This paper addresses the development and testing of a remotely controlled boat platform with an innovative air-ventilated hull. The application of air cavities on the underside of ship hulls is a promising means for r...This paper addresses the development and testing of a remotely controlled boat platform with an innovative air-ventilated hull. The application of air cavities on the underside of ship hulls is a promising means for reducing hydrodynamic drag and pollutant emissions and increasing marine transportation efficiency. Despite this concept＇s potential, design optimization and high-performance operation of novel air-cavity ships remain a challenging problem. Hull construction and sensor instrumentation of the model-scale air-cavity boat is described in the paper. The modular structure of the hull allows for easy modifications, and an electric propulsion unit enables self-propelled operation. The boat is controlled remotely via a radio transmission system. Results of initial tests are reported, including thrust, speed, and airflow rate in several loading conditions. The constructed platform can be used for optimizing air-cavity systems and testing other innovative hull designs. This system can be also developed into a high-performance unmanned boat.展开更多
A new air distribution pattern,air curtain jet ventilation was presented.The ventilation or airflow patterns and the air velocity produced by air curtain jet were investigated in detail.To identify the airflow charact...A new air distribution pattern,air curtain jet ventilation was presented.The ventilation or airflow patterns and the air velocity produced by air curtain jet were investigated in detail.To identify the airflow characteristics of this novel air curtain jet ventilation system,a full-scale room was used to measure the jet velocity with a slot-ventilated supply device,with regards to the airflow fields along the vertical wall as well as on the horizontal floor zones.The airflow fields under three supply air velocities,1.0,1.5 and 2.0 m/s,were carried out in the full-scale room.The experimental results show the velocity profiles of air distribution,the airflow fields along the attached vertical wall and the air lake zones on the floor,respectively.The current experimental research is helpful for heating,ventilation and air conditioning(HVAC) engineers to design better air distribution in rooms.展开更多
The current mine safety monitoring system used can only get the air volume change of roadway placed air velocity transducers, as this change is caused by this roadway, or for other roadway, and fault source has one po...The current mine safety monitoring system used can only get the air volume change of roadway placed air velocity transducers, as this change is caused by this roadway, or for other roadway, and fault source has one point or more, which be- longs to the problem of fault source diagnosis for ventilation system. Ventilation system fault can be attributed to the variation of air resistance of branch in the entire network. If the changes of air resistance for each branch in ventilation system are ana- lyzed, then it is impossible to place air velocity transducers in every branch. Therefore, the problem of the minimum quantities and location for placing air velocity transducers should be mainly studied. The relationship of air resistance and air volume variation of matrix method has been proposed, which can reflect the variation relationship between the air volume of the branch and air resistance of the relevant branches. Fault roadway range library of ventilation network built to determine fault roadway range will cause air velocity to exceed the limit. Minimum and full coverage of distribution method has been proposed, and the concept of branch coverage degree and impact roadway range library has also been brought forword to get the macro-distribution of air velocity transducers.展开更多
A HVAC （heating ventilating and air conditioning） system is generally designed to ventilate an indoor space. In windy and snowy climates dispersed snow particles in ambient air can enter the intake duct, potentially...A HVAC （heating ventilating and air conditioning） system is generally designed to ventilate an indoor space. In windy and snowy climates dispersed snow particles in ambient air can enter the intake duct, potentially causing a serious problem. The study addresses the influence of suction volumetric flow rates, the potential discrepancy of snow intake based upon the wind direction in relation to the intake vent, and the possible difference in amounts of infiltrated snow particles in varying intake vent design and locations. The necessary characteristic quantities are defined. The simulation results show the rate of infiltration and the efficiency of the chosen intake designs. The magnitude and direction of wind influences snow infiltration significantly. The daily amount of infiltrated snow is introduced to be the characteristic measure of the infiltration in design of the HVAC systems.展开更多
The content of contribution is to analyse suggested renovation of school building in term of energy performance and indoor environment quality. There were three selected variants of possible reno ration of school buil...The content of contribution is to analyse suggested renovation of school building in term of energy performance and indoor environment quality. There were three selected variants of possible reno ration of school building. At first, it was installation of equipment for heat recovery into existing mechanical ventilation system. There were further evaluated possibilities how to use glass atrium or ground air-heat exchanger in mechanical ventilation system. These suggested variants were analysed in field of energy performance, namely in term of impacts on heat demand for space heating in order to keep required parameters of indoor environment quality according to standard STN EN 15251 （operative temperature, relative air humidity, air change rate）. The analysis was elaborated by using energy simulation tool Design Builder in order to evaluate yearlong operation of buildings.展开更多
Latvian children under the age of 7 can spend up to 60 hours per week in daycare centers and therefore it is very important to establish a healthy and comfortable daycare environment that children will find pleasant a...Latvian children under the age of 7 can spend up to 60 hours per week in daycare centers and therefore it is very important to establish a healthy and comfortable daycare environment that children will find pleasant and stimulating to stay in. This study investigates indoor air quality and thermal comfort within six daycare centers （old, renovated and new-built） in moderate climate zone of Latvia. Measurements of carbon dioxide, air temperature and relative humidity were carried out, and data regarding daycare center characteristics and maintenance activities was collected via combination of field visits, record analysis and interviews. It was found that carbon dioxide concentrations exceeded 1000 ppm in 75% of daycare centers studied, with the highest （1356 ppm） measured in a renovated facility with the natural ventilation system. Thus installation of more efficient ventilation system （mechanical） is recommended to provide acceptable indoor air quality, since opening of windows itself cannot provide the optimal conditions indoors. In all facilities the temperature was kept above 20℃ and the average relative humidity was 40±35%, creating comfortable thermal environment for children.展开更多
基金Foundation item： Supported by the National Science Foundation （CMMI-1026264 and EEC-1157094）.
