An optimized control system for a direct expansion evaporative condenser air conditioning system

Abstract

The utility model provides an optimization control system of direct expansion type evaporation condensing air conditioning system, is equipped with baffle between the air inlet side and air outlet side, is equipped with pressure difference transmitter between baffle and partition wall, still include air pressure sampling module, pressure difference calculation module, optimization control module, air pressure sampling module is by full pressure pressure -taking pipe, static pressure pressure -taking pipe and pilot pressure pipe constitutes, pressure difference calculation module is by pressure difference transmitter constitutes, and full pressure pressure -taking pipe is respectively arranged in the air inlet side and air outlet side of evaporation condenser, static pressure pressure -taking pipe is located air outlet side and is parallel to the airflow setting, the utility model discloses the pressure difference of the air inlet side and air outlet side of condensing evaporator is obtained, judges the scale formation of condensing evaporator to clean up maintenance in time, through the actual condensing air volume of evaporation condenser is collected, controls the increase and decrease of condensing fan, guarantees the heat exchange capacity of condenser to meet the requirement, can realize the efficient energy -conserving operation of evaporation condenser.

Description

Technical Field

[0001] This utility model relates to the field of subway station air conditioning systems, specifically an optimized control system for a direct expansion evaporative condensing air conditioning system. Background Technology

[0002] Subway station air conditioning systems typically consist of water-cooled chillers, cooling towers, cooling water pumps, chilled water pumps, and combined air conditioning units. The cooling towers are located on the ground and exchange heat with the air. As subway networks become more dense, acquiring land for ground-level cooling towers in urban core areas is becoming increasingly difficult. In addition, noise and water drift issues caused by the operation of cooling towers frequently lead to complaints from nearby residents.

[0003] A direct expansion evaporative condensing air conditioning system consists of a direct expansion evaporative condensing unit on the condensing heat dissipation side and a direct expansion air handling unit on the evaporative air supply side. Compared to traditional station ventilation and air conditioning water systems, the direct expansion evaporative condensing system eliminates cooling towers, cooling water, and chilled water systems. It uses an evaporative condenser combined with direct evaporative refrigerant cooling, eliminating the energy consumption of chilled water and cooling water pumps, thus achieving the goals of saving and simplifying system piping and energy conservation. The evaporative condensing end of the direct expansion evaporative air conditioning unit in subway stations mainly comes in three forms: machine room type, duct type, and air wall type.

[0004] In subway stations using direct expansion evaporative condensing air conditioning systems, improper design of the supply and exhaust airflow can easily lead to short-circuiting or poor exhaust flow within the supply and exhaust shafts, creating "localized heat islands." This frequently results in deterioration of the heat transfer efficiency of the evaporative condenser, and in severe cases, affects unit performance or even causes shutdown. Furthermore, the heat exchanger fins of the evaporative condensing unit are prone to scaling, directly impacting the unit's heat exchange performance. The control of the external exhaust fan and airflow in direct expansion evaporative condensing units is generally achieved through refrigerant condensation temperature control. In actual use, improper selection of the external exhaust fan makes it impossible to calculate and determine a reasonable fan frequency based on the condensation temperature, leading to the fan operating at a fixed frequency for extended periods. Additionally, long-term operation of the evaporative condensing unit causes severe scaling at baffles and other locations, affecting heat exchange efficiency and resulting in excessive fan energy consumption. Utility Model Content

[0005] The purpose of this invention is to solve the problem of poor heat exchange effect caused by the inability to collect air volume in existing direct expansion evaporative condensing air conditioning systems and thus control the loading and unloading of the condenser fan.

[0006] An optimized control system for a direct expansion evaporative condensing air conditioning system includes a fan, a partition wall, and a water pump. The fan is mounted on the partition wall as the air inlet side. A baffle is provided between the air inlet side and the air outlet side. A differential pressure transmitter is provided between the baffle and the partition wall.

[0007] The optimized control system of the direct expansion evaporative condensing air conditioning system includes a wind pressure sampling module, a differential pressure calculation module, and an optimized control module. The wind pressure sampling module consists of a total pressure tapping pipe, a static pressure tapping pipe, and a pressure guiding pipe. The differential pressure calculation module consists of a differential pressure transmitter. The optimized control module controls the operating frequency of the fan.

