Indirect evaporative cooler, aircraft ground air conditioning unit and control method thereof

Abstract

The present invention belongs to the field of refrigeration equipment and relates to an indirect evaporative cooler, an aircraft ground air conditioning unit, and a control method thereof. The indirect evaporative cooling pipes are arranged in a plurality of horizontal rows, with a plurality of indirect evaporative cooling pipes spaced apart in each row, and the indirect evaporative cooling pipes in adjacent rows are staggered. The left and right sides of the cross section of the indirect evaporative cooling pipe are respectively formed by two spaced-apart convex arcs, the bottoms of the two convex arcs are respectively connected to a first concave arc, the convex arcs and the first concave arcs transitioning tangently and smoothly, and the bottoms of the two first concave arcs are tangent. The top of the cross section is formed by a second concave arc, the ends of the second concave arc are respectively connected to the tops of the two convex arcs. This ensures that the ambient air and cooling water used for cooling are in close contact with the entire outer wall of the indirect evaporative cooling pipe, thereby enhancing heat exchange and reducing wind resistance.

Description

Technical Field

[0001] The present invention belongs to the field of refrigeration equipment and relates to an indirect evaporative cooler, an aircraft ground air conditioning unit and a control method thereof. Background Art

[0002] An indirect evaporative cooler is an air conditioning device that uses outdoor ambient air to exchange heat with the desired air. Its operating principle is to use the outdoor air to promote the evaporation of cooling water distributed outside the indirect evaporative cooling pipes, thereby absorbing heat from the desired air inside the pipes, thereby cooling the desired air. Currently, traditional indirect evaporative cooling pipes are constructed in two types: circular and elliptical.

[0003] The circular or elliptical structure of traditional indirect evaporative cooling pipes often causes cooling water droplets to fall directly from the outer wall of one indirect evaporative cooling pipe onto the outer wall of the indirect evaporative cooling pipe below it. This makes it difficult for the cooling water to adhere to the entire outer wall of the indirect evaporative cooling pipe, causing the cooling water to circulate ineffectively between the sprinkler and the water collection pan, resulting in cooling water waste and reduced heat exchange efficiency. This structure also causes ambient air to separate as it flows upward through the indirect evaporative cooling pipes, creating a significant vortex zone that prevents the air from adhering to the upper half of the pipe's outer wall and, consequently, from removing heat from that upper half. This not only affects heat exchange efficiency but also increases wind resistance. Summary of the Invention

[0004] The present invention aims to overcome the shortcomings of the prior art by providing an indirect evaporative cooler, an aircraft ground air conditioning unit, and a control method thereof, which allow ambient air and water used for cooling to adhere closely to the entire outer wall of the indirect evaporative cooling duct, thereby increasing the contact area between the ambient air and the indirect evaporative cooling duct, enhancing the heat exchange effect, and reducing wind resistance.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] An indirect evaporative cooler comprises a plurality of indirect evaporative cooling pipes;

[0007] All indirect evaporative cooling pipes are arranged in several horizontal rows, with several indirect evaporative cooling pipes arranged at intervals in each row, and the indirect evaporative cooling pipes between adjacent horizontal rows are staggered;

[0008] The left and right sides of the cross section of the indirect evaporative cooling pipe are respectively two convex arcs set at intervals, the bottom of the two convex arcs are respectively connected to a first concave arc, the convex arcs are tangent to the first concave arcs and transition smoothly, and the bottoms of the two first concave arcs are tangent; the top of the cross section is a second concave arc, and the two ends of the second concave arc are respectively connected to the tops of the two convex arcs.

[0009] Preferably, the vertical direction of the cross section of the indirect evaporative cooling pipe is the major axis, the horizontal direction is the minor axis, the radii of the convex arc and the first concave arc are both 10 to 12 times the length of the minor axis, and the radius of the second concave arc is 0.25 to 0.5 times the length of the minor axis.

[0010] Preferably, it also includes a fresh air inlet, a secondary air inlet, an air filter, an evaporative cooling exhaust fan, a water filter, a water sprayer, a water collecting tray and a cooling water pipeline; the fresh air inlet and the secondary air inlet outlet are both connected to the air filter, the evaporative cooling exhaust fan, the water filter, the water sprayer, the indirect evaporative cooling pipe and the water collecting tray are arranged in sequence from top to bottom, the indirect evaporative cooling pipe is located at the air filter outlet, the fresh air inlet is connected to the inside of the indirect evaporative cooling pipe, the secondary air inlet is connected to the outside of the indirect evaporative cooling pipe and the evaporative cooling exhaust fan; the water collecting tray is connected to the water inlet of the cooling water pipeline, and the water sprayer is connected to the water outlet of the cooling water pipeline.

[0011] Preferably, a plurality of diverter plates of different lengths are provided along the height direction below the indirect evaporative cooling pipe, each diverter plate is tilted along the horizontal direction, and each diverter plate is located behind the secondary air inlet.

[0012] Preferably, the diverter plates are all provided with a slope, and the slope direction is consistent with the air inlet direction.

[0013] An aircraft ground air conditioning unit comprises a primary module, a secondary module, a tertiary module, a quaternary module and an air supply section;

[0014] The first-level module, the second-level module, the third-level module, the fourth-level module and the air supply section are sequentially connected by an air-conditioning air supply channel, and the first-level module includes an indirect evaporative cooler;

[0015] The secondary module includes an absorption refrigeration unit, a solar thermal collector, and an air-oil heat exchanger. The solar thermal collector is connected to the absorption refrigeration unit and the air-oil heat exchanger through a heat transfer oil pipeline, and the cooling water pipeline is connected to the absorption refrigeration unit.

[0016] The third-stage module adopts a steam compression refrigeration unit; the fourth-stage module adopts an electric heater; the air supply section includes a blower and a fresh air supply outlet, and the fresh air supply outlet is connected to the outside of the aircraft ground air-conditioning unit.

[0017] Preferably, the absorption refrigeration unit includes a generator; the solution outlet of the generator is connected to the absorber, the solution pump, the solution heat exchanger and the solution inlet of the generator in sequence using a solution pipeline to form a solution circulation pipeline; the water vapor outlet of the generator is connected to the first-level condenser, the first-level evaporator and the water vapor inlet of the absorber in sequence using a steam-water pipeline; the absorber and the first-level condenser are both connected to the cooling water pipeline; the heat transfer oil pipeline is connected to the generator.

[0018] Preferably, the vapor compression refrigeration unit includes a compressor, a secondary condenser, a liquid receiver, a secondary evaporator and a gas-liquid separator which are cyclically connected in sequence.

[0019] Preferably, the generator includes a closed outer shell, an inner shell is provided in which a solution is provided, the inner shell has an open top, and the bottom of the inner shell is slidingly sealed with the inner wall of the outer shell. A solution outlet is provided at the bottom of the inner shell of the generator, and the solution outlet is connected to the outside of the outer shell of the generator by a solution outlet pipe. The part of the heat transfer oil pipe connected to the generator and the secondary condenser are both located in the inner shell.

