The energy efficiency ratio of air conditioning cold water system is 0.0 164, which is better than the requirement of water pump energy efficiency in the standard. The "standard" of variable frequency speed regulation technology requires that the ventilation and air conditioning system should not reduce the energy utilization efficiency when using part of the load and part of the space. Therefore, the dynamic characteristics of air conditioning load are fully considered in the design, and variable frequency motors are installed in the circulating water pump and air handling unit of air conditioning to make the water pump and air cabinet adapt to the changing law of air conditioning load. When the air conditioning load is lower than the peak load, the speed of fan and water pump is adjusted by frequency converter to reduce the air supply volume and the circulating flow of water pump, which obviously saves the transportation energy consumption of Feng Shui system. Considering the high density of people, the large amount of fresh air required and the high energy consumption of fresh air in the exhibition center, the heat recovery technology adopts practical and reliable air heat recovery measures in the design. Some air handling units are equipped with fresh air and exhaust heat exchange devices, which precool and dehumidify outdoor fresh air with high heat and humidity in summer and preheat and humidify outdoor dry fresh air at low temperature in winter, thus reducing fresh air energy consumption and reducing the installed capacity of air conditioning cold and heat source units.
The "standard" of displacement ventilation technology encourages the adoption of new energy-saving air conditioning methods. Therefore, the convention and exhibition center is designed to adopt displacement air supply mode in air-conditioned places with large space, and the fresh air slightly lower than the temperature of indoor personnel activity area is directly transported to the personnel activity area at a very low speed, forming a layer of air lake on the floor, which is heated when the air supply meets the indoor heat source, generating upward convective airflow and forming the dominant airflow of indoor air movement. The air outlet is located at the top of the room to discharge dirty air. Compared with traditional mixed ventilation, displacement ventilation does not need to consider eliminating the residual heat and unclean air in the whole room, but only the residual heat and unclean air in the personnel activity area, so its energy consumption is only 57% ~ 59% of that of the whole room mixed ventilation system [6], and the indoor air quality is improved, and the concentration of unclean air in the personnel activity area is only 50% of that of the traditional mixed ventilation system [6].
It can be seen that using displacement ventilation technology not only saves energy consumption, but also improves indoor air quality and thermal comfort. Multi-ventilation technology According to the requirements of the Standard for outdoor fresh air, the air conditioning and ventilation system adopts multi-ventilation technology, which is an air conditioning technology that uses natural ventilation, mechanical ventilation and air conditioning to maintain a satisfactory indoor environment. The fresh air inlet and its passage of the all-air system are configured according to the fresh air volume, and the air conditioning season operates according to the minimum fresh air volume by adjusting the opening of fresh air and return air valves; In the transitional season, outdoor fresh air is introduced by mechanical ventilation, or natural ventilation is carried out by opening external windows to eliminate indoor residual heat, minimize the running time of air conditioning units and reduce the energy consumption of air conditioning operation.
Indoor hourly temperature under natural ventilation and mechanical ventilation. Statistical analysis shows that the indoor temperature is below 30℃ and above 15℃ for 1320h, accounting for more than 90% of the total working time. The temperature of a few rooms is higher than 30℃ for a few times, and the total time when the room temperature is higher than 30℃ in transition season is 1 1h, mostly at noon. More than 95% of the time when the room temperature is below 15℃ is from 20: 00 to 8: 00, which is not working time, and the requirements of human comfort are not considered.
Building energy consumption analysis is a necessary means of building energy-saving diagnosis [8]. In order to compare the energy consumption of the air conditioning scheme with that of the traditional air conditioning scheme, two working conditions are defined according to the architectural design, which are named scheme I and scheme II respectively. Scheme 1 has been described in detail in 2. 1 ~ 2.6. Scheme 2 uses water chillers and gas-fired hot water boilers as cold and heat sources; The performance of fan and water pump is the same as that of scheme 1, but the control mode is different, and constant current control is adopted; The heat recovery device is not considered in the air-conditioned room exhaust system, and the large space air conditioner adopts the whole room mixed ventilation mode, with air conditioning and mechanical ventilation all year round. The COP of water chiller is 4.2, the recovery efficiency of fresh air total heat recovery device is 0.7, the boiler efficiency is 0.9, the comprehensive efficiency of power production and transportation is 0.5, and the boiler gas volume is converted into electric energy. The monthly cumulative power consumption of air conditioning and ventilation systems in each scheme (heating month is ignored because of the low cooling power consumption; Similarly, the cooling month ignores the heating power consumption). The total electricity consumption of the scheme is 254000kWh in one year and 62 1.600kWh in two years, which is 59% less than that of the second scheme. Green building requires that "the total energy consumption of building design is lower than 80% of the value specified in national and local energy-saving standards". To sum up, after only optimizing the air conditioning system design, the target energy saving rate reached 75%.
Convention and Exhibition Center is the first three-star green building project in Taizhou. In this paper, the energy-saving theory of building system is deeply studied [9- 10], and the coupling relationship of various factors in building energy consumption is systematically grasped, and the energy-saving mode of multi-field collaborative research of HVAC specialty is implemented in the design. The exhibition center was put into use in August, 20 1 1. During the refrigeration operation of the air conditioning system,
The HVAC system of the convention and exhibition center does not adopt very complicated new technologies, but adopts suitable and low-cost technologies-ground source heat pump, variable frequency speed regulation, air heat recovery, displacement ventilation and multiple ventilation. Not only energy consumption is greatly reduced, but also ventilation brings health effects. Low-carbon environmental protection is the direction of sustainable building development. The design of this project was completely carried out under the guidance of "Green Building Evaluation Standard", and the air conditioning system also experienced a period of cooling and heating operation test, with obvious energy-saving effect, which provided a reference for green building design in China in the future.
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