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

Abstract

The 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 of the aircraft ground air conditioning unit. All the indirect evaporative cooling pipelines are arranged in a plurality of transverse rows, a plurality of indirect evaporative cooling pipelines are arranged in each row at intervals, and the indirect evaporative cooling pipelines in the adjacent transverse rows are arranged in a staggered mode; the left side and the right side of the cross section of the indirect evaporative cooling pipeline are respectively provided with two convex arcs which are arranged at an interval, the bottoms of the two convex arcs are respectively connected with a first concave arc, the convex arcs and the first concave arcs are tangent and in smooth transition, 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 connected with the tops of the two convex arcs respectively. Ambient air and cooling water for cooling are tightly attached to the whole outer wall of the indirect evaporative cooling pipeline, the heat exchange effect is enhanced, and wind resistance is reduced.

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 required air. Its working principle is to use outdoor ambient air to promote the evaporation of cooling water sprayed on the outside of the indirect evaporative cooling pipe, absorb the heat of the required air inside the indirect evaporative cooling pipe, and achieve the purpose of cooling the required air. At present, the structural forms of traditional indirect evaporative cooling pipes are round tube type and elliptical tube type.

[0003] For traditional indirect evaporative cooling pipes, their circular or elliptical structural forms often cause cooling water droplets to directly hit the outer wall of the indirect evaporative cooling pipe below from the outer wall of a certain indirect evaporative cooling pipe. Subsequently, it is 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 collecting tray, resulting in waste of cooling water volume and reduction of heat exchange efficiency. At the same time, this structural form also causes flow separation when ambient air flows upward through the indirect evaporative cooling pipe, generating an obvious eddy current area, which cannot adhere to the upper half of the outer wall of the pipe, and then cannot take away the heat on the upper half of the outer wall of the pipe, not only affecting the heat exchange efficiency, but also increasing the wind resistance. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art, and provide an indirect evaporative cooler, an aircraft ground air-conditioning unit and a control method thereof, so that the ambient air and water for cooling closely adhere to the entire outer wall of the indirect evaporative cooling pipe, increase the contact area between the ambient air and the indirect evaporative cooling pipe, increase the heat exchange effect, and reduce the wind resistance.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: An indirect evaporative cooler includes a plurality of indirect evaporative cooling pipes; All the indirect evaporative cooling pipes are arranged in several horizontal rows, and several indirect evaporative cooling pipes are arranged at intervals in each row, and the indirect evaporative cooling pipes between adjacent horizontal rows are arranged staggeredly; On the left and right sides of the cross-section of the indirect evaporative cooling pipe are respectively two outward convex arcs arranged at intervals, and the bottoms of the two outward convex arcs are respectively connected to a first inward concave arc, and the outward convex arc and the first inward concave arc are tangent and smoothly transitioned, and the bottoms of the two first inward concave arcs are tangent; the top of the cross-section is a second inward concave arc, and the two ends of the second inward concave arc are respectively connected to the tops of the two outward convex arcs.

[0006] Preferably, the vertical direction of the cross-section of the indirect evaporation cooling pipe is the major axis, and the horizontal direction is the minor axis. The radii of both the convex arc and the first concave arc are 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.

[0007] Preferably, it further includes a fresh air inlet, a secondary air inlet, an air filter, an evaporation cooling exhaust fan, a water filter, a sprayer, a water collecting tray, and a cooling water pipeline; the outlets of both the fresh air inlet and the secondary air inlet are connected to the air filter. The evaporation cooling exhaust fan, the water filter, the sprayer, the indirect evaporation cooling pipe, and the water collecting tray are arranged in sequence from top to bottom. The indirect evaporation cooling pipe is located at the outlet of the air filter. The fresh air inlet is connected to the inside of the indirect evaporation cooling pipe, and the secondary air inlet is connected to the outside of the indirect evaporation cooling pipe and the evaporation cooling exhaust fan; the water collecting tray is connected to the water inlet of the cooling water pipeline, and the sprayer is connected to the water outlet of the cooling water pipeline.

[0008] Preferably, below the indirect evaporation cooling pipe, a number of flow splitting plates with different lengths are arranged along the height direction. Each flow splitting plate is inclined along the horizontal direction, and each flow splitting plate is located behind the secondary air inlet.

[0009] Preferably, the flow splitting plates are all provided with slopes, and the slope direction is the same as the air inlet direction.

[0010] An aircraft ground air conditioning unit includes a first-stage module, a second-stage module, a third-stage module, a fourth-stage module, and a air supply section; The first-stage module, the second-stage module, the third-stage module, the fourth-stage module, and the air supply section are sequentially connected through an air conditioning air supply channel. The first-stage module includes an indirect evaporative cooler; The second-stage module includes an absorption refrigeration unit, a solar collector, and a gas-oil heat exchanger. The solar collector is respectively connected to the absorption refrigeration unit and the gas-oil heat exchanger in a circulating manner through a heat transfer oil pipeline, and the cooling water pipeline is connected to the absorption refrigeration unit; The third-stage module uses a vapor compression refrigeration unit; the fourth-stage module uses an electric heater; the air supply section includes an air supply fan and a fresh air supply outlet, and the fresh air supply outlet is connected to the outside of the aircraft ground air conditioning unit.

[0011] Preferably, the absorption refrigeration unit includes a generator; the solution outlet of the generator is sequentially connected with an absorber, a solution pump, a solution heat exchanger, and the solution inlet of the generator through a solution pipeline to form a solution circulation pipeline; the steam outlet of the generator is sequentially connected with a first-stage condenser, a first-stage evaporator, and the steam inlet of the absorber through a steam-water pipeline; both the absorber and the first-stage condenser are connected with a cooling water pipeline; the heat transfer oil pipeline is connected to the generator.

[0012] Preferably, the vapor compression refrigeration unit includes a compressor, a second-stage condenser, a liquid receiver, a second-stage evaporator, and a gas-liquid separator that are sequentially connected in a cycle.

[0013] Preferably, the generator includes a closed outer shell, an inner shell is arranged in the inner shell, a solution is arranged in the inner shell, the top of the inner shell is open, the bottom of the inner shell is slidingly sealed with the inner wall of the outer shell, a solution outlet is arranged at the bottom of the inner shell of the generator, the solution outlet is connected to the outside of the outer shell of the generator by a solution outlet pipe, and the part of the heat transfer oil pipe connected to the generator and the secondary condenser are both located in the inner shell.

[0014] A control method for the aircraft ground air conditioning unit includes the following steps: Under refrigeration conditions, the indirect evaporative cooler, absorption refrigeration unit and steam compression refrigeration unit are turned on in sequence, and the gas-oil heat exchanger and electric heater are turned off; 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; 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; When the medium temperature in the heat transfer oil pipeline is higher than the set temperature, the medium flow rate in the heat transfer oil pipeline is increased. When the medium temperature in the heat transfer oil pipeline is lower than the wind temperature of the fresh air after passing through the indirect evaporative cooler, the air-oil heat exchanger is closed and the power of the electric heater is increased.

