The article analyses the problem of determining the operating parameters of the district heating substation cooperating with the air heating system in technological air conditioning systems equipped with heat exchange...The article analyses the problem of determining the operating parameters of the district heating substation cooperating with the air heating system in technological air conditioning systems equipped with heat exchangers with high efficiency of heat recovery.Attention was paid to the correct selection of heat exchangers for the heat output balance depending on the heat recovery protection algorithms against a drop in the temperature of the heat transfer surface below 0℃.Critical parameters were determined in Polish climatic conditions,at which the operation of the heat recovery exchanger in the air conditioning system is switched off or limited.It has been proven that the proper functioning of the district heating substation cooperating with the installation of air conditioning with high heat recovery efficiency requires the use of two heat exchangers with different characteristics,equipped with properly selected temperature control systems.The optimal model of cooperation between the technological air conditioning system and the heating substation was also indicated.展开更多
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 HVA...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.展开更多
Different cities have different climate conditions and outdoor temperature and humidity, so the scheme of an environment control in subway should be analyzed by considering objective conditions, project cost and opera...Different cities have different climate conditions and outdoor temperature and humidity, so the scheme of an environment control in subway should be analyzed by considering objective conditions, project cost and operating status. In this paper, a physical and mathematical model is built according to the design of Shenyang subway (line 1), the boundary conditions of the model are defined by the design and experiments, the numerical analysis of ventilating scheme and air conditioning scheme is introduced individually, and the temperature field and air flow field of the two schemes are compared, so that the feasibility of using a ventilating scheme in subway of northeast cities is discussed. Considering comfort and economy, it can be concluded that mechanical ventilation is feasible in subway of northeast cities because the air temperature there is not very high in summer.展开更多
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 con...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.展开更多
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 de...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.展开更多
Energy performance assessment on central air-conditioning system is essential to optimize operating, reduce operating costs, improve indoor environmental quality, and determine whether the retrofitting of the equipmen...Energy performance assessment on central air-conditioning system is essential to optimize operating, reduce operating costs, improve indoor environmental quality, and determine whether the retrofitting of the equipment is necessary. But it is difficult to evaluate it reasonably and comprehensively due to its complexity. A "holistic" approach was discussed to evaluate the energy performance of central air-conditioning system for an extra-large commercial building in a subtropical city. All procedures were described in detail, including field investigation method, field measurement instruments, data processing and data analyzing. The main factors affecting energy consumption of air-conditioning system were analyzed and the annual cooling-energy use intensity of this building was calculated and also compared with other shopping malls and other types of buildings in Guangzhou. And COP(coefficient of performance) of chiller, water transfer factor of chilled water system and cooling water system were taken into consideration. At last, the thermal comfort and indoor air quality issues were addressed. The results show that the chilled water pumps are over-sized and the indoor environmental quality should be improved. The purpose of this work is to provide reference for energy performance assessment method for air-conditioning system.展开更多
Mature technologies exist to reduce the heating,ventilation,and air-conditioning(HVAC) energy associated with ventilation and use ventilation proactively to save energy.This study investigated the energy use impacts i...Mature technologies exist to reduce the heating,ventilation,and air-conditioning(HVAC) energy associated with ventilation and use ventilation proactively to save energy.This study investigated the energy use impacts in U.S.office buildings of multiple alternative ventilation strategies that combined:economizing,demand controlled ventilation(DCV),supply air temperature reset(SR),and/or a doubled ventilation rate.We used energy simulations in a Monte Carlo analysis,sampling 17 building inputs and varying locations to match the climate zone distribution of the U.S.office stock.Results indicated the possibility for significant savings compared to a baseline that ventilated constantly at a minimum rate in both a small office type with a constant air volume(CAV) HVAC system and a medium office type with a variable air volume(VAV) system.In 95%of instances,HVAC source energy savings were 5-25%in the small-CAV office(median:11%) and 6-42%in the medium-VAV office(median:27%).In the small-CAV office,DCV typically saved the most energy,usually from heating,and heating degree days and occupant density were decisive influences.In the medium-VAV office,economizing and SR were most important,DCV usually only had minor impacts,and zone temperature setpoints,along with climate indicators,were the critical influences.Other than infiltration,envelope characteristics did not strongly influence energy impacts.The untapped primary energy savings of alternative ventilation strategies over the 74%of U.S.office floorspace reasonably represented by our modeling was estimated at 36 TWh per year,with an annual value of U.S.$ 1.25 billion.展开更多
