Manufacturers classify bus air conditioning systems as electric or diesel, depending on the vehicle’s propulsion method. Their core difference lies in the power source. The former uses the power supply of the electric bus to drive the electric compressor; the latter uses the engine of the traditional bus to drive the compressor through a belt. The refrigeration cycle principle of the two is exactly the same. Therefore, many core bus air conditioning parts are the same. This article mainly explains the common parts of the two and their main functions.
Main function: compress low-temperature and low-pressure gaseous refrigerant into high-temperature and high-pressure gaseous refrigerant. Then push the refrigerant to circulate in the system.
The models and drive methods of electric compressors and traditional compressors are different. But the core functions and types are basically the same. Now, the mainstream uses scroll bus air conditioning compressors. Scroll compressors have static scrolls and moving scrolls, and refrigerant compression is achieved through the meshing of the two.
Features of scroll compressors
1) Excellent performance, high efficiency and energy saving (high volumetric efficiency), more than 30% higher in volumetric efficiency than traditional reciprocating compressors;
2) Beautiful appearance, roof installation, space saving, compact system design, easy installation and maintenance;
3) Smooth operation, low noise and vibration, meeting environmental protection requirements.
Bus air conditioning compressor performance directly determines the refrigeration efficiency. Some manufacturers use reciprocating compressors, which have a simple structure and low cost, so the price is low. Low-priced bus air conditioners are likely to face insufficient cooling effects.
If you want to know about diesel bus air conditioning, click here.
If you want to know about electric bus air conditioning, click here.
Core function: cool the high-temperature, high-pressure refrigerant vapor discharged from the compressor to condense it into medium-temperature, high-pressure refrigerant liquid. The condenser divides the refrigerant into three stages: superheated gas, gas–liquid two‑phase mixture, and supercooled liquid.
Common types are tube-sheet type, tube-belt type, and parallel flow type. Our company's bus air conditioning condenser adopts the Copper Tube Aluminum Fin structure. It belongs to the tube-sheet structure. The condenser core fins use high-grade hydrophilic corrugated fins. This configuration increases the heat dissipation area and improves the heat dissipation efficiency.
Features of Copper Tube Aluminum Fin
Compared with the common parallel flow core, this Copper Tube Aluminum Fin has strong corrosion resistance, oxidation resistance, easy cleaning, and long service life. It is one of the optional options for top bus air conditioning parts.
Core function: The evaporator is a low-temperature, low-pressure liquid refrigerant that has been throttled by the expansion valve. It absorbs the heat of the air in the bus and vaporizes, thereby reducing the temperature in the bus.
Common types are the same as condensers. The evaporator we use is also the Copper Tube Aluminum Fin. This greatly increases the service life of the bus air conditioner. This is responsible for customers. Reducing after-sales problems means reducing the actual expenditure of customers.
Evaporator and condenser are two important components in the bus air conditioning system. They achieve heat exchange between two bodies at different temperatures, so we commonly call them heat exchangers. For ease of understanding, the condenser belongs to the "radiator". The evaporator belongs to the "heat absorber".
Advantages of Copper Tube Aluminum Fin:
1) Internal threaded copper tube, prevents the occurrence of fluid laminar layer, improves the heat transfer coefficient in the tube, and also increases the heat transfer area;
2) Corrugated fins, enhance air disturbance on the fin side, strengthen heat transfer outside the tube, increase heat transfer area, and improve heat transfer efficiency.
3) We coat the fins with a hydrophilic film to prevent water from accumulating on their surface and stop the fan from carrying water when the air conditioner turns on.
Core function: pressure reduction and throttling. Throttle and reduce the medium-temperature and high-pressure liquid refrigerant to low-temperature and low-pressure mist refrigerant. Automatically adjust the refrigerant flow entering the evaporator according to the superheat of the refrigerant at the evaporator outlet, so that the evaporator works in the best state.
Components of the expansion valve: temperature sensing element, capillary, diaphragm, transmission rod, ball valve. The temperature sensing element is installed at the evaporator outlet to sense the refrigerant temperature.
The opening and closing degree of the expansion valve directly affects the bus air conditioning pressure. If the opening and closing degree is too large, the pressure on the low-pressure side is too high, and the cooling effect decreases; if the opening and closing degree is too small, the pressure on the high-pressure side is too high, and the compressor is overloaded. If the temperature sensing element fails, the flow regulation will be out of control, affecting the cooling effect. Therefore, it is also very important in bus air conditioning parts.
Core functions: absorb moisture, filter harmful acidic substances, impurities, etc. The filter drier currently used mainly uses molecular sieve as a desiccant, and the molecular sieve is in the form of sintered blocks.
The filter drier itself generally does not have any faults. We replace it only when the refrigerant oil deteriorates, the system contains excessive water, or contamination occurs.
Fans are divided into condenser fans and evaporator fans due to different positions and shapes.
Evaporator fan function: drive the fan blades, force the evaporator heat exchange, and send out the evaporator cold air. Generally, a centrifugal fan is used.
Condenser fan function: drive the fan blades, force the condenser heat exchange, and discharge the condenser heat. Generally, an axial flow fan is used.
Among them, the evaporator fan is the cooling that passengers can intuitively feel. Therefore, we set up three speed adjustment. It is convenient for the driver to freely adjust according to the actual temperature. Avoid too cold and too hot.
Core functions:
1) Separate gas from liquid to prevent liquid refrigerant from entering the compressor.
2) Ensure oil return of the compressor.
3) Store a small amount of refrigerant.
4) Filter impurities to prevent them from entering the compressor.
Principle:
Due to the different densities of gas and liquid, when liquid and gas flow together, the centrifugal force on the liquid is greater than that on the gas, so the liquid tends to separate centrifugally. The liquid adheres to the separation wall and gathers together downward due to gravity, and the gas is discharged through the discharge pipe.
This customer has the ability to install it himself. He bought a cabinet of bus air conditioners from us at one time. The customer feedback is excellent.
The second half of the video shows the equipment and factory inspection of our TKT bus air conditioner manufacturing workshop.
Established in 1998 in Henan, China, TKT is a leading manufacturer and supplier in the field of EV Thermo Control System with main product range like Battery Thermal Management Systems (BTMS), Bus HVAC, Truck HVAC, etc.
As a reliable partner of global automotive manufacturers like BYD, Tata Motors, Marcopolo, Daewoo, Isuzu, Yutong, Switch Mobility, Neoplan, and CAT, etc. TKT offers OEM services, customized solutions, and excellent after-sales support.
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