[0008] The total pressure tapping pipes are respectively installed on the air inlet side and air outlet side of the evaporator-condenser; one end of the total pressure tapping pipe is sealed, and the other end is connected to the pressure guiding pipe, and the other end of the pressure guiding pipe is connected to the differential pressure transmitter to transmit the pressure signal to the differential pressure transmitter.

[0009] The static pressure tapping pipe is located on the air outlet side of the direct expansion evaporative condensing air conditioning system and is arranged parallel to the airflow. The first end of the static pressure tapping pipe is open, and the second end is connected to the pressure guiding pipe through a differential pressure transmitter.

[0010] In a further preferred embodiment, the total pressure tapping pipe on the air inlet side is located outside the fan, and the total pressure tapping pipe on the air outlet side is located outside the baffle plate, with the total pressure tapping pipe installed vertically.

[0011] In a further preferred embodiment, the total pressure tapping tube has equally spaced and uniformly opened total pressure tapping holes of the same size, and the openings of the total pressure tapping holes are parallel to and directly facing the airflow direction.

[0012] In a further preferred embodiment, the static pressure tapping tube has static pressure tapping holes of the same size evenly spaced on its body, and the static pressure tapping holes are arranged at the bottom to ensure that the static pressure tapping holes will not collect dynamic pressure signals.

[0013] Further optimized, the air pressure sampling module collects the pressure on the air inlet and air outlet sides through the total pressure tapping pipe and the static pressure tapping pipe, respectively; the pressure difference calculation module calculates the pressure difference between the air inlet and air outlet sides of the direct expansion evaporative condensing air conditioning system and the dynamic pressure on the air outlet side of the evaporator condenser; the optimization control module determines whether the direct expansion evaporative condensing air conditioning system needs cleaning and maintenance based on the magnitude of the pressure difference, calculates the actual condensing air volume based on the dynamic pressure, and controls the load adjustment of the condenser fan based on the difference between the actual condensing air volume and the displayed air volume.

[0014] This invention provides an optimized control system for a direct expansion evaporative condensing air conditioning system. By acquiring the pressure difference between the air inlet and outlet sides of the evaporator, the system determines the scaling condition of the evaporator and enables timely cleaning and maintenance. Furthermore, by collecting the actual condensing airflow of the evaporator, the system controls the load adjustment of the condenser fan to ensure that the condenser's heat exchange capacity meets requirements. This optimized control system for a direct expansion evaporative condensing air conditioning system enables highly efficient and energy-saving operation of the evaporator. Attached Figure Description

[0015] Figure 1 This is a structural diagram of the optimized control system of the direct expansion evaporative condensing air conditioning system of this utility model;

[0016] Figure 2 This is a schematic diagram of the full-pressure tapping tube in this utility model;

[0017] Figure 3 This is a modular composition diagram of the direct expansion evaporative condensing air conditioning system of this utility model;

[0018] Figure 4 This is a detailed control flowchart of this utility model.

[0019] In the diagram: 1. Partition wall; 2. Fan; 3. Water pump; 4. Air inlet side; 5. Air outlet side; 6. Total pressure tap; 61. Total pressure tap hole; 7. Pressure guide pipe; 8. Differential pressure transmitter; 9. Static pressure tap; 10. Baffle plate. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] The preferred embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0022] Example 1:

[0023] This utility model provides an optimized control system for a direct expansion evaporative condensing air conditioning system, in conjunction with reference to [the relevant documentation]. Figure 1 The structural diagram of the optimized control system of the direct expansion evaporative condensing air conditioning system of this utility model includes a fan 2, a partition wall 1 and a water pump 3. The fan 2 is installed on the partition wall 1 as the air inlet side 4. A baffle 10 is provided between the air inlet side 4 and the air outlet side 5. A differential pressure transmitter 8 is provided between the baffle 10 and the partition wall 1.

[0024] The optimized control system of the direct expansion evaporative condensing air conditioning system includes a wind pressure sampling module, a differential pressure calculation module, and an optimized control module. See the diagram for a detailed module composition. Figure 3 The wind pressure sampling module consists of a total pressure tapping pipe 6, a static pressure tapping pipe 9, and a pressure guiding pipe 7. The differential pressure calculation module consists of a differential pressure transmitter 8. The optimization control module controls the operating frequency of the fan 2.