This paper will provide a proposed solution for saving energy consumption due to residential air conditioners by reducing the window air conditioners type which is the most consumed energy and has a big percent of spr...This paper will provide a proposed solution for saving energy consumption due to residential air conditioners by reducing the window air conditioners type which is the most consumed energy and has a big percent of spreading inside KSA than the split type, also it will discuss some restrictions for trading and manufacturing of air conditioner devices inside KSA besides some restrictions on market and buildings to achieve the objective of reducing the consumption of energy which become a big trend in kingdom vision 2030. The results of this suggesting solution will help the decision-makers to start its plan for execution as it has a big difference between using window type from 2022 till 2030 and if we stop its sales and replace by an efficient one of split AC type in energy consumption in addition to CO<sub>2</sub> emission reduction and decreasing of energy cost, hence our kingdom can save petroleum raw materials and keeping the environment to become clean from pollutants so that these resources are delivered to successive generations correct and clean as we received them from those before us.展开更多
Residential heating, ventilation and air conditioning(HVAC) provides important demand response resources for the new power system with high proportion of renewable energy. Residential HAVC scheduling strategies that a...Residential heating, ventilation and air conditioning(HVAC) provides important demand response resources for the new power system with high proportion of renewable energy. Residential HAVC scheduling strategies that adapt to realtime electricity price signals formulated by demand response program and ambient temperature can significantly reduce electricity costs while ensuring occupants' comfort. However, since the pricing process and weather conditions are affected by many factors, conventional model-based method is difficult to meet the scheduling requirements in complex environments. To solve this problem, we propose an adaptive optimal scheduling strategy for residential HVAC based on deep reinforcement learning(DRL) method. The scheduling problem can be regarded as a Markov decision process(MDP). The proposed method can adaptively learn the state transition probability to make economical decision under the tolerance violations. Specifically, the residential thermal parameters obtained by the leastsquares parameter estimation(LSPE) can provide a basis for the state transition probability of MDP. Daily simulations are verified under the electricity prices and temperature data sets, and numerous experimental results demonstrate the effectiveness of the proposed method.展开更多
High temperature heat hazard at mineral mine becomes more and more serious as the increase of mining depth.Heat sources at working faces of mineral mines are complex and are of different characteristics,presenting new...High temperature heat hazard at mineral mine becomes more and more serious as the increase of mining depth.Heat sources at working faces of mineral mines are complex and are of different characteristics,presenting new challenges for air conditioning systems.In this paper,heat sources at four types of working faces are summarized and their characteristics are investigated.Based on this,simplified equations,which are linear with length of working faces,are proposed to calculate heat dissipation rates.So that the main heat sources of different working faces can be found,and cooling load of air conditioning systems can be calculated.Then,considering main heat sources of coal mines,a typical working face is designed to investigate performances of different ventilation systems and air conditioning systems.Simulation results show that segmented ventilation systems(SC)and heat shield assisted centralized ventilation systems(CCHS)can realize much better temperature distributions at working faces.However,cooling load can be greatly reduced for CCHS,when untreated air is supplied to the coal seam side.Based on this,free cooling assisted air conditioning systems are designed,and annual average energy efficiency ratio(EERann)of the systems are investigated and compared between direct evaporate cooling and indirect evaporate cooling(IEC).For SC,as compared with scenarios without free-cooling,IEC can increase EERann by 15%-23%and 22%-32%under Benxi and Datong ambient conditions,respectively.Besides,to ensure high EERann,CCHS is preferred and it is essential to increase thermal insulation of air ducts.展开更多
When a historic façade needs to be preserved or when the seismic considerations favor use of a concrete wall system and fire considerations limit exterior thermal insulation,one needs to use interior thermal insu...When a historic façade needs to be preserved or when the seismic considerations favor use of a concrete wall system and fire considerations limit exterior thermal insulation,one needs to use interior thermal insulation systems.Interior thermal insulation systems are less effective than the exterior systems and will not reduce the effect of thermal bridges.Yet they may be successfully used and,in many instances,are recommended as a complement to the exterior insulation.This paper presents one of these cases.It is focused on the most successful applications of capillary active,dynamic interior thermal insulation.This happens when such insulation is integrated with heating,cooling and ventilation,air conditioning(HVAC)system.Starting with a pioneering work of the Technical University in Dresden in development of capillary active interior insulations,we propose a next generation,namely,a bio-fiber thermal insulation.When completing the review,this paper proposes a concept of a joint research project to be undertaken by partners from the US(where improvement of indoor climate in exposed coastal areas is needed),China(indoor climate in non-air conditioned concrete buildings is an issue),and Germany(where the bio-fiber technology has been developed).展开更多
文摘The article analyses the problem of determining the operating parameters of the district heating substation cooperating with the air heating system in technological air conditioning systems equipped with heat exchangers with high efficiency of heat recovery.Attention was paid to the correct selection of heat exchangers for the heat output balance depending on the heat recovery protection algorithms against a drop in the temperature of the heat transfer surface below 0℃.Critical parameters were determined in Polish climatic conditions,at which the operation of the heat recovery exchanger in the air conditioning system is switched off or limited.It has been proven that the proper functioning of the district heating substation cooperating with the installation of air conditioning with high heat recovery efficiency requires the use of two heat exchangers with different characteristics,equipped with properly selected temperature control systems.The optimal model of cooperation between the technological air conditioning system and the heating substation was also indicated.
