The performance core of the constant temperature and humidity test chamber - temperature uniformity, humidity control accuracy, and response speed - is largely determined by the collaborative design of its "respiratory system", that is, the air duct structure and the circulating fan. Optimizing this system is the key to improving the overall performance of the device.
1、 Optimization of Air Duct Structure: The Art of Guiding Airflow
The core mission of the air duct is to create a stable and uniform airflow field inside the box, avoiding blind spots, eddies, or short circuits.
Adopting a vertical laminar flow design with top air outlet and bottom return air: This is currently the most mainstream and efficient solution. The airflow flows vertically downwards like a piston, evenly covering the sample, and then returns through the bottom return air port, effectively reducing the temperature stratification caused by lateral airflow and ensuring the uniformity of each point in the workspace.
Precision design of air duct cavity and guide plate:
Uniform flow design: Install porous uniform flow plates or guide vanes at specific angles in front of the air outlet to convert the concentrated wind pressure generated by the fan into a uniform and smooth air curtain, preventing the airflow from directly impacting the sample.
Fluid dynamics simulation: Using computational fluid dynamics software to simulate air ducts during the design phase, accurately predicting airflow organization, velocity field, and temperature field, thereby optimizing the angle, shape, and position of the guide plate and eliminating vortices from the source.
Avoiding airflow short circuits: Carefully design the position and area of the air outlet and return outlet to ensure that the airflow must flow through the entire workspace before returning, forcing heat and humidity to fully exchange with the sample, rather than directly taking shortcuts.
2、 Optimization of circulating fan: the core of providing stable power
The fan is the "heart" that drives the entire air circulation system, and its performance directly determines the wind speed and pressure.
Matching fan performance and system resistance: Accurately calculate the required air volume and pressure of the system based on the box volume, sample load, and heating and humidification capacity. Choosing a high-performance backward tilting centrifugal fan provides a smoother and more stable air volume wind pressure curve, especially when overcoming system resistance caused by components such as filters, evaporators, and heaters. It performs better than forward tilting fans and has higher efficiency and lower energy consumption.
Introducing stepless speed regulation or EC (electronic reversing) fans:
Stepless speed regulation: allows users to smoothly adjust the fan speed according to testing needs (such as "windless" testing where samples are afraid of scattering) or load size, achieving precise control of air volume.
EC fan: This is a revolutionary optimization. The EC fan adopts built-in frequency conversion technology, which provides motor efficiency, wider speed range, and precise speed control. It not only significantly saves energy and reduces noise, but also adjusts the output air volume in real-time and linearly based on the deviation between the set temperature and humidity values and the actual values, achieving dynamic response and greatly improving control accuracy and stability.
summary
The optimization of air ducts and fans is a systematic project. A laminar air duct optimized by CFD, combined with an efficient and intelligent EC fan, constitutes the core competitiveness of modern high-performance constant temperature and humidity test chambers. This combination ensures temperature and humidity stability in the shortest possible time and maintains uniformity throughout the workspace, providing the most reliable environmental simulation conditions for product reliability testing.