Direct expansion type heat pump heat exchange system

Abstract

The utility model relates to a direct expansion type heat pump heat exchange system, which is used for adjusting the temperature of mine fresh air flowing into a mine shaft, and is characterized in that the direct expansion type heat pump heat exchange system is arranged close to the ground and comprises a control part, a direct expansion type heat pump, an air duct and wellhead equipment, the temperature of the sucked air is adjusted, and then the sucked air is conveyed to the air duct; the direct expansion type heat pump is communicated with the wellhead equipment through the air duct, so that the air with the adjusted temperature is conveyed to the wellhead equipment; the wellhead equipment is communicated with a mine shaft, air with the temperature adjusted serves as mine fresh air to be conveyed to the mine shaft, the control part controls the overall action of the direct expansion type heat pump heat exchange system, the direct expansion type heat pump heat exchange system can be switched into a heating mode and a refrigerating mode, and in the heating mode, the direct expansion type heat pump enables the temperature of the mine fresh air to rise; and in the refrigeration mode, the direct expansion type heat pump enables the temperature of the mine fresh air to be reduced.

Description

Technical Field

[0001] This utility model relates to a direct expansion heat pump heat exchange system, and in particular to a direct expansion heat pump heat exchange system for heating and cooling mine fresh air at the mine air inlet. Background Technology

[0002] During mine operation, to ensure miners' health and safety and improve production efficiency and safety, air-source heat pumps are used to regulate the temperature of fresh air entering the mine shaft. Generally, air-source heat pumps use shell-and-tube heat exchangers. In winter, they extract low-grade heat energy from outdoor air. The high-temperature, high-pressure working fluid inside the shell-and-tube heat exchanger can raise the temperature of the heat medium to 40℃~60℃. The heated heat medium flows into the fresh air temperature control unit installed in the fresh air room on the mine shaft. Outdoor air is heated to above 2℃ in the fresh air temperature control unit and then introduced into the mine shaft as fresh air for mine shaft antifreeze. On the other hand, in summer, air-source heat pumps are used to cool the air before it is used as fresh air for mine shaft cooling. The temperature regulation process of mine fresh air involves the following multiple heat exchanges: heat exchange between outdoor air and the working fluid, heat exchange between the working fluid and the heat medium, and heat exchange between the heat medium and the mine fresh air. Utility Model Content

[0003] Problems to be solved by the utility model

[0004] Existing air source heat pump heat exchange systems have complex structures and suffer from problems such as complex control, multiple heat exchanges, and low heat exchange efficiency. Heat exchange efficiency refers to the efficiency of heat exchange equipment in the energy conversion process, mainly involving heat transfer efficiency, energy consumption, environmental standards, and economics.

[0005] Heat transfer efficiency is a core indicator for measuring the energy efficiency of heat exchange equipment. High heat transfer efficiency means more efficient energy transfer and utilization, reducing energy waste. By monitoring the energy consumption of equipment, its energy efficiency level during operation can be assessed. Low energy consumption usually means that the equipment is more economical and efficient during operation. High-efficiency heat exchange equipment can reduce greenhouse gas emissions, meet modern environmental protection requirements, and reduce negative environmental impacts. In the long run, high-efficiency heat exchange equipment can reduce energy costs and bring better economic benefits.

[0006] The researchers of this invention analyzed and found that the main factors affecting the heat exchange efficiency of a heat exchange system include: system design, pipe insulation, automatic control, and maintenance. Optimizing the overall system structure can improve heat exchange efficiency and reduce heat loss. Optimizing the pipe insulation method can reduce heat loss during transmission and improve system thermal efficiency. Introducing automatic control allows for automatic adjustment of the heat transfer medium flow rate and temperature according to actual needs, avoiding energy waste. Regular maintenance and upkeep of the heat exchange system can ensure good heat exchange performance.

[0007] The researchers of this invention consider improving heat exchange efficiency through the following means: improving the overall structure of the heat exchange system to reduce the number of heat exchange cycles; simplifying the pipe structure to facilitate proper insulation of the pipes; introducing automatic control to achieve precise temperature regulation; and simplifying the heat exchange structure to facilitate regular maintenance and upkeep of the heat exchange system.