基金Supported by the National Natural Science Foundation of China(50878177)the Rearch Fund for the Doctoral Program of Higher Education
文摘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.
文摘Different cities have different climate conditions and outdoor temperature and humidity, so the scheme of an environment control in subway should be analyzed by considering objective conditions, project cost and operating status. In this paper, a physical and mathematical model is built according to the design of Shenyang subway (line 1), the boundary conditions of the model are defined by the design and experiments, the numerical analysis of ventilating scheme and air conditioning scheme is introduced individually, and the temperature field and air flow field of the two schemes are compared, so that the feasibility of using a ventilating scheme in subway of northeast cities is discussed. Considering comfort and economy, it can be concluded that mechanical ventilation is feasible in subway of northeast cities because the air temperature there is not very high in summer.
文摘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.
文摘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.
基金Project(2011B061200043)supported by the Guangdong Provincial Department of Science and Technology,China
文摘Energy performance assessment on central air-conditioning system is essential to optimize operating, reduce operating costs, improve indoor environmental quality, and determine whether the retrofitting of the equipment is necessary. But it is difficult to evaluate it reasonably and comprehensively due to its complexity. A "holistic" approach was discussed to evaluate the energy performance of central air-conditioning system for an extra-large commercial building in a subtropical city. All procedures were described in detail, including field investigation method, field measurement instruments, data processing and data analyzing. The main factors affecting energy consumption of air-conditioning system were analyzed and the annual cooling-energy use intensity of this building was calculated and also compared with other shopping malls and other types of buildings in Guangzhou. And COP(coefficient of performance) of chiller, water transfer factor of chilled water system and cooling water system were taken into consideration. At last, the thermal comfort and indoor air quality issues were addressed. The results show that the chilled water pumps are over-sized and the indoor environmental quality should be improved. The purpose of this work is to provide reference for energy performance assessment method for air-conditioning system.
文摘Mature technologies exist to reduce the heating,ventilation,and air-conditioning(HVAC) energy associated with ventilation and use ventilation proactively to save energy.This study investigated the energy use impacts in U.S.office buildings of multiple alternative ventilation strategies that combined:economizing,demand controlled ventilation(DCV),supply air temperature reset(SR),and/or a doubled ventilation rate.We used energy simulations in a Monte Carlo analysis,sampling 17 building inputs and varying locations to match the climate zone distribution of the U.S.office stock.Results indicated the possibility for significant savings compared to a baseline that ventilated constantly at a minimum rate in both a small office type with a constant air volume(CAV) HVAC system and a medium office type with a variable air volume(VAV) system.In 95%of instances,HVAC source energy savings were 5-25%in the small-CAV office(median:11%) and 6-42%in the medium-VAV office(median:27%).In the small-CAV office,DCV typically saved the most energy,usually from heating,and heating degree days and occupant density were decisive influences.In the medium-VAV office,economizing and SR were most important,DCV usually only had minor impacts,and zone temperature setpoints,along with climate indicators,were the critical influences.Other than infiltration,envelope characteristics did not strongly influence energy impacts.The untapped primary energy savings of alternative ventilation strategies over the 74%of U.S.office floorspace reasonably represented by our modeling was estimated at 36 TWh per year,with an annual value of U.S.$ 1.25 billion.
