Artificial climate chamber double-cold-source air conditioning system and control method thereof

Abstract

The invention belongs to the technical field of energy-saving air conditioning equipment, and particularly relates to an artificial climate chamber double-cold-source air conditioning system and a control method thereof.The artificial climate chamber double-cold-source air conditioning system comprises a double-cold-source module, a water circulation module, a tail end heat exchange module and a control module, and the double-cold-source module comprises a water-cooling cold source unit and a fluorine pump natural cold source unit; the water-cooling cold source unit is used for providing mechanical refrigerating capacity; the fluorine pump natural cold source unit is used for providing cooling capacity by using a natural cold source; the water circulation module comprises a two-way valve, a water mixing pump, a one-way valve and a plurality of hand valves; the tail end heat exchange module comprises a fan coil and a fluorine pump coil and is used for transmitting the cold energy into the phytotron; the control module comprises a PID controller and a temperature and humidity sensor. A natural cold source is reasonably utilized, the mechanical refrigeration operation time is shortened, the problem that an existing artificial climate chamber air conditioner system is too high in energy consumption is solved, and the method is suitable for scientific research breeding and other scenes with strict requirements for environmental parameters.

Description

Technical Field

[0001] This invention belongs to the technical field of energy-saving air conditioning equipment, specifically relating to an artificial climate chamber dual-cold-source air conditioning system and its control method. Background Technology

[0002] 2022 and 2023 are the years for the full implementation of major bio-breeding projects, which require accelerating the cultivation of new varieties of various crops and promoting the industrialization of bio-breeding.

[0003] Breeding technology has gone through four stages: primitive domestication and selection (version 1.0), conventional breeding (version 2.0), molecular breeding (version 3.0), and intelligent breeding (version 4.0). Currently, the breeding industry is in a transitional stage combining hybridization breeding and molecular breeding, and the breeding process is moving from an art form in the field to a scientific one in the laboratory. Artificial climate chambers, because they can provide precise and controllable light, temperature, and humidity environments, have become the preferred laboratory for scientific research and breeding experiments.

[0004] However, the lighting and air conditioning systems of artificial climate chambers require continuous electricity, resulting in high energy consumption and becoming a key factor affecting the operating costs. Existing air conditioning systems for artificial climate chambers mainly employ two schemes: one is direct cooling via a refrigerant system, suitable for scenarios with a small number of laboratories, often a single-unit system; the other is an indirect cooling scheme, where the refrigerant system generates chilled water, which is then transported to indoor fan coil units for cooling, enabling centralized cooling for multiple units. Both schemes rely on compressors to provide cooling capacity, and the compressor is the most powerful component in the air conditioning system. Continuous operation leads to excessive power consumption, making it difficult to meet energy-saving requirements. Therefore, how to reduce the energy consumption of the air conditioning system while ensuring precise control of temperature and humidity in artificial climate chambers has become an urgent technical problem to be solved. Summary of the Invention

[0005] To address the problems in the existing technology, the purpose of this invention is to provide a dual-cold-source air conditioning system for an artificial climate chamber and its control method. This overcomes the shortcomings of existing artificial climate chamber air conditioning systems that rely on the continuous operation of the compressor, resulting in excessive energy consumption. By making reasonable use of natural cold sources and shortening the mechanical refrigeration operation time or reducing the operating frequency, the overall power consumption of the air conditioning system is significantly reduced while ensuring precise control of indoor temperature and humidity, thus achieving the goal of energy saving.

[0006] To achieve the above objectives, the present invention is implemented according to the following technical solution:

[0007] An artificial climate chamber dual-cold-source air conditioning system includes a dual-cold-source module, a water circulation module, a terminal heat exchange module, and a control module. The dual-cold-source module includes a water-cooled cold source unit and a refrigerant pump natural cold source unit. The water-cooled cold source unit includes a connected compressor, evaporator, condenser, and throttling device for providing mechanical refrigeration capacity. The refrigerant pump natural cold source unit includes a connected heat exchanger, fan, refrigerant pump, and electronic expansion valve for providing cooling capacity using natural cold source. The heat exchanger in the refrigerant pump natural cold source unit does not have a compressor and mainly uses refrigerant for heat dissipation, relying on the temperature difference between indoors and outdoors to achieve cold capacity exchange with the outdoors.