[0008] This invention provides a direct expansion heat pump heat exchange system with a simple structure and improved heat exchange efficiency.

[0009] Solution for solving the problem

[0010] This utility model relates to a direct expansion heat pump heat exchange system for adjusting the temperature of fresh air flowing into a mine shaft. The system is characterized by being positioned close to the ground and includes a control unit, a direct expansion heat pump, an air duct, and a shaft opening device. The direct expansion heat pump draws in air, adjusts its temperature, and delivers it to the air duct. The air duct connects the direct expansion heat pump to the shaft opening device, allowing the temperature-adjusted air to be delivered there. The shaft opening device is connected to the mine shaft, ensuring the temperature-adjusted air is delivered as fresh air to the shaft. The control unit controls the overall operation of the direct expansion heat pump heat exchange system, switching between heating and cooling modes. In heating mode, the direct expansion heat pump raises the temperature of the fresh air; in cooling mode, it lowers the temperature of the fresh air.

[0011] The direct expansion heat pump heat exchange system is characterized in that the direct expansion heat pump comprises: a first fan, a first heat exchanger, a compressor, a reversing valve, a second fan, a second heat exchanger, and an expansion valve. The first fan is located at the end of the direct expansion heat pump away from the air duct and is used to discharge the air after passing through the first heat exchanger to the outside. The second fan is located at the end of the direct expansion heat pump near the air duct and is used to guide the air after passing through the second heat exchanger towards the air duct. The first heat exchanger, the compressor, the reversing valve, the second heat exchanger, and the expansion valve constitute the circulation path of the direct expansion heat pump. The heat exchange working fluid circulates in the circulation path. The control unit controls the reversing valve, thereby switching between the heating mode and the cooling mode.

[0012] The direct expansion heat pump heat exchange system is characterized in that, in the direct expansion heat pump, the heat exchange medium undergoes two heat exchanges, and the intake air is delivered to the air duct after its temperature is adjusted.

[0013] The direct expansion heat pump heat exchange system is characterized in that an air valve and a fire damper are provided in the air duct, the air valve is located at one end of the air duct near the direct expansion heat pump and can regulate the flow rate of air delivered from the direct expansion heat pump to the air duct, and the fire damper is located in the air duct on the side closer to the wellhead equipment than the air valve.

[0014] The direct expansion heat pump heat exchange system is characterized in that the extension length of the air duct extending in a straight line is ≥20 meters.

[0015] The direct expansion heat pump heat exchange system is characterized in that the extension length of the air duct extending in a straight line is <20 meters, and the direct expansion heat pump and the air duct meet the established explosion-proof requirements.

[0016] The direct expansion heat pump heat exchange system is characterized in that the control unit takes into account the temperature difference caused by the extension length of the air duct to control the airflow, so that the fresh air entering the mine shaft is at a predetermined temperature.

[0017] The direct expansion heat pump heat exchange system is characterized in that the predetermined temperature of the mine fresh air is above 2℃ and below 26℃; when the temperature of the mine fresh air is ≥2℃, the temperature of the inlet air of the air duct is ≥6℃; and when the temperature of the mine fresh air is ≤26℃, the temperature of the inlet air of the air duct is ≤20℃.

[0018] The direct expansion heat pump heat exchange system is characterized in that the first heat exchanger and the second heat exchanger are surface coolers with a copper tube finned structure.

[0019] The direct expansion heat pump heat exchange system is characterized in that the wellhead equipment has an air inlet door and an air inlet fan, which can introduce air as fresh air for the mine.

[0020] Effects of the utility model

[0021] The direct expansion heat pump heat exchange system of this invention eliminates the need for a mine inlet heating chamber or an inlet air heating unit (air supply unit), resulting in a simple system with low investment. Furthermore, by reducing the number of heat exchange cycles, heat exchange efficiency is improved. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the operation of the direct expansion heat pump heat exchange system involved in this utility model in heating mode.