文摘This paper will provide a proposed solution for saving energy consumption due to residential air conditioners by reducing the window air conditioners type which is the most consumed energy and has a big percent of spreading inside KSA than the split type, also it will discuss some restrictions for trading and manufacturing of air conditioner devices inside KSA besides some restrictions on market and buildings to achieve the objective of reducing the consumption of energy which become a big trend in kingdom vision 2030. The results of this suggesting solution will help the decision-makers to start its plan for execution as it has a big difference between using window type from 2022 till 2030 and if we stop its sales and replace by an efficient one of split AC type in energy consumption in addition to CO<sub>2</sub> emission reduction and decreasing of energy cost, hence our kingdom can save petroleum raw materials and keeping the environment to become clean from pollutants so that these resources are delivered to successive generations correct and clean as we received them from those before us.
基金supported in part by the Fundamental Research Funds for the Central Universities (No. 2018JBZ004)the National Natural Science Foundation of China (No. 52007004)。
文摘Residential heating, ventilation and air conditioning(HVAC) provides important demand response resources for the new power system with high proportion of renewable energy. Residential HAVC scheduling strategies that adapt to realtime electricity price signals formulated by demand response program and ambient temperature can significantly reduce electricity costs while ensuring occupants' comfort. However, since the pricing process and weather conditions are affected by many factors, conventional model-based method is difficult to meet the scheduling requirements in complex environments. To solve this problem, we propose an adaptive optimal scheduling strategy for residential HVAC based on deep reinforcement learning(DRL) method. The scheduling problem can be regarded as a Markov decision process(MDP). The proposed method can adaptively learn the state transition probability to make economical decision under the tolerance violations. Specifically, the residential thermal parameters obtained by the leastsquares parameter estimation(LSPE) can provide a basis for the state transition probability of MDP. Daily simulations are verified under the electricity prices and temperature data sets, and numerous experimental results demonstrate the effectiveness of the proposed method.
基金The authors appreciate the support from the National Natural Science Foundation of China(No.51706015)from the Fundamental Research Funds for the Central Universities(FRF-IDRY-19-01).
文摘High temperature heat hazard at mineral mine becomes more and more serious as the increase of mining depth.Heat sources at working faces of mineral mines are complex and are of different characteristics,presenting new challenges for air conditioning systems.In this paper,heat sources at four types of working faces are summarized and their characteristics are investigated.Based on this,simplified equations,which are linear with length of working faces,are proposed to calculate heat dissipation rates.So that the main heat sources of different working faces can be found,and cooling load of air conditioning systems can be calculated.Then,considering main heat sources of coal mines,a typical working face is designed to investigate performances of different ventilation systems and air conditioning systems.Simulation results show that segmented ventilation systems(SC)and heat shield assisted centralized ventilation systems(CCHS)can realize much better temperature distributions at working faces.However,cooling load can be greatly reduced for CCHS,when untreated air is supplied to the coal seam side.Based on this,free cooling assisted air conditioning systems are designed,and annual average energy efficiency ratio(EERann)of the systems are investigated and compared between direct evaporate cooling and indirect evaporate cooling(IEC).For SC,as compared with scenarios without free-cooling,IEC can increase EERann by 15%-23%and 22%-32%under Benxi and Datong ambient conditions,respectively.Besides,to ensure high EERann,CCHS is preferred and it is essential to increase thermal insulation of air ducts.
文摘When a historic façade needs to be preserved or when the seismic considerations favor use of a concrete wall system and fire considerations limit exterior thermal insulation,one needs to use interior thermal insulation systems.Interior thermal insulation systems are less effective than the exterior systems and will not reduce the effect of thermal bridges.Yet they may be successfully used and,in many instances,are recommended as a complement to the exterior insulation.This paper presents one of these cases.It is focused on the most successful applications of capillary active,dynamic interior thermal insulation.This happens when such insulation is integrated with heating,cooling and ventilation,air conditioning(HVAC)system.Starting with a pioneering work of the Technical University in Dresden in development of capillary active interior insulations,we propose a next generation,namely,a bio-fiber thermal insulation.When completing the review,this paper proposes a concept of a joint research project to be undertaken by partners from the US(where improvement of indoor climate in exposed coastal areas is needed),China(indoor climate in non-air conditioned concrete buildings is an issue),and Germany(where the bio-fiber technology has been developed).