[0020] A control method for the aircraft ground air conditioning unit includes the following steps:

[0021] Under cooling conditions, the indirect evaporative cooler, absorption refrigeration unit and vapor compression refrigeration unit are turned on in sequence, and the gas-oil heat exchanger and electric heater are turned off;

[0022] When the medium temperature in the heat transfer oil pipeline is higher than the set temperature, the flow rate of the medium in the heat transfer oil pipeline is increased; when the medium temperature in the heat transfer oil pipeline is lower than the set temperature, the connection between the heat transfer oil pipeline and the absorption refrigeration unit is cut off; when the medium temperature in the heat transfer oil pipeline is higher than the set temperature, the heat transfer oil pipeline and the absorption refrigeration unit are reconnected;

[0023] Under heating conditions, the gas-oil heat exchanger and electric heater are turned on, and the indirect evaporative cooler, absorption refrigeration unit, and vapor compression refrigeration unit are turned off;

[0024] When the medium temperature in the thermal oil pipeline is higher than the set temperature, the medium flow rate in the thermal oil pipeline is increased. When the medium temperature in the thermal oil pipeline is lower than the wind temperature after the fresh air passes through the indirect evaporative cooler, the gas-oil heat exchanger is closed and the power of the electric heater is increased.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention utilizes the structural interaction of the convex arc and the first concave arc of the indirect evaporative cooling duct to ensure that ambient air moving upward from the bottom adheres closely to the entire outer wall of the indirect evaporative cooling duct, and water moving downward from the top also adheres closely to the entire outer wall of the indirect evaporative cooling duct. The ambient air flowing through the indirect evaporative cooling duct fully evaporates the water on the outer wall of the indirect evaporative cooling duct, and the evaporative latent heat removes the heat of the fresh air inside the indirect evaporative cooling duct. This prevents flow separation and the formation of significant vortex zones when the ambient air passes through the indirect evaporative cooling duct, effectively improving the heat exchange intensity in the upper half of each indirect evaporative cooling duct while reducing wind resistance. The second concave arc at the top of the indirect evaporative cooling duct is used to catch water droplets falling from the indirect evaporative cooling duct above it. Due to the ambient air turbulence caused by the second concave arc, the water caught by the second concave arc smoothly overflows and adheres to the entire outer wall of the indirect evaporative cooling duct, preventing water from falling from the upper indirect evaporative cooling duct directly onto the lower indirect evaporative cooling duct, which would waste water and reduce heat exchange intensity.

[0027] The present invention incorporates a diverter plate beneath the indirect evaporative cooling pipe. This deflects ambient air smoothly upward upon entering the indirect evaporative cooler, resulting in a stable airflow and no large vortices, significantly reducing flow resistance. Furthermore, the diverter plate ensures that incoming ambient air evenly contacts different locations outside the indirect evaporative cooling pipe. This significantly increases the contact area between the ambient air and the pipe, as well as the heat exchange intensity, compared to traditional indirect evaporative coolers.

[0028] This invention uses an indirect evaporative cooler as the primary cooling stage, fully utilizing the dry air energy on the apron and improving unit efficiency. It also employs an absorption refrigeration unit as the secondary cooling stage. A solar collector and absorption refrigeration unit are combined, utilizing a high-temperature medium derived from solar energy as the absorption refrigeration unit's heat source, thereby improving the absorption refrigeration unit's efficiency. Furthermore, a solar collector and an air-to-oil heat exchanger are combined as the primary heating stage, a vapor compression refrigeration unit as the third cooling stage, and an electric heater as the second heating stage. Ultimately, the present invention achieves multi-stage cooling and heating, improving the efficiency of aircraft ground air conditioning units and reducing energy consumption.

[0029] The present invention recycles the waste heat of the steam compression refrigeration unit and uses it as a heat source for the absorption refrigeration unit, thereby further improving the efficiency of the absorption refrigeration unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a structural schematic diagram of an indirect evaporative cooler according to Example 1 of the present invention;

[0031] Figure 2 Schematic cross-sectional view of an indirect evaporative cooler according to Example 1 of the present invention;

[0032] Figure 3 Schematic diagram of a cross section of a single indirect evaporative cooling pipeline according to Example 1 of the present invention;

[0033] Figure 4 Velocity cloud diagram of the numerical simulation flow field of an indirect evaporative cooler equipped with a traditional indirect evaporative cooling pipe and an indirect evaporative cooling pipe according to Example 1 of the present invention.

[0034] Figure 5 The numerical simulation flow field velocity cloud diagrams of the conventional indirect evaporative cooler without a diverter plate and the indirect evaporative cooler according to Example 1 of the present invention with a diverter plate.

[0035] Figure 6 This is a structural diagram of an aircraft ground air conditioning unit according to embodiment 2 of the present invention;

[0036] Figure 7 This is a schematic structural diagram of the secondary module and tertiary module of an aircraft ground air conditioning unit according to embodiment 2 of the present invention;

[0037] Figure 8 Schematic diagram of the internal structure of the generator according to embodiment 3 of the present invention;

[0038] Figure 9 This is a schematic diagram of the upward movement of the generator inner shell according to Example 3 of the present invention;

[0039] Figure 10 enthalpy-psychrometric diagrams of the cooling process of a conventional aircraft ground air conditioning unit and an aircraft ground air conditioning unit according to Example 3 of the present invention;

[0040] Figure 11 This is a psychrometric diagram of the heating process of an aircraft ground air conditioning unit according to embodiment 3 of the present invention.

[0041] Among them: 1. Fresh air inlet, 2. Secondary air inlet, 3. Air filter, 4. Indirect evaporative cooling pipe, 5. Evaporative cooling exhaust fan, 6. Water filter, 7. Sprinkler, 8. Cooling water pump, 9. Cooling water filter, 10. First cooling water pipeline electric valve, 11. Second cooling water pipeline electric valve, 12. Third cooling water pipeline electric valve, 13. Fourth cooling water pipeline electric valve, 14. First thermal oil pipeline electric valve, 15. Second thermal oil pipeline Electric valve, 16, gas-oil heat exchanger, 17, first electric airtight air valve, 18, first stage evaporator, 19, second electric airtight air valve, 20, solar collector, 21, third thermal oil pipeline electric valve, 22, fourth thermal oil pipeline electric valve, 23, thermal oil pump, 24, thermal oil pipeline temperature sensor, 25, first stage condenser, 26, absorber, 27, generator, 28, solution pump, 29, solution heat exchanger, 30, compressor, 31, second stage cooling Condenser, 32. Expansion valve, 33. Liquid receiver, 34. Secondary evaporator, 35. Gas-liquid separator, 36. Refrigerant pipe, 37. Electric heater, 38. Blower, 39. Fresh air outlet, 40. Cooling water pipe, 41. Thermal oil pipe, 42. Water collecting tray, 43. Solution pipe, 44. First temperature sensor, 45. Second temperature sensor, 46. Third temperature sensor, 47. Fourth temperature sensor, 48. Baffle, 49. Air conditioning air supply channel, 50. Conductivity meter, 51. Solenoid valve, 52. Thermal oil heat exchange coil, 53. Diverter plate, 54. First solution temperature sensor, 55. Second solution temperature sensor, 56. Solution concentration sensor, 57. Flow sensor, 58. Soda-water pipeline, 59. Outer shell, 60. Inner tank, 61. First-level module, 62. Second-level module, 63. Third-level module, 64. Fourth-level module, 65. Air supply section, 66. Outer convex arc, 67. First inner concave arc, 68. Second inner concave arc. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0043] Example 1:

[0044] like Figure 1As shown, this embodiment provides an indirect evaporative cooler, including a fresh air inlet 1, a secondary air inlet 2, an air filter 3, an indirect evaporative cooling pipe 4, an evaporative cooling exhaust fan 5, a water filter 6, a spray water device 7, a cooling water pump 8, a cooling water filter 9 and a water collecting tray 42. The fresh air inlet 1 and the secondary air inlet 2 are arranged vertically in parallel, the fresh air inlet 1 is located above the secondary air inlet 2, and the outlets of the fresh air inlet 1 and the secondary air inlet 2 are both connected to the air filter 3. The indirect evaporative cooling pipe 4 is arranged in the air filter 6. At the outlet of the device 3, the water collecting tray 42 is arranged below the indirect evaporative cooling pipe 4, the spray waterer 7 is located above the indirect evaporative cooling pipe 4, the water filter 6 is located above the spray waterer 7, the evaporative cooling exhaust fan 5 is located above the water filter 6, the fresh air inlet 1 corresponds to the position of the indirect evaporative cooling pipe 4, the fresh air inlet 1 is connected to the inside of the indirect evaporative cooling pipe 4, the secondary air inlet 2 corresponds to the position below the indirect evaporative cooling pipe 4, the secondary air inlet 2 is connected to the outside of the indirect evaporative cooling pipe 4 and the evaporative cooling exhaust fan 5.