文摘This paper addresses the development and testing of a remotely controlled boat platform with an innovative air-ventilated hull. The application of air cavities on the underside of ship hulls is a promising means for reducing hydrodynamic drag and pollutant emissions and increasing marine transportation efficiency. Despite this concept＇s potential, design optimization and high-performance operation of novel air-cavity ships remain a challenging problem. Hull construction and sensor instrumentation of the model-scale air-cavity boat is described in the paper. The modular structure of the hull allows for easy modifications, and an electric propulsion unit enables self-propelled operation. The boat is controlled remotely via a radio transmission system. Results of initial tests are reported, including thrust, speed, and airflow rate in several loading conditions. The constructed platform can be used for optimizing air-cavity systems and testing other innovative hull designs. This system can be also developed into a high-performance unmanned boat.
基金Projects(50778145, 50278025) supported by the National Natural Science Foundation of ChinaProject(2009ZDKG-47) supported by "13115" Science and Technology Innovation Program of Shaanxi Province, China
文摘A new air distribution pattern,air curtain jet ventilation was presented.The ventilation or airflow patterns and the air velocity produced by air curtain jet were investigated in detail.To identify the airflow characteristics of this novel air curtain jet ventilation system,a full-scale room was used to measure the jet velocity with a slot-ventilated supply device,with regards to the airflow fields along the vertical wall as well as on the horizontal floor zones.The airflow fields under three supply air velocities,1.0,1.5 and 2.0 m/s,were carried out in the full-scale room.The experimental results show the velocity profiles of air distribution,the airflow fields along the attached vertical wall and the air lake zones on the floor,respectively.The current experimental research is helpful for heating,ventilation and air conditioning(HVAC) engineers to design better air distribution in rooms.
文摘The current mine safety monitoring system used can only get the air volume change of roadway placed air velocity transducers, as this change is caused by this roadway, or for other roadway, and fault source has one point or more, which be- longs to the problem of fault source diagnosis for ventilation system. Ventilation system fault can be attributed to the variation of air resistance of branch in the entire network. If the changes of air resistance for each branch in ventilation system are ana- lyzed, then it is impossible to place air velocity transducers in every branch. Therefore, the problem of the minimum quantities and location for placing air velocity transducers should be mainly studied. The relationship of air resistance and air volume variation of matrix method has been proposed, which can reflect the variation relationship between the air volume of the branch and air resistance of the relevant branches. Fault roadway range library of ventilation network built to determine fault roadway range will cause air velocity to exceed the limit. Minimum and full coverage of distribution method has been proposed, and the concept of branch coverage degree and impact roadway range library has also been brought forword to get the macro-distribution of air velocity transducers.
文摘A HVAC （heating ventilating and air conditioning） system is generally designed to ventilate an indoor space. In windy and snowy climates dispersed snow particles in ambient air can enter the intake duct, potentially causing a serious problem. The study addresses the influence of suction volumetric flow rates, the potential discrepancy of snow intake based upon the wind direction in relation to the intake vent, and the possible difference in amounts of infiltrated snow particles in varying intake vent design and locations. The necessary characteristic quantities are defined. The simulation results show the rate of infiltration and the efficiency of the chosen intake designs. The magnitude and direction of wind influences snow infiltration significantly. The daily amount of infiltrated snow is introduced to be the characteristic measure of the infiltration in design of the HVAC systems.
文摘The content of contribution is to analyse suggested renovation of school building in term of energy performance and indoor environment quality. There were three selected variants of possible reno ration of school building. At first, it was installation of equipment for heat recovery into existing mechanical ventilation system. There were further evaluated possibilities how to use glass atrium or ground air-heat exchanger in mechanical ventilation system. These suggested variants were analysed in field of energy performance, namely in term of impacts on heat demand for space heating in order to keep required parameters of indoor environment quality according to standard STN EN 15251 （operative temperature, relative air humidity, air change rate）. The analysis was elaborated by using energy simulation tool Design Builder in order to evaluate yearlong operation of buildings.
文摘Latvian children under the age of 7 can spend up to 60 hours per week in daycare centers and therefore it is very important to establish a healthy and comfortable daycare environment that children will find pleasant and stimulating to stay in. This study investigates indoor air quality and thermal comfort within six daycare centers （old, renovated and new-built） in moderate climate zone of Latvia. Measurements of carbon dioxide, air temperature and relative humidity were carried out, and data regarding daycare center characteristics and maintenance activities was collected via combination of field visits, record analysis and interviews. It was found that carbon dioxide concentrations exceeded 1000 ppm in 75% of daycare centers studied, with the highest （1356 ppm） measured in a renovated facility with the natural ventilation system. Thus installation of more efficient ventilation system （mechanical） is recommended to provide acceptable indoor air quality, since opening of windows itself cannot provide the optimal conditions indoors. In all facilities the temperature was kept above 20℃ and the average relative humidity was 40±35%, creating comfortable thermal environment for children.