[0015] Compared with the prior art, the present invention has the following beneficial effects: According to the present invention, the ambient air moving upward from the bottom will be closely attached to the entire outer wall of the indirect evaporative cooling pipe, and the water moving downward from the top will also be closely attached to the entire outer wall of the indirect evaporative cooling pipe. The ambient air flows through to fully evaporate the water on the outer wall of the indirect evaporative cooling pipe, and the heat of the fresh air inside the indirect evaporative cooling pipe is taken away by the evaporation latent heat, so as to avoid the flow separation and the generation of obvious eddy current areas of the ambient air when passing through the indirect evaporative cooling pipe, effectively improve the heat exchange intensity of the upper half of each indirect evaporative cooling pipe, and reduce the wind resistance at the same time. The second concave arc at the top of the indirect evaporative cooling pipe is used to receive the water droplets dropped from the indirect evaporative cooling pipe above the pipe. Due to the turbulence of the ambient air caused by the second concave arc, the water received by the second concave arc will smoothly overflow and adhere to the entire outer wall of the indirect evaporative cooling pipe, so as to avoid the water droplets from the upper indirect evaporative cooling pipe directly falling on the lower indirect evaporative cooling pipe, which will cause the waste of water and the reduction of heat exchange intensity.

[0016] A flow splitter plate is arranged below the indirect evaporative cooling pipeline in the present invention. After the ambient air enters the indirect evaporative cooler, it will smoothly deflect upward, with stable air flow, no large eddies will be formed, and the flow resistance will be greatly reduced. At the same time, due to the effect of the flow splitter plate, the ambient air will evenly contact different positions outside the indirect evaporative cooling pipeline after entering the indirect evaporative cooler. Compared with the traditional indirect evaporative cooler, the contact area between the ambient air and the indirect evaporative cooling pipeline and the heat transfer intensity are greatly improved.

[0017] The present invention uses an indirect evaporative cooler as the primary refrigeration, making full use of the dry air energy on the apron and improving the efficiency of the unit. An absorption refrigeration unit is used as the secondary refrigeration. By combining a solar collector and an absorption refrigeration unit, the high-temperature medium obtained based on solar energy is used as the heat source of the absorption refrigeration unit, improving the efficiency of the absorption refrigeration unit. And the combination of the solar collector and the air-oil heat exchanger is used as the primary heating, the vapor compression refrigeration unit is used as the tertiary refrigeration, and the electric heater is used as the secondary heating. Finally, the unit of the present invention realizes multi-stage refrigeration and heating, improves the efficiency of the aircraft ground air-conditioning unit, and reduces the energy consumption.

[0018] The present invention recovers and utilizes the waste heat of the vapor compression refrigeration unit as the heat source of the absorption refrigeration unit, further improving the efficiency of the absorption refrigeration unit. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the indirect evaporative cooler according to Embodiment 1 of the present invention; Figure 2 It is a schematic cross-sectional view of the indirect evaporative cooler according to Embodiment 1 of the present invention; Figure 3 It is a schematic cross-sectional view of a single indirect evaporative cooling pipeline according to Embodiment 1 of the present invention; Figure 4 It is a numerical simulation flow field velocity contour map of the traditional indirect evaporative cooling pipeline and the indirect evaporative cooling pipeline according to Embodiment 1 of the present invention set in the indirect evaporative cooler.

[0020] Figure 5 It is a numerical simulation flow field velocity contour map of the traditional indirect evaporative cooler without a flow splitter plate and the indirect evaporative cooler according to Embodiment 1 of the present invention with a flow splitter plate set.

[0021] Figure 6 It is a schematic structural diagram of the aircraft ground air-conditioning unit according to Embodiment 2 of the present invention; Figure 7 It is a schematic structural diagram of the secondary module and the tertiary module of the aircraft ground air-conditioning unit according to Embodiment 2 of the present invention; Figure 8 It is a schematic internal structure diagram of the generator according to Embodiment 3 of the present invention; Figure 9 Schematic diagram of the upward movement of the generator inner tank in Embodiment 3 of the present invention; Figure 10 Enthalpy-humidity diagram of the refrigeration process of a traditional aircraft ground air conditioner unit and the aircraft ground air conditioner unit in Embodiment 3 of the present invention; Figure 11 Enthalpy-humidity diagram of the heating process of the aircraft ground air conditioner unit in Embodiment 3 of the present invention.

[0022] Wherein: 1. Fresh air inlet, 2. Secondary air inlet, 3. Air filter, 4. Indirect evaporation cooling pipeline, 5. Evaporation cooling exhaust fan, 6. Water filter, 7. Sprinkler, 8. Cooling water pump, 9. Cooling water filter, 10. Electric valve of the first cooling water pipeline, 11. Electric valve of the second cooling water pipeline, 12. Electric valve of the third cooling water pipeline, 13. Electric valve of the fourth cooling water pipeline, 14. Electric valve of the first heat transfer oil pipeline, 15. Electric valve of the second heat transfer oil pipeline, 16. Gas-oil heat exchanger, 17. First electric airtight valve, 18. Primary evaporator, 19. Second electric airtight valve, 20. Solar collector, 21. Electric valve of the third heat transfer oil pipeline, 22. Electric valve of the fourth heat transfer oil pipeline, 23. Heat transfer oil pump, 24. Heat transfer oil pipeline temperature sensor, 25. Primary condenser, 26. Absorber, 27. Generator, 28. Solution pump, 29. Solution heat exchanger, 30. Compressor, 31. Secondary condenser, 32. Expansion valve, 33. Receiver, 34. Secondary evaporator, 35. Gas-liquid separator, 36. Refrigerant pipeline, 37. Electric heater, 38. Supply fan, 39. Fresh air supply outlet, 40. Cooling water pipeline, 41. Heat transfer oil pipeline, 42. Water collecting tray, 43. Solution pipeline, 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. Heat transfer oil heat exchange coil, 53. Flow dividing plate, 54. First solution temperature sensor, 55. Second solution temperature sensor, 56. Solution concentration sensor, 57. Flow sensor, 58. Steam-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 implementation manners

[0023] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application.

[0024] Embodiment 1: As Figure 1As shown in the figure, this embodiment provides an indirect evaporative cooler, which includes 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 sprayer 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 side by side, with the fresh air inlet 1 above the secondary air inlet 2. The outlets of both the fresh air inlet 1 and the secondary air inlet 2 are connected to the air filter 3. The indirect evaporative cooling pipe 4 is arranged at the outlet of the air filter 3. The water collecting tray 42 is arranged below the indirect evaporative cooling pipe 4. The sprayer 7 is located above the indirect evaporative cooling pipe 4. The water filter 6 is located above the sprayer 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, and 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, and the secondary air inlet 2 is connected to the outside of the indirect evaporative cooling pipe 4 and the evaporative cooling exhaust fan 5.

