Analysis of 4 major reasons for the high energy consumption of building HVAC systems

Analysis of 4 major reasons for the high energy consumption of building HVAC systems

1. Analysis of the high energy consumption of the building HVAC system

　　 The reasons for the high energy consumption of building HVAC systems are mainly reflected in the following aspects:

① The unreasonable design of the air-conditioning regulation system caused the chiller, fan and water pump to deviate from the high-efficiency point of operation, and the energy utilization was not high. In addition, the management method of the chiller, fan and water pump during operation was biased, and the system was switched on and off. The switching is not timely, so that the air conditioning efficiency is wasted in unnecessary operating conditions.

②The structural insulation of the building adopts glass curtain wall structure, and the design of orientation and depth is unreasonable, which makes the air conditioning system appear unevenly cold and hot in the inner and outer areas, and the outer area is greatly affected by external meteorological factors, resulting in higher temperature seasons Cooling is needed, and heating is needed at low temperatures.

　　③There is water imbalance in the system. Insufficient amount of chilled water makes the temperature of chilled water high, and the refrigeration of the chiller is in a low-efficiency state. This makes users with insufficient water supply not enough in terms of temperature and humidity, which affects the energy-saving effect of the air conditioning system.

④In addition to the HVAC system design, there are also a series of problems in the operation and management of the system. For example, the air-conditioning equipment is not cleaned in time, filters, condensers, etc. are blocked, which hinder the normal operation of the air-conditioning system, or due to various impurities Entering the air-conditioning system affects the processing effect of the chiller and shortens the service life of the chiller.

Analysis of 4 major reasons for the high energy consumption of building HVAC systems

　　 2. Energy saving optimization of HVAC system

　　 1. Energy-saving design of air conditioning system

　　 First is the design of the energy storage system for air conditioning, which is mainly divided into two aspects: cold storage and heat storage. In terms of cold storage, it uses ice solidification media or water cooling media to store cold energy in the sensible or latent heat state in the media. Once the media melts or the temperature increases, the stored cold energy can be used. The cold storage medium flow is stored in the chiller, heat exchanger, etc. of the air-conditioning system. When designing, the upstream and downstream of the chiller must be connected in series and in parallel according to the capacity of the chiller. In terms of heat storage, the system’s heat source selects an electric boiler, which uses electricity during low electricity consumption to heat water and stores it in a water tank. When electricity consumption peaks, it automatically cuts off the electric boiler and uses the hot water stored in the water tank for heating. Heating. The second is the heat recovery technology, which is divided into exhaust air waste heat and condensation heat. The former is to ensure indoor air quality. The fresh air system is used to dilute indoor harmful gases. When fresh air enters the room, the old air needs to be discharged indoors. , In order to reduce the load of the fresh air, but the old air discharged indoors will invisibly take away the indoor heat. Therefore, the HVAC exhaust system uses the energy of the old air exhaust to pre-cool the fresh air through heat exchangers and exchangers. Preheating can reduce the heat loss of the exhaust air while reducing the load of the fresh air. The latter is to connect various systems and heat recovery equipment. The temperature of the refrigerant in the plate heat exchanger is relatively high, and the heat provided by it is stored in the heat preservation water tank, which can meet people's thermal energy needs to the greatest extent. If the hot water heating demand cannot be met by the condenser mode of the refrigeration unit, a water source heat pump can be added to the system for auxiliary heating. In addition, this HVAC system can not only avoid discharging condensation heat into the air, but also avoid harmful gases from being discharged into the air, minimizing the occurrence of air pollution, and has great advantages in environmental protection and energy saving. Finally, use the cooling and heating load reduction technology to reduce the cost of refrigerators, boilers, circulating pumps, air-conditioning boxes, etc. based on the cooling and heating loads. In addition, after the cooling and heating loads are reduced, the power consumption of the air conditioning system will also be required. Reduce, play a role in saving operating costs. Regarding the technology to reduce the heat and cold load, the author believes that the invisible loss of indoor cold and heat should be reduced through the improvement of the insulation and heat insulation performance of building walls, doors and windows, such as reasonable planning of the area ratio of doors, windows and walls, and reasonable design of shading Windows etc. Analysis of 4 major reasons for the high energy consumption of building HVAC systems 　　 2. Energy utilization design of air conditioning system The first is the design of the natural cold source of the air conditioning system. On the one hand, the cooling tower is used for cooling. On the basis of the original air conditioning water system, relevant pipes and equipment are added. When the temperature is below the specified value, the chiller Closed, so that the circulating cooling water can continuously supply cold energy to the air conditioning system after passing through the cooling tower, and provide enough cooling load for the indoor. The author believes that the plate heat exchanger can not only ensure the clean environment of the chilled water system, but also allow the chilled water to operate normally. It is a more suitable mode for cooling tower functions to reduce cooling costs, and the energy-saving effect is more obvious. On the other hand, it is the cooling design of fresh air. The role of fresh air has been described in detail above. In terms of introduction, direct introduction is adopted to allow the fresh air with lower temperature and humidity to directly take away the indoor heat and humidity load, reducing the centralized refrigeration system The energy saving effect is obvious. The second is the use of water source heat pump technology, which uses groundwater, rivers, lakes and other water sources, or uses industrial, domestic wastewater and other renewable water sources for heating and cooling of HVAC systems. This technology can quickly realize the transfer of low temperature and high temperature. The indoor temperature in summer is "extracted" and stored in the water body. In winter, the heat in the water body is released to provide indoor heating; on the contrary, the cold source stored in winter is supplied for use in summer. 　　 Once again, it is the ground-source heat pump technology that uses the thermal resources of the shallow underground soil to realize the transfer of low-temperature to high-temperature energy after inputting high-level energy such as electric energy, so that the high-efficiency and energy-saving technology of heating and cooling of the air conditioning system can be realized. The advantage of ground source heat pump technology is that it can extract underground heat energy above the ambient temperature for indoor heating in winter, and release indoor heat energy into the ground below ambient temperature in summer. The ground-source heat pump air-conditioning system utilizes renewable resources. It can provide heating and cooling without cooling towers or outdoor cold air, and will not have a major impact on the appearance of the building. It is environmentally friendly and energy-saving, and has low operating costs. Finally, it is the use of solar energy supply technology in the design of energy-saving systems for building HVAC, which can be divided into passive and active modes. The former has a relatively simple structure and can achieve solar energy without using any auxiliary energy. Continuous supply, and will not occupy too much area of ​​the building, the layout and structure are more reasonable, and the latter is not suitable for ordinary civil buildings except for large buildings. However, whether it is active mode or passive mode, the solar heating and cooling system of HVAC must consist of fans, radiators, heat storage equipment, and heat collection equipment. These heating and cooling technologies are increasingly being used in buildings. Among energy-saving designs, the current HVAC solar system is mainly designed as a heat-collecting wall in the building envelope. 　　3. Operation management design of air conditioning system 　　 The operation and management of the building HVAC system is a key step in the realization of energy-saving technology. It plays a role of more than 20% in the energy-saving design of the entire HVAC system. The primary task of the operation and management of the air-conditioning system is to improve the overall quality of the managers through training, and to make the operation and management work orderly based on the system energy-saving management system. The second is to continuously improve the energy-saving concept of operation and management personnel, so that all personnel can pay attention to the problem of building energy consumption, and in the work of energy-saving research and energy auditing of air-conditioning systems, equipment management personnel are allowed to conduct energy consumption through energy equipment statistics. Analysis has promoted the effective development of energy-saving operation and management of air-conditioning systems.