Analysis and Modeling of the Central Air-Conditioning System in Intelligent Buildings

The central air conditioning system in an intelligent building (IB) was analyzed and modeled in order to perform the optimization scheduling strategy of the central air conditioning system. A set of models proposed and a type of periodically autoregressive model (PAR) based on the improved genetic algorithms (IGA) were used to perform the optimum energy saving scheduling. The example of the Liangmahe Plaza was taken to show the effectiveness of the methods.

Study on the Elman Neural Network Operation Control Strategy of the Central Air Conditioning Chilled Water System

The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time delay characteristics, presented use feed forward coupling compensation method, to eliminate the coupling effect between temperature and pressure. In this paper, the Elman neural network controller is designed for the first time, and the simulation results show that the response time of Elman neural network controller is shorter, the system is more stable and the overshoot is small.

Optimum Energy Management of the Central Air-Conditioning System in Intelligent Buildings

An optimum energy saving scheduling strategy of the central air conditioning system in an intelligent building (IB) was proposed. Based on the system analysis a set of models of the central air conditioning system was established. The periodically autoregressive models (PARM) based on genetic algorithms (GA) were used to predict the next day’s cold load. The improved genetic algorithms (IGA) with stochastic real number coding were used to finish the optimum energy saving scheduling of the system. The simulation results for the building of the Liangmahe Plaza show that the proposed strategy can save energy up to about 24 5%.

Practice and analysis of recycling non-drinking water from air-condition and reverse-osmosis system into rainwater collection system

This paper is based on the rainwater collection project in the retrofit of the Dongyi teaching block in Zhejiang University Xixi Campus.The analysis incorporates the local meteorological data, recycling water utilization, and precipitation adjustment.The rainwater collection system in this program also adds the condensation water from the heating, ventilation and air conditioning （ HVAC） system and the concentration from the reverse-osmosis system used for watering greens and supplying waterscapes.By calculating, the quantity of the HVAC condensation water in summer is 3.48 m3/d, and the quantity of the reverse-osmosis concentrated water is 198 to 396 L/d.This method solves the water shortage caused by high evaporation in summer and low precipitation in winter.Supported by empirical monitoring data, the proposed method significantly increases the economic efficiency of the system during the summer period.

A Case Study:Distribution of Bacterial and Fungal Aerosols in Air-Conditioning Systems in Shaanxi History Museum

In order to investigate the bacteria and fungi aerosol characteristic distribution in HVAC-system and its components at Shaanxi History Museum.Measurements were performed to probe the bacteria and fungi aerosol in HVAC systems,located at Xi'an city,China.The results showed that there was fungi growth inside the ventilation ducts,fungi contamination was worse than bacteria,and both of them were distributed into occupied space with the air supply ducts.The dominating genera of fungi was found to be Penicillium spp.and Aspergillus spp.,which was respectively 46.1% and 20.7% in settling fungi,and the dominating genera of fungi in dust were Cladosporium spp.and Penicillium spp.,which was 41.8% and 30.1% respectively.It suggests that available measures to improve and control the performance of HVAC-systems such as the maintenance,management and cleaning should be taken to prevent this pollution and to develop strategies to keep this pollution away.

An Energy-Saving Control Strategy on Central Air-Conditioning System

An energy-saving control strategy based on predictive control for central air-conditioning systems is proposed in this paper. The cold load model is developed to describe the dynamic characteristics of temperature control systems, and then parameters in the cold load model and in the central air-conditioning system model are estimated. Generalized predictive control (GPC) is used to establish an optimization model to minimize the consumption of energy and the control error of temperature. The simulated annealing (SA) algorithm, combined with quadratic programming, is adopted to solve the optimal problem. Contrasted with the simulation of traditional PID control, the results prove the effectiveness of this proposed strategy.

Energy Efficient Air Conditioning System Using Geothermal Cooling-Solar Heating in Gujarat, India

It is well known that one unit of electrical energy saved is equal to more than two units produced. One way of economizing the power is utilization of energy efficient systems at all locations. In the present study, the air conditioning system is analysed and an innovative way is suggested. We use natural low temperature of shallow sub surface (1 - 3 m) of the earth—geothermal cooling system. It is known that majority of the households and the apartment complexes in India have two tanks for water storage. One is the underground water sump and the other is the overhead water tank. In our study, we use these two water storage systems for space cooling during summer and also for heating during winter. The main aim of our paper is air-conditioning of the space in an economic way to save electricity. It is based on a simple idea of transferring the low temperature from underground water sump to the room in the house using water as a mode of transport. Since India is a tropical country located at low latitude, most of the year, the air temperature is high and demands space cooling. However, for a couple of months during severe winter months (Dec.-Jan.) at Ahmedabad, heating of the space is required. For heating the space, we suggest to use the well-known solar water heater. Effective use of heat exchanger is shown through computation, modelling schemes and lab experiment. We recommend geothermal cooling for 10 months in a year and solar hot water system during 2 months of winter. It is observed that the ambient air temperature of 35°C - 40°C in the room can be brought down to 26°C without much consumption of electricity. In a similar manner, the room temperature at night (13°C) during winter in Ahmedabad can be increased to 27°C through circulation of water from solar water heater in the heat exchanger.

