature refrigerant gas, which enters the ground heat exchange device (3); The high-pressure and high-temperature refrigerant gas in the ground heat exchange device (3) releases heat to the user end, obtaining high-pressure and high-temperature refrigerant liquid and entering the throttling device (4); The throttling device (4) throttles, decompresses and cools the high-pressure and high-temperature refrigerant liquid to obtain a low-pressure and low-temperature refrigerant liquid which enters the liquid supply pipe (11); The circulating water pump (5) circulates the geothermal well water internally through the circulating water pipe (6).

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