[0045] The evaporative cooling exhaust fan 5 draws in ambient air from the secondary air inlet 2. A baffle 48 is provided between the fresh air inlet 1 and the secondary air inlet 2. The water collecting tray 42 is connected to the water inlet of the cooling water pipeline 40 through the cooling water filter 9. The water sprayer 7 is connected to the water outlet of the cooling water pipeline 40 through the cooling water pump 8. The cooling water pipeline 40 is used for the circulation of cooling water.

[0046] like Figure 2 As shown, there are multiple indirect evaporative cooling pipes 4. From the cross-sectional perspective of the indirect evaporative cooler, multiple indirect evaporative cooling pipes 4 are arranged in multiple horizontal rows, and the multiple horizontal rows are arranged vertically. Multiple indirect evaporative cooling pipes 4 are arranged at intervals in each row, and the indirect evaporative cooling pipes 4 between adjacent horizontal rows are staggered.

[0047] like Figure 3As shown, the vertical direction of the cross section of the indirect evaporative cooling pipe 4 is the major axis, the horizontal direction is the minor axis, the major axis length is 80mm to 120mm, the minor axis length is 10mm to 15mm, and the left and right sides of the cross section of the indirect evaporative cooling pipe 4 are two convex arcs 66 arranged at intervals. The bottoms of the two convex arcs 66 are respectively connected to a first concave arc 67. The convex arc 66 and the first concave arc 67 are tangent to each other and smoothly transition. The bottoms of the two first concave arcs 67 are tangent to each other. The radii of the convex arc 66 and the first concave arc 67 are both 10 to 12 times the length of the minor axis. The top of the cross section is a second concave arc 68, and the two ends of the second concave arc 68 are respectively connected to the tops of two convex arcs 66. The radius of the second concave arc 68 is 0.25 to 0.5 times the length of the minor axis. The lateral relative pitch of the indirect evaporative cooling pipe 4 is 1.1 to 2.0, and the vertical relative pitch is 0.55 to 1.0. The lateral relative pitch refers to the ratio of the lateral distance between the centers of two adjacent indirect evaporative cooling pipes 4 in the same horizontal row to the minor axis; the vertical relative pitch refers to the ratio of the vertical distance between the centers of two adjacent indirect evaporative cooling pipes 4 in adjacent horizontal rows to the major axis.

[0048] The fresh air coming in from the fresh air inlet 1 passes through the inside of each indirect evaporative cooling pipe 4, and the ambient air coming in from the secondary air inlet 2 flows in the external gap of the adjacent indirect evaporative cooling pipe 4. The indirect evaporative cooling pipe 4 uses the structural effect of the outer convex arc 66 and the first inner concave arc 67. The ambient air moving from bottom to top will be closely attached to the entire outer wall of the indirect evaporative cooling pipe 4, and the water moving from top to bottom will also be closely attached to the entire outer wall of the indirect evaporative cooling pipe 4. The flow of ambient air causes the water on the outer wall of the indirect evaporative cooling pipe 4 to fully evaporate, and the heat of the fresh air inside the indirect evaporative cooling pipe 4 is taken away by the evaporation latent heat, thereby avoiding flow separation and generation of obvious vortex areas when the ambient air passes through the indirect evaporative cooling pipe 4, effectively improving the heat exchange intensity of the upper half of each indirect evaporative cooling pipe 4, and reducing wind resistance at the same time.

[0049] Because conventional indirect evaporative cooling ducts 4 are circular or elliptical in shape, this causes upward-flowing ambient air to separate and generate significant eddy currents as it passes through the ducts. To mitigate this effect, the only solution is to reduce the spacing between the ducts 4 to increase the contact area between the ambient air and the outer surface of the ducts 4, thereby enhancing heat exchange. However, reducing the spacing between the ducts 4 reduces the air flow area, which inevitably increases the resistance to ambient air flowing through the ducts 4. In this embodiment, the indirect evaporative cooling ducts 4, through the structural interaction of the outwardly convex arc 66 and the first inwardly concave arc 67, ensure that upward-flowing ambient air adheres to the entire outer wall of the ducts 4 due to the "Coanda effect." Similarly, downward-flowing water adheres to the entire outer wall of the ducts 4 due to the "Coanda effect." This not only improves heat exchange efficiency but also avoids the increased wind resistance caused by reducing the spacing between the ducts 4.

[0050] In this embodiment, the second concave arc 68 at the top of the indirect evaporative cooling pipe 4 is used to catch water droplets falling from the indirect evaporative cooling pipe 4 above the pipe. Due to the turbulence of the ambient air caused by the second concave arc 68, the water caught by the second concave arc 68 will smoothly overflow and adhere to the outer wall of the indirect evaporative cooling pipe 4, avoiding the waste of water caused by the water falling from the upper indirect evaporative cooling pipe 4 directly falling on the lower indirect evaporative cooling pipe 4.

[0051] like Figure 4 As shown, Figure 4 (a) is a numerical simulation of the flow field velocity cloud diagram of ambient air flowing outside a traditional indirect evaporative cooling pipe. Due to the circular cross-section of the traditional indirect evaporative cooling pipe, when the ambient air flows through the traditional indirect evaporative cooling pipe from bottom to top, flow separation occurs in the upper half of the pipe's outer wall, generating a significant eddy zone. The ambient air cannot adhere to the upper half of the pipe's outer wall and is unable to remove heat from the upper half of the pipe's outer wall, which not only affects the heat exchange efficiency but also increases the wind resistance. Figure 4(b) is a numerically simulated velocity contour of the ambient air flowing outside the indirect evaporative cooling duct 4 of this embodiment. The indirect evaporative cooling duct 4 of this embodiment, through the structural interaction of the outwardly convex arc 66 and the first inwardly concave arc 67, allows the ambient air flowing upward from bottom to top to adhere closely to the entire outer wall of the indirect evaporative cooling duct 4 due to the "Coanda effect." This prevents flow separation and produces no significant eddy currents, resulting in lower wind resistance and smoother flow. The ambient air contacts the entire outer wall of the duct, effectively increasing the heat exchange area and the amount of heat exchanged. Through numerical simulation, with all other factors remaining constant, the indirect evaporative cooler of this embodiment achieves a 22.5% increase in heat exchange and a 26.9% decrease in ambient air flow resistance compared to conventional indirect evaporative coolers, achieving excellent results in both improved heat exchange and reduced resistance.

[0052] Below the indirect evaporative cooling pipe 4, a plurality of diverter plates 53 of different lengths are arranged along the height direction. From top to bottom, the length of each diverter plate 53 is 1 / 6, 2 / 6, 3 / 6, 4 / 6 and 5 / 6 of the length of the indirect evaporative cooling pipe 4 respectively. Each diverter plate 53 is tilted in the horizontal direction. Each diverter plate 53 is located behind the secondary air inlet 2. The diverter plate 53 is used to divert the ambient air coming in from the secondary air inlet 2 so that the air is evenly exposed to different positions outside the indirect evaporative cooling pipe 4. The diverter plates 53 are all provided with a slope, and the slope direction is consistent with the air inlet direction to facilitate drainage.