[0008] The water circulation module includes a water supply pipeline, and a two-way valve, a mixing pump, a check valve, and multiple manual valves installed on the water supply pipeline. The two-way valve is installed at the return end of the water supply pipeline. The inlet and outlet ends of the mixing pump are connected to the return end and the supply end of the water supply pipeline, respectively. The check valve and multiple manual valves are used to control the on / off state of the water circuit. The multiple manual valves include manual valve 1 and manual valve 2 installed at both ends of the mixing pump, and manual valve 3 and manual valve 4 installed at both ends of the fan coil unit.

[0009] The terminal heat exchange module includes an integrated fan coil unit and a refrigerant pump coil unit. The fan coil unit is connected to the water supply and return ends of the water circulation module, respectively. The indoor air first passes through the refrigerant pump coil unit and then through the fan coil unit, which can transfer the cooling capacity to the artificial climate room to achieve temperature and humidity regulation.

[0010] The control module includes a PID controller and a temperature and humidity sensor. The temperature and humidity sensor, refrigerant pump, mixing pump, and two-way valve are all electrically connected to the PID controller. The temperature and humidity sensor is used to collect the temperature and humidity inside the artificial climate chamber, as well as the outdoor ambient temperature. The PID controller controls the operation of the dual cold source module and the water circulation module based on the collected data to ensure that the temperature and humidity inside the artificial climate chamber remain stable within the set range.

[0011] This invention also proposes a control method for a dual-cold-source air conditioning system in an artificial climate chamber, comprising the following steps: Based on the indoor set temperature T set To control the target, based on the set temperature T set With ambient temperature T w The difference-based switching operation mode includes the following steps: S1, First set the temperature T set With ambient temperature T w The difference is compared with the set values ​​ΔT1 and ΔT2, where ΔT1 > ΔT2; S2, when T set -T w When ΔT1 is greater than or equal to T, the natural refrigerant pump cooling mode is activated; when ΔT2 is less than or equal to T... set -T w When T ≤ ΔT1, the combined cooling mode is activated; when Tset -T w When the temperature is ≤ΔT2, the water-cooled cold source cooling mode is activated.

[0012] Preferably, in step S2, the natural refrigerant pump cooling mode includes the following steps: the two-way valve maintains the lower limit opening, and the control module adjusts the speed of the refrigerant pump in the natural refrigerant pump unit through a PID control algorithm to meet the cooling demand using the natural refrigerant source.

[0013] Preferably, in step S2, the combined cooling mode includes the following steps: simultaneously activating the water-cooled cold source unit and the refrigerant pump natural cold source unit, and the control module adjusting the opening degree of the two-way valve and the speed of the refrigerant pump respectively through the PID control algorithm, so that the two work together to meet the cooling demand.

[0014] Preferably, in step S2, the water-cooled cold source refrigeration mode includes the following steps: the refrigerant pump natural cold source unit is turned off, the control module adjusts the opening of the two-way valve through the PID control algorithm, and the water-cooled cold source unit provides cooling capacity independently.

[0015] Preferably, the calculation formula for the PID control algorithm is as follows: u(k) = u(k-1) + P(k) + I(k) + D(k) =u(k-1) + Kp[e(k)-e(k-1)]+(10 / Ti)×e(k)+Kd×[e(k)-2e(k-1)+e(k-2)] In the formula, u(k): represents the actual output of the device at time k, in units of %; u(k-1): represents the actual output of the device at time k-1, in units of %; e(k): represents the deviation of the target control parameter at time k, e(k) = detected value - set value; e(k-1): represents the deviation of the target control parameter at time k-1; Kp: is the proportional coefficient of PID control, with a value range of 0~1000; Ti: is the integral time of PID control, with a value range of 0~32767; T: is the sampling period of PID control, in units of s, with a value range of 1~20; Kd: is the derivative coefficient of PID control.

