Supply Air Volume Research Articles

Preliminary Study on Air Distribution Mode of wall attached duct multi-directional Jet Supply in Occupied Zone

Based on comparative analysis of the existing air distribution modes in heating, ventilation and air conditioning(HVAC) system, a novel ventilation mode based on wall attached duct multi-directional jet supply in occupied zone (WADMDJ) was presented. Air distribution characteristics are studied by CFD numerical simulation. The results show that this kind of air supply mode is similar to displacement ventilation (DV) and can form air lake phenomenon in the aspect of velocity and temperature distribution under the condition of lower air supply velocity. What’s more, this mode can satisfy larger air supply volume and higher cooling load than that of traditional displacement ventilation. The research indicates that this ventilation system could be used for room ventilation and air-conditioning engineering more efficiently under the reasonable parameter settings of supply air velocity and temperature.

DETERMINATION OF AIR EXCHANGE IN PUBLIC BUILDING PREMISES HAVING LARGE AREA OF TRANSLUCENT STRUCTURES

The paper considers reasons of internal air parameter mismatch in warm season of the year for public building premises having large area of translucent structures. The main reason of uncomfortable air environment is an underestimated value of air supply volume due to air exchange calculation according to multiplicity factor or air exchange rate per one person which are determinative values only for cold period and transient conditions. In other words multiplicity factor and air exchange rate do not take into account equipment abundance in modern offices and heat input of the office equipment is rather significant value. The paper contains an analysis and comparison of the existing air exchange rates for the Republic of Belarus, Russian Federation, European countries and USA. Calculation of heat input and air exchange for public building premises during warm season of the year for assimilation of evident heat excess has been made at various orientations of curtain walls. The paper provides structure of heat input into premises. The required rate of air supply volume per one person has been determined on the basis of air exchange and it has been compared with the existing air exchange rate. The required rate averagely exceeds the standard one by 12-fold. But this does not mean that there is necessity to increase the rate in such a way because it entails an increase in capital and operational costs. In this connection the paper reviews variants for improvement of micro-climate in the building premises with large area of translucent structures: automatic regulation of heat transfer in heating appliances during cold period of the year; usage of air conditioning and increase in temperature difference of input and output air during warm period.

Retraction Notice: Study and Analysis of Human Survival Parameters in Mine Refuge Station

In order to study life support key techniques in mine refuge station, test the clinical emergency response of par- ticipants and human survival parameters in rescue state. A manned test with 50 miners for 48h in a real underground ref- uge station was conducted in Guilaizhuang gold mine. The experiment simulated rescue living environment of human and consisted of three stages (the passive stage, the compressed air supplying stage, and the compressed O2 supplying stage). By monitoring environmental concentrations of O2, CO2, temperature, relative humidityand human activity states dur- ing the test, the O2 consumption, CO2 production and respiration quotient was obtained and analysed in different activi- ties, time quantum and O2 concentration. On the basis, the minimum air supply volumes for the survival of test personnel were determined. That is 0.067m 3 /min per person and is far lower than the national standard�0.3m 3 /min per person�. During the test, no people experienced discomfort by health check and questionnaire. It is expected that the conclusions provide an important reference for the design of underground refuge stations and mine emergency rescue.

Effect of nozzle air supply temperature and volume flowrate on the jet flow from a typical ventilation nozzle in aircraft cabins

A ventilation nozzle’s airflow characteristics could have an influence on a passenger’s thermal comfort and dispersion of pollutants in an aircraft cabin, but there is little published research in this area. In this article, the temperature and air velocity from a nozzle jet were measured in a simulated three-row aircraft cabin at more than 220 points for both isothermal and non-isothermal jets. The non-isothermal jets were tested for air supply temperature differences of ± 5 and 10℃, and the isothermal jets for volume flowrates of 1.86 × 10−7, 2.67 × 10−7, and 4.03 × 10−7 m3/h. The results show that both the nozzle jet’s temperature and air velocity distributions are axially symmetrical and that the decay of the jet is rapid. The equation for the air velocity distribution was used to calculate the air velocity at any point in the main jet region for different volume flowrates. The temperature difference was shown to have little effect on the air velocity distribution for the main region of a nozzle jet, whereas the air flowrate was shown to significantly affect the air velocity distribution. This suggests that the effect of nozzle jet on passenger’s thermal comfort is mostly due to its air velocity distribution rather than temperature distribution.