[0053] like Figure 5 As shown, Figure 5 (a) shows the numerically simulated flow field velocity contour of ambient air entering a conventional indirect evaporative cooler. Due to the lack of diverter plate 53, large vortices form on either side of the conventional indirect evaporative cooler. These vortices ineffectively flow through the vortices, preventing effective heat exchange with indirect evaporative cooling pipe 4. Furthermore, the vortices increase the flow resistance and energy consumption of the ambient air. Furthermore, due to the lack of diverter plate 53, the ambient air only contacts and exchanges heat with approximately half the length of indirect evaporative cooling pipe 4, significantly impacting the heat exchange area and heat transfer capacity. Figure 5(b) shows a numerically simulated velocity contour of the flow field after ambient air enters the indirect evaporative cooler of this embodiment. Due to the presence of diverter plate 53, ambient air enters the indirect evaporative cooler of this embodiment and is smoothly deflected upward, without forming large vortices on the left or right sides. The airflow is stable, significantly reducing the flow resistance of the ambient air compared to conventional indirect evaporative coolers, thereby lowering energy consumption. Furthermore, due to the presence of diverter plate 53, ambient air enters the indirect evaporative cooler of this embodiment and contacts various locations outside the indirect evaporative cooling pipe 4, exchanging heat with the pipe for approximately two-thirds of its length. Compared to conventional indirect evaporative coolers, the contact length and area between the ambient air and the indirect evaporative cooling pipe 4 of this embodiment is increased by 33%, resulting in a correspondingly significant increase in heat exchange. Comparing only the differences caused by the presence of diverter plate 53 and the absence of diverter plate 53, numerical simulations show that the indirect evaporative cooler of this embodiment achieves a 10.3% increase in heat exchange compared to conventional indirect evaporative coolers.

[0054] Example 2:

[0055] like Figure 6 As shown, this embodiment provides an aircraft ground air conditioning unit, including a primary module 61, a secondary module 62, a tertiary module 63, a quaternary module 64 and an air supply section 65 connected in sequence.

[0056] In this embodiment, the primary module 61 is used for primary cooling, and the primary module 61 uses the indirect evaporative cooler described in Example 1 to implement the cooling process.

[0057] The cooling water pipeline 40 of the indirect evaporative cooler is provided with two loops, and the inlets and outlets of the two loops are provided with electric valves, including a first cooling water pipeline electric valve 10, a second cooling water pipeline electric valve 11, a third cooling water pipeline electric valve 12 and a fourth cooling water pipeline electric valve 13. The four electric valves are used to control the on-off and switching of the cooling water pipeline 40.

[0058] In this embodiment, the secondary module 62 is used for secondary cooling and primary heating. The secondary module 62 includes an absorption refrigeration unit, a solar thermal collector 20 and an air-oil heat exchanger 16. The solar thermal collector 20 is connected to the absorption refrigeration unit and the air-oil heat exchanger 16 in a circular manner using a heat transfer oil pipeline 41. The solar thermal collector 20 serves as one of the heat sources of the absorption refrigeration unit. Figure 7As shown, the secondary module 62 specifically includes a solar collector 20, a thermal oil pump 23, a generator 27, a primary condenser 25, an expansion valve 32, a primary evaporator 18, a conductivity meter 50, an absorber 26, a flow sensor 57, a second solution temperature sensor 55, a solution heat exchanger 29, a solution pump 28, a solution concentration sensor 56, a first solution temperature sensor 54, a first electric sealed air valve 17, a second electric sealed air valve 19, an air-oil heat exchanger 16, a first thermal oil pipeline electric valve 14, a second thermal oil pipeline electric valve 15, a third thermal oil pipeline electric valve 21, a fourth thermal oil pipeline electric valve 22, a thermal oil pipeline temperature sensor 24 and a thermal oil heat exchange coil 52.

[0059] The solar thermal collector 20 is of concentrating type and made of frosted material to prevent reflection from affecting the pilot's sight. The internal heat collecting medium is thermal oil. The solar thermal collector 20, thermal oil pump 23, thermal oil heat exchange coil 52, gas-oil heat exchanger 16, first thermal oil pipeline electric valve 14, second thermal oil pipeline electric valve 15, third thermal oil pipeline electric valve 21, fourth thermal oil pipeline electric valve 22 and thermal oil pipeline temperature sensor 24 are connected through thermal oil pipeline 41. Thermal oil pipeline 41 is used for the circulation of thermal oil. The oil heat exchange coil 52 is arranged in the internal solution of the generator 27. The thermal oil heat exchange coil 52 is used to heat the internal solution of the generator 27. The thermal oil pipeline temperature sensor 24 controls the connection and disconnection of the thermal oil pipeline 41 and the thermal oil heat exchange coil 52 or the gas-oil heat exchanger 16 according to the collected temperature of the thermal oil; and switches the winter and summer operating conditions of the thermal oil pipeline 41 by controlling the on and off of the first thermal oil pipeline electric valve 14, the second thermal oil pipeline electric valve 15, the third thermal oil pipeline electric valve 21 and the fourth thermal oil pipeline electric valve 22.

[0060] The thermal oil pipeline 41 between the solar collector 20 and the thermal oil heat exchange coil 52 is connected or shut off through the second thermal oil pipeline electric valve 15 and the third thermal oil pipeline electric valve 21, and the thermal oil pipeline 41 between the solar collector 20 and the gas-oil heat exchanger 16 is connected or shut off through the first thermal oil pipeline electric valve 14 and the fourth thermal oil pipeline electric valve 22. During cooling, the solar collector 20 is connected to the thermal oil heat exchange coil 52. At this time, the first thermal oil pipeline electric valve 14 is closed, the second thermal oil pipeline electric valve 15 is opened, the fourth thermal oil pipeline electric valve 22 is closed, and the third thermal oil pipeline electric valve 21 is opened. During heating, the opposite is true. At that time, the solar collector 20 and the gas-oil heat exchanger 16 are connected.

[0061] The first electric airtight damper 17 and the second electric airtight damper 19 are arranged vertically and placed at the front of the secondary module 62, blocking the air conditioning air supply duct 49. The air-oil heat exchanger 16 and the first-stage evaporator 18 are arranged vertically and placed behind the first electric airtight damper 17 and the second electric airtight damper 19. The fresh air inlets of the air-oil heat exchanger 16 and the first-stage evaporator 18 are connected to the outlets of the first electric airtight damper 17 and the second electric airtight damper 19, respectively. The rear end of the first electric airtight damper 17 is connected to the air-oil heat exchanger 16, and the rear end of the second electric airtight damper 19 is connected to the first-stage evaporator 18. The air flow through the channel is controlled by controlling the opening and closing of the first electric airtight damper 17 and the second electric airtight damper 19, thereby switching between winter and summer operating conditions.

[0062] The solution outlet of the generator 27, the solution concentration sensor 56, the absorber 26, the flow sensor 57, the solution pump 28, the solution heat exchanger 29 and the solution inlet of the generator 27 are connected in sequence through the solution pipe 43 to form a solution circulation pipeline; the water vapor outlet of the generator 27, the solenoid valve 51, the primary condenser 25, the expansion valve 32, the primary evaporator 18, the conductivity meter 50 and the water vapor inlet of the absorber 26 are connected in sequence through the steam-water pipe 58; the absorber 26 and the primary condenser 25 are both connected to the cooling water pipe 40, and the heat of the absorber 26 and the primary condenser 25 is taken away through the cooling water pipe 40, thereby improving the cooling efficiency of the secondary module 62 and reducing energy consumption. The heat taken away is eventually dissipated through the evaporation of the external cooling water of the indirect evaporative cooling pipe 4.

[0063] like Figure 8 and Figure 9 As shown, generator 27 includes a closed housing 59, within which is disposed a silicone rubber bladder 60 containing a solution. The inner bladder 60 and the outer bladder 59 form a pneumatic cylinder-like structure. The top of the inner bladder 60 is open, and the bottom of the inner bladder 60 is slidably sealed against the inner wall of the outer bladder 59. A solution outlet is provided at the bottom of the inner bladder 60 of the generator 27, which is connected to the exterior of the outer bladder 59 of the generator 27 via a solution outlet pipe. The solution outlet pipe is a retractable carbon steel pipe. The top of the outer bladder 59 of the generator 27 is provided with a solution inlet and a water vapor outlet. A heat transfer oil heat exchange coil 52 is connected to the heat transfer oil pipe 41 and is located within the generator 27, immersed in the solution within the inner bladder 60 of the generator 27. The secondary condenser 31 is located within the generator 27, immersed in the solution within the inner bladder 60 of the generator 27. The tops of the heat transfer oil heat exchange coil 52 and the secondary condenser 31 are at different heights, but the bottoms are at the same height.