[0025] The air pressure sampling module collects the pressure on the air inlet side 4 and the air outlet side 5 through the total pressure tapping pipe 6 and the static pressure tapping pipe 9, respectively; the pressure difference calculation module calculates the pressure difference between the air inlet side 4 and the air outlet side 5 of the direct expansion evaporative condensing air conditioning system, and the dynamic pressure on the air outlet side 5 of the evaporator condenser; the optimization control module determines whether the direct expansion evaporative condensing air conditioning system needs cleaning and maintenance based on the magnitude of the pressure difference, calculates the actual condensing air volume based on the dynamic pressure, and controls the load adjustment of the condenser fan 2 based on the difference between the actual condensing air volume and the displayed air volume.

[0026] The total pressure tapping pipes 6 are respectively arranged on the air inlet side 4 and the air outlet side 5 of the evaporator condenser; the total pressure tapping pipes 6 on the air inlet side 4 are located outside the fan 2, and the total pressure tapping pipes 6 on the air outlet side 5 are located outside the baffle plate 10. The total pressure tapping pipes 6 are installed vertically.

[0027] One end of the total pressure tapping tube 6 is sealed, and the other end is connected to the pressure guiding tube 7. The other end of the pressure guiding tube 7 is connected to the differential pressure transmitter 8 to transmit the pressure signal to the differential pressure transmitter 8. The total pressure tapping tube 6 has equally spaced and uniformly opened total pressure tapping holes 61 of the same size. The openings of the total pressure tapping holes 61 are parallel to the airflow direction.

[0028] The static pressure tapping pipe 6 is located on the air outlet side 5 of the direct expansion evaporative condensing air conditioning system and is arranged parallel to the airflow. The first end of the static pressure tapping pipe 9 has an opening, and the second end is connected to the pressure guiding pipe 7 through a differential pressure transmitter 8. The static pressure tapping pipe 9 has static pressure tapping holes of the same size that are evenly spaced on its body. The static pressure tapping holes are arranged at the bottom to ensure that the static pressure tapping holes will not collect dynamic pressure signals.

[0029] This invention provides an optimized control system for a direct expansion evaporative condensing air conditioning system. By acquiring the pressure difference between the air inlet and outlet sides of the evaporator, the system determines the scaling condition of the evaporator and enables timely cleaning and maintenance. Furthermore, by collecting the actual condensing airflow of the evaporator, the system controls the load adjustment of the condenser fan to ensure that the condenser's heat exchange capacity meets requirements. This optimized control system for a direct expansion evaporative condensing air conditioning system enables highly efficient and energy-saving operation of the evaporator.

[0030] Example 2:

[0031] This embodiment provides an optimized control system for an expansion-type evaporative condensing air conditioning system. By collecting the actual condensing air volume of the evaporator condenser, it controls the load increase and decrease of the condenser fan 2 to ensure that the heat exchange capacity of the condenser meets the requirements. Figure 2 The schematic diagram of the total pressure tapping pipe 6 in this utility model shows the process for obtaining air pressure as follows:

[0032] Considering that the air velocity on the air inlet side 4 and the air outlet side 5 of the evaporator condenser may be uneven, a relatively accurate air pressure can be obtained by evenly distributing pressure taps.

[0033] Assume the total pressure on the air inlet side 4 of the evaporator-condenser is P1.

[0034] Among them, P i Let n be the total pressure of the i-th total pressure tap 61, and n be the number of the 4 total pressure taps 61 on the air inlet side.

[0035] Assume the total pressure on the outlet side 5 of the evaporator-condenser is P2.

[0036] Among them, P j Let m be the total pressure of the j-th total pressure tap 61, and m be the number of total pressure taps 61 on the air outlet side 5.

[0037] Under normal circumstances, the number n of the total pressure taps 61 on the air inlet side 4 is equal to the number m of the total pressure taps 61 on the air outlet side 5.