[0016] In all of the above operating modes, the fan coil unit maintains a fixed speed and is not adjusted.

[0017] The specific control process for each mode is as follows: (1) Natural refrigerant pump cold source refrigeration mode (Example: T) set =20℃, T w =-5℃, ΔT1=20℃, ΔT2=10℃, T set -T w =25℃>ΔT1): Based on the indoor set temperature T setUsing the current temperature T as the data acquisition target, the PID control algorithm adjusts the refrigerant pump speed between PumpMin (minimum speed) and PumpMax (maximum speed). Using the condenser temperature and set temperature as data acquisition targets, the PID control algorithm adjusts the fan speed between the minimum and maximum fan speeds. Using the suction superheat and superheat setpoint as data acquisition targets, the PID control algorithm adjusts the electronic expansion valve opening to control the refrigerant pump system flow rate. For example, when the indoor temperature T = 22℃, the control module increases the refrigerant pump speed until the indoor temperature drops to 20℃; when the refrigerant pump speed reaches PumpMax, and T... set When the temperature is above 3℃ for 1 hour, switch to combined cooling mode.

[0018] (2) Combined cooling mode (Example: T) set =20℃, T w =5℃, ΔT1=20℃, ΔT2=10℃, ΔT2<T set -T w =15℃<ΔT1): The water-cooled cold source unit and the refrigerant pump natural cold source unit are decoupled and operate independently. The two-way valve and the refrigerant pump are both regulated by independent PID. The two-way valve and the refrigerant pump maintain the lower limit opening to ensure that both can play a cooling role. The goal of both is to stably control the indoor temperature and humidity, rather than controlling the temperature or humidity separately.

[0019] (3) Water-cooled cold source refrigeration mode (Example: T) set =20℃, T w =15℃, ΔT1=20℃, ΔT2=10℃, T set -T w =5℃<ΔT2): Based on the indoor set temperature T set Using the current temperature T as the target, the opening of the two-way valve is adjusted through a PID control algorithm. The opening is between ValvMin (minimum opening) and ValveMax (maximum opening). For example, when the indoor temperature T=22℃, the two-way valve gradually opens to the maximum opening until the indoor temperature drops to 20℃.

[0020] The beneficial effects of this invention are: (1) Significantly reduce energy consumption: By utilizing natural cold sources, the operating time of the water-cooled cold source unit compressor is shortened or its operating load is reduced, which significantly reduces the overall energy consumption of the air conditioning system compared to the existing single cold source system; (2) Precise temperature and humidity control: The PID control algorithm is used to realize the closed-loop control of each component. Combined with the three-stage operation mode switching, the indoor temperature deviation is controlled within ±0.5℃ and the humidity deviation is controlled within ±3% RH, which meets the strict requirements of scientific research and breeding for environmental parameters. (3) Stable system operation: The decoupled independent control strategy in the combined cooling mode avoids mutual interference when the two cold sources operate in tandem, and improves the stability and reliability of the system operation; (4) Wide range of applications: It can automatically switch the operating mode according to different ambient temperatures, and is suitable for artificial climate chambers in different climate zones, especially for energy-saving operation in winter or low temperature environments. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0023] Figure 2 This is a schematic diagram of the water circulation module of the present invention.

[0024] Figure 3 This is a schematic diagram of the control principle of the dual-cold-source air conditioning system for the artificial climate chamber of the present invention.

[0025] Figure 4 This is a schematic diagram of the PID control algorithm of the present invention. Detailed Implementation

[0026] The present invention will now be clearly described with reference to the accompanying drawings and specific embodiments. This description is merely illustrative and is not intended to limit the scope of the invention. Any modifications, equivalent substitutions, or improvements made by those skilled in the art based on the embodiments of the present invention without inventive effort to obtain all other embodiments should be included within the scope of protection of the present invention.