[0064] The inner liner 60 of the generator 27 moves up and down within the outer shell 59 to maintain a constant water vapor pressure above the liquid surface of the solution in the inner liner. This constant pressure adjusts the height of the inner liner 60, thereby adjusting the solution level, and then adjusting the immersion depth of the secondary condenser 31 in the solution, ultimately achieving the purpose of regulating the amount of heat applied to the solution by the secondary condenser 31. The amount of heat applied to the solution is proportional to the immersion depth of the secondary condenser 31 in the solution. The solution pump 28 is a fixed-frequency pump. A solution concentration sensor 56 and a first solution temperature sensor 54 are provided on the solution pipe 43 at the bottom outlet of the generator 27. A flow sensor 57 and a second solution temperature sensor 55 are provided on the solution pipe 43 at the outlet of the absorber 26.

[0065] In this embodiment, a first temperature sensor 44 is provided between the primary module 61 and the secondary module 62. A second temperature sensor 45 is provided behind the gas-oil heat exchanger 16 and the primary evaporator 18.

[0066] In this embodiment, the three-stage module 63 is used for tertiary cooling. The three-stage module 63 adopts a steam compression refrigeration unit, which includes a compressor 30, a secondary condenser 31, a liquid storage tank 33, a secondary evaporator 34 and a gas-liquid separator 35 connected in sequence through a refrigerant pipe 36.

[0067] In this embodiment, the fourth-stage module 64 is used for secondary heating. The fourth-stage module 64 adopts the electric heater 37 to heat the fresh air through the electric heater 37. A third temperature sensor 46 is provided between the third-stage module 63 and the fourth-stage module 64.

[0068] In this embodiment, the air supply section 65 includes a fourth temperature sensor 47, a blower 38, and a fresh air supply port 39. The blower 38 is connected from the interior of the aircraft ground air conditioning unit to the fresh air inlet 1. The fresh air supply port 39 can be connected to an air supply hose or other equipment external to the aircraft ground air conditioning unit to supply processed fresh air to the aircraft. The fresh air is sucked into the fresh air inlet 1 by the blower 38 and enters the air conditioning supply duct 49.

[0069] In this embodiment, an air conditioning air supply duct 49 is provided inside the aircraft ground air conditioning unit, which extends from the front end to the rear end. The interior of the indirect evaporative cooling duct 4, the primary evaporator 18, the air-oil heat exchanger 16, the secondary evaporator 34, the electric heater 37 and the blower 38 are all located in the air conditioning air supply duct 49. Equipment components other than the above-mentioned equipment components are separated from the air conditioning air supply duct 49 by partitions.

[0070] The specific workflow of the cooling mode of this embodiment is as follows: At the start of operation, the evaporative cooling exhaust fan 5 is turned on, drawing ambient air in through the secondary air inlet 2. The cooling water pump 8 is turned on, the first cooling water pipeline electric valve 10 and the third cooling water pipeline electric valve 12 are opened, and the second cooling water pipeline electric valve 11 and the fourth cooling water pipeline electric valve 13 are closed. The cooling water in the water collection tray 42 is pumped to the water sprayer 7, and then sprayed onto the outside of the indirect evaporative cooling pipe 4 through the water sprayer 7. The air supply fan 38 is turned on, drawing fresh air into the air conditioning supply channel 49 through the fresh air inlet 1 and into the interior of the indirect evaporative cooling pipe 4. The ambient air causes the cooling water sprayed onto the outside of the indirect evaporative cooling pipe 4 to evaporate, absorbing heat from the fresh air in the indirect evaporative cooling pipe 4, thereby cooling the fresh air.

[0071] Specifically, a baffle 48 is placed between the fresh air inlet 1 and the secondary air inlet 2. The fresh air flows only inside the indirect evaporative cooling duct 4, and the ambient air flows outside the indirect evaporative cooling duct 4. The ambient air is discharged outside the aircraft ground air conditioning unit through the evaporative cooling exhaust fan 5. The fresh air and ambient air do not come into contact or mix.

[0072] Specifically, in order to prevent the water sprayed by the water sprayer 7 from being blown to the outside by the evaporative cooling exhaust fan 5, the present embodiment blocks the water by using the water filter 6 to reduce the ineffective loss of water.

[0073] Specifically, the cooling water flows through the water collecting tray 42, the cooling water filter 9, and the water sprayer 7 through the cooling water pump 8 to cool the fresh air.

[0074] In this embodiment, the fresh air after being cooled once by the first-level module 61 enters the second-level module 62. After the temperature reaches the set temperature through the first temperature sensor 44, the first cooling water pipeline electric valve 10 and the third cooling water pipeline electric valve 12 are closed, and the second cooling water pipeline electric valve 11 and the fourth cooling water pipeline electric valve 13 are opened to allow the cooling water to enter the absorber 26 and the first-level condenser 25, and then enter the spray water device 7. At the same time, the thermal oil pump 23 is opened, the first thermal oil pipeline electric valve 14 and the fourth thermal oil pipeline electric valve 22 are closed, the second thermal oil pipeline electric valve 15 and the third thermal oil pipeline electric valve 21 are opened, the solution pump 28 is opened, and then the first electric sealed air valve 17 is closed, and the second electric sealed air valve 19 is opened to allow the fresh air to flow through the first-level evaporator 18 for secondary cooling.

[0075] Specifically, the first cooling water pipeline electric valve 10, the second cooling water pipeline electric valve 11, the third cooling water pipeline electric valve 12, the fourth cooling water pipeline electric valve 13, the first thermal oil pipeline electric valve 14, the second thermal oil pipeline electric valve 15, the third thermal oil pipeline electric valve 21 and the fourth thermal oil pipeline electric valve 22 all use solenoid valves.

[0076] Specifically, the solution may be a lithium bromide-water solution, and the solution flows between the generator 27 , the absorber 26 and the solution heat exchanger 29 through the action of the solution pump 28 .

[0077] Specifically, the thermal oil pump 23 flows between the concentrating solar collector 20 and the thermal oil heat exchange coil 52 located inside the generator 27. The thermal oil heats up in the concentrating solar collector 20 and then enters the thermal oil heat exchange coil 52 inside the generator 27, transferring heat to the solution in the generator 27, vaporizing the water in the solution into high-pressure, high-temperature water vapor. This high-pressure, high-temperature water vapor then flows to the primary condenser 25, where it is cooled by the cooling water, releasing heat and condensing into a high-pressure liquid. This liquid is then throttled by the expansion valve 32 and converted into a low-pressure, low-temperature gas-liquid two-phase flow. The liquid enters the coil of the primary evaporator 18, where it evaporates and absorbs heat, removing heat from the fresh air outside the coil, thereby cooling the fresh air. Finally, the low-temperature, low-pressure water vapor passes through the water vapor inlet of the absorber 26 and enters the coil of the absorber 26. After being cooled by the cooling water outside the coil of the absorber 26, it is dissolved again in the solution inside the coil of the absorber 26. After the solution is pressurized by the solution pump 28, it passes through the solution heat exchanger 29 and finally returns to the generator 27, and the cycle repeats.