[0025] The evaporative cooling exhaust fan 5 sucks ambient air from the secondary air inlet 2. A baffle 48 is arranged 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 pipe 40 through the cooling water filter 9. The sprayer 7 is connected to the water outlet of the cooling water pipe 40 through the cooling water pump 8. The cooling water pipe 40 is used for the circulating flow of cooling water.

[0026] As Figure 2 shown, the number of the indirect evaporative cooling pipes 4 is multiple. From the perspective of the cross-section of the indirect evaporative cooler, multiple horizontal rows are arranged between multiple indirect evaporative cooling pipes 4, 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 arranged staggeredly.

[0027] As Figure 3As shown, the vertical direction of the cross section of the indirect evaporative cooling pipe 4 is the long axis, the horizontal direction is the short axis, the long axis length is 80mm-120mm, the short axis length is 10mm-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, and 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, and the radii of the convex arc 66 and the first concave arc 67 are both 10-12 times the length of the short 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.

[0028] The fresh air entering from the fresh air inlet 1 passes through the interior of each indirect evaporative cooling pipe 4, and the ambient air entering from the secondary air inlet 2 flows in the external gap of the adjacent indirect evaporative cooling pipe 4. Through the structural effect of the outer convex arc 66 and the first inner concave arc 67 of the indirect evaporative cooling pipe 4, the ambient air moving from bottom to top will be close to the entire outer wall of the indirect evaporative cooling pipe 4, and the water moving from top to bottom will also be close 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, so as to avoid flow separation and generation of obvious eddy current area when the ambient air passes through the indirect evaporative cooling pipe 4, thereby effectively improving the heat exchange intensity of the upper half of each indirect evaporative cooling pipe 4 and reducing the wind resistance.

[0029] Since the structure of the conventional indirect evaporative cooling pipe 4 is circular or elliptical, the ambient air flowing from bottom to top will separate and generate obvious eddy zones when passing through the indirect evaporative cooling pipe 4. In order to reduce this effect, the contact area between the ambient air and the outer surface of the indirect evaporative cooling pipe 4 can only be increased by reducing the spacing of the indirect evaporative cooling pipe 4 to achieve the purpose of strengthening heat exchange. However, reducing the spacing of the indirect evaporative cooling pipe 4 will reduce the air circulation area, which will inevitably increase the resistance of the ambient air flowing through the indirect evaporative cooling pipe 4. The indirect evaporative cooling pipe 4 of this embodiment, through the structural effect of the outer convex arc 66 and the first inner concave arc 67, makes the ambient air moving from bottom to top close to the entire outer wall of the indirect evaporative cooling pipe 4 under the action of the "Coanda effect", and the water moving from top to bottom will also close to the entire outer wall of the indirect evaporative cooling pipe 4 under the action of the "Coanda effect". This can not only improve the heat exchange intensity, but also avoid the problem of increased wind resistance caused by the reduction of the spacing of the indirect evaporative cooling pipe 4.

[0030] In this embodiment, the second concave arc 68 at the top of the indirect evaporative cooling pipe 4 is used to receive water droplets falling from the indirect evaporative cooling pipe 4 above the pipe. Due to the effect of the ambient air turbulence caused by the second concave arc 68, the water received by the second concave arc 68 will smoothly overflow and adhere to the outer wall of the indirect evaporative cooling pipe 4, avoiding the water waste caused by the water falling from the upper indirect evaporative cooling pipe 4 directly falling on the lower indirect evaporative cooling pipe 4.

[0031] like Figure 4 As shown, Figure 4 (a) is a numerical simulation flow field velocity cloud diagram of ambient air flowing outside a traditional indirect evaporative cooling pipe. Since the cross-section of a traditional indirect evaporative cooling pipe is circular, 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 outer wall of the pipe, and an obvious eddy zone is generated. The ambient air cannot adhere to the upper half of the outer wall of the pipe, and then cannot take away the heat from the upper half of the outer wall of the pipe, which not only affects the heat exchange efficiency but also increases the wind resistance. Figure 4(b) is the numerical simulation flow field velocity contour map of the ambient air flowing outside the indirect evaporation cooling pipe 4 in this embodiment. Due to the structural effects of the outward convex arc 66 and the first inward concave arc 67 of the indirect evaporation cooling pipe 4 in this embodiment, the ambient air flowing from bottom to top closely adheres to the entire outer wall of the indirect evaporation cooling pipe 4 under the action of the "Coanda effect", without flow separation and obvious eddy current areas, with smaller wind resistance and smoother flow. The ambient air contacts the entire outer wall of the pipe, effectively increasing the heat exchange area and the amount of heat exchanged. Through numerical simulation calculations, under the condition that other factors are the same, the heat exchange capacity of the indirect evaporative cooler in this embodiment is 22.5% higher than that of the traditional indirect evaporative cooler, and the flow resistance of the ambient air decreases by 26.9%, achieving excellent heat exchange and resistance reduction effects.

[0032] Below the indirect evaporation cooling pipe 4, a plurality of shunt plates 53 with different lengths are arranged along the height direction. The lengths of each shunt plate 53 from top to bottom are 1 / 6, 2 / 6, 3 / 6, 4 / 6, and 5 / 6 of the length of the indirect evaporation cooling pipe 4 respectively. Each shunt plate 53 is inclined in the horizontal direction and is located behind the secondary air inlet 2. The shunt plates 53 are used to shunt the ambient air entering from the secondary air inlet 2, so that the air evenly contacts different positions outside the indirect evaporation cooling pipe 4. The shunt plates 53 are all provided with slopes, and the slope direction is the same as the air inlet direction to facilitate drainage.

[0033] As Figure 5 shown, Figure 5 (a) is the numerical simulation flow field velocity contour map of the ambient air after entering the traditional indirect evaporative cooler. Since the shunt plates 53 are not provided, after the ambient air enters the traditional indirect evaporative cooler, a relatively large eddy current is formed on each of the left and right sides. The ambient air at these two places flows ineffectively at the eddy current areas and does not effectively exchange heat with the indirect evaporation cooling pipe 4. Moreover, the generation of the eddy current will also increase the flow resistance of the ambient air and increase energy consumption. At the same time, since the shunt plates 53 are not provided, after the ambient air enters the traditional indirect evaporative cooler, it only contacts and exchanges heat with the indirect evaporation cooling pipe 4 for about half of the length of the pipe, and the heat exchange area and the amount of heat exchanged are greatly affected. Figure 5(b) is the numerical simulation flow field velocity contour map after the ambient air enters the indirect evaporative cooler of this embodiment. Due to the installation of the flow splitter 53, after the ambient air enters the indirect evaporative cooler of this embodiment, it deflects smoothly upward without forming large eddies on the left and right sides, and the air flow is stable. Therefore, compared with the traditional indirect evaporative cooler, the flow resistance of the ambient air is greatly reduced, and the energy consumption is reduced. At the same time, due to the installation of the flow splitter 53, the ambient air enters the indirect evaporative cooler of this embodiment and contacts different positions outside the indirect evaporative cooling pipe 4 more evenly, and exchanges heat with the pipe about 2 / 3 of the length of the pipe. Compared with the traditional indirect evaporative cooler, the contact length and area between the ambient air and the indirect evaporative cooling pipe 4 of this embodiment are increased by 33%, and the heat exchange amount is also significantly increased accordingly. If only comparing the differences caused by whether the flow splitter 53 is installed or not, through numerical simulation calculation, it is obtained that the heat exchange amount of the indirect evaporative cooler of this embodiment is increased by 10.3% compared with the traditional indirect evaporative cooler.

[0034] Embodiment 2: As Figure 6 shown, this embodiment provides an aircraft ground air conditioning unit, which includes a first-stage module 61, a second-stage module 62, a third-stage module 63, a fourth-stage module 64 and a air supply section 65 connected in sequence.

[0035] In this embodiment, the first-stage module 61 is used for primary refrigeration, and the first-stage module 61 uses the indirect evaporative cooler described in Embodiment 1 to realize the refrigeration process.

[0036] The cooling water pipeline 40 of the indirect evaporative cooler is provided with two loops, and electric valves are arranged at the inlets and outlets of the two loops, 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.

[0037] In this embodiment, the second-stage module 62 is used for secondary refrigeration and primary heating. The second-stage module 62 includes an absorption refrigeration unit, a solar collector 20 and a gas-oil heat exchanger 16. The solar collector 20 is respectively connected in a cycle with the absorption refrigeration unit and the gas-oil heat exchanger 16 by a heat-conducting oil pipeline 41. The solar collector 20 is used as one of the heat sources of the absorption refrigeration unit, such as Figure 7As shown, the secondary module 62 specifically includes a solar collector 20, a heat-conducting 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 closed air valve 17, a second electric closed air valve 19, an air-oil heat exchanger 16, a first heat-conducting oil pipeline electric valve 14, a second heat-conducting oil pipeline electric valve 15, a third heat-conducting oil pipeline electric valve 21, a fourth heat-conducting oil pipeline electric valve 22, a heat-conducting oil pipeline temperature sensor 24, and a heat-conducting oil heat exchange coil 52.

[0038] The solar collector 20 is of the concentrating type and is made of frosted material to prevent reflection from affecting the pilot's line of sight. The heat-collecting medium inside it is heat-conducting oil; the solar collector 20, the heat-conducting oil pump 23, the heat-conducting oil heat exchange coil 52, the air-oil heat exchanger 16, the first heat-conducting oil pipeline electric valve 14, the second heat-conducting oil pipeline electric valve 15, the third heat-conducting oil pipeline electric valve 21, the fourth heat-conducting oil pipeline electric valve 22, and the heat-conducting oil pipeline temperature sensor 24 are connected through a heat-conducting oil pipeline 41. The heat-conducting oil pipeline 41 is used for the circulation of heat-conducting oil. The heat-conducting oil heat exchange coil 52 is arranged in the internal solution of the generator 27 and is used to heat the internal solution of the generator 27. The heat-conducting oil pipeline temperature sensor 24 controls the connection and disconnection between the heat-conducting oil pipeline 41 and the heat-conducting oil heat exchange coil 52 or the air-oil heat exchanger 16 according to the collected temperature of the heat-conducting oil; by controlling the on-off of the first heat-conducting oil pipeline electric valve 14, the second heat-conducting oil pipeline electric valve 15, the third heat-conducting oil pipeline electric valve 21, and the fourth heat-conducting oil pipeline electric valve 22, the winter and summer working conditions of the heat-conducting oil pipeline 41 are switched.

[0039] The heat-conducting oil pipeline 41 between the solar collector 20 and the heat-conducting oil heat exchange coil 52 is connected or disconnected through the second heat-conducting oil pipeline electric valve 15 and the third heat-conducting oil pipeline electric valve 21. The heat-conducting oil pipeline 41 between the solar collector 20 and the air-oil heat exchanger 16 is connected or disconnected through the first heat-conducting oil pipeline electric valve 14 and the fourth heat-conducting oil pipeline electric valve 22. When refrigerating, the solar collector 20 is connected to the heat-conducting oil heat exchange coil 52. At this time, the first heat-conducting oil pipeline electric valve 14 is closed, the second heat-conducting oil pipeline electric valve 15 is opened, the fourth heat-conducting oil pipeline electric valve 22 is closed, and the third heat-conducting oil pipeline electric valve 21 is opened. When heating, it is just the opposite. At that time, the solar collector 20 is connected to the air-oil heat exchanger 16.

[0040] The first electric airtight damper 17 and the second electric airtight damper 19 are arranged vertically at the very front of the secondary module 62, blocking the air supply channel 49 of the air conditioner. The gas-oil heat exchanger 16 and the primary evaporator 18 are arranged vertically behind the first electric airtight damper 17 and the second electric airtight damper 19. The fresh air inlets of the gas-oil heat exchanger 16 and the primary evaporator 18 are respectively connected to the outlets of the first electric airtight damper 17 and the second electric airtight damper 19. The rear end of the first electric airtight damper 17 is connected to the gas-oil heat exchanger 16, and the rear end of the second electric airtight damper 19 is connected to the primary evaporator 18. By controlling the opening and closing of the first electric airtight damper 17 and the second electric airtight damper 19, the flow channel of the air flow is controlled, thereby switching between winter and summer operating conditions.

[0041] 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 sequentially connected through the solution pipeline 43 to form a solution circulation pipeline; the steam 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 steam inlet of the absorber 26 are sequentially connected through the steam-water pipeline 58; both the absorber 26 and the primary condenser 25 are connected with the cooling water pipeline 40. The heat of the absorber 26 and the primary condenser 25 is taken away through the cooling water pipeline 40 to improve the refrigeration efficiency of the secondary module 62 and reduce energy consumption. The heat taken away is finally dissipated through the evaporation of the external cooling water in the indirect evaporative cooling pipeline 4.

[0042] As Figure 8 and Figure 9 shown, the generator 27 includes a closed outer shell 59. Inside the outer shell 59, a silicone rubber bladder-type inner liner 60 is provided. A solution is provided in the inner liner 60. The inner liner 60 and the outer shell 59 of the generator 27 form a structure similar to a pneumatic cylinder. The top of the inner liner 60 is open, and the bottom of the inner liner 60 is slidably and sealed with the inner wall of the outer shell 59. A solution outlet is provided at the bottom of the inner liner 60 of the generator 27. The solution outlet is connected to the outside of the outer shell 59 of the generator 27 through a solution outlet pipeline. The solution outlet pipeline uses a telescopic carbon steel pipe. A solution inlet and a steam outlet are provided at the top of the outer shell 59 of the generator 27. The heat-conducting oil heat exchange coil 52 is connected in parallel to the heat-conducting oil pipeline 41. The heat-conducting oil heat exchange coil 52 is located inside the generator 27 and immersed in the solution of the inner liner 60 of the generator 27. The secondary condenser 31 is located inside the generator 27 and immersed in the solution of the inner liner 60 of the generator 27. The top heights of the heat-conducting oil heat exchange coil 52 and the secondary condenser 31 are different, and the bottom heights are the same.

