First, advanced temperature and humidity control equipment
High precision air conditioning system
Cooling and dehumidification functions:
The key is to use air conditioning units with high cooling capacity and dehumidification adjustment accuracy. For example, the cooling capacity adjustment accuracy of some precision air conditioning units can reach ±0.1kW, and the dehumidification adjustment accuracy can reach ±0.1kg/h. This is because the compressor uses advanced frequency conversion technology, which can accurately adjust the cooling and dehumidification power according to the actual heat and humidity load.
The evaporator and condenser design of the air conditioning system is also critical. Efficient evaporators ensure that the refrigerant absorbs enough heat and moisture from the air, while optimized condensers dissipate the heat quickly. For example, the evaporator adopts the structure of copper tube and aluminum fins, which increases the heat transfer area and improves the heat transfer efficiency.
Air circulation system:
Reasonable air circulation design can ensure the uniformity of indoor temperature and humidity. The air conditioning unit is equipped with a powerful supply fan and return fan, which can make the indoor air form a good circulation. The positions of the supply and return air outlets need to be carefully planned, and generally adopt the mode of up and down or side and side.
For example, in some large constant temperature and humidity laboratories, computer fluid dynamics (CFD) simulation is used to optimize the layout of the return air, so that the air is evenly distributed in the laboratory, and the local temperature and humidity difference is too large. The wind speed adjustment range of the blower is wide, which can be accurately controlled according to actual needs, and can generally be adjusted between 0.5-3m /s.
Intelligent humidifier and dehumidifier
Humidifier:
For laboratories that require precise humidity control, steam humidifiers are a good choice. It can regulate humidity by controlling the amount of steam produced. Some advanced steam humidifiers can control humidity accuracy up to ±1% RH.
The working principle is to convert water into steam by means of electric heating or electrode humidification, and then evenly transport the steam to the indoor air. The humidifier can be linked to humidity sensors and controllers to automatically adjust the steam output based on real-time humidity monitoring data in the room.
Dehumidifier:
Rotary dehumidifier is widely used in high precision humidity control. Its core component is the hygroscopic wheel, which contains a hygroscopic medium, such as silica gel or molecular sieve. When the air passes through the runner, the water is adsorbed by the hygroscopic medium, so as to achieve the purpose of dehumidification.
The dehumidification of the wheel dehumidifier can be precisely adjusted according to the speed and size of the wheel. For example, by changing the speed of the runner, the adjustment accuracy of the dehumidification can reach ±0.05kg/h, which can effectively cope with small changes in humidity in the laboratory.

Second, high-precision temperature and humidity monitoring system
High quality sensor
Temperature sensor:
Platinum resistance temperature sensor (PT100) is a common equipment for high precision temperature monitoring. Its resistance value shows a good linear relationship with the change of temperature, and the measurement accuracy can reach ±0.1℃.
The working principle of the PT100 sensor is based on the resistance temperature characteristics of the metal platinum, and when the temperature changes, its resistance value changes accordingly. Through the high precision measurement circuit, the resistance value can be accurately obtained, and then the temperature value can be calculated. The stability of this sensor is good, and the accuracy drift of long-term use is small.
Humidity sensor:
Capacitive humidity sensors perform well in high precision humidity measurement. It uses the principle of humidity sensitive capacitors, when the ambient humidity changes, the capacitance value will also change. Its measurement accuracy can reach ± 1%RH - ± 2%RH.
For example, in some high-precision laboratories, the capacitive humidity sensor imported from Switzerland is used, which uses a special polymer material as a humidity sensitive medium inside, which responds quickly to changes in humidity and can maintain high-precision measurement over a wide humidity range.
Distributed monitoring network
In order to grasp the temperature and humidity of the laboratory comprehensively and accurately, it is necessary to establish a distributed monitoring network. Install temperature and humidity sensors in different locations in the laboratory, such as around the test bench, inside the equipment, and in the corner.
Through the data acquisition system, the data of each sensor is collected and transmitted to the central controller. The data acquisition system can use wired (such as RS-485 bus) or wireless (such as ZigBee) communication mode. For example, when RS-485 bus is used for communication, the data transmission rate is high, the anti-interference ability is strong, and the long-distance stable communication of multiple sensors can be realized.

Third, accurate control system
PID controller
PID (Proportional Integral-differential) controller is the core component of high precision temperature and humidity control. According to the deviation between the set value and the actual measured value, the control quantity is calculated by three operations: proportion, integral and differential.
For example, in temperature control, when the actual temperature is higher than the set temperature, the proportional item will immediately produce a control signal proportional to the deviation, so that the cooling capacity of the air conditioning unit is increased; The integral term will accumulate deviation, which is used to eliminate the steady-state error of the system. The differential term adjusts the control signal in advance according to the rate of temperature change, preventing temperature overshoot. The parameters of the PID controller (proportional coefficient, integral time and differential time) can be determined by experiment and simulation optimization to achieve the best control effect.
Intelligent control algorithm and software
In addition to the traditional PID control, some advanced intelligent control algorithms can be used, such as fuzzy control, neural network control and so on. Fuzzy control can deal with uncertainty and nonlinear problems in temperature and humidity control.
For example, in humidity control, when the humidity is in a fuzzy boundary state, the fuzzy control algorithm can adjust the working state of the humidifier or dehumidifier according to the empirical rules and the current temperature and humidity trend. At the same time, the supporting control software can realize the setting of temperature and humidity, real-time monitoring data display, historical data record and analysis and other functions. Through the software can easily set the temperature and humidity control parameters, view the temperature and humidity curve, and can set the alarm threshold, when the temperature and humidity exceeds the set range, the alarm will be issued in time.

Fourth, good laboratory enclosure structure
Thermal insulation material
The use of high-quality thermal insulation materials on the wall, roof and floor of the laboratory can effectively reduce the influence of external environment on indoor temperature and humidity. For example, exterior walls can be made of polystyrene foam (EPS) or polyurethane foam (PU).
The thermal conductivity of PU foam board is low, generally between 0.02-0.03 W/(m · K), which can prevent the transfer of heat well. The thickness of the wall is determined according to the temperature and humidity requirements of the laboratory and the climate conditions of the region, generally about 100-200mm. The ground can be laid with insulation and moisture-proof materials, such as expanded perlite insulation panels, to prevent underground moisture and heat from entering the room.
Airtight treatment
The opening parts of the laboratory, such as doors and Windows, should be air-tight treatment to prevent the leakage of outdoor air. The use of high-performance sealing strips and double-layer sealing doors and Windows can effectively improve the air tightness of the laboratory.
For example, double-layer insulating glass doors and Windows not only have good insulation performance, but also reduce the penetration of outside air. The sealing strip can choose rubber or silicone material, which has good sealing performance and long service life. The laboratory after airtight treatment can reduce temperature and humidity fluctuations caused by air exchange and help maintain the stability of indoor temperature and humidity.