Environmental conditions are a major factor affecting the quality and reliability of equipment. For equipment used in environments with rapidly changing atmospheric conditions, the effect of a warming environment is something to consider. This environment brings various effects of the environment and equipment, such as deformation or breakage of parts, failure of insulation, locking or relaxation of moving parts, changes in electrical equipment and electronic, electronic or mechanical devices from condensation or freezing equipment. The fact that the equipment can work well in the environment of the heating system directly reflects the adaptability of the equipment in this environment.
According to method 503.4 (Temperature Shock Test) of the US Military Standard ML-STD-810 F, equipment that can be used in an environment with rapid air temperature changes will be tested for shock and temperature. The laboratory must be able to prepare another test condition within 5 minutes of changing the sample. The cycle time of the test is 1 min and the wind speed around the sample does not exceed 1.7 m/s.
How to build fire testing equipment? What types of tests are used for equipment? What type of cooling system does the equipment use? How to determine the cooling capacity and heating capacity of the equipment is the main problem that must be solved before building the equipment.
The structure of the thermal shock test equipment generally has three types: single room type, vertical lifting type and horizontal double type. Compared to the three types above, the single-room type can do well with a few practical applications due to the large capacity of cooling and heating; a vertical lift type avoids the effect of external surfaces through internal rotation. However, since the lifting device itself is a heat load, it consumes cold or heat, so this method is often used in small laboratories. For medium and large laboratories, this method is not suitable because the lifting device is heavy; the two-room model reduces the room by turning the corner between the two rooms, thus reducing the cooling power and the heating of the equipment. However, the horizontal rotation device is important and the external environment will affect it. Therefore, the choice of the research method will be evaluated according to the different conditions. For small equipment, vertical lifting methods can save room, which can reduce costs; for medium and large-scale test equipment, as long as the standard is reasonable, and can meet the requirements of national and military standards; horizontal two-room test standards are the best choice.
2.1 The action used for
Humorous temperature with lower rooms, high room, control system, administrative, of the transition device and other equipment. Low room provides lower platform for weather conditions and may make low conditions to do. Higher rooms provide high-quality platforms for the weather conditions to start the higher light test; The refrigerator is giving the temperature for the building and low heat; The heating system provides a higher room for high temperature; The management process results in the management and equipment in the test process; The frequency device is used to change testing tests during the test.
2.2 Structure of the equipment
In order to meet the requirements of the thermal shock test, the building design and ventilation conditions must be carefully planned. The structure of the low-temperature room should meet the speed and speed during the process of use from the hot temperature to the low temperature and the temperature is important, and ensure the uniformity of the air and the temperature in the room; The structure of the high temperature room should meet the requirements of the effective heating of the equipment through the high temperature heating system. Of heating, and ensure the uniformity of air and temperature in the room.
The type of air distribution is an important link in the design of the equipment. The most common types of air transmissions include top side air and full port air compensation and bottom side air. Since the general orifice air supply mode has the advantages of fast and good airflow mixing, uniform and uniform airflow distribution, and fast attenuation of the difference in temperature and wind speed, the distribution of temperature and air speed in the working area is the same thing. Therefore, the ventilation systems of low temperature rooms and high temperature rooms accept return air conditions under full ventilation. The air circulation system is as follows: the air that flows into the room is taken in by a fan and is mixed with cold air to make refrigeration air or hot air is produced by heating process, and then enters the pressure that makes the layer on the side of the air circulate. Duct to increase the air flow and pressure, and send it to the house.
Low temperature room and high temperature room are fixed with steel insulation layer and insulation layer. A full orifice plate is placed at some height from the upper wall. A complete orifice plate and upper wall form a stable pressure bed. At the front of the room is a door, and the back of the room provides air circulation and a fan.
2.3 Switching devices
In order to quickly understand the conversion function, the conversion tool accepts the model of the train conversion, which has a car and a model car. As support for the sample, a sample truck is transported and tested between two sample rooms; the transfer trolley allows the specimen and specimen trolley to be moved easily from one room to another. The bottom wheel is set to rotate on the bottom track, and the top track is fixed for easy docking with the track in both rooms and moving the model vehicle.
At present, the refrigeration mode of the lower room is generally steam compressor refrigeration or air refrigeration. Air conditioners have the following advantages over steam appliances: high refrigeration rates at low temperatures, easy to achieve low temperatures, and high temperature control; it is not susceptible to resource leaks. Small air leakage has little effect on the refrigeration performance, and the refrigeration performance is stable. The refrigerant is air, without any harm to the environment: reliable operation, easy operation, good maintenance and cheap to run. For high temperature test equipment, the temperature change should be fast, and air cooling is a better choice.
Coolant mode uses a turbo expander for secondary compression. Increased turbine expansion ratio Increases heat drop and improves cooling capacity. As a good pressure rising refrigeration mode has the advantages of high refrigeration rate, good control efficiency, strong refrigeration efficiency, stable start and stop and control system, low installed power, operational energy consumption and equipment costs, and the system adopts good pressure rise refrigeration system. . The refrigeration system is divided into two parts: ventilation and refrigeration. Parts of the air include air compressor unit, after cooler, drying tower, water separator, etc. The refrigeration unit includes a turbine, a cooler, a cooler, a filter, etc.
High temperature rooms are heated by electricity; A silicon regulator is used to control and control the electricity to realize the uninterrupted adjustment of the heating amount.
4. Conclusion
Thanks to the air condition that cools the air and the type of music that turns the device, the index required for the quick recovery of the temperature in 5 min and the quick change of the sample in 1 min between two rooms is found. The cooling capacity and heating capacity of the equipment are reduced by having a double-roof design. The successful development of two types of thermal shock equipment has some reference points for the development of similar large and medium-sized thermal shock equipment and thermal shock testing.