How much do you know about air conditioning Remove the air-conditioning mystery layer by layer
The working principle of air conditioning supplements the fourth and fifth points:
Compressor
Description:
1) Positive displacement refrigeration compressors compress the quantitative gas periodically absorbed by changing the volume of the working chamber. The centrifugal compressor relies on centrifugal force to continuously compress the absorbed gas.
2) The rotary refrigeration compressor replaces the reciprocating motion of the piston in the piston compressor by the rotary motion of the rotary body to change the working volume of the cylinder, thereby compressing a certain amount of low-pressure gaseous refrigerant.
3) Currently commonly used compressors mainly include piston compressors, scroll compressors, screw compressors and centrifugal compressors. Among them, piston refrigeration compressors are mostly medium-sized (standard refrigeration capacity 60~600KW) and small (less than 60KW), but due to their high noise and low efficiency, they are prone to failures, so there are not many currently used; scroll refrigeration compressors At present, it is mainly used in small refrigeration systems, which are widely used in small systems such as household air conditioners and commercial VRVs. The screw compressor has a series of unique advantages such as simple structure, high reliability, convenient operation and maintenance, and mature technology. It has been widely used in refrigeration , Air-conditioning and various technological processes; centrifugal compressor has simple and compact structure, few moving parts, reliable work, durable and low operating cost. It is generally suitable for refrigeration systems larger than 500RT, and can achieve stepless adjustment to make the load of the unit Work in the range of 30%~100%.
4) Indexes for evaluating the advancement of refrigeration compressor energy consumption:
a. Coefficient of performance of refrigeration compressor COP
Namely: the cooling capacity per unit shaft power. Shaft power (compressor power consumption) refers to the power transmitted from the motor to the compressor shaft, which mainly includes the power consumed directly for compressed air and the power consumed to overcome the frictional resistance of the motion mechanism.
b. Energy efficiency ratio EER: the cooling capacity per unit of motor input power. This indicator takes into account the impact of drive motor efficiency on energy consumption.
5. Lithium bromide absorption refrigeration
Two types of absorption chillers in common use at present:
1) Ammonia absorption refrigeration: ammonia is the refrigerant, water is the absorbent, and the refrigeration temperature is +1~-45 ℃;
2) Lithium bromide absorption refrigeration: water is the refrigerant, lithium bromide is the absorbent, and the refrigeration temperature is above 0 ℃.
Brief introduction of lithium bromide:
Lithium bromide is a colorless granular crystal, non-toxic. Melting point: 549 ℃; boiling point: 1265 ℃. Lithium bromide is extremely water-absorbing, and its solubility in water at 20°C is 111.2g/100g of water.
Schematic diagram of lithium bromide absorption refrigeration
Refrigeration cycle:
After the high-pressure gas refrigerant releases heat to the cooling water in the condenser and is condensed into a liquid state, it decompresses and cools down through the throttling device and enters the evaporator. In the evaporator, the liquid is vaporized into low-pressure refrigerant vapor, while absorbing the heat of the cooled medium to produce a refrigeration effect.
Absorption cycle:
In the absorber, the liquid absorbent is used to absorb the low-pressure gaseous refrigerant produced by the evaporator to form a refrigerant-absorbent solution, which is pressurized by the solution pump and enters the generator. In the generator, the solution is heated and boiled, and the low-boiling refrigerant vaporizes to form a high-pressure gaseous refrigerant, which is separated from the absorbent. The former enters the condenser to liquefy, the latter returns to the absorber to absorb the low-pressure gaseous refrigerant again
Next, let’s talk about the knowledge that affects the quality of air conditioners and the classification of air conditioners.
Three national standards that affect the quality of air conditioning
1. Cooling (heating) capacity
The amount of heat removed from a confined space by an air conditioner in a cooling (heating) operation unit time, the legal unit of measurement is W (watts). National standards stipulate that the actual cooling capacity of air conditioners should not be less than 95% of the rated cooling capacity. Input power: The power consumed by the air conditioner in cooling (heating) operation under rated conditions, in W.
2. Energy efficiency ratio
Also known as the coefficient of performance, it reflects the unit W/W between the cooling capacity and the cooling power when the air conditioner is in cooling operation.
According to national standards, the standard value of energy efficiency ratio of 2500W air conditioners is 2.65; the standard value of energy efficiency ratio of 2500W to 4500W air conditioners is 2.70/
3. Noise
The noise generated when the air conditioner is running is mainly produced by the internal evaporator and the external condenser.
The state stipulates that the noise of the indoor unit of the air conditioner with a cooling capacity of less than 2000W should not exceed 45 decibels, and the outdoor unit should not exceed 55 decibels; the noise of the 2500W split air conditioner indoor unit should not exceed 48 decibels, and the outdoor unit should not exceed 58 decibels.
Classification of air conditioners:
According to different functional requirements:
1. Comfortable air conditioning
1.1 Household air conditioners, 1.2 Commercial air conditioners
2. Process air conditioning
Clean air conditioner
2.1 Household air conditioners
According to different places of use and cooling capacity, it can be divided into: household air conditioners and household central air conditioners.
2.1.1 Household air conditioners
Household air conditioners include window air conditioners and split air conditioners, which are suitable for rooms with small building area and not very large cooling capacity.
1) Window type: The entire air conditioner as a whole, such as a window machine. The cooling range is generally 1800W~5000W.
2)Split type: divide the air conditioner into an indoor part and an outdoor part. The cooling range is generally 1800W~9000W.
2.2 Commercial central air-conditioning (large central air-conditioning)
1.Schematic diagram of commercial central air conditioning