[0027] Example 1 like Figure 1-2 As shown, this embodiment of the invention provides a dual-cold-source air conditioning system for an artificial climate chamber, including a dual-cold-source module, a water circulation module, a terminal heat exchange module, and a control module. The dual-cold-source module includes a water-cooled cold-source unit and a refrigerant pump natural cold-source unit. The water-cooled cold-source unit includes a connected compressor, evaporator, condenser, and throttling device for providing mechanical refrigeration capacity. The refrigerant pump natural cold-source unit includes a connected heat exchanger, fan, refrigerant pump, and electronic expansion valve for providing cooling capacity using natural cold source. The heat exchanger in the refrigerant pump natural cold-source unit does not have a compressor and mainly uses refrigerant for heat dissipation, relying on the temperature difference between indoors and outdoors to achieve cold capacity exchange with the outdoors.

[0028] The water circulation module includes a water supply pipeline, and a two-way valve, a mixing pump, a check valve, and multiple manual valves installed on the water supply pipeline. The two-way valve is located at the return end of the water supply pipeline. The inlet and outlet ends of the mixing pump are connected to the return end and the supply end of the water supply pipeline, respectively. The check valve and multiple manual valves are used to control the on / off of the water circuit and ensure the safe operation of the water circuit. The multiple manual valves include manual valves 1 and 2 located at both ends of the mixing pump, and manual valves 3 and 4 located at both ends of the fan coil unit.

[0029] The terminal heat exchange module includes an integrated fan coil unit and a refrigerant pump coil unit. The fan coil unit is connected to the water supply and return ends of the water circulation module, respectively. The indoor air first passes through the refrigerant pump coil unit and then through the fan coil unit, which can transfer the cooling capacity to the artificial climate room to achieve temperature and humidity regulation.

[0030] The control module includes a PID controller and a temperature and humidity sensor. The temperature and humidity sensor, refrigerant pump, mixing pump, and two-way valve are all electrically connected to the PID controller. The temperature and humidity sensor is used to collect the temperature and humidity inside the artificial climate chamber, as well as the outdoor ambient temperature. The PID controller controls the operation of the dual cold source module and the water circulation module based on the collected data to ensure that the temperature and humidity inside the artificial climate chamber remain stable within the set range.

[0031] Example 2 like Figure 3-4 As shown, this embodiment of the invention provides a control method for a dual-cold-source air conditioning system in an artificial climate chamber, comprising the following steps: Based on the indoor set temperature T set To control the target, based on the set temperature T set With ambient temperature T w The difference-based switching operation mode includes the following steps: S1, First set the temperature T set With ambient temperature T w The difference is compared with the set values ​​ΔT1 and ΔT2, where ΔT1 > ΔT2; S2, when T set -T w When ΔT1 is greater than or equal to T, the natural refrigerant pump cooling mode is activated; when ΔT2 is less than or equal to T... set -T w When T ≤ ΔT1, the combined cooling mode is activated; when T set -T w When the temperature is ≤ΔT2, the water-cooled cold source cooling mode is activated.

[0032] It should be noted that in step S2, the natural refrigerant pump cooling mode includes the following steps: the two-way valve maintains its lower limit opening, and the control module adjusts the refrigerant pump speed of the natural refrigerant pump unit through a PID control algorithm to meet the cooling demand using natural refrigerant; the combined cooling mode includes the following steps: the water-cooled refrigerant unit and the refrigerant pump natural refrigerant unit are activated simultaneously, and the control module adjusts the two-way valve opening and the refrigerant pump speed respectively through a PID control algorithm, so that the two work together to meet the cooling demand; the water-cooled refrigerant cooling mode includes the following steps: the refrigerant pump natural refrigerant unit is turned off, and the control module adjusts the two-way valve opening through a PID control algorithm, so that the water-cooled refrigerant unit provides cooling capacity independently.

[0033] It should be further explained that the calculation formula for the PID control algorithm is as follows: u(k) = u(k-1) + P(k) + I(k) + D(k) =u(k-1) + Kp[e(k)-e(k-1)]+(10 / Ti)×e(k)+Kd×[e(k)-2e(k-1)+e(k-2)] In the formula, u(k): represents the actual output of the device at time k, in units of %; u(k-1): represents the actual output of the device at time k-1, in units of %; e(k): represents the deviation of the target control parameter at time k, e(k) = detected value - set value; e(k-1): represents the deviation of the target control parameter at time k-1; Kp: is the proportional coefficient of PID control, with a value range of 0~1000; Ti: is the integral time of PID control, with a value range of 0~32767; T: is the sampling period of PID control, in units of s, with a value range of 1~20; Kd: is the derivative coefficient of PID control.

