How to ask the property for the central air conditioning test report?

You can call the property directly or ask for it in the property hall.

The central air conditioning system consists of one or more cold and heat source systems and multiple air conditioning systems. This system is different from the traditional refrigerant air conditioner, such as VRV, which centrally processes air to meet the comfort requirements. The principle of liquid gasification refrigeration is adopted to provide the required cooling capacity for the air conditioning system and offset the heat load of the indoor environment; The heating system provides the required heat for the air conditioning system to offset the cold and heat load of the indoor environment. Refrigeration system is an important part of central air-conditioning system, and its type, operation mode and structural form directly affect the economy, efficiency and rationality of central air-conditioning system.

Working principle: 1. Refrigeration principle: liquid vaporization refrigeration uses the heat absorption of liquid vaporization and the heat release of condensation to realize refrigeration. Liquid evaporates to form steam. When the liquid (refrigerant) is in a closed container, there is no other gas except the vapor generated by the liquid and the liquid itself, and the liquid and the vapor will reach equilibrium under a certain pressure. The steam at this time is called saturated steam, the pressure is called saturated pressure, and the temperature is called saturated temperature. When the liquid is in equilibrium, it will no longer evaporate. At this time, if a part of steam is pumped out of the container, the liquid will inevitably continue to vaporize to generate a part of steam to maintain this balance. When a liquid vaporizes, it absorbs heat, which is called latent heat of vaporization. The latent heat of vaporization comes from the cooled object, which makes the cooled object cool. In order to make this process continue, it is necessary to continuously extract steam from the container and condense it into liquid before returning to the container. If the vapor extracted from the container is directly condensed into liquid, the temperature of the required cooling medium is lower than the evaporation temperature of the liquid. We hope that the condensation of steam is carried out at room temperature, so it is necessary to increase the pressure of steam to the saturation pressure at room temperature. Refrigerant will evaporate at low temperature and low pressure, resulting in cold effect; And condense at normal temperature and high pressure to release heat to surrounding environment or cooling medium. Steam condenses into high-pressure liquid at normal temperature and high pressure, and its pressure needs to be reduced to evaporation pressure before it can enter the container. The liquid vaporization refrigeration cycle consists of four processes: working medium vaporization, steam pressurization, high-pressure steam condensation and high-pressure liquid decompression. 2. Heating principle: the low-pressure gas sucked by the compressor is compressed by the compressor into high-temperature and high-pressure gas, and the high-temperature gas raises the water temperature through the heat exchanger, and at the same time, the high-temperature gas will condense into liquid. The liquid then enters the evaporator to evaporate. (Evaporators also need heat exchange media. According to different heat exchange media, different machines have different models and structures. Commonly used are air cooling and ground source. After the liquid passes through the evaporator, it becomes low-pressure and low-temperature gas, and the low-temperature gas is sucked by the compressor again for compression. In this way, the circulating water on the air conditioning side will become hot water of about 45-55 degrees. The hot water is sent to the room that needs heating through the pipeline, and the room is equipped with a fan coil unit, so that the hot water can exchange heat with the air to achieve the purpose of heating.