Various Energy-Saving Approaches to a TFT-LCD Panel Fab

This study employs the developed simulation software for the energy use of the high-tech fabrication plant (hereafter referred as a fab) to examine six energy-saving approaches for the make-up air unit (MAU) of a TFT-LCD (thin-film transistor liquid-crystal display) fab. The studied approaches include: (1) Approach 1: adjust the set point of dry bulb temperature and relative humidity in the cleanroom; (2) Approach 2: lower the flow rate of supply air volume in the MAU; (3) Approach 3: use a draw-through type instead of push through type MAU; (4) Approach 4: combine the two stage cooling coils in MAU to a single stage coil; (5) Approach 5: reduce the original MAU exit temperature from 16.5 °C to 14.5 °C; and (6) Approach 6: avoid an excessive increase in pressure drop over the filter by replacing the HEPA filter more frequently. The simulated results are further compared to the measured data of the studied TFT-LCD fab in Taiwan. The simulated results showed that Approach 1 exhibits more significant influence on annual power consumption than the other approaches. The advantage/disadvantage of each approach is elaborated. The impact of the six approaches on the annual power consumption of the fab is also discussed.

Attempt to Improve Indoor Air Quality in Kindergartens

This paper presents the results of the investigation devoted to the quality of indoor air in classrooms of selected Polish kindergartens. The kindergartens buildings were built between 1970 and 1993 and had gravity ventilation systems. The variability of basic IAQ parameters. The outcomes confirmed low quality of the indoor air in these buildings. Certain modifications aimed at improving IAQ were proposed during the investigations. Two solutions were implemented: twofold increase in the volume of supply air and installing indoor air cleaning devices based on the radiant catalytic ionization technology (RCI).

Indoor air quality and ventilation requirement in residential buildings: A case study of Tehran, Iran

The ventilation system is a key device to ensure both healthful indoor air quality (IAQ) and thermal comfort in buildings. The ventilation system should make the IAQ meet the standards such as ASHRAE 62. This study deals with a new approach to modeling the ventilation and IAQ requirement in residential buildings. In that approach, Elite software is used to calculate the air supply volume, and CONTAM model as a multi-zone and contaminant dispersal model is employed to estimate the contaminants' concentrations. Amongst various contaminants existing in the residential buildings, two main contaminates of carbon dioxide (<TEX>$CO_2$</TEX>) and carbon monoxide (CO) were considered. CO and <TEX>$CO_2$</TEX> are generated mainly from combustion sources such as gas cooking and heating oven. In addition to the mentioned sources, <TEX>$CO_2$</TEX> is generated from occupants' respirations. To show how that approach works, a sample house with the area of <TEX>$80m^2$</TEX> located in Tehran was considered as an illustrative case study. The results showed that <TEX>$CO_2$</TEX> concentration in the winter was higher than the acceptable level. Therefore, the air change rate (ACH) of 4.2 was required to lower the <TEX>$CO_2$</TEX> concentration below the air quality threshold in the living room, and in the bedrooms, the rate of ventilation volume should be 11.2 ACH.

Study and Analysis of Human Survival Parameters in Mine Refuge Station

In order to study life support key techniques in mine refuge station, test the clinical emergency response of participants and human survival parameters in rescue state. A manned test with 50 miners for 48h in a real underground refuge station was conducted in Guilaizhuang gold mine. The experiment simulated rescue living environment of human and consisted of three stages (the passive stage, the compressed air supplying stage, and the compressed O supplying stage). By monitoring environmental concentrations of O2, CO2, temperature, relative humidity, and human activity states during the test, the O2 consumption, CO2 production and respiration quotient was obtained and analysed in different activities, time quantum and O2 concentration. On the basis, the minimum air supply volumes for the survival of test personnel were determined. That is 0.067m/min per person and is far lower than the national standard 0.3m/min per person. During the test, no people experienced discomfort by health check and questionnaire. It is expected that the conclusions provide an important reference for the design of underground refuge stations and mine emergency rescue.

공동주택에서의 플러쉬아웃 현황 및 개선방향을 위한 연구

Volatile organic compounds in buildings from finishing materials, adhesives, built-in furniture, etc. can cause headaches, atopic dermatitis, etc. for occupants in the buildings. To mitigate this, the Korean government has obligated to flush out the buildings after new construction and before occupancy since 2011. In this study, the current status of performing flush-out in multi-family residential buildings in Korea were analyzed, and its improvement would be proposed. At first, a questionnaire survey was conducted to figure out the current status of flush-out performances targeting a number of construction companies who have already constructed multi-family residential buildings with compliance of the obligation. Through the analysis of this survey, several conditions that need to be improved for flush-out were identified. Secondly, the identified conditions were evaluated in varying conditions using a simulation program to figure out an effective way of performing flush-out rather than as it is. As a result, a flush-out performance period with an appropriate supply air volume, and indoor temperature and humidity were identified to be improved through the survey, and it revealed through the simulation that the flush-out should be performed at least 14 days to reduce the indoor air pollution more than a half.

