Step 1: Understanding medical drug refrigerators, laboratory refrigerators, and medical cold storage boxes

1. Purpose:

Drug storage cabinets and laboratory refrigerators can actually be classified as one type of product, named according to their purpose and application scenarios. Both are low-temperature equipment, suitable for universities, research institutes, public institutions, biomedical and chemical enterprises, hospitals, etc., for storing laboratory reagents, consumables, drugs, biological products, etc. (hereinafter collectively referred to as drug storage cabinets).

2. Working Principle:

A drug storage cabinet consists of a refrigeration system, a digital temperature control system, an air circulation system, temperature sensors, etc. Temperature control is primarily achieved by the instrument controlling the refrigeration system, which is key to the drug storage cabinet.

The refrigeration system is mainly composed of core components such as a compressor, condenser, evaporator, and expansion valve. These devices are connected in sequence by pipes to form a closed system. When the system operates, the compressor draws the low-temperature, low-pressure refrigerant vapor generated by the evaporator into the cylinder. After compression by the compressor, the pressure increases (and temperature also rises) to slightly greater than the pressure inside the condenser, at which point the high-pressure refrigerant vapor in the cylinder is discharged into the condenser. (Therefore, the compressor plays the role of compressing and transporting the refrigerant.) In the condenser, the high-temperature, high-pressure refrigerant vapor exchanges heat with cooler air (or room temperature water) and condenses into liquid refrigerant. This liquid refrigerant then passes through the expansion valve, cools down (and depressurizes), and enters the evaporator, where it absorbs heat from the object to be cooled and then vaporizes. In this way, the object is cooled, and the refrigerant vapor is drawn back by the compressor. Thus, in the refrigeration system, a cycle is completed through four processes: compression, condensation, expansion, and evaporation.

Step 2: Determine the Volume

The volume of a drug storage cabinet is generally determined by considering the scale of the laboratory, the amount of drugs and reagents to be stored, and the available space for placing the drug storage cabinet. In typical manufacturer models, the numeric suffix indicates the volume of the drug storage cabinet: for example, in GYYP-900, "900" indicates the volume of the drug storage cabinet is 900.

Step 3: Understand Existing Market Brands

Generally, a relatively complete summary can be found on some professional instrument websites, or many can be found by directly searching on Baidu. It should be noted that some brands produce products similar to fresh-keeping cabinets used in supermarkets or retail stores, which are relatively rough in terms of materials and manufacturing. It is more reliable to choose products from manufacturers specializing in instruments.

Mainstream brands are as follows:

Imported: Thermo, Sanyo

Domestic: Haier, Zhongke Meiling, Xiamen Guoyi, Qingdao Aucma, Beijing Fuyilian, etc.

Step 4: Compare the characteristics of various brands in detail to find the one suitable for you.

Consideration should mainly be given to hardware, temperature control performance, and after-sales service.

In terms of hardware, the main consideration should be the brand of compressor used by the product. Prioritize choosing a good compressor, as the compressor is the heart of refrigeration equipment; a reputable brand in the industry should be Secop (formerly Danfoss).

Temperature control performance mainly involves comparing temperature uniformity. Temperature control accuracy is generally similar, with a typical temperature range of 0-10 degrees Celsius.

Regarding after-sales service, it's almost impossible for every brand to have its own service team in every location. Even for brands like Hai*, after-sales service is outsourced, and medical products typically use after-sales agencies for home appliances, which usually can't handle them. Given the current situation, it's generally more reliable to find a brand with a general agent in your local area, as agent companies usually have their own after-sales capabilities.

Step 5: Common Issues

1. Differences between drug storage cabinets (laboratory refrigerators) and household refrigerators.

Firstly, some refrigerators used in laboratories need to achieve precise constant temperature, requiring higher temperature control performance. For example, some constant temperature cabinets in blood banks must achieve precise control of plus or minus 1 degree Celsius. Household refrigerators generally have lower temperature requirements and poorer temperature uniformity.

Secondly, laboratory refrigerators have high requirements for material selection, panel thickness, and foaming, while household refrigerators, due to their lower selling price, need to keep costs very low, so the choice of compressors and panels is primarily cost-driven.

Thirdly, most laboratory refrigerators are designed with air-cooling principles, while household refrigerators generally use direct cooling, which is also a cost consideration.

In addition, laboratory refrigerators should have a temperature display panel to monitor the temperature inside the cabinet at any time, preventing unnecessary losses. Laboratory refrigerators should also have a safety lock, especially for certain special experimental items, requiring dedicated personnel for management.

2. Differences between air-cooling and direct cooling methods.

Laboratory refrigerators generally use air-cooling for refrigeration, forming a stable and uniform airflow inside the refrigerator compartment through a fan to achieve precise temperature control. The evaporator in the refrigeration system uses a finned type, which has a higher cost.

Household refrigerators generally use direct cooling, which, in simple terms, is contact refrigeration. They typically do not have a fan. The evaporator used is a roll-bond evaporator, which is much cheaper than a finned evaporator. While the cost is reduced, temperature control performance cannot be guaranteed.