Refrigerant leak detection sensor
Refrigeration technology plays a vital role in our lives in modern times, whether it is in home air conditioning, commercial refrigeration equipment, or industrial production processes, it is indispensable to continue to innovate in this field.
What is refrigerant?
Refrigerant is the medium used to transfer heat and change the state of matter in a refrigeration system. It accomplishes the task of absorbing and releasing heat through the processes of evaporation and condensation in the refrigeration cycle, thus realizing the goal of temperature regulation and maintaining the internal temperature of the equipment.
Refrigerant usually has a low boiling point and high freezing point in order to complete the process of evaporation and condensation in the common temperature range. During evaporation, the refrigerant absorbs heat and transforms itself from a liquid to a gas, while during condensation, the refrigerant releases heat and transforms itself from a gas to a liquid.
Common refrigerants include Freon, ammonia, hydrofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and others. The choice of different types of refrigerants depends on application areas, environmental friendliness, energy efficiency, and safety considerations. Refrigerants play a key role in a variety of refrigeration installations such as air conditioners, refrigeration equipment, cold stores, cooling systems, etc., enabling them to regulate temperatures efficiently and meet the needs of different environments.
Why is it important to test the refrigerant?
Testing refrigerants is very important and is based on the following considerations:
Environmental protection: Refrigerants may have a negative impact on the environment. Some commonly used refrigerants, such as Freon, are fluorocarbons, which may lead to the destruction of the ozone layer and are greenhouse gases. Therefore, timely detection of refrigerant leaks helps to minimize the negative impact on the atmosphere and the environment, in line with environmental regulations and sustainable development.
Equipment safety: Refrigerant leaks may affect the normal operation of refrigeration equipment. Excessive leakage may lead to a drop in system pressure, slowing down or interrupting the refrigeration cycle, reducing the performance of the equipment, or even leading to equipment failure. By testing the refrigerant, potential problems can be detected in time to maintain proper operation and extend the life of the equipment.
Energy Efficiency: Proper circulation of refrigerant is critical to maintaining efficient operation of refrigeration equipment. Leaks can lead to a reduction in refrigerant volume, which can affect cooling effectiveness. By regularly testing the refrigerant, the proper amount of refrigerant can be maintained in the system, ensuring that the equipment operates at high efficiency and reducing energy consumption.
Safety precautions: Certain refrigerants can be hazardous to human health at high concentrations. Early detection of refrigerant leaks can prevent personnel from being exposed to hazardous substances, and timely safety measures can be taken to ensure workplace safety.
Regulatory compliance: In many regions, there are strict regulations and standards regarding the use and leakage of refrigerants. By detecting refrigerants, companies can ensure compliance and avoid potential fines and legal liabilities.
Refrigerant leak detection sensor technology
The core device of the refrigerant leak detection system is the Refrigerant leak detection sensor. Currently, the sensing technologies for refrigerant leak monitoring mainly include Non-dispersive Infrared (NDIR), Metal Oxide Semiconductor, MOS, and other technologies. Semiconductor, MOS, which can be categorized as Chemiresistive principle) and Thermal Conductivity (TC).
MOS semiconductor sensors increase sensitivity by heating the material that reacts with the gas, and the change in resistance value caused by the redox reaction between the gas and the semiconductor confirms the concentration of the gas by the magnitude of the change in resistance value.
However, the disadvantages of MOS sensors are obvious. First, MOS sensors have poor long-term stability and tend to lose accuracy over time. Secondly, MOS sensors have poor selectivity and are easily affected by other volatile organic substances (e.g. alcohol). Finally, if the humidity of the air changes, the detection results of semiconductor sensors will also be affected, so the measurement accuracy of semiconductor sensors is still to be considered.
The biggest problem is that when exposed to high concentrations of refrigerants and other gases, the performance of MOS sensors can degrade or even fail permanently. This effectively means that MOS sensors are “single-use” and may require labor-intensive replacement after a refrigerant leak.
Gas sensors using thermal conductivity technology also have the advantage of being low-cost. The heat exchange principle was first used for flow detection and is a well-established detection technology. However, for gas detection, this technology is not as mature and there are no examples of it being used in bulk on the market, so it is not the best idea to be the first to take advantage of it.
NDIR Refrigerant Sensor has a built-in light source, which emits a certain amount of light that is transmitted to the photosensitive element. Combustible gases entering the sensor are exposed to the light. Combustible gases have the property of absorbing certain wavelengths of light, and the photosensitive element detects the light attenuated by the absorption. The concentration of the combustible gas is calculated based on the degree of light attenuation.
NDIR-type sensors have high gas selectivity, do not react to gases other than combustible gases, and have high detection accuracy, good stability, and long life. Based on these characteristics, the number of air conditioning manufacturers using NDIR has been increasing in recent years.