[0034] In addition, the fan coil unit maintains a fixed speed in all operating modes and is not adjusted.

[0035] Example 3 This invention describes the operation process of a natural refrigerant pump cooling mode: the artificial climate chamber is set to a temperature T. set =20℃, set humidity RH se t=60%, ambient temperature T w =-5℃, at which point T set -T w=25℃≥20℃, the system starts the natural refrigerant pump cooling mode. The control module collects the current indoor temperature T=22℃ and humidity RH=62%, and calculates the refrigerant pump speed adjustment through the PID control algorithm: the PID parameters are set to Kp=5.0, Ti=10s, T=2s, Kd=1.0; e(k)=22-20=2℃, e(k-1)=23-20=3℃ (assuming the previous temperature was 23℃); u(k)=u(k-1)+5.0×(2-3)+(10 / 10)×2×2+1.0×(2-2×3+4) (assuming e (k-2)=4℃); Calculations showed that after increasing the refrigerant pump speed from the current 30% to 50% and running continuously for 30 minutes, the indoor temperature dropped to 20℃, and the refrigerant pump speed stabilized at 40%. Simultaneously, the control module collected the condenser temperature at -3℃, set the temperature to -4℃, and adjusted the fan speed from 40% to 55% using a PID control algorithm to ensure condenser heat dissipation. The suction superheat was collected at 5℃, set the superheat to 4℃, and the electronic expansion valve opening was adjusted from 60% to 55% using a PID control algorithm to stabilize the refrigerant pump system flow. After 2 hours of operation, the indoor temperature and humidity stabilized within the set range, and the system continued to operate in natural refrigerant pump cooling mode without starting the compressor, significantly reducing energy consumption.

[0036] Example 4 This invention describes the operation process of a combined cooling mode: The set temperature T inside the artificial climate chamber set =20℃, set humidity RH set =60%, ambient temperature T w =5℃, at which point 10℃≤T set -T w When the temperature is between 15℃ and 20℃, the system activates the combined cooling mode. The control module collects the current indoor temperature (T=23℃) and humidity (RH=65%): On the natural refrigerant pump side: the pump speed is gradually increased from 30% to 80% (not reaching PumpMax=100%) using a PID control algorithm; on the water-cooled side: the two-way valve opening is gradually increased from the lower limit of 10% to 40% using a PID control algorithm. After one hour of operation, the indoor temperature drops to 20℃ and the humidity drops to 60%. The control module then stabilizes the pump speed at 50% and the two-way valve opening at 25%, with the two operating independently to continuously maintain stable indoor temperature and humidity. When the humidity is below the setpoint, a humidifier can be used to compensate.

[0037] Example 5 This invention describes the operation process of a water-cooled cold source refrigeration mode: The set temperature T inside the artificial climate chamber set =20℃, set humidity RH set=60%, ambient temperature T w =15℃, at this time T set -T w When the temperature is between 5℃ and 10℃, the system activates water-cooled cold source mode. The control module collects the current indoor temperature T=21℃ and humidity RH=63%, and adjusts the opening of the two-way valve through the PID control algorithm: e(k)=21-20=1℃, e(k-1)=22-20=2℃; u(k)=u(k-1)+5.0×(1-2)+(10 / 10)×1×2+1.0×(1-2×2+3); the opening of the two-way valve increases from 20% to 35%. After running for 20 minutes, the indoor temperature drops to 20℃, and the opening of the two-way valve stabilizes at 28%, continuously maintaining stable indoor temperature and humidity.