[0038] The pressure signal P1 of the inlet side 4 total pressure tapping pipe 6 and the signal P2 of the outlet side 5 total pressure tapping pipe 6 are connected to the differential pressure transmitter 8 through the pressure guide pipe 7.

[0039] The differential pressure transmitter 8 automatically calculates the pressure difference ΔP between the inlet side 4 and the outlet side 5 of the evaporator-condenser based on the total pressure of the inlet side 4 and the outlet side 5. t .

[0040] ΔP t =P1-P2

[0041] The pressure signal P3 from the static pressure tap 9 is connected to the differential pressure transmitter 8 via the pressure guide pipe 7. The differential pressure transmitter 8 automatically calculates the dynamic pressure ΔP on the outlet side 5 of the evaporator-condenser. d .

[0042] ΔP d =P1-P3

[0043] Based on the dynamic pressure ΔP on the air outlet side 5 of the evaporator condenser d Calculate the actual condensing air volume V of the evaporator-condenser r .

[0044]

[0045] In the formula, ρ is the air density and S is the air passage area.

[0046] As can be seen, the differential pressure calculation module calculates the differential pressure ΔP between the inlet side 4 and the outlet side 5 based on the sampled total pressure signal and static pressure signal. t and actual condensate air volume V rThen, the differential pressure signal and the actual condenser air volume signal are transmitted to the optimization control module.

[0047] The optimized control module will optimize the pressure difference ΔP between the air inlet side 4 and the air outlet side 5. t Compare with the set threshold ε.

[0048] If ΔP t If ΔP > ε, the system determines that the evaporator-condenser may have severe scaling and issues an alarm indicating that the evaporator-condenser needs cleaning and maintenance; if ΔP t If the value is less than or equal to ε, the system determines that the heat exchange capacity of the evaporator and condenser meets the heat exchange requirements, and the system operates normally.

[0049] For a direct expansion evaporative condensing air conditioning system, the condensing heat dissipation Q cond It can be obtained from the following formula:

[0050] Q cond =m r (h cond -h sub )

[0051] In the formula, m r h is the mass flow rate of the refrigerant. cond h is the enthalpy of condensation of the refrigerant. sub Let ΔT be the enthalpy of the refrigerant after subcooling. Assume the temperature rise of the air after passing through the evaporator-condenser is ΔT, and the specific heat capacity of the air is c. p According to the principle of thermal equilibrium, we have:

[0052] Q cond =ρV d c p ΔT=m r (h cond -h sub )

[0053] The required display condenser cooling airflow for the evaporator-condenser

[0054] The enthalpy of condensation of the refrigerant, h cond Enthalpy h of the refrigerant after subcooling sub Parameters such as the refrigerant mass flow rate and the temperature rise ΔT of air passing through the evaporator-condenser can be directly obtained through a direct expansion evaporative condensing air conditioning system.

[0055] For stations using direct expansion evaporative condensing air conditioning systems, improper design of the subway's supply and exhaust airflow can easily lead to short-circuiting or poor exhaust flow within the supply and exhaust shafts, resulting in "localized heat islands" and deteriorating heat transfer efficiency of the evaporative condenser. In such cases, the displayed condensing airflow V of the direct expansion evaporative condensing air conditioning system... d Will be related to the actual condensing air volume V rThere are significant differences. To ensure the heat dissipation effect of the evaporator-condenser and the efficient and energy-saving operation of the system, it is necessary to base the reading on the displayed condensing air volume V. d With actual condensing air volume V r The deviation is used to control the operating frequency of condenser fan 2. On the other hand, considering sensor error and system stability, the display condenser air volume V is set. d With actual condensing air volume V r The allowable percentage deviation δ.

[0056] when At that time, the optimized control module controls the condenser fan 2 to increase its frequency.

[0057] when At that time, the optimization control module does not control the condenser fan 2.

[0058] To ensure the efficient operation of the direct expansion evaporative condensing air conditioner, the condensing heat dissipation air volume V is displayed. d With actual condensing air volume V r The permissible deviation percentage δ can be set to no more than 5%.

