Constant temperature and humidity laboratory design scheme

In today's rapidly developing technology, many fields have increasingly stringent environmental requirements, leading to the emergence of constant temperature and humidity laboratories. Simply put, a constant temperature and humidity laboratory is a place that uses intelligent control modes to precisely adjust the indoor temperature and humidity. Through precise control of the functions of the unit's refrigeration, dehumidification, heating, and humidification, it achieves precise control of the indoor temperature and humidity, with errors controllable within a very small range. Its importance is self-evident.

Such laboratories have extremely wide applications. In textile testing systems, constant temperature and humidity ensure accurate and reliable test results, avoiding data deviations caused by environmental factors. Paper testing also depends on it; unstable temperature and humidity will cause changes in the water content of paper, affecting the accuracy of paper performance testing. This is even more true in the field of metrological calibration; high-precision measurements require a stable environment, and constant temperature and humidity laboratories can provide a solid guarantee. Paint testing and packaging testing also rely on this; a stable environment ensures the consistency and accuracy of product quality testing. In addition, constant temperature and humidity laboratories play a key role in precision machining, three-coordinate detection, and research institutions, creating suitable conditions for the smooth progress of various work.

△ Industry Testing Temperature and Humidity Requirements

The construction of a constant temperature and humidity laboratory has many considerations. In terms of laboratory decoration, the requirements for heat preservation and moisture resistance are extremely high. The four sides usually use color-coated steel composite panels. Considering fire prevention needs, rock wool color-coated steel panels are generally selected. However, rock wool has poor thermal insulation performance, so a layer of phenolic aldehyde aluminum foil insulation board is often added to the outside to enhance the thermal insulation effect of the exterior wall and achieve energy saving and consumption reduction. The top is sealed with color-coated steel plates, and a phenolic aldehyde aluminum foil board is added for insulation. The floor is treated with phenolic aldehyde insulation board for heat preservation and moisture resistance. For viewing windows, double-layer hollow glass windows are used to ensure good airtightness.
 

△ Constant Temperature and Humidity Laboratory

Laboratory air conditioning is the core of temperature and humidity control, requiring high precision and low failure rates. There are currently two main ways to adjust the cooling capacity. Frequency conversion regulation changes the compressor power by changing the power supply properties, allowing the compressor to operate under low or overload conditions while adjusting the cooling system flow rate. However, this method requires many cumbersome steps, and each step must be perfectly matched; otherwise, malfunctions are very likely, and the failure rate is quite high in reality. The chilled water unit uses cold water of about 7℃ as the cold source, and adjusts the water flow by controlling the opening and closing of the electric valve to easily control the cooling capacity. The electric valve has a simple structure, similar to a household faucet, so the failure rate is almost zero, and the control effect is stable. By reasonably calculating the room's heat and humidity load and dew point, matching the air volume, cooling capacity, heating capacity, and humidification capacity, and then using PLC to control each component for stepless control, coupled with highly sensitive and linear sensors, the temperature can be controlled to ±0.5℃, and the humidity to ±2%. However, this method needs to be calculated and matched according to the actual area and load of each laboratory. There is no standard prefabricated unit; they are all custom-made, generally using a combination of combined air conditioning units, the disadvantage being large floor space, poor overall system stability, complex maintenance, and difficult repair after problems occur.

△ Control Panel

Ventilation methods have also gone through several stages of development. From the initial bottom air outlet to upper natural air supply, upper diffuser air supply, the most advanced is now the upper air duct + micro-porous ceiling air supply, and lower floor return air method. This method allows the laboratory's air supply to be soft and uniform, and the temperature and humidity control is more stable. The fresh air system is also indispensable; on the one hand, it provides fresh air for the staff, ensuring their health; on the other hand, it makes a huge contribution to the stability of the laboratory temperature and humidity. To prevent the laboratory from being disturbed by the outside world, fresh air must be supplied to the room to maintain positive pressure in the laboratory and prevent outside air from entering, ensuring long-term temperature and humidity stability.

△ Constant Temperature and Humidity Laboratory

The construction requirements for constant temperature and humidity laboratories are also very strict. It generally includes a constant temperature and humidity experimental area, a buffer room, and an air conditioning room, and each area must be on the same construction plane. The constant temperature and humidity room technology must meet ISO and GB standards, and the temperature of each constant temperature and humidity laboratory can be controlled within the set value ±0.01℃~±1℃, the relative humidity within the set value ±(1~2)%, and the wind speed at 0.25m/s. There are also requirements for building construction; there should be no strong magnetic fields, vibrations, heat sources, odors, pollution, or other interfering factors around the building. The floor-to-ceiling height should be above 2.8m (clear height under the beam), and the number of doors and windows should be minimized and insulation measures taken. To meet the laboratory's functional requirements, the air supply mostly uses perforated plate upper air supply and lower return air, with an indoor clear height of 2.5~2.85m, no windows, and a reduced number of doors. Newly built constant temperature rooms do not have water supply and drainage or heating pipeline facilities, while remodeled ones need to have the water supply and drainage and heating pipelines treated with heat insulation and moisture-proof measures according to the standards. The fire protection in the laboratory should not use a sprinkler system; if it needs to be installed, it is recommended to choose a gas fire extinguishing system. Air conditioning equipment room construction requires it to be built in a location with an exterior wall, with an independent power supply system and grounding system, and equipped with water supply and drainage, with the drainage treated to prevent odors. The thermal insulation wall should use materials with a thermal conductivity within the range of 0.021～0.12Kcal/m·H·℃(λ=0.0244～0.1395w/m·k), a water absorption rate of no more than 10%, excellent thermal insulation performance, good water resistance, flame retardant and non-flammable, environmentally friendly, and good size stability.

△ Air Conditioning Equipment Room

Constant temperature and humidity laboratories play an irreplaceable role in many fields. Their precise environmental control technology and strict construction requirements jointly build a technological fortress that ensures the precise conduct of scientific research and industrial production. With the continuous advancement of technology, it will continue to be upgraded and improved, contributing to the development of more fields.