[0043] The inner tank 60 of the generator 27 moves up and down in the outer shell 59 to keep the water vapor pressure above the solution level in the inner tank constant. By adjusting the height of the inner tank 60 through this constant pressure, the solution level is adjusted, and then the immersion depth of the secondary condenser 31 in the solution is adjusted. Finally, the heating amount of the secondary condenser 31 to the solution is adjusted. The heating amount of the solution is proportional to the immersion depth of the secondary condenser 31 in the solution. The solution pump 28 is a constant-frequency pump. A solution concentration sensor 56 and a first solution temperature sensor 54 are provided on the solution pipeline 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 pipeline 43 at the outlet of the absorber 26.

[0044] In this embodiment, a first temperature sensor 44 is provided between the first-stage module 61 and the second-stage module 62. A second temperature sensor 45 is provided behind the gas-oil heat exchanger 16 and the first-stage evaporator 18.

[0045] In this embodiment, the third-stage module 63 is used for three-stage refrigeration. The third-stage module 63 adopts a vapor compression refrigeration unit, which includes a compressor 30, a secondary condenser 31, a liquid receiver 33, a secondary evaporator 34, and a gas-liquid separator 35 connected in sequence through a refrigerant pipeline 36.

[0046] In this embodiment, the fourth-stage module 64 is used for two-stage heating. The fourth-stage module 64 adopts an electric heater 37 to heat the fresh air. A third temperature sensor 46 is provided between the third-stage module 63 and the fourth-stage module 64.

[0047] In this embodiment, the air supply section 65 includes a fourth temperature sensor 47, a blower 38, and a fresh air supply outlet 39. The blower 38 communicates from the inside of the aircraft ground air-conditioning unit to the fresh air inlet 1. The fresh air supply outlet 39 can be connected to facilities such as an external air supply hose of the aircraft ground air-conditioning unit to supply the processed fresh air to the aircraft. The fresh air is sucked from the fresh air inlet 1 by the blower 38 and enters the air-conditioning air supply channel 49.

[0048] In this embodiment, an air-conditioning air supply channel 49 communicating from the front end to the rear end is provided inside the aircraft ground air-conditioning unit. The indirect evaporative cooling pipeline 4, the first-stage evaporator 18, the gas-oil heat exchanger 16, the secondary evaporator 34, the electric heater 37, and the blower 38 are all in the air-conditioning air supply channel 49. Equipment components other than the above-mentioned equipment components are separated from the air-conditioning air supply channel 49 by partitions.

[0049] The specific working process of the refrigeration condition in this embodiment is as follows: When starting to work, turn on the evaporative cooling exhaust fan 5, suck the ambient air through the secondary air inlet 2, turn on the cooling water pump 8, turn on the electric valve 10 of the first cooling water pipeline and the electric valve 12 of the third cooling water pipeline, close the electric valve 11 of the second cooling water pipeline and the electric valve 13 of the fourth cooling water pipeline, pump the cooling water in the water collecting tray 42 to the sprayer 7, and sprinkle it outside the indirect evaporative cooling pipeline 4 through the sprayer 7. Turn on the air supply fan 38, suck the fresh air through the fresh air inlet 1 into the air supply channel 49 of the air conditioner, and enter the inside of the indirect evaporative cooling pipeline 4. The ambient air promotes the evaporation of the cooling water sprinkled outside the indirect evaporative cooling pipeline 4, absorbs the heat of the fresh air in the indirect evaporative cooling pipeline 4, and achieves the purpose of cooling the fresh air.

[0050] Specifically, there is a baffle 48 between the fresh air inlet 1 and the secondary air inlet 2. The fresh air only flows inside the indirect evaporative cooling pipeline 4, and the ambient air flows outside the indirect evaporative cooling pipeline 4. The ambient air is discharged outside the aircraft ground air conditioner unit through the evaporative cooling exhaust fan 5. The fresh air and the ambient air do not contact or mix.

[0051] Specifically, in order to prevent the water sprayed by the sprayer 7 from being blown outside by the evaporative cooling exhaust fan 5, this embodiment blocks the water through the water filter 6 to reduce the ineffective loss of water.

[0052] Specifically, the cooling water flows between the water collecting tray 42, the cooling water filter 9, and the sprayer 7 through the cooling water pump 8 to cool the fresh air.

[0053] In this embodiment, the fresh air cooled once by the first-stage module 61 enters the second-stage module 62. After the temperature is measured by the first temperature sensor 44 and reaches the set temperature, the electric valve 10 of the first cooling water pipeline and the electric valve 12 of the third cooling water pipeline are closed, the electric valve 11 of the second cooling water pipeline and the electric valve 13 of the fourth cooling water pipeline are opened, so that the cooling water enters the absorber 26 and the first-stage condenser 25, and then enters the sprayer 7. At the same time, turn on the heat conduction oil pump 23, close the electric valve 14 of the first heat conduction oil pipeline and the electric valve 22 of the fourth heat conduction oil pipeline, open the electric valve 15 of the second heat conduction oil pipeline and the electric valve 21 of the third heat conduction oil pipeline, turn on the solution pump 28, and then close the first electric airtight valve 17 and open the second electric airtight valve 19, so that the fresh air flows through the first-stage evaporator 18 for secondary cooling.

[0054] Specifically, the electric valve 10 of the first cooling water pipeline, the electric valve 11 of the second cooling water pipeline, the electric valve 12 of the third cooling water pipeline, the electric valve 13 of the fourth cooling water pipeline, the electric valve 14 of the first heat conduction oil pipeline, the electric valve 15 of the second heat conduction oil pipeline, the electric valve 21 of the third heat conduction oil pipeline, and the electric valve 22 of the fourth heat conduction oil pipeline all adopt solenoid valves.

[0055] Specifically, the solution can be a lithium bromide - aqueous solution, which flows between the generator 27, the absorber 26, and the solution heat exchanger 29 under the action of the solution pump 28.

[0056] Specifically, the heat - conducting oil flows between the concentrating solar collector 20 and the heat - conducting oil heat - exchange coil 52 inside the generator 27 under the action of the heat - conducting oil pump 23. The heat - conducting oil is heated up in the concentrating solar collector 20, and after entering the heat - conducting oil heat - exchange coil 52 inside the generator 27, it transfers heat to the solution in the generator 27, causing the water vapor in the solution in the generator 27 to vaporize into high - pressure and high - temperature water vapor. The high - pressure and high - temperature water vapor goes to the primary condenser 25, releases heat and condenses into a high - pressure liquid after being cooled by the cooling water in the primary condenser 25, and then becomes a low - pressure and low - temperature gas - liquid two - phase flow after throttling through the expansion valve 32. After entering the coil inside the primary evaporator 18, it evaporates and absorbs heat, taking away the heat of the fresh air outside the coil of the primary evaporator 18 to achieve the purpose of cooling the fresh air. Finally, the low - temperature and low - pressure water vapor enters the absorber 26 through the water - vapor inlet of the absorber 26, enters the coil inside the absorber 26, is cooled by the cooling water outside the coil of the absorber 26, and then redissolves into the solution inside the coil of the absorber 26. The solution is boosted in pressure by the solution pump 28, passes through the solution heat exchanger 29, and finally returns to the generator 27, repeating the cycle in this way.

