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Knowledge Series on Multi-split systems
2025/9/29
Definition:
A multi-split air conditioning system is a direct evaporative air conditioning system composed of one outdoor unit and multiple indoor units, which are connected through refrigerant pipelines to achieve both cooling and heating functions.
2. Working Principle
1) Refrigeration: The outdoor unit's compressor dissolves high-temperature and high-pressure refrigerant gas, which is condensed into high-pressure liquid through the outdoor heat exchanger. Then, it passes through the expansion valve and is throttled into low-pressure liquid, entering the indoor unit's evaporator to absorb heat and evaporate. After returning to the outdoor unit, it is compressed, completing the refrigeration cycle.
2) Heating: The four-way valve switches. The outdoor unit acts as an evaporator to absorb heat from the air, while the indoor unit acts as a condenser to release heat for heating. The direction of the refrigerant circulation is opposite to that of refrigeration.
Ii. System Composition and Component Composition of Multi-split Systems
1. Outdoor unit: Composed of a compressor, four-way valve, oil separator, accumulator, heat exchanger, fan, etc., it is responsible for the compression, condensation and evaporation of the refrigerant.
2. Indoor unit: Composed of a heat exchanger, electronic expansion valve, fan, etc., it is responsible for the throttling, evaporation and condensation of the refrigerant to achieve air supply heat exchange. Common types include wall-mounted, ceiling-mounted, duct, and cassette types, etc.
3. Refrigerant pipeline: Copper pipes are used to connect the indoor and outdoor units. The pipe diameter and insulation material should be selected according to the design requirements.
4. Communication cable: Connects the indoor and outdoor units and the controller to achieve signal transmission and data exchange.
5. Control system: It includes centralized controllers, line controllers, wireless remote controls, etc., to achieve centralized management and decentralized control of the system.
Iii. Advantages and Disadvantages of Multi-split Air Conditioners
It has good energy-saving performance and can automatically adjust the compressor frequency and refrigerant flow rate according to the actual indoor load. It has a relatively high energy efficiency when operating at partial load.
2. It is flexible and convenient to install. Only the refrigerant pipeline and wires need to be connected between the outdoor unit and the indoor unit. The installation is relatively simple, occupies a small space, and can flexibly adapt to various building structures and spatial layouts.
3. Flexible control: Each indoor unit can be independently controlled to run and stop, meeting the personalized temperature requirements of different rooms at different times.
4. It offers good comfort, featuring rapid cooling and heating capabilities as well as high-precision temperature control functions. Meanwhile, the indoor units come in various forms and can be selected based on the decoration style and space layout to achieve uniform air supply and small temperature fluctuations.
5. The system capacity is limited. The cooling or heating capacity of a single multi-split system is limited. For large buildings, multiple systems may need to be combined, which increases costs and management difficulties.
6. The installation requirements are high. There are certain restrictions on the length and drop of the refrigerant pipeline. Exceeding these restrictions will affect the system performance. Meanwhile, the refrigerant pipeline is long and has many joints. Once a leakage problem occurs, it will affect the cooling and heating effect, and even cause the entire system to collapse.
7. The initial investment is relatively high, and the equipment and installation costs are also relatively high, which may put certain pressure on users with limited budgets.