[0023] Figure 2 This is a schematic diagram illustrating the operation of the direct expansion heat pump heat exchange system involved in this utility model in cooling mode. Detailed Implementation

[0024] To make the objectives, technical solutions and advantages of this utility model clearer, the embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0025] The direct expansion heat pump heat exchange system 1 (hereinafter, sometimes simply referred to as heat exchange system 1) involved in this embodiment is used to adjust (heat up and cool down) the temperature of fresh mine air entering the mine shaft. Heat exchange system 1 is installed close to the ground for easy installation and maintenance. Heat exchange system 1 includes: a direct expansion heat pump 2, an air duct 3, shaft opening equipment 4, and a control unit 5. The control unit 5 controls the overall operation of the system.

[0026] Outdoor air contains heat energy at its lowest grade ambient temperature (T0). To utilize this heat energy, a heat pump, such as a direct expansion heat pump 2, is needed. In winter, the direct expansion heat pump 2 draws in outdoor air, increasing the heat energy of some of the drawn-in air to become hot air. The outlet of the direct expansion heat pump 2 is connected via a duct 3 to a wellhead device 4 installed on the mine shaft. The hot air flows into the wellhead device 4 through the duct 3, and either directly or after mixing with other air, it flows into the mine shaft as fresh air, raising the temperature of the mine shaft. Conversely, in summer, the direct expansion heat pump 2 draws in outdoor air, decreasing the heat energy of some of the drawn-in air to become cold air. The cold air flows into the wellhead device 4 through the duct 3, and either directly or after mixing with other air, it flows into the mine shaft as fresh air, cooling the mine shaft.

[0027] The direct expansion heat pump 2 includes: a first fan 21, a first heat exchanger 22, a compressor 23, a reversing valve 24, a second fan 25, a second heat exchanger 26, and an expansion valve 27. The first fan 21 is located at the end of the direct expansion heat pump 2 furthest from the air duct 3, and is used to exhaust the air after passing through the first heat exchanger 22 to the outside. The second fan 25 is located at the end of the direct expansion heat pump 2 closest to the air duct 3, and is used to guide the air after passing through the second heat exchanger 26 towards the air duct 3. The first heat exchanger 22, compressor 23, reversing valve 24, second heat exchanger 26, and expansion valve 27 form the circulation path of the direct expansion heat pump 2, in which the heat exchange working fluid circulates. The specific operating mode of the direct expansion heat pump 2 will be described later.

[0028] One end of the air duct 3 is connected to the direct expansion heat pump 2, and the other end is connected to the wellhead equipment 4 (e.g., the wellhead room). Outdoor air, after being conditioned by the direct expansion heat pump 2, flows through the air duct 3 to the wellhead equipment 4 and is then introduced into the mine shaft. An air valve 31 and a fire damper 32 are installed in the air duct 3. The air valve 31 is not particularly limited and can be an electric, pneumatic, or manual valve. Preferably, the air valve 31 is located at the end of the air duct 3 closest to the direct expansion heat pump 2 and is used to regulate the flow rate of air supplied from the direct expansion heat pump 2 to the air duct 3. The fire damper 32 is not particularly limited and can be an electric, pneumatic, or manual fire damper. Preferably, the fire damper 32 is located in the air duct 3 on the side closer to the wellhead equipment 4 than the air valve 31, and closes in case of danger to protect the direct expansion heat pump 2 and other equipment.

[0029] The shaft opening device 4 is installed above the mine shaft, directly introducing air from the ventilation duct into the mine shaft, or mixing air from the ventilation duct with other air before introducing it into the mine shaft. When it is necessary to mix air from the ventilation duct with other air before introducing it into the mine shaft, an air inlet door and an air intake fan (not shown) also need to be installed on the shaft opening device 4 to introduce outdoor air. With the air inlet door and air intake fan installed on the shaft opening device 4, the temperature of the fresh air introduced into the mine shaft can be further regulated.

[0030] The air from the direct expansion heat pump 2 experiences temperature changes as it flows through the duct 3 due to ambient temperature, and these temperature changes increase with the length of the duct. To improve heat exchange efficiency, the duct 3 needs insulation, such as by covering it with an insulation layer and / or coating it with an insulating coating. However, these measures increase installation and maintenance costs. Therefore, a straight, simple structure for the duct 3 is desirable, facilitating installation and maintenance. Furthermore, a shorter duct length is also desirable, further simplifying installation and maintenance.

