What Are the Different Types of Refrigeration Parts?

Air conditioning and refrigeration accessories are referred to as "cold parts", which refer to air conditioning and refrigeration parts and components, and are the basic components of air conditioning and refrigeration equipment.

Refrigeration accessories

The working principle of refrigeration is that the compressor compresses the steam with lower pressure into steam with higher pressure, which reduces the volume of the steam and increases the pressure. The compressor sucks the lower pressure working medium vapor from the evaporator, increases the pressure and sends it to the condenser, which condenses into a higher pressure liquid in the condenser. After the low liquid, it is sent to the evaporator, which absorbs heat and evaporates in the evaporator to become a steam with lower pressure, and then sends it to the inlet of the compressor to complete the refrigeration cycle.

The evaporator is a very important part of the four major pieces of refrigeration. The low-temperature condensed gas passes through the evaporator to exchange heat with the outside air, vaporizes and absorbs heat, and achieves the cooling effect.

The evaporator is composed of a heating chamber and an evaporation chamber. The heating chamber provides the liquid with the heat required for evaporation, which promotes the boiling and vaporization of the liquid; the evaporation chamber completely separates the gas and liquid phases. The vapor generated in the heating chamber carries a large amount of liquid foam. After reaching the evaporation chamber in a large space, these liquids can be separated from the vapor by the action of self-condensation or defoamer. The demister is usually located on top of the evaporation chamber.

The evaporator is divided into three types: normal pressure, pressurization and decompression according to the operating pressure. According to the movement of the solution in the evaporator, there are: circulating type. The boiling solution passes through the heating surface many times in the heating chamber, such as the central circulation tube type, suspension basket type, external heating type, Levin type and forced circulation type. One-way type. The boiling solution passes through the heating surface once in the heating chamber without circulating flow, and the concentrated liquid is discharged, such as rising film type, falling film type, stirring film type and centrifugal film type. Direct contact type. The heating medium is in direct contact with the solution for heat transfer, such as an immersion combustion evaporator. During the operation of the evaporation device, a large amount of heating steam is consumed. In order to save heating steam, a multi-effect evaporation device and a steam recompression evaporator can be used. Five-ring refrigeration shell and tube evaporator is widely used in chemical, light industry, petroleum and other sectors.

Inorganic compounds

The abbreviation for inorganic compounds is specified as R7 (). The brackets represent a set of numbers that is an integer part of the molecular weight of the inorganic substance.

Alkanes and halogenated hydrocarbons

The molecular formula of alkanes is CmH2m + 2; the molecular formula of halogenated hydrocarbons is CmHnFxClyBrz (2m + 2 = n + x + y + z), and their abbreviations are specified as R (m-1) (n + 1) (x) B (z).

Non-azeotropic mixed refrigerant

The abbreviated symbol of non-azeotropic mixed refrigerant is R4 (). The brackets represent a group of numbers. This group of numbers is the sequence number for the refrigerant, starting from 00.

Naphthenes, alkenes and their halides

The abbreviated symbols stipulate that the naphthenes and their halogenated products begin with the letters "RC", and the alkenes and their halogenated products begin with the letters "R1.

Organic refrigerant

Arbitrarily numbered in 600 sequences.

The temperature of refrigeration involves a wide range, including evaporation temperature te, suction temperature ts, condensation temperature tc, and exhaust temperature td. What determines the operating conditions of the refrigeration system are the evaporation temperature te and the condensation temperature tc.

Evaporation temperature te

The temperature at which the liquid refrigerant boils and vaporizes in the evaporator. te cannot be detected directly, only its evaporation temperature can be obtained by detecting the corresponding evaporation pressure.

Condensing temperature tc

The temperature at which the superheated vapor of the refrigerant is condensed into a liquid after the heat is released in the condenser. Condensing temperature cannot be detected directly. By detecting its corresponding condensation pressure. Condensing temperature is high, and its condensing pressure is relatively high, they correspond to each other. The condensing temperature is too high, the unit load is heavy, and the motor is overloaded, which is unfavorable for operation. Its cooling capacity decreases accordingly and power consumption increases.

Exhaust temperature td

The temperature of the exhaust port (including the temperature of the exhaust port take over), there must be a temperature measurement device to detect the exhaust temperature. Generally, small computers are not set up. The temporary measurement can be detected with a semiconductor thermometer, but the error is large. The exhaust temperature is affected by the intake temperature and the condensation temperature. When the intake or condensation temperature increases, the exhaust temperature also rises accordingly. Therefore, the exhaust temperature must be controlled to stabilize the exhaust temperature.

Inspiratory temperature ts

The temperature of the gas in the suction connection pipe needs a temperature measuring device to detect the temperature of the suction gas. Generally, small units do not have a temperature measuring device. When testing and debugging, it is generally estimated by hand. The air intake temperature of the air-conditioning unit is generally required to control ts = 15 or so. Exceeding this value has a certain effect on the cooling effect.