Identifying key design parameters of the integrated energy system for a residential Zero Emission Building in Norway

This study examined an integrated solution of the building energy supply system consisting of flat plate solar thermal collectors in combination with a ground-source heat pump and an exhaust air heat pump for the heating and cooling, and production of domestic hot water. The supply energy system was proposed to a 202 m2 single-family demo dwelling (SFD), which is defined by the Norwegian Zero Emission Building standard. The main design parameters were analyzed in order to find the most essential parameters, which could significantly influenced the total energy use. This study found that 85% of the total heating demand of the SFD was covered by renewable energy. The results showed that the solar energy generated by the system could cover 85–92% and 12–70% of the domestic hot water demand in summer and winter respectively. In addition, the solar energy may cover 2.5–100% of the space heating demand. The results showed that the supply air volume, supply air and zone set point temperatures, auxiliary electrical volume, volume of the DHW tank, orientation and tilt angle and the collector area could influenced mostly the total energy use.

The Effect of Orifice Plate on Flow Field and Thermal Environment in Oven Box

Air velocity in oven box is an important factor. The value of air velocity will affect the result of drying. This paper use the method of numerical simulation to research the effect of orifice plate on flow field and thermal environment in oven box. The results show the change rate of thermal environment &amp; air flow field in oven box is depend on supply air volume, and the use of orifice plate will affect the flow field obviously.

Pressure Gradient Control and Energy-saving Operation Strategy Study on a Multi-zone Cleanroom

Pressure gradient control is an effective technical measure to prevent the external pollution and cross-contamination from different clean areas of a multi-zone cleanroom, which played a key role for the quality control of cleanroom. In this paper, modelling analysis combined with experimental investigations conducted on a multi-zone cleanroom experimental platform. A series of investigations were conducted on the experimental platform with supply air volume variation by electronic frequency conversion on air-supply fan unit. The characteristics of cleanroom such as cleanliness, ventilation rate, pressure gradient were all measured. An energy-saving operation strategy for multi-zone cleanroom has been gained. Experimental investigations proved that the determined principle of pressure gradient setting is feasible for reliable and energy-saving operation. It is also proved through experiments that about 24.5% energy consumption decreased when adopted the operation strategy.

생물안전밀폐시설에서 Multizone과 CFD 연동해석에 의한 실내기류 및 Influenza A 오염농도해석

Abstract To maintain a negative pressure, the supply, exhaust airvolume are adjusted by setting volume damper and theinfiltration through leakage area of the door between rooms in biosafety laboratory. Multizone simulation is useful way topredict room pressure, supply and exhaust air volume. But in a particular room, local change such as airflow and contaminantsconcentration distribution can not be evaluated unfortunately. Through this study, a coupled multizone and CFD simulation was performed, indoor air flow and local contaminants con-centration distribution in a particular room of BSL lab are predicted. The results show that all zones of BSL lab are wellventilated by unidirectional flow without local stagnation. In addition, in case that unexpected biohazard is occured in BSLlab, multizone simulation results about the spread of pollutants along movement of the occupant also show that contaminantsconcentration is removing totally without the spread of the outside. In conclusion, a coupled multizone and CFD simulationcan be applied to interpret differential pressure in room and local change of physical quantity in a particular room suchas airflow and Influenza A contaminants concentration distribution. This simulation method is useful to enhance the reliabilityand accuracy of biosafety laboratory design.

Design of Control Scheme for Variable Air Volume Air-Conditioning System

The air quantity of variable air volume system for the rooms and the total air quantity of the system changes with the change of room load. Combined with the system composition in the laboratory, the paper determines the control scheme of the variable air volume system, that is, indoor temperature-control, indoor positive pressure control, air distribution static pressure control, air-supply temperature control and new air volume control. The dotted lines with arrows mean the output signals from the control unit to actuator, and the solid lines with arrows represent the input signals from the actuator to the control unit.

Theoretical and Experimental Study on Radiant Models of Building Inner Surfaces

A simultaneously solving model is established to predict inner surface temperature and indoor air temperature. The radiation of the model is set with direct radiant model, Gebhart radiant model and effective radiant model respectively. Under different heat flow and supply air volume, inner surface temperature and indoor air temperature are calculated by the model and compared with measured data. The research results show that Gebhart radiant model has same calculation accuracy with effective radiant model and it can reduce the amount of calculation.