[0031] According to the "Coal Mine Safety Regulations," a certain safe distance must be maintained between electrical equipment and the mine entrance based on explosion-proof requirements. Therefore, in the absence of explosion-proof electrical equipment, the straight-line extension length of the ventilation duct 3 from the air valve 31 to the inlet of the mine entrance equipment 4 can be more than 20m.

[0032] Alternatively, in accordance with the relevant provisions of the current national standard "Code for Design of Electrical Installations in Explosive Atmospheres" GB50058, explosion-proof electrical equipment (e.g., air valve 31, fire damper 32, etc.) can be adopted based on established explosion-proof requirements. When using explosion-proof electrical equipment, the straight-line extension length of the duct 3 from the air valve 31 to the inlet of the wellhead equipment 4 can be less than 20m. Alternatively, the fire damper 32 can be installed on the side wall of the wellhead equipment 4, thus making the extension length of the duct 3 approximately 0m.

[0033] Furthermore, the control unit 5 can control the opening of the air valve 31 to automatically adjust the flow rate and / or velocity of the air from the direct expansion heat pump 2, thereby controlling the temperature of the air flowing into the air duct 3. It should be noted that when the extension length of the air duct 3 is long (e.g., 20m), the heat loss of the air flowing through the air duct 3 needs to be considered for automatic control. Even with insulation, there will still be heat loss when the straight extension length of the air duct 3 is 20m. Therefore, there will be a temperature difference between the air temperature at the inlet of the air duct 3 (air valve 31) and the air temperature at the inlet of the wellhead equipment 4. The control unit 5 needs to take this temperature difference into account for automatic control.

[0034] Generally, the normal operating temperature requirement for mines is above 2℃ in winter and below 26℃ in summer. The researchers of this invention have confirmed through experiments that, with a straight extension length of 20m for ventilation duct 3, in winter, to ensure the temperature of the fresh air entering the mine shaft is ≥2℃, the air temperature at the inlet of ventilation duct 3 needs to be ≥6℃; conversely, in summer, to ensure the temperature of the fresh air entering the mine shaft is ≤26℃, the air temperature at the inlet of ventilation duct 3 needs to be ≤20℃.

[0035] Therefore, when introducing automatic control to improve heat exchange efficiency, the complexity of the heat exchange system increases the number of computational factors to be considered. In this invention, the heat exchange system has a simple structure, reducing the computational factors to be considered and improving the efficiency of automatic control, thereby further enhancing heat exchange efficiency.

[0036] In this embodiment, the first heat exchanger 22 and the second heat exchanger 26 are not particularly limited. For example, they can be surface coolers or copper tube finned structures.

[0037] The following describes the specific working method of the direct expansion heat pump heat exchange system 1 involved in this embodiment.

[0038] First, let's explain the working principle of a direct expansion heat pump. A direct expansion heat pump typically includes: an evaporator, where the working fluid absorbs heat energy from an external heat source and evaporates, changing from a liquid to a gaseous state and absorbing a large amount of heat energy; a compressor, where the evaporated vapor is drawn into and compressed, becoming a high-temperature, high-pressure vapor; a condenser, where the compressed, high-temperature, high-pressure vapor enters the condenser, where it is condensed into a liquid state, releasing a large amount of heat energy; and an expansion valve, where the condensed liquid working fluid expands and throttles, causing its pressure and temperature to drop, becoming a low-temperature, low-pressure two-phase gas-liquid working fluid.

[0039] Secondly, the working mode of the direct expansion heat pump 2 in winter heating mode and summer cooling mode will be further explained. Figure 1 This is a schematic diagram illustrating the operation of the direct expansion heat pump heat exchange system involved in this utility model in heating mode. Figure 2 This is a schematic diagram illustrating the operation of the direct expansion heat pump heat exchange system involved in this utility model in cooling mode.

[0040] In winter, when the ambient temperature is low, the direct expansion heat pump 2 operates in heating mode. In this case, the first heat exchanger 22 acts as an evaporator, and the second heat exchanger 26 acts as a condenser.