STUDY OF THE HEAT AND HUMIDITY TRANSFER PROCESSES BETWEEN AIR AND WATER IN THE AIR WASHER

The processes of heat and humidity transfer between air and water are what to be studied mainly in the paper, we put forward some main factors which influence the processes of heat and humidity transfer in the air washer. We come to the conclusion that we can change these main factors to achieve different heat and humidity transfer processes and decide processes of heat and humidity transfer of air and water with the initial temperature of spraying water in the air washer. All these results can make things convenient for the air conditioning management.

Design of Fuzzy Controller for Central Air Conditioner

A structure of central air conditioning system in building and its running pattern are proposed in order to perform optimum energy saving strategy. The design of room temperature controller is taken as an example to discuss the design of fuzzy controller using common microprogrammed control unit (MCU) in detail. Based on fuzzy theory the query control tables fixed in read only memory (ROM) of MCU are established to realize the energy saving in the room temperature controller and the reasoning procedure is analyzed. The diagram of hardware design and the flow chart of software of room temperature controller are presented. The results show that the proposed method is practical and effective to achieve the energy saving goal.

Experimental Study of Energy-Saving Air-Conditioner with Hot Water

Energy-saving air-conditioner with hot water is an air source heat pump air-conditioner,which can also supply hot water.The hot water is heated by a double pipe condenser connected with an air-cooled condenser in series in the system.This experiment of the energy-saving air-conditioner was carried out in the enthalpy-difference air-conditioner laboratory.The hot water temperature and the compressor's discharge and suction pressure were recorded in the working condition,where the ambient temperature was at 43 ℃,35 ℃,21 ℃,7 ℃,and 2 ℃ separately.The results showed that the system operated stably and reliably.This system can supply 240 L hot water at 50 ℃ in the whole year,and its coefficience of performance(COP)is much higher than the conventional air source heat pump system.Its energy conservation was proved by comparing the thermal efficiency with other sourece water heaters.

夏热冬冷地区某三甲医院空调制冷机房运行性能实测研究

医院建筑夏季供冷需求高,实现制冷机房高效运行具有显著的节能减排效益。以夏热冬冷地区某三甲医院为研究对象,通过对其空调制冷机房在夏季的运行性能进行实测研究,总结出冷水机组运行负荷率偏低,蒸发器与冷凝器换热性能不佳,冷水、冷却水系统缺乏合理调控导致的大流量小温差等问题,并提出了优化措施。研究结果旨在为同类建筑制冷机房节能运维提供建议。

Experimental investigation of integrated air purifying technology for bioaerosol removal and inactivation in central air-conditioning system

In this research, high voltage static electricity and ultraviolet technologies were integrated to an air purifying device which can be used to trap and kill airborne bacteria and viruses in central air-conditioning systems. An experimental platform was built to mimic the central air system, in which the efficacy of the newly built device was examined. In addition to the standard physical and chemical tests, bacteriophages were used to simulate airborne viruses in the experimental system. The bacteriophage suspension was aerosolized into the air with ultrasonic wave atomization.The result showed that more than 86% removal efficiency of micro-particles (<10 micron in diameter) were removed after the device was in operation in a building and more than 95% of bacteriophages in the experimental system. It is concluded that the integrated air purifier is suitable for controlling air quality and preventing virus transmission through the central air system.

基于主动水蓄冷的冷水机组节能优化策略研究

针对目前空调行业中应用蓄冷技术进行经济性优化过程中能耗普遍增加的问题,提出一种以保持冷水机组高能效运行为核心的节能优化运行策略,该策略通过小型蓄冷罐储存和释放冷量,主动调控冷水主机的负荷率,保持冷水主机长时间处于高效运行状态以实现节能。以一座医院的中央空调系统的运行数据为数据来源,建立空调系统物理模型进行模拟,得到冷水主机在不同环境条件下的性能曲线,用于准确描述每时刻冷水主机的高效运行状态。在最大冷负荷为9979 kW的供冷季典型日,相比于无主动水蓄冷的常规冷水机组运行策略,可节省日用电量2777 kW·h,占当日中央空调系统用电量的6.0%,并在整个供冷季节省中央空调系统用电量2.35%,节省冷水主机用电量4.45%。

从水逆探讨空调病的发生机制与治疗策略

水逆发生原因为水气内停,逆犯三焦,其阳气闭郁,津液失布的特性与空调病的病机具有共通性。通过分析空调病寒燥伤阳,气不布津的关键病机,结合空调病发病表现出的头晕头痛、咳嗽恶寒、咽痛鼻塞等一系列症候,提出温阳启闭,化气布津的治疗总则,选方以五苓散为基础方,根据患者阳伤、气闭、水停的偏重,加用真武汤以温阳布津、柴胡桂枝干姜汤以通阳开玄、猪苓汤以滋阴利水,以恢复津液之转输,三焦之气化。

MEASUREMENT TECHNOLOGY OF HEAT AND COOL

The popularization of large scale central air conditioning system (CACS) has brought forward a new pro blem,i.e. how to measure the cooling and heating quantum accurately. This problem will directly affect the qua lity of modern property management. So the study on the technology of measuring heat and cool is very necessary. In this paper, the detailed thermal analysis and the mathematical model of relative parameters that affect the measurement of heat and cool are discussed. A sample instrument based on the model is made, After the trial use by several customers, the device is proved to be practical, worthwhile and of good capacity.