[0078] Specifically, the heat transfer oil heat exchange coil 52 transfers heat to the solution in the generator 27, causing the water in the solution in the generator 27 to vaporize into high-pressure and high-temperature water vapor. At this time, the temperature and concentration of the solution in the generator 27 are increased, becoming a high-temperature concentrated solution. The high-temperature concentrated solution enters the solution heat exchanger 29 under the action of the solution pump 28, exchanges heat with the low-temperature dilute solution from the absorber 26, and then enters the absorber 26, absorbs the low-temperature and low-pressure water vapor from the first-level evaporator 18, forms a low-temperature dilute solution, enters the solution heat exchanger 29, and finally returns to the generator 27, and repeats the cycle.

[0079] Specifically, after the four electric valves of the cooling water pipeline are switched, the cooling water flows through the cooling water pump 8 between the water collection tray 42, the cooling water filter 9, the absorber 26, the first-stage condenser 25 and the outside of the indirect evaporative cooling pipe 4, not only taking away the heat of the fresh air, but also taking away the heat of the absorber 26 and the first-stage condenser 25.

[0080] In this embodiment, the fresh air after secondary cooling in the first-stage evaporator 18 enters the third-stage module 63. After the temperature is measured by the second temperature sensor 45 and reaches the set temperature, the compressor 30 is turned on to start the third-stage module 63. After the fresh air enters the second-stage evaporator 34, it is cooled again.

[0081] After the third-stage module 63 is turned on, the heat generated by the secondary condenser 31 inside the generator 27 is also transferred to the solution in the generator 27, vaporizing the water in the solution into high-pressure, high-temperature water vapor. This high-pressure, high-temperature water vapor then flows to the primary condenser 25, where it is cooled by the cooling water there, releasing heat and condensing into a high-pressure liquid. This high-pressure, high-temperature water vapor then passes through the expansion valve 32, transforming into a low-pressure, low-temperature gas-liquid two-phase flow. It then enters the coils of the primary evaporator 18, where it evaporates and absorbs heat, removing heat from the fresh air outside the coils of the primary evaporator 18, further cooling the fresh air. Finally, the low-temperature, low-pressure water vapor enters the coils of the absorber 26, where it is cooled by the cooling water outside the absorber 26 coils and redissolved into the solution inside the absorber 26 coils. After being pressurized by the solution pump 28, it passes through the solution heat exchanger 29 and returns to the generator 27, repeating the cycle.

[0082] In this embodiment, after the third temperature sensor 46 measures the temperature of the tertiary module 63 , the refrigeration output of the tertiary module 63 is adjusted by adjusting the rotation speed of the compressor 30 .

[0083] like Figure 10 As shown, the bold line represents the psychrometric diagram for the cooling process of the aircraft ground air conditioning system of this embodiment. Point W represents the state of outdoor air in summer, point W1 represents the state after cooling by the first-stage module 61, point W2 represents the state after cooling by the second-stage module 62, and point O represents the state after cooling by the third-stage module 63. The thin line represents the cooling process of a conventional aircraft ground air conditioning system, which uses vapor compression refrigeration to process fresh air from point W to point O. The enthalpy corresponding to point W is 58 kJ / (kg·°C), point W1 represents 54 kJ / (kg·°C), point W2 represents 44 kJ / (kg·°C), and point O represents 12 kJ / (kg·°C). During the cooling process from point W to point W1 in this embodiment, the cooling capacity provided by the indirect evaporative cooler is utilized, fully utilizing the energy of dry air and achieving an energy efficiency approximately three times that of a conventional vapor compression refrigeration unit. During the cooling process from point W1 to point W2 in the aircraft ground air conditioning unit of this embodiment, the cooling capacity provided by the absorption refrigeration unit is utilized. The heat sources of the absorption refrigeration unit are the solar collector 20 and the secondary condenser 31 in the tertiary module 63, both of which are free energy sources. Therefore, compared with conventional units, the aircraft ground air conditioning unit of this embodiment utilizes multiple free energy sources, significantly reducing energy consumption.

[0084] The specific workflow for the heating mode of this embodiment is as follows: At the start of operation, the blower 38 is turned on, allowing fresh air to enter the air conditioning supply duct 49 through the fresh air inlet 1. The evaporative cooling exhaust fan 5 and cooling water pump 8 in the first-stage module 61 are turned off, and the first cooling water pipeline electric valve 10, second cooling water pipeline electric valve 11, third cooling water pipeline electric valve 12, and fourth cooling water pipeline electric valve 13 are closed, so that the first-stage module 61 is not in operation. Simultaneously, the thermal oil pump 23 is turned on, the first thermal oil pipeline electric valve 14 and fourth thermal oil pipeline electric valve 22 are opened, the second thermal oil pipeline electric valve 15 and third thermal oil pipeline electric valve 21 are closed, and the solution pump 28 is turned off, so that the cooling mode of the second-stage module 62 is turned off. Then, the first electric airtight air valve 17 is opened, and the second electric airtight air valve 19 is closed, allowing fresh air to flow through the air-oil heat exchanger 16 for heating.

[0085] Specifically, the heat collected by the concentrating solar collector 20 is transferred to the heat transfer oil, which enters the gas-oil heat exchanger 16 through the heat transfer oil pipeline 41 and transfers the heat to the fresh air, so that the fresh air is heated once.

[0086] When the fresh air temperature after the secondary module 62 measured by the second temperature sensor 45 is lower than the set temperature, the power of the electric heater 37 of the fourth module 64 is adjusted so that the final air outlet temperature meets the requirement.

[0087] like Figure 11 The figure shows the psychrometric diagram for the heating process of the aircraft ground air conditioning system of this embodiment. Point W represents the outdoor air state in winter, point W1 represents the state after preheating by the secondary module 62, and point O represents the state after heating by the quaternary module 64. Conventional aircraft ground air conditioning systems use electric heaters to heat the outdoor air from point W to point O. The enthalpy corresponding to point W is 11 kJ / (kg·°C), the enthalpy corresponding to point W1 is 14 kJ / (kg·°C), and the enthalpy corresponding to point O is 51 kJ / (kg·°C). The heating process of the aircraft ground air conditioning system of this embodiment uses free heat from the solar collector 20 from point W to point W1. Therefore, compared with conventional aircraft ground air conditioning systems, the heating energy consumption of this embodiment is expected to be reduced by (14-11) / (51-11) = 7.5%.

[0088] Example 3:

[0089] This embodiment provides a control method for an aircraft ground air conditioning unit, which is applied to the aircraft ground air conditioning unit provided in Example 2. The control method for the aircraft ground air conditioning unit includes the following steps:

[0090] Refrigeration conditions:

[0091] Before connecting the machine, first turn on the cooling water pump 8 and the evaporative cooling exhaust fan 5, start the first-level module 61, and turn on the blower 38 to cool the fresh air.

[0092] Specifically, before connecting the machine, open the first cooling water pipeline electric valve 10 and the third cooling water pipeline electric valve 12, and close the second cooling water pipeline electric valve 11 and the fourth cooling water pipeline electric valve 13.

[0093] After the first temperature sensor 44 measures the temperature, when the fresh air temperature reaches the preset temperature, the thermal oil pump 23 is turned on, the first cooling water pipeline electric valve 10 and the third cooling water pipeline electric valve 12 are closed, and the second cooling water pipeline electric valve 11 and the fourth cooling water pipeline electric valve 13 are opened to start the secondary module 62 to perform secondary cooling.

[0094] Specifically, the first electric airtight air valve 17 is closed and the second electric airtight air valve 19 is opened at the same time, so that the fresh air flows through the primary evaporator 18 for secondary cooling.

[0095] The fresh air after secondary cooling in the primary evaporator 18 of the secondary module 62 enters the tertiary module 63. After the temperature is measured by the second temperature sensor 45 and reaches the preset temperature, the compressor 30 is turned on to start the operation of the tertiary module 63. After the fresh air enters the secondary evaporator 34, the fresh air is cooled three times.

[0096] Specifically, after the third temperature sensor 46 measures the temperature of the tertiary module 63 , the refrigeration output of the tertiary module 63 is adjusted by adjusting the rotation speed of the compressor 30 .