[0041] like Figure 1 As shown, in heating mode, the control unit 5 controls the reversing valve 24 in the direct expansion heat pump 2, causing the working fluid to flow sequentially through the first heat exchanger 22, compressor 23, second heat exchanger 26, and expansion valve 27 in the circulation path. The low-temperature, low-pressure liquid working fluid exchanges heat with a portion of the air drawn into the direct expansion heat pump 2 in the first heat exchanger 22 (first heat exchange), absorbing heat energy from the air and evaporating into vapor. The air, having absorbed heat energy and cooled, becomes cold air and is discharged to the outside by the first fan 21. The vaporized working fluid is compressed by the compressor 23, becoming a high-temperature, high-pressure vapor during compression. This high-temperature, high-pressure vapor is sent to the second heat exchanger 26, where it releases heat energy and exchanges heat with another portion of the air drawn into the direct expansion heat pump 2 (second heat exchange), gradually condensing into a liquid. After absorbing heat in the second heat exchanger 26, the air, now heated, is guided by the second fan 25 to the air duct 3 and flows into the mine shaft via the air duct 3 and the shaft opening equipment 4. On the other hand, the liquid working fluid is expanded and throttled by the expansion valve 27, becoming a low-temperature, low-pressure gas-liquid two-phase working fluid, which flows to the first heat exchanger 22 and re-enters the circulation.

[0042] In other words, two heat exchanges occur in the heating mode. The working fluid and a portion of the air undergo a first heat exchange in the first heat exchanger 22 (evaporator). The working fluid absorbs heat and its temperature rises, and the air that has absorbed heat is discharged to the outside. The working fluid and another portion of the air undergo a second heat exchange in the second heat exchanger 26 (condenser). The air that has absorbed heat and its temperature rises becomes hot air, which is guided by the second fan 25 to the air duct 3, and then flows into the mine shaft through the air duct 3 and the shaft opening equipment 4.

[0043] During the summer, when the ambient temperature is high, the direct expansion heat pump 2 operates in cooling mode. In this case, the first heat exchanger 22 acts as a condenser, and the second heat exchanger 26 acts as an evaporator.

[0044] like Figure 2As shown, in the cooling mode, the control unit 5 controls the reversing valve 24 in the direct expansion heat pump 2, causing the working fluid to flow sequentially through the second heat exchanger 26, compressor 23, first heat exchanger 22, and expansion valve 27 in the circulation path. The low-temperature, low-pressure liquid working fluid exchanges heat with a portion of the air drawn into the direct expansion heat pump 2 in the second heat exchanger 26 (first heat exchange). The working fluid absorbs heat energy from the air and evaporates into vapor. The air, having absorbed heat energy and cooled, becomes cold air, which is guided by the second fan 25 to the air duct 3 and flows into the mine shaft via the air duct 3 and the shaft opening equipment 4. The vapor working fluid is compressed by the compressor 23, becoming a high-temperature, high-pressure vapor during compression. This high-temperature, high-pressure vapor is sent to the first heat exchanger 22, where it releases heat energy and exchanges heat with another portion of the air (second heat exchange). The working fluid is gradually condensed into a liquid state. The air, having absorbed heat energy in the first heat exchanger 22 and increased in temperature, becomes hot air and is discharged to the outside by the first fan 21. On the other hand, the liquid working fluid, after being expanded and throttled by the expansion valve 27, becomes a low-temperature, low-pressure gas-liquid two-phase working fluid, which flows to the second heat exchanger 26 and re-enters the cycle.

[0045] In other words, two heat exchanges occur in the cooling mode. The working fluid and a portion of the air undergo the first heat exchange in the second heat exchanger 26 (evaporator). The working fluid absorbs heat and its temperature rises, while the air, having absorbed heat and its temperature decreased, becomes cold air. This cold air is guided by the second fan 25 to the air duct 3, and then flows into the mine shaft via the air duct 3 and the shaft opening equipment 4. The working fluid and the remaining air undergo the second heat exchange in the first heat exchanger 22 (condenser). The working fluid releases heat to the air, and the air, having absorbed heat and its temperature increased, becomes hot air, which is then discharged to the outside by the first fan 21.

[0046] According to this embodiment, the mine air inlet does not require a mine entrance heating chamber or a mine entrance air temperature control unit (air supply unit), thus the system has a simple structure and low installation and maintenance costs. Tests have shown that by reducing one heat exchange stage, heat exchange efficiency can be improved by more than 15%.

