The direction of frosting in the refrigeration system is exquisite, do you know?
First, the direction of frost formation is the compressor return air inlet gradually began to frost in the direction of the evaporator. Possible reasons are: 1. The throttle valve opening is too large, the appearance is that the condensing return liquid temperature and pressure are normal or slightly higher, and the compressor return air inlet gradually starts to frost in the direction of the evaporator. 2. The evaporator does not normally absorb heat, or the amount of cold produced by the evaporator cannot be taken away. The representation is that the return liquid temperature and pressure are normal or slightly lower, and the compressor is gradually condensed toward the evaporator from the gas return port. After a long time, all the ice is frozen from the compressor return port to the evaporator and the throttle valve to the evaporator section. After the zui, there is a low pressure. The inspection method is: · Look at the air filter is clean; · See if the fan speed is normal; · Is the evaporator clean? ·The air supply system is blocked; · Is the belt too loose? Second, if the direction of frost formation is the expansion valve to the evaporator, the possible reasons: 1. Less refrigerant (leakage), the appearance is that the condenser return temperature is high but the pressure is not high, and the throttle valve gradually starts to frost in the direction of the evaporator. 2. The opening degree of the expansion valve is too small, the appearance is that the condensation liquid return temperature and the pressure are normal or slightly lower, and the throttle valve gradually starts to frost in the direction of the evaporator. 3. Check the sight glass to see the refrigerant condition, the foaming is serious, it may be the system leakage; the refrigerant in the liquid mirror does not bubble or seldom bubbling, it may be that the expansion valve is too small, or blocked, generally There will be a large temperature difference before and after the blockage. The surface of the evaporator fin is frosted, and the evaporator temperature of the frosted portion is lower than 0 ° C. The frosting speed is related to the ambient temperature and humidity. There are two phenomena in the evaporator frosting: 1) A phenomenon is the blooming from the evaporator outlet, which fills the entire evaporator surface over time. The occurrence of this phenomenon is too much liquid supply for the evaporator (the capillary system reacts obviously), and the entire refrigeration system of the household air conditioner may be a problem with the return air system and the control system: a. The return air filter dust blockage, the surface of the evaporator fin dust block, the fan capacitor is bad or the capacity is small, the fan motor does not turn, the speed is slow, and the like, causing the evaporator heat exchange load to decrease. b. Long-term cooling operation in the case of a cooling operation or a change in the return air temperature sensor resistance when the ambient temperature is low. In the household air conditioner, if the control system has the anti-freeze protection function, the controller automatically turns off the compressor and the outdoor fan for protection when the control system detects that the evaporator coil temperature is lower than 0 °C after the refrigeration system is running for a period of time. The fan runs at high speeds. When the indoor evaporator coil temperature is greater than 10 °C during the protection period, the protection is resumed and the refrigeration operation is resumed. If the surface of the long-term evaporator is found to be frosted, the system evaporator coil sensor and return air temperature sensor may be faulty or the control system may not have anti-freeze protection. c. Some air conditioners have a continuous operation function. When the continuous operation function is turned on, the operation of the refrigeration system is not controlled by the temperature of the temperature sensor. When the operation time is long, frost on the surface of the evaporator may occur. Just turn off the continuous run function. During maintenance, first check the evaporator fins, fan system, controller return air temperature and coil temperature sensor, the ambient temperature at the time of operation, and confirm that there are no problems in the inspection components to determine whether the system has a large amount of fluorine. The high rate of fluorine is generally a phenomenon that may occur after the system is refilled with refrigerant. Here is a point to note that the system fluorine rate may be more likely to run on the evaporator surface under high ambient temperature conditions, and frosting on the evaporator surface may occur when operating at low ambient temperatures. 2) Another phenomenon is that the frost starts from the throttling of the capillary. Over time, the surface of the evaporator is frosted on the surface of the evaporator, and most of the surface of the evaporator has no condensation. This phenomenon occurs on the evaporator of the refrigeration system. In terms of the lack of liquid supply. For the entire refrigeration system of a household air conditioner, there may be a leakage of the system or a half-blocking of the throttle system. Differentiate the system with a leak or throttling system with a half block: a. The condenser has a high air outlet temperature, a large current, and some frost and no refrigeration at the inlet of the evaporator, and the throttle system has a semi-blocking phenomenon. The faulty part of the filter before the capillary inlet is dirty or the indoor and external connecting liquid tubes (thin tubes) are crushed to form a secondary throttling. b. The condenser outlet air temperature is not high, the current is small, and some of the frost at the inlet of the evaporator is not cooled, and most of the pipelines of the refrigeration system have leak points. The faulty system piping, welding points, interface, valve core, bonnet, and especially the system piping have oil stains. System capacity protection should be available in the home air conditioner control system. In the cooling mode, after 30 minutes of continuous operation of the compressor, the indoor evaporator coil temperature is ≥25°C or above (some manufacturers use indoor ambient temperature - indoor coil temperature ≤ 4 °C), stop compressor, external fan, indoor fan Run at the set wind speed. Entry protection generally requires a power outage to exit. Some control systems do not have the ability to protect the function. When the