Energy-saving design method of air conditioning system in hotel buildings?

What is the specific content of energy-saving design method of air conditioning system in hotel buildings? Zhong Da Consulting will answer your questions below.

In recent years, Xue Zhifeng and Jiang Yi from Tsinghua University, Wang Changqing and Long Weiding from Tongji University, and Liu Jiaping and Liu Yang from Xi University of Architecture and Technology have conducted a large number of energy consumption surveys on public buildings in Beijing, Shanghai and Xi. According to relevant data, public buildings generally have more than 30% energy-saving potential. With the continuous improvement of hotel buildings, its energy consumption is also increasing. According to statistics, the energy consumption of some hotel buildings has accounted for 10% ~ 15% of the annual income, and energy consumption has become one of the important factors of profit. The energy consumption of air conditioning system accounts for about 50% of the total energy consumption of hotel buildings, so how to design energy-saving air conditioning system has become an important practical problem. According to the present situation of air-conditioning system in hotel buildings, this paper discusses energy-saving measures from the design of air-conditioning system. 1 Calculation of hotel air conditioning load 1. 1 Estimation of cooling load of air conditioning system There are many factors to be considered in cooling load calculation, and the calculation process is complicated, so air conditioning designers often use empirical indicators or simplified calculation indicators to estimate cooling load, and some estimate cooling load according to typical projects that have been built and operated. However, at present, the common problem in hotel buildings is that the expected cooling load is too large, resulting in too large installed cooling capacity. According to the survey, 79. 2% of the hotel buildings have an actual capacity load index of 58W /m2~8 1.4W /m2 (including less than 58W /m2), and the other 20.8% have an actual capacity load index of 8 1. 5W /m2~ 104。 7W /m2。 In addition, according to the investigation data of air conditioning load changes in hotels in Beijing and Changsha, more than 98% of the air conditioning systems in hotel buildings operate below 80% of the design load, and more than 80% operate below 50%~55% of the design load. Mastering the distribution characteristics of these air conditioning loads is also of great significance to the design of air conditioning systems and the selection of equipment. 1.2 fresh air load The fresh air load of the air conditioning system in hotels accounts for a large proportion of the total load, so how to choose the fresh air volume is an important issue in air conditioning design. However, the regulations on the selection of fresh air volume of air conditioning system in hotel buildings are not uniform, and the health requirements and energy saving requirements should be taken into account when designing. 2. Energy-saving design of hotel air-conditioning system 2. 1 Energy-saving of cold and heat source system After the cold and heat load of hotel air-conditioning system is determined, the choice of cold and heat source form and equipment of air-conditioning system should be considered. At present, the main problems of cold and heat sources in large public buildings are unreasonable system mode, excessive selection of chillers and improper operation and maintenance. There are various forms of air-conditioning cold sources, so the factors such as air-conditioning area, use, cooling and heating load, local meteorological conditions, energy structure, price, environmental protection regulations and so on should be fully considered when selecting. According to the Code for Design of Heating, Ventilation and Air Conditioning and the characteristics of air conditioning in hotel buildings, it can be selected according to the following principles: 1) The cold source should be selected between the electric compression refrigeration unit and the absorption refrigeration unit; 2) In areas with urban central heating or waste heat from factories, the steam lithium bromide absorption refrigerator can be used, which is beneficial to improve the utilization rate of heating network and balance the load of heating network; 3) Gas absorption chiller can be used in areas with urban natural gas and large seasonal gas price and price difference; 4) Water source heat pump units can be used in areas with stable natural water sources; 5) In areas with dry climate, such as Northwest China, evaporative cooling technology should be given priority; 6) Air-cooled chillers can be used in small and medium-sized buildings in arid and water-deficient areas; 7) In areas where the time-of-use electricity price is implemented and the peak-valley difference is large, low-valley electricity can be used to store cold, which can produce good economic benefits; 8) In most cases, an electric compression cooler can be used. 2.2 Energy saving of air conditioning air system An important measure for energy saving of air conditioning air system is exhaust cooling and heat recovery, the essence of which is pre-cooling and preheating fresh air. The Code for Design of Heating, Ventilation and Air Conditioning stipulates that the air conditioning system should be equipped with a heat recovery device. If the total heat exchanger is installed in the air conditioning system, the fresh air energy consumption can be saved by 60%~80%, which is equivalent to reducing the air conditioning load 10%~20%. The necessary condition of exhaust heat recovery is the combination of fresh air and exhaust air, and it is necessary to comprehensively consider the system division, air duct layout, and the layout of return air fans and heat recovery devices. The total heat recovery device relies on the temperature difference between fresh air and exhaust air and the partial pressure difference of steam to realize heat and moisture exchange. In order to make the heat exchange equipment run efficiently, the fresh air and exhaust air entering the heat recovery device must first pass through the air filter, and the ambient temperature of the device should be kept above -5℃, otherwise it may frost and fail to work normally. In the cold area in the north, the heat recovery device cannot be operated directly in winter, so it is necessary to preheat the cold air to above -5℃ and set up an automatic temperature control device. Bypass ventilation pipes should be set at the connection of fresh air and exhaust pipes and heat recovery devices to ensure the normal operation of the air conditioning system under abnormal working conditions, and also ensure the safety and reliability of the system. 