[0059] Example 3

[0060] This embodiment provides an optimized control system for an expansion-type evaporative condensing air conditioning system, including a wind pressure sampling module, a differential pressure calculation module, and an optimized control module. The control process is performed according to the following steps; see the detailed control flowchart. Figure 4 :

[0061] S1, the total pressure P1 on the air inlet side 4, the total pressure P2 on the air outlet side 5 and the static pressure P3 of the evaporator-condenser are collected through the total pressure tapping pipe 6 and the static pressure tapping pipe 9, respectively.

[0062] S2, calculate the pressure difference ΔP between the inlet and outlet sides of the evaporator-condenser using the pressure difference calculation module. t And actual condensing air volume V r .

[0063] S3, the optimization control module compares the pressure difference ΔP between the inlet and outlet air sides. t Based on a set threshold ε, it determines whether to issue an alarm indicating that the evaporator-condenser needs cleaning and maintenance. Simultaneously, it calculates the actual condensing airflow V. r With display of condensate air volume V d The difference in operating frequency of the condenser fan 2 is controlled to ensure the efficient and energy-saving operation of the system.

[0064] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the protection scope of the present invention.

Claims

1. An optimized control system for a direct expansion evaporative condensing air conditioning system, comprising a fan (2), a partition wall (1), and a water pump (3), wherein the fan (2) is mounted on the partition wall (1) as the air inlet side (4), characterized in that, A baffle plate (10) is provided between the air inlet side (4) and the air outlet side (5), and a differential pressure transmitter (8) is provided between the baffle plate (10) and the partition wall (1); The optimized control system of the direct expansion evaporative condensing air conditioning system includes a wind pressure sampling module, a differential pressure calculation module, and an optimized control module. The wind pressure sampling module consists of a total pressure tapping pipe (6), a static pressure tapping pipe (9), and a pressure guiding pipe (7). The differential pressure calculation module consists of a differential pressure transmitter (8). The optimized control module controls the operating frequency of the fan (2). The total pressure tapping pipe (6) is respectively installed on the air inlet side (4) and air outlet side (5) of the evaporator condenser; one end of the total pressure tapping pipe (6) is sealed and the other end is connected to the pressure guide pipe (7); the other end of the pressure guide pipe (7) is connected to the differential pressure transmitter (8) to transmit the pressure signal to the differential pressure transmitter (8). The static pressure tapping pipe (9) is located on the air outlet side (5) of the direct expansion evaporative condensing air conditioning system and is set parallel to the airflow. The first end of the static pressure tapping pipe (9) is open, and the second end is connected to the pressure guiding pipe (7) through a differential pressure transmitter (8).

2. The optimized control system for a direct expansion evaporative condensing air conditioning system according to claim 1, characterized in that, The total pressure tapping pipe (6) on the air inlet side (4) is located outside the fan (2), and the total pressure tapping pipe (6) on the air outlet side (5) is located outside the baffle plate (10). The total pressure tapping pipe (6) is installed vertically.

3. The optimized control system for a direct expansion evaporative condensing air conditioning system according to claim 2, characterized in that, The pressure tapping tube (6) has pressure tapping holes (61) of the same size evenly spaced on its body, and the openings of the pressure tapping holes (61) are parallel to the airflow direction.

4. The optimized control system for a direct expansion evaporative condensing air conditioning system according to claim 1, characterized in that, The static pressure tapping tube (9) has static pressure tapping holes of the same size evenly spaced on its tube body. The static pressure tapping holes are arranged at the bottom to ensure that the static pressure tapping holes will not collect dynamic pressure signals.

5. An optimized control system for a direct expansion evaporative condensing air conditioning system according to any one of claims 1 to 4, characterized in that, The wind pressure sampling module collects the pressure on the air inlet side (4) and the air outlet side (5) through the total pressure tap (6) and the static pressure tap (9), respectively; the pressure difference calculation module calculates the pressure difference between the air inlet side (4) and the air outlet side (5) of the direct expansion evaporative condensing air conditioning system and the dynamic pressure on the air outlet side (5) of the evaporator condenser; the optimization control module determines whether the direct expansion evaporative condensing air conditioning system needs cleaning and maintenance based on the magnitude of the pressure difference, calculates the actual condensing air volume based on the dynamic pressure, and controls the loading and unloading of the condenser fan based on the difference between the actual condensing air volume and the displayed air volume.

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