compressor is running continuously, the compressor may be overheated. Third, the evaporator freezes The entire evaporator freezes because the refrigerant in the evaporator is in the process of vaporization and heat absorption! Didn't get more calories! Reduce the temperature in the limited space on the outer wall of the copper tube to below 0 degrees! That is, after the temperature of the cooling medium (air) is lower than the dew point temperature, dew drops are formed on the outer wall of the evaporator! The temperature drops below 0 degrees! Cause icing! Why the temperature is below 0 degrees! It is because the amount of air to be treated on the outer surface of the evaporator is small! So the heat transfer is more complete! So the first two analyses of the bamboo are all about why the air volume is not enough to discuss! As for the third point: if the evaporator outlet freezes and the return superheat is reduced! It is possible that there are too many refrigerants! One of the necessary conditions for the evaporator to freeze is that the evaporation temperature must be below 0 degrees! And more refrigerants will cause the evaporation temperature to rise! Add a little impossible factor: the value of the evaporator inlet air state is small! That is, the inlet air temperature is low or the humidity is small! In addition, the evaporator manufacturing process does not use hydrophilic treatment! Causes the condensate to not leave the evaporator smoothly! Hot swap time is too long! 1. Less refrigerant. In the absence of refrigerant, the pressure in the system is correspondingly reduced, and the pressure drop causes the evaporation temperature of the refrigerant to decrease, usually below zero degrees Celsius, causing the moisture in the air to directly condense into frost. Instead of normal water, in this case, the split-unit air conditioner indoor unit coil temperature probe (detecting the indoor evaporator coil temperature) can also detect a certain temperature drop of the coil (if not, the air conditioner Will protect the machine), in this case, the split air conditioner indoor unit will freeze, and the process should be boot--external high-pressure tube frosting--inner evaporator at the entrance to the frost--inner knot Ice - the ice is blowing out the ice (in severe cases) - the internal fan is stuck (in severe cases). 2. The evaporator is dirty. In the case where the internal evaporator is dirty, the air volume of the internal machine will be seriously reduced, so that the heat absorbed by the refrigerant during the internal combustion cannot be replenished from the indoor hot air (I am on the refrigerant) In the case of evaporating temperature changes is not very understandable, I hope someone will add), at this time the internal evaporator will slowly begin to dew condensation to icing. The process should be started--the wind is small (the air outlet effect is good, but the indoor temperature does not fall down, and the air outlet sometimes has a misty water vapor. Usually, this phenomenon occurs in places with poor operating conditions, such as bars. , karaoke, hairdressing room (hair block) restaurant, etc. 3. The fan speed is slow. The situation is very similar to that of the evaporator, but the operating environment is good when observed, the evaporator is clean, and the human body feels low wind speed. 4. The continuous operation of the air conditioner is too long. This kind of state is especially common in some enterprises and institutions, but it often occurs on a larger cabinet internal machine. This is generally not the case with small split hang-ups (estimated to have a low cooling capacity). Especially on the 5P air conditioner, it will freeze after a long time of operation, but the icing part is different from the above cases, and the icing part is generally near the end of the steamer, especially in the outer air return pipe. (Low pressure, inhalation), sometimes the ice will be thick and thick. However, this state does not reflect its cooling effect. 5. The indoor humidity is too large and the running time is too long. Similar to the previous case, but it mostly occurs on the split hang-up, especially in some hotel kitchens, cold dishes, etc., which require long-term operation and high environmental humidity. 6, the internal and external machine connection copper tube has a flattened. This kind of situation has also occurred frequently. The state of its manifestation is mostly frosting or icing from the flattened area (the ice is running for a long time), and the reason is explored. It should be that the refrigerant has a secondary throttling in the place where it flows through the flattening. It has not evaporated in the throttling place, and most of the flattened places cannot exchange heat with the outside air, resulting in The temperature at the flattening is getting lower and lower, and the Zui ends the ice.
[Sample requirements] Vtm Sampling Tube With Swab,Disposable Collection Tube Of Virus Samples,Hi Media Vtm Kit,Amylase Sample Collection Tube Jilin Sinoscience Technology Co. LTD , https://www.contoryinstruments.com
The collected nasopharyngeal swab samples should be transported at 2°C to 8°C and sent for inspection immediately, and the sample delivery and storage time should not exceed 48 hours.
[Testing method]
1. Before sampling, mark the relevant sample information on the label of the sampling tube.
2. According to different sampling requirements, use a sampling swab to sample in the nasopharynx.
3. The specific sampling methods are as follows:
a) Nasal swab: Gently insert the swab head into the nasal palate, stay for a while and then slowly turn to exit. Wipe the other nostril with another swab, immerse the swab head in the sampling solution, and discard the tail.
b) Pharyngeal swab: Wipe bilateral pharyngeal tonsils and posterior pharyngeal wall with a swab, also immerse the swab head in the sampling solution, and discard the tail.
4. Quickly put the swab into the sampling tube.
5. Break the part of the sampling swab higher than the sampling tube, and tighten the tube cover.
6. Freshly collected clinical specimens should be transported to the laboratory within 48 hours at 2°C to 8°C.
[Explanation of test results]
After the sample is collected, the sampling solution turns slightly yellow, which will not affect the nucleic acid test result.
[Limitations of the test method]
1. For samples that are seriously contaminated due to improper storage after collection, the final test results will be affected.
2. If the sample is not stored at the specified temperature, the final test result will be affected.