Experimental Investigations on Effect of Particles Removal in Cleanroom with Non-Unidirectional Airflow

Efficient airflow delivery is key to achieve effective contamination control for a high-performance cleanroom. The influence of airflow organization on effect of particles removal in cleanroom with non-unidirectional airflow was investigated in this paper. A series of experiments were conducted on a cleanroom experimental platform with different airflow organization modes and supply air volume variation by frequency converter ( 40 to 50 Hz, 5Hz interval) on air-supply fan unit. The results showed that higher cleanliness could be gained at local area in cleanroom with radial airflow organization. Moreover, the outcomes from these experiments indicated that particle concentration at measuring points appeared more orderly when the cleanroom operated with radial airflow organization. The conclusion can be drawn that radial airflow can benefit contamination control at local area for cleanroom operation with non-unidirectional airflow when compared with ceiling-supply and wall-return airflow organization.

Capturing Energy-Saving Opportunities in Air-Supply System for Cleanroom with Non-Unidirectional Airflow

In order to improve design method and optimize control strategy used in non-unidirectional airflow cleanroom, the influence of airflow organization and supply air volume on characterization of mini-environments in a non-unidirectional cleanroom was studied in the paper. A series of investigations were conducted on a cleanroom experimental platform with different airflow organization modes and supply air volume variation by electronic frequency conversion (35 to50Hz, 5Hz interval) on air-supply fan unit. The characterization such as cleanliness , pressure difference between clean zone and outdoor were measured during these experiments. It is shown that radiation air-supply airflow organization can offer higher cleanliness when compared with traditional ceiling-supply and wall-return airflow for non-unidirectional airflow cleanroom without increase power consumption. Taking variable electronic frequency on air-supply fan unit is efficient measure for energy-saving in cleanroom operation.

Experimental Study of Airflow Designs for Data Centers

Growth in ICT has led to increased demands on data centers. Highly reliable operations of data centers require an efficient and robust air-conditioning system. In most data centers, circulating air enters at the floor level, and returns at the ceiling level (floor supply design). However, the authors have developed an airflow design in which air is both supplied and returned at the ceiling level (ceiling supply design). To compare the cooling characteristics of both designs, temperatures were measured in a full-scale model of a data center. For both designs, changes in cooling characteristics were evaluated in response to changes in heat density, supply-air volume, and supply-air temperature. In addition, the authors studied the effects of separating cold and hot aisles by hanging walls from the ceiling between aisles. Dimensionless indices, dimensionless rack-temperatures, and values of the rack-cooling index (RCI) were used to compare the cooling characteristics of the two designs. The authors confirm that ceiling supply design is more robust regarding changes in major design parameters compared to floor supply design.

Cooling Effect of Mechanical Ventilation in Grape Greenhouse Based on CFD Numerical Simulation

The effect of air volume supplied by top mechanical ventilation on multi-span greenhouse temperature field is studied with different ambient temperatures through CFD numerical simulation. The cooling effects of different mechanical ventilation volumes are compared in the same ambient temperature conditions such as summer calm and high illumination. Thus, the best supply air volume is found to provide a theoretical support for mounting ventilator at multi-span greenhouse top for cooling. Results show that a smaller mechanical ventilation volume can meet the cooling requirements when temperature is lower outside greenhouse. However, single mechanical ventilation has been unable to meet the cooling requirement when ambient temperature is too high outside greenhouse.

Combustion Properties of Straw Briquettes

The low bulk density of straw is one of the major barriers, which blocks the collection, handling, transportation and storage. Densification of biomass into briquettes/pellets is a suitable method of increasing the bulk density of biomass. Yet in the process, a tremendous amount of air is ejected from biomass grind, which brings substantial specific variation including combustion property. Among them, combustion property is critical for proper design and operation of burning facilities. Therefore, a series of tests about combustion properties of 75mm diameter corn briquettes were done. First, the combustion process (ignition, full flaming and glowing phases.), precipitation of tar were investigated by a heating stove, then, Some ash sample from the muffle burner was subjected to an ash melting characteristic test. The results show the combustion of briquettes takes more time than that of raw straw from ignition to complete combustion; in order to meet complete combustion in a short time, the raw straw needs more supply air volume than briquettes under the same α value; the temperature of furnace chamber should been controlled under 900°C, which help to reduce the dark smoke, tar and slag.