[0047] The above are merely embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this utility model should be included within the scope of the claims of this utility model.

[0048] For example, in this embodiment, the system operates in heating mode during winter and cooling mode during summer. However, it is not limited to this and can switch between heating and cooling modes according to changes in ambient temperature. Additionally, when there is no need to adjust the temperature of the mine's fresh air, it can switch to a normal ventilation mode without activating the heat pump, introducing fresh air into the mine solely through the air inlet door and fan of the wellhead equipment 4.

Claims

1. A direct expansion heat pump heat exchange system for adjusting the temperature of fresh mine air flowing into the mine shaft, characterized in that, The direct expansion heat pump heat exchange system is installed close to the ground and includes a control unit, a direct expansion heat pump, air ducts, and wellhead equipment. The direct expansion heat pump can draw in air, adjust the temperature of the drawn-in air, and then deliver it to the air duct; the air duct connects the direct expansion heat pump to the wellhead equipment, so that the temperature-adjusted air is delivered to the wellhead equipment; the wellhead equipment is connected to the mine shaft, so that the temperature-adjusted air is delivered to the mine shaft as fresh air. The control unit controls the overall operation of the direct expansion heat pump heat exchange system and can switch between heating mode and cooling mode. In the heating mode, the direct expansion heat pump raises the temperature of the mine fresh air, and in the cooling mode, the direct expansion heat pump lowers the temperature of the mine fresh air.

2. The direct expansion heat pump heat exchange system according to claim 1, characterized in that, The direct expansion heat pump comprises: a first fan, a first heat exchanger, a compressor, a reversing valve, a second fan, a second heat exchanger, and an expansion valve. The first fan is located at the end of the direct expansion heat pump away from the air duct, and is used to exhaust the air after passing through the first heat exchanger to the outside. The second fan is located at one end of the direct expansion heat pump near the air duct, and is used to guide the air after passing through the second heat exchanger towards the air duct. The first heat exchanger, the compressor, the reversing valve, the second heat exchanger, and the expansion valve constitute the circulation path of the direct expansion heat pump, and the heat exchange working fluid circulates in the circulation path. The control unit controls the reversing valve, thereby switching between the heating mode and the cooling mode.

3. The direct expansion heat pump heat exchange system according to claim 2, characterized in that, In the direct expansion heat pump, the heat exchange medium undergoes two heat exchanges, and the intake air is temperature-adjusted before being delivered to the air duct.

4. The direct expansion heat pump heat exchange system according to claim 2, characterized in that, The air duct is equipped with an air valve and a fire damper. The air valve is located at one end of the air duct near the direct expansion heat pump and can regulate the flow rate of air delivered from the direct expansion heat pump to the air duct. The fire damper is located in the air duct on the side closer to the wellhead equipment than the air valve.

5. The direct expansion heat pump heat exchange system according to claim 4, characterized in that, The duct extends in a straight line for a length of ≥20 meters.

6. The direct expansion heat pump heat exchange system according to claim 4, characterized in that, The extension length of the air duct along a straight line is less than 20 meters, and the direct expansion heat pump and the air duct meet the established explosion-proof requirements.

7. The direct expansion heat pump heat exchange system according to claim 5 or 6, characterized in that, The control unit takes into account the temperature difference caused by the extension length of the air duct to control the flow so that the fresh air entering the mine shaft is at a predetermined temperature.

8. The direct expansion heat pump heat exchange system according to claim 7, characterized in that, The predetermined temperature for the mine's fresh air is between 2°C and 26°C. When the temperature of the fresh air in the mine is ≥2℃, the temperature of the inlet air in the air duct is ≥6℃. When the temperature of the fresh air in the mine is ≤26℃, the temperature of the inlet air in the air duct is ≤20℃.

9. The direct expansion heat pump heat exchange system according to claim 2, characterized in that, The first heat exchanger and the second heat exchanger are surface coolers, which are copper tubes with finned structures.

10. The direct expansion heat pump heat exchange system according to claim 2, characterized in that, The wellhead equipment has an air inlet door and an air intake fan, which can introduce air as fresh air for the mine.

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