基于群智能的中央空调系统故障预测维护技术

中央空调系统是大型建筑物中不可或缺的组成部分,其运行效率和可靠性直接影响到能源消耗和居住舒适度。然而,系统故障可能导致显著的维护成本和运行中断。群智能技术,源于生物系统的集体行为研究,如蚁群、鱼群和鸟群的自组织现象,已被应用于优化复杂问题的解决方案。本文介绍了群智能技术在中央空调系统故障预测和维护中的应用,探讨了基于群智能的预终身维护策略,包括实时监控、预防性维护调度及资源优化配置,旨在提高系统的可靠性和效率。

高校食堂空气源热水系统的应用

以南通市某高校食堂项目为例,结合高校食堂的热水用水特点,对高校食堂热水热源、热水定额、冷水温度等各参数对高校食堂热水系统的影响进行探讨,并给出合理的取值建议。

基于热舒适需求的空调系统风-水协同调控技术研究

公共建筑空调系统能耗在建筑总能耗中占有非常大的比例,如果在动态负荷变化下一直处于设计工况运行,在浪费冷量的同时又会导致能耗过高。结合实际工程案例建立展厅舒适度与空调系统模型,基于室内PMV(Predicitive Mean Vote,预测平均投票数)参数确定不同人数时空调系统最佳运行调控策略,使空调系统既能保证室内舒适度,又能最大程度降低运行能耗。结果表明,优化后送风量由原来的26 000 m^(3)/h下降至4 400~12 000 m^(3)/h;不同人数时的水阀开度在0.25~0.81之间变化;室内人数最多时节能率达11.9%,并且随着室内人数的减少节能率逐渐增加。研究结论对于指导公共建筑空调系统的节能运行具有重要的意义。

Strategy of constructing virtual peaking unit by public buildings’central air conditioning loads for day-ahead power dispatching

With the gradually widely usage of the air conditioning(AC) loads in developing countries, the urban power grid load has swiftly increased over the past decade.Especially in China, the AC load has accounted for over30% of the maximum load in many cities during summer.This paper proposes a scheme of constructing a virtual peaking unit(VPU) by public buildings’ cool storage central AC(CSCAC) systems and non-CSCAC(NCSCAC)systems for the day-ahead power network dispatching(DAPND). Considering the accumulation effect of different meteorological parameters, a short term load forecasting method of public building’s central AC(CAC) baseline load is firstly discussed. Then, a second-order equivalent thermal parameters model is established for the public building’s CAC load. Moreover, the novel load reduction control strategies for the public building’s CSCAC system and the public building’s NCSCAC system are respectively presented. Furthermore, based on the multiple-rank control strategy, the model of the DAPND with the participation of a VPU is set up. The VPU is composed of large-scale regulated public building’s CAC loads. To demonstrate the effectiveness of the proposed strategy, results of a sample study on a region in Nanjing which involves 22 public buildings’ CAC loads are described in this paper. Simulated results show that, by adopting the proposed DAPND scheme, the power network peak load in the region obviously decreases with a small enough deviation between the regulated load value and the dispatching instruction of the VPU. The total electricity-saving amount accounts for7.78% of total electricity consumption of the VPU before regulation.

Prevalence and risk factors of dry eye disease in young and middle-aged office employee:a Xi’an Study

AIM:To estimate the prevalence of and risk factors for dry eye disease(DED)in young and middle-aged office employee in Xi’an.METHODS:This cross-sectional study of the prevalence of and risk factors for DED investigated 486 young and middle-aged Chinese office employee in Xi’an.DED symptoms and potential risk factors were assessed using the ocular surface disease index combined with a risk factors questionnaire,and tear function was evaluated using the tear film break-up time and Schirmer’s test.Possible risk factors for DED were estimated by binary Logistic regression analysis.RESULTS:DED was diagnosed in 100 females and 96 males,giving a prevalence of 40.3%[95%confidence interval(CI)=36.0%-44.7%].The multivariate binary Logistic regression model indicated that the possible risk factors for DED were being female(OR=1.592,95%CI=1.034-2.451,P=0.035),being aged≥40 y(OR=1.593,95%CI=1.034-2.454,P=0.035),using a VDT daily for>6 h(OR=1.990,95%CI=1.334-2.971,P=0.001),the presence of central air conditioning(OR=1.548,95%CI=1.053-2.276,P=0.026),and self-reported dryness of the mouth and nose(OR=1.589,95%CI=1.071-2.357,P=0.021).CONCLUSION:There is a high prevalence of clinically diagnosed DED in young and middle-aged video displayterminal(VDT)users.Interventions against the modifiable risk factors should be taken to prevent the occurrence and development of DED in this population.