[0057] Specifically, the heat - conducting oil heat - exchange coil 52 transfers heat to the solution in the generator 27, causing the water vapor in the solution in the generator 27 to vaporize into high - pressure and high - temperature water vapor. At this time, both the temperature and concentration of the solution in the generator 27 increase, becoming a high - temperature and concentrated solution. The high - temperature and concentrated solution enters the solution heat exchanger 29 under the action of the solution pump 28, exchanges heat with the low - temperature and dilute solution from the absorber 26, and then enters the absorber 26, absorbs the low - temperature and low - pressure water vapor from the primary evaporator 18, forms a low - temperature and dilute solution, enters the solution heat exchanger 29, and finally returns to the generator 27, repeating the cycle in this way.

[0058] Specifically, after the switching of the four cooling - water pipeline electric valves, the cooling water is changed to flow between the water collecting tray 42, the cooling - water filter 9, the absorber 26, the primary condenser 25, and the indirect evaporation cooling pipeline 4 by the cooling water pump 8, taking away not only the heat of the fresh air but also the heat of the absorber 26 and the primary condenser 25.

[0059] In this embodiment, the fresh air after being secondarily cooled by the primary evaporator 18 enters the tertiary module 63. After the temperature is measured by the second temperature sensor 45 and reaches the set temperature, the compressor 30 is turned on so that the tertiary module 63 starts to work. After the fresh air enters the secondary evaporator 34, it is cooled again.

[0060] After the third - stage module 63 is turned on, the heat generated by the secondary condenser 31 inside the generator 27 will also be transferred to the solution in the generator 27, causing the water vapor in the solution in the generator 27 to vaporize into high - pressure and high - temperature water vapor. The high - pressure and high - temperature water vapor goes to the primary condenser 25, releases heat and condenses into a high - pressure liquid after being cooled by the cooling water in the primary condenser 25, and then becomes a low - pressure and low - temperature gas - liquid two - phase flow after throttling through the expansion valve 32. After entering the coil inside the primary evaporator 18, it evaporates and absorbs heat, and then takes away the fresh - air heat outside the coil of the primary evaporator 18, achieving the purpose of cooling the fresh air again. Finally, the low - temperature and low - pressure water vapor enters the coil inside the absorber 26, is cooled by the cooling water outside the coil of the absorber 26, and then redissolves into the solution inside the coil of the absorber 26. After being boosted by the solution pump 28, it returns to the generator 27 after passing through the solution heat exchanger 29, and so on in a cycle.

[0061] In this embodiment, after the third - stage module 63 measures the temperature according to the third temperature sensor 46, it adjusts the refrigeration output of the third - stage module 63 by adjusting the rotation speed of the compressor 30.

[0062] As Figure 10 shown, the thick line is the enthalpy - humidity diagram of the refrigeration process of the aircraft ground air - conditioning unit in this embodiment. Point W is the state point of the outdoor air in summer, point W1 is the state point after being cooled by the first - stage module 61, point W2 is the state point after being cooled by the second - stage module 62, and point O is the state point after being cooled by the third - stage module 63; the thin line is the refrigeration process of the traditional aircraft ground air - conditioning unit, and the fresh air is processed from point W to point O through vapor - compression refrigeration. The enthalpy value corresponding to point W is 58 kJ / (kg·°C), the enthalpy value corresponding to point W1 is 54 kJ / (kg·°C), the enthalpy value corresponding to point W2 is 44 kJ / (kg·°C), and the enthalpy value corresponding to point O is 12 kJ / (kg·°C). In the refrigeration process of this embodiment, the cold energy used from point W to point W1 is provided by the indirect evaporative cooler, making full use of the dry - air energy, and the energy efficiency is about 3 times that of the traditional vapor - compression refrigeration unit. In the refrigeration process of the aircraft ground air - conditioning unit in this embodiment, the cold energy used from point W1 to point W2 is provided by the absorption refrigeration unit, and the heat sources of the absorption refrigeration unit are the solar collector 20 and the secondary condenser 31 in the third - stage module 63, both of which are free energy. Therefore, compared with the traditional unit, the aircraft ground air - conditioning unit in this embodiment uses a variety of free energies, and the energy consumption can be greatly reduced.

[0063] The specific working process of the heating condition in this embodiment is as follows: When starting to work, turn on the supply fan 38 to allow fresh air to enter the air supply channel 49 of the air conditioner through the fresh air inlet 1. Turn off the evaporative cooling exhaust fan 5 and the cooling water pump 8 in the first-stage module 61, and close the electric valves 10, 11, 12, and 13 of the first, second, third, and fourth cooling water pipelines, so that the first-stage module 61 does not work. At the same time, turn on the heat-conducting oil pump 23, open the electric valves 14 and 22 of the first and fourth heat-conducting oil pipelines, close the electric valves 15 and 21 of the second and third heat-conducting oil pipelines, and turn off the solution pump 28, so that the second-stage module 62 shuts down the refrigeration work. Then open the first electric airtight valve 17 and close the second electric airtight valve 19 to allow the fresh air to flow through the air-oil heat exchanger 16 for heating up.

[0064] Specifically, the heat collected by the concentrating solar collector 20 is transferred to the heat-conducting oil, and the heat-conducting oil enters the air-oil heat exchanger 16 through the heat-conducting oil pipeline 41 to transfer the heat to the fresh air, so that the fresh air is heated once.

[0065] When the temperature of the fresh air after the second-stage module 62 measured by the second temperature sensor 45 is lower than the set temperature, adjust the power of the electric heater 37 of the fourth-stage module 64 to make the final outlet air temperature meet the requirements.

[0066] As Figure 11 shown, it is the enthalpy-humidity diagram of the heating process of the aircraft ground air-conditioning unit in this embodiment. Point W is the state point of the outdoor air in winter, point W1 is the state point after preheating by the second-stage module 62, and point O is the state point after heating up by the fourth-stage module 64. The traditional aircraft ground air-conditioning unit uses an electric heater to heat the outdoor air from point W to point O. The enthalpy value corresponding to point W is 11 kJ / (kg·°C), the enthalpy value corresponding to point W1 is 14 kJ / (kg·°C), and the enthalpy value corresponding to point O is 51 kJ / (kg·°C). In the heating process of the aircraft ground air-conditioning unit in this embodiment, the free heat obtained by the solar collector 20 is used from point W to point W1. Therefore, compared with the traditional aircraft ground air-conditioning unit, the heating energy consumption of this embodiment is expected to be reduced by (14 - 11) / (51 - 11) = 7.5%.