[0038] The embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A dual-cold-source air conditioning system for an artificial climate chamber, comprising a dual-cold-source module, a water circulation module, a terminal heat exchange module, and a control module, characterized in that: The dual-cooling-source module includes a water-cooled cooling source unit and a refrigerant pump natural cooling source unit. The water-cooled cooling source unit includes a connected compressor, evaporator, condenser, and throttling device to provide mechanical refrigeration capacity. The refrigerant pump natural cooling source unit includes a connected heat exchanger, fan, refrigerant pump, and electronic expansion valve to provide cooling capacity using natural cooling source. The water circulation module includes a water supply pipeline, and a two-way valve, a mixing pump, a check valve and multiple manual valves installed on the water supply pipeline. The two-way valve is installed at the return end of the water supply pipeline. The inlet and outlet ends of the mixing pump are connected to the return end and the supply end of the water supply pipeline, respectively. The check valve and multiple manual valves are used to realize the on-off control of the water circuit. The terminal heat exchange module includes an integrated fan coil unit and a refrigerant pump coil unit. The fan coil unit is connected to the water supply and return ends of the water circulation module, respectively, to transfer cooling capacity to the artificial climate chamber. The control module includes a PID controller and a temperature and humidity sensor. The temperature and humidity sensor, refrigerant pump, mixing pump, and two-way valve are all electrically connected to the PID controller. The temperature and humidity sensor is used to collect the temperature and humidity inside the artificial climate chamber, as well as the outdoor ambient temperature. The PID controller controls the operation of the dual cold source module and the water circulation module based on the collected data to ensure that the temperature and humidity inside the artificial climate chamber remain stable within the set range.

2. The control method for a dual-cold-source air conditioning system in an artificial climate chamber according to claim 1, characterized in that: Includes the following steps: Based on the indoor set temperature T set To control the target, based on the set temperature T set With ambient temperature T w The difference-based switching operation mode includes the following steps: S1, First set the temperature T set With ambient temperature T w The difference is compared with the set values ​​ΔT1 and ΔT2, where ΔT1 > ΔT2; S2, when T set -T w When ΔT1 is greater than or equal to T, the natural refrigerant pump cooling mode is activated; when ΔT2 is less than or equal to T... set -T w When T ≤ ΔT1, the combined cooling mode is activated; when T set -T w When the temperature is ≤ΔT2, the water-cooled cold source cooling mode is activated.

3. The control method for a dual-cold-source air conditioning system in an artificial climate chamber according to claim 2, characterized in that: In step S2, the natural refrigerant pump cooling mode includes the following steps: the two-way valve maintains the lower limit opening, and the control module adjusts the speed of the refrigerant pump in the natural refrigerant pump unit through the PID control algorithm to meet the cooling demand using the natural refrigerant source.

4. The control method for a dual-cold-source air conditioning system in an artificial climate chamber according to claim 3, characterized in that: In step S2, the combined cooling mode includes the following steps: simultaneously activating the water-cooled cold source unit and the refrigerant pump natural cold source unit, the control module adjusts the opening degree of the two-way valve and the speed of the refrigerant pump respectively through the PID control algorithm, and the two work together to meet the cooling demand.

5. The control method for a dual-cold-source air conditioning system in an artificial climate chamber according to claim 4, characterized in that: In step S2, the water-cooled cold source refrigeration mode includes the following steps: the refrigerant pump natural cold source unit is turned off, the control module adjusts the opening of the two-way valve through the PID control algorithm, and the water-cooled cold source unit provides cooling capacity independently.

6. The control method for a dual-cold-source air conditioning system in an artificial climate chamber according to claim 5, characterized in that: The calculation formula for the PID control algorithm is as follows: u(k) = u(k-1) + P(k) + I(k) + D(k) =u(k-1) + Kp[e(k)-e(k-1)]+(10 / Ti)×e(k)+Kd×[e(k)-2e(k-1)+e(k-2)] In the formula, u(k): represents the actual output of the device at time k, in units of %; u(k-1): represents the actual output of the device at time k-1, in units of %; e(k): represents the deviation of the target control parameter at time k, e(k) = detected value - set value; e(k-1): represents the deviation of the target control parameter at time k-1; Kp: is the proportional coefficient of the PID control; Ti: is the integral time of the PID control. T: Sampling period for PID control, in seconds; Kd: Differential coefficient for PID control.

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