Air-cooled Direct Expansion Constant Temperature and Humidity Laboratory Air Conditioner

Air-cooled Direct Expansion Constant Temperature and Humidity Laboratory Air Conditioner

In scientific research, testing, measurement and other fields, the laboratory on the stability of the environment temperature and humidity, precision requirements are extremely high - a small temperature and humidity fluctuations may lead to experimental data deviation, sample failure, instrumentation precision degradation and even experimental failure. Air-cooled direct expansion constant temperature and humidity laboratory air conditioner as an integrated cooling, heating, humidification, dehumidification function of the integrated equipment, with the “air-cooled cooling” “direct expansion cycle” features, can accurately control the laboratory temperature and humidity, to become a small and medium-sized laboratory (area) Usually 50-300 square meters) of the mainstream choice.

The core of the equipment realizes temperature and humidity control through “refrigerant cycle” and “air treatment cycle”:

Refrigerant cycle (refrigeration / heating):

Refrigeration: the compressor will be high temperature and high pressure refrigerant into the outdoor condenser (air-cooled heat dissipation), liquefied exothermic by the expansion valve throttling, into a low-temperature, low-pressure liquid into the indoor evaporator, absorbing the heat of the air (cooling) and then evaporated, back to the compressor to complete the cycle.

Heating: switch the refrigerant flow direction through the four-way valve, the evaporator and condenser function interchangeable (similar to the principle of heat pump), indoor evaporator exothermic warming.

Air treatment cycle (humidification / dehumidification):

Dehumidification: when the indoor humidity is higher than the set value, the refrigeration system starts, the water vapor in the air condenses into water on the surface of the evaporator (sensible heat dehumidification), lowering the humidity content in the air; if you need to dehumidify the air in depth, it can be equipped with a low-temperature evaporator (the temperature is lower than the dew point of the air).

Humidification: When the humidity is lower than the set value, water vapor is released to the air through the electrode humidifier tank (water is heated and evaporated by the electrode) or ultrasonic humidifier (water is atomized by high-frequency vibration) to enhance the humidity.

Special Design of Laboratory Air-cooled Direct Expansion Constant Temperature and Humidity Air Conditioner

1. High-precision Control Technology

Sensor Selection: Imported temperature and humidity sensors (e.g., Swiss Rozanic, U.S. Honeywell) are adopted, with an accuracy of ±0.2℃ (temperature), ±1% RH (humidity), and a sampling frequency of ≥1 time/second to ensure the real-time data.

PID Intelligent Adjustment: Dynamically adjust the output of the equipment (e.g., cooling capacity, heating power, humidification) through the proportional-integral-derivative algorithm to avoid temperature and humidity “overshoot” (e.g., excessively lower than the set value when cooling), and fluctuations are controlled within ±0.5℃/±2% RH.

Anti-interference design: laboratory equipment (such as centrifuges, ovens) heat dissipation will lead to local temperature and humidity fluctuations, air conditioning needs to have “regional compensation” function - through the linkage of multi-region sensors, to adjust the amount of air supply or the local air outlet air speed to balance the regional differences.

2. Air cleanliness and filtration

Laboratories have high requirements for air cleanliness (to avoid dust contamination of samples or instruments), air conditioners need to be integrated with a multi-stage filtration system:

Primary filtration (G4 level): to remove large particles of dust in the air (≥ 5 μm), to protect the fan and the heat exchanger;

Intermediate filtration (F8 level): to filter particles of ≥ 1 μm (e.g., pollen, mold spores), suitable for general clean laboratories;

High-efficiency filtration ( High-efficiency filtration (H13, optional): filtration of particles ≥0.3μm (such as bacteria, aerosols), to meet the needs of biosafety laboratories (P2 level and above) or electronic clean rooms.

3. Reliability and redundancy design

Laboratory experiments often require continuous operation (e.g., 72-hour biological culture), equipment failure may lead to interruption of experiments, so it is necessary to have:

redundancy of key components: such as dual-compressor (one with a standby), standby humidification tank, a single component failure automatically switches to ensure that the operation will not be interrupted;

self-diagnostic faults: real-time monitoring of the compressor pressure, fan speed, humidification tank water level and other parameters, when the anomaly of automatic alarm (sound and light + remote notification). Fault self-diagnosis: real-time monitoring of compressor pressure, fan speed, humidifying tank water level and other parameters, automatic alarm (sound and light + remote notification), and record the fault code for easy maintenance;

anti-condensation design: low evaporator surface temperature may lead to condensation and dripping, through the linkage control of temperature sensors, to ensure that the evaporator temperature is not lower than the dew point of the air + 1 ℃, to avoid condensate contamination of the laboratory.

4. Energy saving and adaptability optimization

Frequency conversion technology: compressor, fan frequency control, according to the load dynamic adjustment of the output power (such as low-frequency operation when the load is low), energy-saving than fixed-frequency equipment by more than 30%;

Fresh air supplementation: laboratory if you need to be a micro-positive pressure (to prevent the penetration of external contamination), can be designed to 10-15% of the proportion of fresh air, fresh air through the pre-processing (filtration and temperature and humidity regulation) and return air mixing, to avoid waste of energy; wide temperature range of the laboratory to ensure that the evaporator temperature is below the air dew point + 1 ℃ to avoid condensation pollution. Wide temperature range operation: the outdoor unit needs to adapt to extreme climate (such as - 20 ℃ to 45 ℃), low-temperature environment through the “Enhanced Enthalpy Jet” technology to enhance the heating capacity, and high temperature to enhance the fan cooling to ensure the stability of temperature and humidity in the laboratory.