[0097] After normal operation, when the air temperature after the first-level module 61 is higher than the set temperature, the speed of the cooling water pump 8 and the evaporative cooling exhaust fan 5 is increased by controlling to increase the cooling output of the first-level module 61 until the treated air temperature meets the requirements.

[0098] When the temperature indicated by the thermal oil pipeline temperature sensor 24 is higher than the set temperature, it indicates that the solar illumination on that day is higher than the predetermined value. At this time, the output of the secondary module 62 is increased by increasing the rotation speed of the thermal oil pump 23 .

[0099] When the temperature indicated by the thermal oil pipeline temperature sensor 24 is lower than the set temperature, it indicates that the solar illumination on that day is low and does not meet the requirements of the operating energy efficiency ratio. The thermal oil pump 23 is turned off, and the flow of thermal oil in the thermal oil pipeline 41 and the thermal oil heat exchange coil 52 is cut off. When the medium temperature in the thermal oil pipeline 41 is higher than the set temperature, the thermal oil pump 23 is turned on again, and the thermal oil pipeline 41 and the thermal oil heat exchange coil 52 are reconnected.

[0100] When the wind temperature after the three-stage module 63 is higher than the set temperature, the output of the three-stage module 63 is increased by increasing the speed of the compressor 30 in the three-stage module 63 to meet the wind temperature requirement after the three-stage module 63.

[0101] Specifically, after the secondary module 62 is operating normally, when the conductivity meter 50 on the outlet pipe of the first-stage evaporator 18 measures that there is liquid water in the outlet pipe of the first-stage evaporator 18, it means that the first-stage evaporator 18 has not completely evaporated the incoming liquid water, which means that the cooling load demand of the first-stage evaporator 18 is decreasing; at this time, the signal sent by the conductivity meter 50 is used to reduce the opening of the solenoid valve 51 on the water vapor outlet pipe of the generator 27.

[0102] After the opening of the solenoid valve 51 is reduced, the flow rate of high-pressure water vapor entering the primary condenser 25 is reduced, and the water vapor generated in the generator 27 will gather, causing the pressure above the liquid surface of the solution in the inner tank 60 of the generator 27 to increase, pushing the inner tank 60 of the generator 27 downward, so that the secondary condenser 31 is exposed to the solution surface. Figure 8 As shown, the amount of heating of the solution by the secondary condenser 31 is reduced. As the amount of heating of the solution gradually decreases, the outlet pressures of the secondary condenser 31 and the compressor 30 gradually increase.

[0103] Specifically, when the outlet pressure of the compressor 30 reaches 90% of the overpressure alarm pressure, the power of the compressor 30 is reduced.

[0104] As the amount of heat applied to the solution gradually decreases, the amount of solution evaporated from the generator 27 also decreases. At this time, the conductivity meter 50 on the outlet pipe of the first-stage evaporator 18 measures that the liquid water there gradually decreases until it disappears. The opening of the solenoid valve 51 is increased to increase the flow of high-pressure steam from the generator 27 into the first-stage condenser 25. The pressure above the liquid surface of the solution in the inner tank 60 of the generator 27 will decrease accordingly, and the inner tank 60 will move upward, so that the second-stage condenser 31 will be immersed in the solution again to continue heating the solution to promote the evaporation of the solution. Figure 9 As shown, the outlet pressures of the secondary condenser 31 and the compressor 30 gradually decrease.

[0105] When the outlet pressure of the compressor 30 drops to 110% of the minimum allowable pressure, the power of the compressor 30 is increased, and the cycle repeats.

[0106] During the entire process, the thermal oil heat exchange coil 52 is always completely immersed in the solution, which is used to ensure the output of the aircraft ground air conditioning unit at low load, avoid low-load operation of the compressor 30, and realize independent, rapid and stepless adjustment of the cooling capacity of the absorption refrigeration unit, while significantly reducing the frequent adjustment of the power of the compressor 30 and low-load operation.

[0107] Heating conditions:

[0108] When the operating mode of the aircraft ground air conditioning unit is switched from cooling to heating, the cooling water pump 8 and the evaporative cooling exhaust fan 5 are turned off, the first cooling water pipeline electric valve 10, the second cooling water pipeline electric valve 11, the third cooling water pipeline electric valve 12 and the fourth cooling water pipeline electric valve 13 are closed, the first module 61 is closed, the first thermal oil pipeline electric valve 14 and the fourth thermal oil pipeline electric valve 22 are opened, the second thermal oil pipeline electric valve 15 and the third thermal oil pipeline electric valve 21 are closed, the solution pump 28 is turned off, the thermal oil pump 23 is opened, the first electric airtight air valve 17 is opened, the second electric airtight air valve 19 is closed, the fresh air is allowed to flow through the air-oil heat exchanger 16 for heating, and the heating function of the second module 62 is turned on.

[0109] When the temperature indicated by the thermal oil pipeline temperature sensor 24 is higher than the set temperature, it indicates that the solar illumination on that day is higher than the predetermined value. At this time, the heating output of the secondary module 62 is increased by increasing the rotation speed of the thermal oil pump 23 .

[0110] When the temperature indicated by the thermal oil pipeline temperature sensor 24 is lower than the fresh air temperature measured by the first temperature sensor 44, it indicates that the solar illumination on that day is too low. At this time, the thermal oil pump 23 is turned off, and the gas-oil heat exchanger 16 is turned off to reduce the ineffective loss of fresh air heat.

[0111] When the second temperature sensor 45 measures that the temperature of the fresh air after passing through the secondary module 62 is lower than the set temperature, the power of the electric heater 37 of the fourth module 64 is increased so that the final outlet air temperature meets the requirement.

[0112] Specifically, the control system adopted by the control method of the aircraft ground air conditioning unit in this embodiment is a PLC control system.

[0113] Example 4:

[0114] This embodiment provides a control method for preventing solution crystallization in the solution heat exchanger 29. The control method is applied to the aircraft ground air conditioning unit described in Example 2 and specifically includes the following steps:

[0115] Since the water vapor pressure above the liquid surface of the solution in the inner tank 60 of the generator 27 is constant, and the concentrated solution side of the solution heat exchanger 29 is connected to the inside of the generator 27, the pressure of the concentrated solution in the solution heat exchanger 29 and the generator 27 is the same and constant. At this time, the saturated concentration of the solution is only related to the solution temperature. In this way, the traditional problem of the saturated concentration of the solution being coupled with the two factors of solution temperature and internal pressure of the generator 27 is adjusted to a problem related only to the single factor of solution temperature. The saturated concentration of the solution at different temperatures is determined. It is only necessary to ensure that the temperature of the solution at a certain concentration is not lower than the saturated temperature corresponding to the concentration to ensure that the solution does not crystallize.

[0116] The concentration of the concentrated solution at the outlet of the generator 27 is measured by a solution concentration sensor 56 provided at the outlet of the generator 27, and the saturation temperature corresponding to the concentration is calculated.

[0117] The temperature of the concentrated solution at the solution outlet of the generator 27 is measured by a first solution temperature sensor 54 provided at the solution outlet.

[0118] The flow rate of the solution pump 28 and the temperature of the dilute solution are measured respectively by the flow sensor 57 and the second solution temperature sensor 55 provided at the solution outlet of the absorber 26 .

[0119] At this point, the temperature and concentration of the concentrated solution entering solution heat exchanger 29 are known, as are the temperature and flow rate of the dilute solution entering solution heat exchanger 29. Since solution pump 28 is a fixed-frequency pump, its flow rate remains constant. Furthermore, since they are connected through the same pipeline, the flow rates of the concentrated solution and the dilute solution entering solution heat exchanger 29 are equal, thus the flow rate of the concentrated solution entering solution heat exchanger 29 is also known.

[0120] Through heat exchange calculation, the critical temperature of the dilute solution entering the solution heat exchanger 29 can be obtained.

[0121] When the temperature of the dilute solution entering the solution heat exchanger 29 is higher than the critical temperature, the outlet temperature of the concentrated solution will not be lower than the saturation temperature of the concentrated solution at its own concentration. At this time, the concentrated solution will not crystallize. The speed of the evaporative cooling exhaust fan 5 and the cooling water pump 8 should be increased to reduce the temperature of the cooling water, improve the cooling capacity of the cooling water, and thus improve the refrigeration efficiency of the unit.

[0122] When the temperature of the dilute solution entering the solution heat exchanger 29 is lower than the critical temperature, the outlet temperature of the concentrated solution will also be lower than the saturation temperature of the concentrated solution at its own concentration. At this time, the concentrated solution will crystallize. The speed of the evaporative cooling exhaust fan 5 and the cooling water pump 8 should be reduced to increase the temperature of the cooling water, reduce the cooling capacity of the cooling water, and prevent crystallization.

[0123] Ultimately, the goal of reducing the crystallization of concentrated solution in the solution heat exchanger 29 is achieved by accurately controlling the cooling water temperature while ensuring the refrigeration efficiency of the unit, and the cooling water temperature is neither conservatively increased nor aggressively lowered.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An aircraft ground air conditioning unit, characterized in that: It includes a primary module (61), a secondary module (62), a tertiary module (63), a quaternary module (64) and an air supply section (65); The first-stage module (61), the second-stage module (62), the third-stage module (63), the fourth-stage module (64) and the air supply section (65) are sequentially connected via the air-conditioning air supply channel (49), and the first-stage module (61) includes an indirect evaporative cooler; The indirect evaporative cooler includes a plurality of indirect evaporative cooling pipes (4); All the indirect evaporative cooling pipes (4) are arranged in a plurality of horizontal rows, a plurality of indirect evaporative cooling pipes (4) are arranged at intervals in each row, and the indirect evaporative cooling pipes (4) between adjacent horizontal rows are arranged in a staggered manner; The left and right sides of the cross section of the indirect evaporative cooling pipe (4) are respectively provided with two convex arcs (66) spaced apart, the bottoms of the two convex arcs (66) are respectively connected to a first concave arc (67), the convex arcs (66) and the first concave arcs (67) are tangent to each other in a smooth transition, and the bottoms of the two first concave arcs (67) are tangent to each other; the top of the cross section is a second concave arc (68), and the two ends of the second concave arc (68) are respectively connected to the tops of the two convex arcs (66); The secondary module (62) includes an absorption refrigeration unit, a solar heat collector (20) and an air-oil heat exchanger (16). The solar heat collector (20) is connected to the absorption refrigeration unit and the air-oil heat exchanger (16) in a circular manner using a heat transfer oil pipeline (41). The cooling water pipeline (40) is connected to the absorption refrigeration unit. The absorption refrigeration unit includes a generator (27); a solution outlet of the generator (27) is connected to an absorber (26), a solution pump (28), a solution heat exchanger (29) and a solution inlet of the generator (27) in sequence through a solution pipeline (43), thereby forming a solution circulation pipeline; a water vapor outlet of the generator (27) is connected to a first-stage condenser (25), a first-stage evaporator (18) and a water vapor inlet of the absorber (26) in sequence through a steam-water pipeline (58); the absorber (26) and the first-stage condenser (25) are both connected to a cooling water pipeline (40); a heat transfer oil pipeline (41) is connected to the generator (27); The third-stage module (63) adopts a steam compression refrigeration unit; the fourth-stage module (64) adopts an electric heater (37); the air supply section (65) includes a blower (38) and a fresh air supply port (39), and the fresh air supply port (39) is connected to the outside of the aircraft ground air conditioning unit; The vapor compression refrigeration unit includes a compressor (30), a secondary condenser (31), a liquid storage device (33), a secondary evaporator (34), and a gas-liquid separator (35) which are cyclically connected in sequence; The generator (27) includes a closed shell (59), an inner liner (60) is provided in the shell (59), a solution is provided in the inner liner (60), the top of the inner liner (60) is open, and the bottom of the inner liner (60) is slidingly sealed with the inner wall of the shell (59). A solution outlet is provided at the bottom of the inner liner (60) of the generator (27), and the solution outlet is connected to the outside of the shell (59) of the generator (27) by a solution outlet pipe. The part of the heat transfer oil pipe (41) connected to the generator (27) and the secondary condenser (31) are both located in the inner liner (60).

2. The aircraft ground air conditioning unit according to claim 1, characterized in that: The vertical direction of the cross section of the indirect evaporative cooling pipe (4) is the long axis, and the horizontal direction is the short axis. The radii of the outer convex arc (66) and the first inner concave arc (67) are both 10 to 12 times the length of the short axis, and the radius of the second inner concave arc (68) is 0.25 to 0.5 times the length of the short axis.

3. The aircraft ground air conditioning unit according to claim 1, characterized in that: The indirect evaporative cooler further comprises a fresh air inlet (1), a secondary air inlet (2), an air filter (3), an evaporative cooling exhaust fan (5), a water filter (6), a water sprayer (7), a water collecting tray (42) and a cooling water pipeline (40); the outlets of the fresh air inlet (1) and the secondary air inlet (2) are both connected to the air filter (3); the evaporative cooling exhaust fan (5), the water filter (6), the water sprayer (7), the indirect evaporative cooling pipeline (4) and the water collecting tray (42) are arranged in sequence from top to bottom; the indirect evaporative cooling pipeline (4) is located at the outlet of the air filter (3); the fresh air inlet (1) is connected to the inside of the indirect evaporative cooling pipeline (4); the secondary air inlet (2) is connected to the outside of the indirect evaporative cooling pipeline (4) and the evaporative cooling exhaust fan (5); the water collecting tray (42) is connected to the water inlet of the cooling water pipeline (40); and the water sprayer (7) is connected to the water outlet of the cooling water pipeline (40).

4. The aircraft ground air conditioning unit according to claim 3, characterized in that: Below the indirect evaporative cooling pipe (4), a plurality of diverter plates (53) of different lengths are arranged along the height direction, each diverter plate (53) is arranged tilted along the horizontal direction, and each diverter plate (53) is located behind the secondary air inlet (2).

5. The aircraft ground air conditioning unit according to claim 4, characterized in that: The diverter plates (53) are all provided with a slope, and the slope direction is consistent with the air inlet direction.

6. A control method for an aircraft ground air conditioning unit according to any one of claims 1 to 5, characterized in that: The following processes are included: Under the refrigeration condition, the indirect evaporative cooler, the absorption refrigeration unit and the vapor compression refrigeration unit are turned on in sequence, and the gas-oil heat exchanger (16) and the electric heater (37) are turned off; When the temperature of the medium in the heat transfer oil pipeline (41) is higher than the set temperature, the flow rate of the medium in the heat transfer oil pipeline (41) is increased; when the temperature of the medium in the heat transfer oil pipeline (41) is lower than the set temperature, the connection between the heat transfer oil pipeline (41) and the absorption refrigeration unit is cut off; when the temperature of the medium in the heat transfer oil pipeline (41) is higher than the set temperature, the heat transfer oil pipeline (41) and the absorption refrigeration unit are reconnected; Under the heating condition, the gas-oil heat exchanger (16) and the electric heater (37) are turned on, and the indirect evaporative cooler, the absorption refrigeration unit and the vapor compression refrigeration unit are turned off; When the temperature of the medium in the heat transfer oil pipeline (41) is higher than the set temperature, the flow rate of the medium in the heat transfer oil pipeline (41) is increased. When the temperature of the medium in the heat transfer oil pipeline (41) is lower than the temperature of the fresh air after passing through the indirect evaporative cooler, the gas-oil heat exchanger (16) is closed and the power of the electric heater (37) is increased.

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