The difference between high and low temperature test chamber and liquid nitrogen cryogenic chamber

1) Temperature range: the biggest difference between the high and low temperature test chamber and the liquid nitrogen cryogenic cryogenic chamber is that their temperature range is different, and the temperature range of the high and low temperature test chamber can be -80 150; The temperature range of liquid nitrogen cryogenic chamber can be -196 150.

2) Different refrigeration methods: liquid nitrogen cryogenic chamber is to spray liquid nitrogen directly inside the test chamber, and the liquid nitrogen absorbs heat and vaporizes inside the test chamber, takes away the heat, and cools the test chamber; The high and low temperature test chamber is designed in the evaporator of the refrigeration system in the test chamber, and the refrigerant through the throttling device evaporates and vaporizes inside the evaporator (not directly into the test chamber) to absorb the heat outside the evaporator and cool down the test chamber.

3) Different temperature change rates: the cooling rate of liquid nitrogen cryogenic chambers is very fast, which can reach 10 min; The cooling rate of the high and low temperature test chamber is:

Move the boat to park the smoke, and the sunset is new.

The high and low temperature test chamber is one of the environmental test equipment, and the common environmental equipment also includes salt spray test chamber, constant temperature and humidity chamber, rain test chamber, sand and dust test chamber, ultraviolet aging test chamber, and high pressure aging test chamber.

In the process of using the high and low temperature test chamber, there are many precautions, and it is also necessary to maintain it frequently, which can prolong the service life of the test chamber and testing machine. The following is an introduction to the precautions and maintenance of the constant temperature and humidity test chamber by Shanghai Farui Instrument.

1.Before doing the test, the water level of the water tank should be adjusted moderately. Too high will cause water overflow, too low will make the wet bulb test cloth absorb water abnormally, and the water level of the water accumulation cylinder will generally remain at a six-point water level. The adjustment of the water level of the water accumulation cylinder can adjust the height of the water accumulation box. Difference.

Not much, every two or three tests need to be checked and watered. You can look at the water pipe in front of you to replenish water, and the machine will alarm and stop working after there is no failure.

2.This machine is equipped with a test hole on the side of the machine, which can be used when connecting to the test line in the box.

If you want to observe the changes in the box, you can turn on the indoor light switch and know the changes inside through the window.

4.When running the machine below 0, avoid opening the door, because when doing low temperature, if the door is opened, it is easy to cause the ice sealing phenomenon of the internal evaporator and other parts, especially the lower the temperature, the more serious the situation, if it must be opened, the door opening time should be shortened as much as possible.

5.When the low temperature operation is completed, it is necessary to set the temperature condition of 60 to carry out the drying treatment for about half an hour, so as not to affect the measurement time of the next operating condition or the freezing phenomenon.

6.The radiator (condenser) of the freezer should be maintained regularly and kept clean.

7.The humidifier bucket must be completely discharged from the water pipe, so as to prevent it from entering.

Is it better to use liquid nitrogen to refrigerate the high and low temperature test chamber for ultra-low temperature experiments, or to refrigerate the generator set? What's the difference? At this stage, there are many differences: refrigeration method, temperature level, and cooling rate.

One: the refrigeration method is different.

Liquid nitrogen refrigeration is generally to spray liquid nitrogen immediately on the inside of the high and low temperature test chamber plugging cover, and the liquid nitrogen is chemically vaporized in the high and low temperature test chamber, and the heat is sent to deheat the alternating high and low temperature chamber; The refrigeration of the refrigeration generator set is generally the design scheme of the air conditioning evaporator of the refrigeration unit in the test instrument, and the refrigerant inside the air conditioning evaporator is generally selected as the refrigerant for the construction of ecological civilization, and the refrigerant of the throttling device is volatilized and gasified inside the air conditioning evaporator (not immediately into the alternating high and low temperature box), and the heat generated outside the air conditioning evaporator is digested and absorbed, so that the high and low temperature test chamber is deheated.

Two: the temperature level is different.

When the experimental terrain and landform are less than -50 - 205 as much as possible, the liquid nitrogen refrigeration method is generally selected. In view of the experimental topography less than 0 -90 as much as possible, there are many high and low temperature test chambers for the refrigeration method of refrigeration generator set, because liquid nitrogen is pure in consumption, liquid nitrogen is consumed as much as possible for each ultra-low temperature obtained.

Three: the cooling rate is not the same.

The high and low temperature test chamber of liquid nitrogen refrigeration deheats quickly, fully considering the rapid stability of temperature and the problems of the whole process, and the general design scheme is 12 min. The high and low temperature test chamber of refrigeration generator set refrigeration is 1 min because of the increase in the cost of obtaining ultra-low temperature terrain and landform.

According to the above content, I am sure that you have an approximate grasp of the refrigeration method of the high and low temperature test chamber, and people should make an appropriate choice according to the requirements of the test when doing the high and low temperature test chamber.

The high and low temperature test chamber is a test equipment that simulates high temperature and low temperature environment, which is mainly for the adaptability of electrical engineering, electronic products, and various materials in the environment of high temperature and low temperature rapid change, storage, transportation and use.

The refrigeration method of high and low temperature test chamber in the market mostly uses compressor refrigeration, in fact, liquid nitrogen refrigeration can also be used according to the required low temperature and cooling rate. The refrigerant inside the evaporator of the evaporator is generally environmentally friendly, and the refrigerant through the throttling device evaporates and vaporizes inside the evaporator, absorbing the heat outside the evaporator, so as to play the role of cooling; Liquid nitrogen refrigeration generally sprays liquid nitrogen directly into the test chamber, and the liquid nitrogen absorbs heat and vaporizes inside the test chamber to cool down the test chamber.

Compared with compressor refrigeration, the cooling rate of liquid nitrogen refrigeration is faster, generally 10 min, while the high and low temperature test chamber of compressor refrigeration is generally designed with a cooling rate of 1 min due to the high cost of obtaining a low-temperature environment. Generally, for the test environment of 0 -80, the compressor can be refrigerated, and for -40 -195, liquid nitrogen refrigeration is required.

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In order to ensure the requirements of the test chamber for the cooling rate and minimum temperature, the refrigeration system of the test chamber adopts the cascade refrigeration system composed of imported compressors, which has the advantages of reasonable matching, high reliability, convenient use and maintenance.

Refrigeration working principle: The refrigeration cycle adopts the reverse Karuo cycle, which is composed of two isothermal processes and two adiabatic processes, and the process is as follows: the refrigerant is adiabatic compressed to a higher pressure by the compressor insulation, and the work is consumed to increase the exhaust temperature, and then the refrigerant is athermally exchanged with the surrounding medium through the condenser to transfer heat to the surrounding medium.

After the refrigerant expands through the shut-off valve to do work, the refrigerant temperature decreases. Finally, the refrigerant is athermally absorbed from the hotter object through the evaporator, reducing the temperature of the cooled object. This cycle repeats itself to achieve the purpose of cooling.

The design of the refrigeration system applies energy regulation technology, which is an effective treatment method that can not only ensure the normal operation of the refrigeration unit, but also effectively adjust the energy consumption and refrigeration capacity of the refrigeration system, so that the operating cost of the refrigeration system can be reduced to a more economical state.

In addition to fully considering the safety protection of the refrigeration unit and the efficient use of all links, multiple energy-saving measures have been taken at the same time: such as: refrigeration capacity adjustment, gas-liquid bypass adjustment, evaporation temperature adjustment, etc., when the temperature is constant at any low temperature point, there is no need for heating balance, and the operating power can be reduced to half, so that the operating cost and failure rate of the refrigeration system can be reduced to a more economical state.

The intelligent automatic conversion expansion system is adopted, and the refrigerant flow rate is automatically adjusted according to the load + the intelligent electric heating power data value (%) is matched to match the temperature rise and fall (load), and the output power data output value is automatically simulated. This design can save more than 30% of electricity compared to traditional designs.

Refrigeration principleThe compressor compresses the gaseous freon into a gaseous freon with high temperature and high pressure, and then sends it to the condenser (outdoor unit) to dissipate heat and becomes the liquid air conditioning refrigeration principle freon at medium temperature and medium pressure, so the outdoor unit blows hot air.

Liquid Freon Sutra.

The capillary, entering the evaporator (indoor unit), the space suddenly increases, the pressure decreases, the liquid freon will vaporize, (from liquid to gaseous is an endothermic process), absorb a large amount of heat, the evaporator will become cold, the fan of the indoor unit will blow the indoor air from the evaporator, so the indoor unit blows out of the cold air; When the water vapor in the air meets the cold evaporator, it will condense into water droplets and flow out down the water pipe, which is why the air conditioner will produce water.

Then the gaseous freon returns to the compressor to continue compressing and continuing the cycle.

There is a component called the four-way valve during heating, so that the flow direction of Freon in the condenser and evaporator is opposite to that of refrigeration, so when heating, cold air is blown outdoors and hot air is blown in the indoor unit.

In fact, it is the principle of excretion of heat during liquefaction (from gas to liquid) and absorption of heat during vaporization (from liquid to gas) and evaporation of heat, which I learned in junior high school physics. Lithium bromide air conditioning refrigeration principle to be specially proposed here, lithium bromide air conditioning refrigeration refrigeration principle is different from compression air conditioning, absorption refrigeration used working fluid is usually a binary solution, composed of two substances with different boiling points. Among them, the substances with low boiling point are refrigerants, and the substances with high boiling points are absorbents.

Therefore, binary solutions are also known as refrigerant-absorbent working fluid pairs. A binary solution is a mixture of two substances that do not chemically interact with each other. The various physical properties of this homogeneous mixture (e.g., pressure, temperature, concentration, etc.) are completely consistent throughout the mixture, and they cannot be separated into the original constituent substances by purely mechanical precipitation or centrifugation.

Its refrigeration principle is divided into two parts1

The binary solution is heated and boiled by a heat source in the generator, producing refrigerant vapor which is condensed into a refrigerant liquid in the condenser. The liquid refrigerant enters the evaporator after being throttled through the U-shaped tube, and is sprayed under low pressure through the evaporator, and the liquid refrigerant evaporates to absorb the heat of the refrigerant and produce a refrigeration effect. 2. The concentrated solution flowing out of the generator flows into the absorber after being cooled down and depressurized by the heat exchanger, and mixed with the original solution of the absorber to become a concentrated solution of intermediate concentration.

The intermediate concentration solution is conveyed by the absorber pump and sprayed, absorbing the refrigerant vapor from the evaporator into a dilute solution. The dilute solution is pumped from the generator to the generator, where it is regenerated by the heat source to form a concentrated solution again and enter the next cycle. In summary, any refrigeration equipment has four major components (compressor, condenser, evaporator, throttling device), and the refrigerant absorbs or releases heat to achieve the effect of cooling or heating through physical state changes in the refrigerator.

The refrigerator adopts the French original "Taikang" fully enclosed compressor.

The refrigeration system is designed as a unit or a binary cryogenic circuit system.

The multi-wing blower is used to supply air with strong air circulation, avoiding any dead angles, and the temperature and humidity can be evenly distributed in the test area.

The air path circulation air return air design, the wind pressure and wind speed are in line with the test standards, and the temperature and humidity can be stabilized quickly at the moment of opening the door.

The complete separation of heating, cooling, and humidification systems improves efficiency, reduces test costs, increases life, and reduces failure rates.