[0067] Embodiment 3: 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 Embodiment 2. The control method of the aircraft ground air-conditioning unit includes the following processes: Refrigeration condition: Before picking up the plane, first turn on the cooling water pump 8 and the evaporative cooling exhaust fan 5 to start the operation of the first-stage module 61, and turn on the supply fan 38 to cool the fresh air once.

[0068] Specifically, before picking up the plane, open the electric valve 10 of the first cooling water pipeline and the electric valve 12 of the third cooling water pipeline, and close the electric valve 11 of the second cooling water pipeline and the electric valve 13 of the fourth cooling water pipeline.

[0069] After the temperature of the fresh air is measured by the first temperature sensor 44 and reaches the preset temperature, start the heat conduction oil pump 23, close the electric valve 10 of the first cooling water pipeline and the electric valve 12 of the third cooling water pipeline, and open the electric valve 11 of the second cooling water pipeline and the electric valve 13 of the fourth cooling water pipeline, so that the secondary module 62 starts to operate for secondary refrigeration.

[0070] Specifically, at the same time, close the first electric airtight valve 17 and open the second electric airtight valve 19 to allow the fresh air to flow through the primary evaporator 18 for secondary cooling.

[0071] The fresh air that has been secondary cooled by the primary evaporator 18 of the secondary module 62 enters the tertiary module 63. After the temperature of the fresh air is measured by the second temperature sensor 45 and reaches the preset temperature, start the compressor 30, so that the tertiary module 63 starts to operate. After the fresh air enters the secondary evaporator 34, the fresh air is cooled three times.

[0072] Specifically, after the temperature is measured by the third temperature sensor 46 in the tertiary module 63, the refrigeration output of the tertiary module 63 is adjusted by adjusting the speed of the compressor 30.

[0073] After normal operation, when the air temperature after the primary module 61 is higher than the set temperature, increase the speeds of the cooling water pump 8 and the evaporative cooling exhaust fan 5 by control, so that the primary module 61 increases its refrigeration output until the treated air temperature meets the requirements.

[0074] When the temperature shown by the heat conduction oil pipeline temperature sensor 24 is higher than the set temperature, it indicates that the solar irradiance on that day is higher than the predetermined value. At this time, increase the speed of the heat conduction oil pump 23 to increase the output of the secondary module 62.

[0075] When the temperature shown by the heat conduction oil pipeline temperature sensor 24 is lower than the set temperature, it indicates that the solar irradiance on that day is low and does not meet the requirement of the operating energy efficiency ratio. Close the heat conduction oil pump 23 to cut off the heat conduction oil flow in the heat conduction oil pipeline 41 and the heat conduction oil heat exchange coil 52. When the temperature of the medium in the heat conduction oil pipeline 41 is higher than the set temperature, reopen the heat conduction oil pump 23 and reconnect the heat conduction oil pipeline 41 and the heat conduction oil heat exchange coil 52.

[0076] When the air temperature after the tertiary module 63 is higher than the set temperature, increase the speed of the compressor 30 in the tertiary module 63 to increase the output of the tertiary module 63 to meet the requirement of the air temperature after the tertiary module 63.

[0077] Specifically, after the secondary module 62 operates normally, when the conductivity meter 50 on the outlet pipe of the primary evaporator 18 measures that there is liquid water in the outlet pipe of the primary evaporator 18, it indicates that the primary evaporator 18 has not completely evaporated the incoming liquid water, which means that the cooling load demand of the primary evaporator 18 is decreasing; at this time, the opening of the solenoid valve 51 on the pipe at the steam outlet of the generator 27 is adjusted smaller through the signal sent by the conductivity meter 50.

[0078] After the opening of the solenoid valve 51 is adjusted smaller, the flow rate of the high-pressure steam entering the primary condenser 25 decreases, and the steam generated in the generator 27 will accumulate, increasing the pressure above the liquid level of the solution in the inner tank 60 of the generator 27, pushing the inner tank 60 of the generator 27 downward, exposing the secondary condenser 31 out of the solution surface, as Figure 8 shown, thereby reducing the heating amount of the solution by the secondary condenser 31. As the heating amount of the solution gradually decreases, the outlet pressures of the secondary condenser 31 and the compressor 30 gradually increase.

[0079] Specifically, when the outlet pressure of the compressor 30 reaches 90% of the overpressure alarm pressure, the power of the compressor 30 is reduced.

[0080] As the heating amount of the solution gradually decreases, the evaporation amount of the solution in the generator 27 also decreases accordingly. At this time, the conductivity meter 50 on the outlet pipe of the primary evaporator 18 measures that the liquid water there gradually decreases until it disappears, and the opening of the solenoid valve 51 is adjusted larger, increasing the flow rate of the high-pressure steam entering the primary condenser 25 from the generator 27. The pressure above the liquid level of the solution in the inner tank 60 of the generator 27 will decrease accordingly, and the inner tank 60 will move upward, submerging the secondary condenser 31 in the solution again to continue heating the solution to promote the evaporation of the solution, as Figure 9 shown, and the outlet pressures of the secondary condenser 31 and the compressor 30 gradually decrease.

[0081] When the outlet pressure of the compressor 30 decreases to 110% of the minimum allowable pressure, the power of the compressor 30 is increased, and so on in a cycle.

[0082] Throughout the process, the heat transfer 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 the low-load operation of the compressor 30, and can realize the independent, fast and stepless adjustment of the refrigerating capacity of the absorption refrigeration unit. At the same time, it greatly reduces the frequent adjustment and low-load operation of the power of the compressor 30.

[0083] Heating condition: When the operating condition of the aircraft ground air conditioning unit changes from the refrigeration condition to the heating condition, the cooling water pump 8 and the evaporative cooling exhaust fan 5 are turned off, the electric valves 10, 11, 12 and 13 of the first, second, third and fourth cooling water pipelines are closed, so that the first-stage module 61 is closed, the electric valves 14 and 22 of the first heat transfer oil pipeline are opened, the electric valves 15 and 21 of the second and third heat transfer oil pipelines are closed, the solution pump 28 is closed, the heat transfer oil pump 23 is opened, the first electric airtight damper 17 is opened, the second electric airtight damper 19 is closed, the fresh air flows through the air-oil heat exchanger 16 for heating up, and the heating function of the second-stage module 62 is turned on.

[0084] When the temperature shown by the heat transfer oil pipeline temperature sensor 24 is higher than the set temperature, it indicates that the solar illuminance on that day is higher than the predetermined value. At this time, by increasing the rotation speed of the heat transfer oil pump 23, the heating output of the second-stage module 62 is increased.

[0085] When the temperature shown by the heat transfer oil pipeline temperature sensor 24 is lower than the fresh air temperature measured by the first temperature sensor 44, it indicates that the solar illuminance on that day is too low. At this time, the heat transfer oil pump 23 is turned off, the air-oil heat exchanger 16 is closed, and the ineffective loss of fresh air heat is reduced.

[0086] When the fresh air temperature measured by the second temperature sensor 45 after passing through the second-stage module 62 is lower than the set temperature, the power of the electric heater 37 of the fourth-stage module 64 is increased to make the final outlet air temperature meet the requirements.

[0087] Specifically, the control system adopted by the control method of the aircraft ground air conditioning unit in this embodiment is a PLC control system.

[0088] Embodiment 4: This embodiment provides a control method for preventing the solution from crystallizing in the solution heat exchanger 29. The control method is applied to the aircraft ground air conditioning unit described in Embodiment 2, and specifically includes the following process: Since the water vapor pressure above the solution liquid level 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 saturation concentration of the solution is only related to the solution temperature. In this way, the traditional problem of the saturation concentration of the solution being related to the double factors of the solution temperature and the internal pressure of the generator 27 is adjusted to a problem only related to the single factor of the solution temperature. Then the saturation concentration of the solution at different temperatures is determined. As long as it is ensured that the temperature of the solution at a certain determined concentration is not lower than the saturation temperature corresponding to this concentration, the solution can be ensured not to crystallize.

[0089] The concentration of the concentrated solution at the solution outlet of the generator 27 is measured by the solution concentration sensor 56 provided thereon, and the saturation temperature corresponding to this concentration is calculated.

[0090] The temperature of the concentrated solution at the solution outlet of the generator 27 is measured by the first solution temperature sensor 54 provided thereon.

[0091] The flow rate of the solution pump 28 and the temperature of the dilute solution are respectively measured by the flow sensor 57 and the second solution temperature sensor 55 provided at the solution outlet of the absorber 26.

[0092] At this time, the temperature and concentration of the concentrated solution entering the solution heat exchanger 29 are known, and the temperature and flow rate of the dilute solution entering the solution heat exchanger 29 are also known. Since the solution pump 28 is a constant-frequency pump, the flow rate remains unchanged, and since it is the same pipeline, the flow rate of the concentrated solution entering the solution heat exchanger 29 is equal to the flow rate of the dilute solution entering the solution heat exchanger 29. Then, the flow rate of the concentrated solution entering the solution heat exchanger 29 is also known.

[0093] Through heat transfer calculation, the critical temperature of the dilute solution entering the solution heat exchanger 29 can be obtained.

[0094] 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 at the concentration of the concentrated solution itself. At this time, the concentrated solution will not crystallize. The rotation speeds of the evaporation cooling exhaust fan 5 and the cooling water pump 8 should be increased to lower the temperature of the cooling water, improve the cooling capacity of the cooling water, and thus improve the refrigeration efficiency of the unit.

[0095] 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 at the concentration of the concentrated solution itself. At this time, the concentrated solution will crystallize. The rotation speeds of the evaporation cooling exhaust fan 5 and the cooling water pump 8 should be decreased to increase the temperature of the cooling water, reduce the cooling capacity of the cooling water, and prevent crystallization.

[0096] Finally, it is realized that by precisely controlling the temperature of the cooling water, on the premise of ensuring the refrigeration efficiency of the unit, the purpose of reducing the crystallization of the concentrated solution in the solution heat exchanger 29 is achieved, and neither conservatively increasing the temperature of the cooling water nor aggressively decreasing the temperature of the cooling water.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An indirect evaporative cooler, characterized in that: comprising 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 circular arcs (66) arranged at intervals, the bottoms of the two convex circular arcs (66) are respectively connected to a first concave circular arc (67), the convex circular arcs (66) and the first concave circular arcs (67) are tangent to each other in a smooth transition, and the bottoms of the two first concave circular arcs (67) are tangent to each other; the top of the cross section is a second concave circular arc (68), and the two ends of the second concave circular arc (68) are respectively connected to the tops of the two convex circular arcs (66).

2. The indirect evaporative cooler according to claim 1, characterized in that 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 radii of the outer convex arc (66) and the first inner concave arc (67) are both 10 to 12 times the length of the minor axis, and the radius of the second inner concave arc (68) is 0.25 to 0.5 times the length of the minor axis.

3. The indirect evaporative cooler according to claim 1, characterized in that The system 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 indirect evaporative cooler according to claim 3, characterized in that Below the indirect evaporative cooling pipe (4), a plurality of flow dividers (53) of different lengths are arranged along the height direction, each flow divider (53) is arranged obliquely along the horizontal direction, and each flow divider (53) is located behind the secondary air inlet (2).

5. The indirect evaporative cooler according to claim 4, characterized in that The splitter plates (53) are all provided with a slope, and the slope direction is consistent with the air inlet direction.

6. An aircraft ground air conditioning unit, characterized in that: It comprises a primary module (61), a secondary module (62), a tertiary module (63), a quaternary module (64) and an air supply section (65); The primary module (61), the secondary module (62), the tertiary module (63), the quaternary module (64) and the air supply section (65) are connected in sequence by an air conditioning air supply channel (49), and the primary module (61) comprises the indirect evaporative cooler according to any one of claims 1 to 5; 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 cyclically connected to the absorption refrigeration unit and the air-oil heat exchanger (16) respectively through a heat transfer oil pipeline (41); and the cooling water pipeline (40) is connected to the absorption refrigeration unit; 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 an air supply fan (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.

7. The aircraft ground air conditioning unit according to claim 6, characterized in that: The absorption refrigeration unit comprises a generator (27); a solution outlet of the generator (27) is connected in sequence to an absorber (26), a solution pump (28), a solution heat exchanger (29) and a solution inlet of the generator (27) by means of a solution pipeline (43), so as to form a solution circulation pipeline; a water vapor outlet of the generator (27) is connected in sequence to a primary condenser (25), a primary evaporator (18) and a water vapor inlet of the absorber (26) by means of a steam-water pipeline (58); the absorber (26) and the primary condenser (25) are both connected to a cooling water pipeline (40); and a heat transfer oil pipeline (41) is connected to the generator (27).

8. The aircraft ground air conditioning unit according to claim 7, characterized in that: The vapor compression refrigeration unit comprises 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.

9. The aircraft ground air conditioning unit according to claim 8, characterized in that: The generator (27) comprises a closed shell (59), an inner liner (60) is arranged in the shell (59), a solution is arranged in the inner liner (60), the top of the inner liner (60) is open, the bottom of the inner liner (60) is slidably sealed with the inner wall of the shell (59), a solution outlet is arranged 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, and 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).

10. A control method for an aircraft ground air conditioning unit according to any one of claims 6 to 9, characterized in that: The process includes: Under the refrigeration condition, the indirect evaporative cooler, the absorption refrigeration unit and the steam 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 steam 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 air-oil heat exchanger (16) is closed and the power of the electric heater (37) is increased.

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