The common marking method for capacitors in refrigeration accessories is direct labeling. The commonly used units are pF and F. However, some small-capacity capacitors use a digital labeling method. Generally, there are three digits, the first and second digits are valid numbers, and the third digit is a multiple, which means how many zeros are followed. For example: 343 means 34000pF. In addition, if the third digit is 9, it means 10-1, not the power of 9; for example: 479 means 4.7pF. When replacing the capacitor, it should be noted that the voltage withstand value of the capacitor is generally not lower than that of the original capacitor. In more demanding circuits, its capacity generally does not exceed ± 20% of the original capacity. In circuits with less stringent requirements, such as bypass circuits, it is generally required to be not less than 1/2 of the original capacitance and not more than 2 to 6 times the original capacitance.

Detection of fixed capacitors

Detect small capacitances below 10pF. Because the fixed capacitors below 10pF are too small, use a multimeter to measure them. You can only qualitatively check for leakage, internal short circuit or breakdown. When measuring, you can choose a multimeter R × 10k block. Use two test leads to connect the two pins of the capacitor at will. The resistance should be infinite. If the measured resistance value (the pointer swings to the right) is zero, it means that the capacitor leakage is damaged or internal breakdown.

Check whether the fixed capacitor of 10PF 0.01F is charged, and then judge whether it is good or bad. Multimeter uses R × 1k gear. The values of the two transistors are more than 100, and the penetrating current is a little bit. A silicon transistor such as 3DG6 can be used to form a composite tube. The red and black test leads of the multimeter are connected to the emitter e and the collector c of the composite tube, respectively. Due to the amplification effect of the composite triode, the charging and discharging process of the capacitor under test is enlarged, and the multimeter pointer pendulum is enlarged, which is convenient for observation. It should be noted that, during the test operation, especially when measuring a small-capacitance capacitor, it is necessary to repeatedly swap the two points of the tested capacitor pin A and B to see the swing of the multimeter pointer clearly.

For fixed capacitors above 0.01F, the R × 10k range of the multimeter can be used to directly test the capacitor for charging process and internal short-circuit or leakage, and the capacity of the capacitor can be estimated according to the amplitude of the pointer swinging to the right.

Detection of electrolytic capacitors

Electrolytic capacitors have a much larger capacity than ordinary fixed capacitors, so when measuring, you should choose a suitable range for different capacities. In general, the capacitance between 1 ~ 47F can be measured with R × 1k block, and the capacitance larger than 47F can be measured with R × 100 block. ??

Connect the red multimeter of the multimeter to the negative electrode and the black multimeter of the multimeter to the positive electrode. At the moment of contact, the multimeter pointer is deflected to the right by a large degree of deflection (for the same electrical block, the larger the capacity, the larger the swing), and then gradually turn left Until stopped at a certain position. The resistance at this time is the forward leakage resistance of the electrolytic capacitor, which is slightly larger than the reverse leakage resistance. Practical experience shows that the leakage resistance of electrolytic capacitors should generally be more than a few hundred k, otherwise, it will not work properly. In the test, if there is no charging in the forward and reverse directions, that is, the hands do not move, it means that the capacity disappears or the internal circuit is broken; if the measured resistance is small or zero, it means that the capacitor has a large leakage current or has been damaged by breakdown. Can no longer be used.

For electrolytic capacitors with unknown positive and negative markings, the above method of measuring leakage resistance can be used to judge. That is, first measure the leakage resistance arbitrarily, remember its size, and then exchange the test leads to measure a resistance value. The one with the larger resistance value in the two measurements was the positive connection method, that is, the black test lead was connected to the positive electrode, and the red test lead was connected to the negative electrode.

A multimeter is used to block electricity, and the electrolytic capacitor is charged in the forward and reverse directions. The capacity of the electrolytic capacitor can be estimated according to the magnitude of the swing of the pointer to the right.

Detection of variable capacitors

Gently rotate the shaft with your hand, it should feel very smooth, and it should not feel tight or sometimes stuck when loose. When the load axis is pushed forward, backward, up, down, left, right and other directions, the shaft should not be loose.

Rotate the shaft with one hand, and touch the outer edge of the film group with the other hand, and you should not feel any looseness. Variable capacitors with poor contact between the rotating shaft and the moving blade can no longer be used.

Set the multimeter to the R × 10k position. One hand connects the two test leads to the moving and fixed parts of the variable capacitor, and the other hand slowly rotates the shaft several times. The pointer of the multimeter should be at The infinity position does not move. In the process of rotating the shaft, if the pointer sometimes points to zero, it means that there is a short-circuit point between the moving piece and the fixed piece; if it encounters an angle, the multimeter reading is not infinite but shows a certain resistance value, indicating that the variable capacitor moves. There is a leakage phenomenon between the chip and the stator.