2.3 Energy-saving of air-conditioning water system At present, the air-conditioning water system of many hotels has broken through the traditional design mode, and the primary pump system has been running with variable flow, and the operation effect is good. Large temperature difference technology of chilled water is another effective way to save energy in hotel air conditioning water system. Usually, the supply and return water temperature of standard chilled water is 7/ 12℃, while the supply and return water temperature of chilled water with large temperature difference can be set to 7/ 17℃. Under the condition of meeting the comfort requirements of users, the large temperature difference technology of chilled water can reduce the flow of chilled water, thus reducing the transportation energy consumption and the operation of air conditioning host, chilled water pump and terminal equipment. The recovery and utilization of condensation heat of air conditioning water system in hotel buildings is another effective measure to save energy. Hotel buildings generally need to provide 24-hour hot water, so the application of condensation heat recovery technology will receive good social and economic benefits. At present, there are three main forms of condensation heat recovery: 1) chiller with heat recovery device provided by chiller manufacturer; 2) For the existing water chillers, companies specializing in heat recovery can provide supporting services and install heat recovery devices and corresponding supporting equipment; 3) A high-temperature water source heat pump unit is added to the existing air conditioning water system, and the cooling water of the chiller is used as the heat source, and the high-temperature water source heat pump unit provides hot water above 65℃. 3 hotel air conditioning automatic control system The energy consumption of air conditioning system accounts for a large proportion in the total energy consumption of buildings, so in order to reduce the energy consumption of air conditioning system, air conditioning system has become an important part of intelligent building automatic control system. According to statistics, the energy consumption of BA system can be reduced by about 20% after adopting energy-saving measures such as optimal start-stop control of water supply system, optimal number control of operating equipment, enthalpy control, temperature adaptive control and pressure control, so it is of great significance to set up automatic control system in air conditioning system. Generally speaking, the main parameters that need to be monitored and controlled in hotel air conditioning system are: air temperature and humidity, air volume, water volume, pressure or pressure difference, etc. Monitoring components mainly include: temperature sensor, humidity sensor, air volume and water volume sensor, pressure or differential pressure sensor, actuator (including electric and pneumatic actuator and electric valve, etc.). ) and various controllers. In practical engineering, all or part of the above parameters should be selected for monitoring and control after detailed analysis. The task of automatic control system is to control the number of operating units, that is, to use different units to operate jointly according to different cold and heat requirements, so as to achieve the purpose of efficient operation and energy saving. Another main content of air conditioning automatic control system is equipment linkage, fault alarm and centralized management. The main purpose of equipment linkage is not only to reduce the labor intensity of workers, but also to ensure the safe operation of equipment. In addition, the control of many equipment in air conditioning system involves fire fighting, and the linkage between these equipment and fire fighting system also needs to be controlled by automatic control system. Conclusion The load problem should be solved first in the design of air conditioning system, and the problems that need attention are the accuracy of cooling load estimation and the value of fresh air load. The energy-saving problems discussed in this paper are basically based on the operating state (or energy consumption index) of air conditioning system. Improving energy efficiency is also an important measure to save energy, which can reduce investment. The important steps of energy-saving design of air conditioning system include system design, including the design of air system and water system. For wind system, waste heat recovery is an effective energy-saving measure, while for water system, variable flow system has obvious energy-saving effect, and the measures that can also achieve energy-saving effect include large temperature difference technology of chilled water and condensation heat recovery technology. As air-conditioning system designers, we should try our best to apply these advanced technologies to the air-conditioning system design of hotel buildings in order to achieve energy-saving effect as much as possible. Finally, the use of automatic control system is also an important means of energy saving in air conditioning system. The research shows that adopting a well-designed automatic control system can save more than 20% energy consumption, which is one of the main reasons why the automatic control system can be widely used at present.

For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd