7 results
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2. Variation of air condition parameters, in the conditions of the presence of carbon dioxide, in the duct of ventilation installations
- Author
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Cămărășescu Alexandru and Drăgoescu Răzvan
- Subjects
ventilation ,air condition parameters ,carbon dioxide ,microclimate ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Industrial ventilation takes into account the quality of the air inside the IAQ (Indoor Air Quality) and the degree of exposure of workers. In industrial targets the emission regime of contaminants can be 10–100 times higher than in non-industrial targets, but for many pollutants the IAQ levels can be the same. The parameters of the state of the air which are of interest for the technique of ventilation and air conditioning are: air temperature and humidity, atmospheric pressure and air speed. For the study on the variation of the air state parameters inside the industrial ventilation installations, in the experiment laboratory, on the study of the industrial ventilation systems, the experiment was performed on the variation of the air state parameters in the conditions of circulation through the ventilation duct. an amount of carbon dioxide. Prior to the introduction of carbon dioxide into the duct, the ventilation system was started, at nominal parameters. During the experiment, the operating parameters of the drive motor were changed using a frequency converter on levels 50; 40; 30; 20; 10 and 5 Hz. The ventilation system used was structured by means of flow converters which were fixed in the open position. The ventilation system as well as the flow variators were operated by the SCADA type command and control system The paper will present the analysis of the variation of state parameters (temperature, humidity, absolute pressure and air speed) by introducing a constant amount of carbon dioxide in the ventilation duct.
- Published
- 2024
- Full Text
- View/download PDF
3. Les bioraffineries - ou comment satisfaire la demande en aliments, énergie at molécules d'origine végetale pour la chimie?
- Author
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CHAUVET, ean-Marie
- Subjects
CARBON offsetting ,CARBON dioxide ,FOOD supply ,BIOECONOMICS ,CLIMATE change ,BIOMASS - Abstract
Copyright of IAA Industries Agro-Alimentaires is the property of Ste Ad hoc and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2021
4. Low temperature vacuum sublimation refrigerators on carbon dioxide as working fluid
- Author
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Porutchikov Artem Frolovich and Trubin Dmitriy Pavlovich
- Subjects
carbon dioxide ,low pressure sublimation ,refrigeration machine ,low temperature medical freezers ,refrigerants ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The paper presents the results of theoretical and experimental analysis of a vacuum-freeze-drying refrigeration machine based on carbon dioxide. Such refrigeration machines can be equipped with refrigerators for the needs of medicine, where low temperatures are widely in demand in the range from minus 80 degrees Celsius to minus 130 degrees Celsius. The problem of developing alternative refrigeration machines is dictated by modern environmental requirements for working substances, which are gradually being tightened and soon the use of familiar freons will become impossible. For the air conditioning and commercial refrigeration industry, new substances are being actively developed, such as hydrofluoroolefins (HFOs), hydrocarbons can also serve as substitutes for hydrofluorocarbons and their mixtures, but it must be considered that they are combustible and explosive. A carbon dioxide vacuum sublimation unit may be an alternative to modern freon vapor compression refrigeration units for the indicated temperature range, but subject to comparable energy costs during its operation. The article examined the three-stage and four-stage cycles of a vacuum-freeze-drying refrigeration machine, conducted their theoretical comparison in terms of COP with a cascade cycle on hydrocarbon working substances. It can be noted that the COP of the considered cycles are close, but the environmental friendliness, safety and non-combustibility of carbon dioxide gives the advantages of a vacuum freeze-drying refrigeration machine.
- Published
- 2020
- Full Text
- View/download PDF
5. [Environmental impact of tobacco]
- Author
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Esfandiar, Aminian, Isabelle, Jacot Sadowski, and Jacques, Cornuz
- Subjects
Tobacco ,Humans ,Forestry ,Tobacco Products ,Carbon Dioxide ,Environment ,Crop Production - Abstract
Tobacco has not only negative effects on health; it also has an environmental impact. Each year, tobacco production requires 22 000 billion liters of water, mainly for cultivation. Thousands hectares of forestland are cleared annually, largely for the desiccation of tobacco leaves. Cigarette production is responsible for 84 million tons of CO2 equivalent. This paper reviews the environmental impact of the production and consumption of cigarettes from tobacco growing and manufacturing to consumption and waste production, and compares it with current consumption data.Le tabac a non seulement des effets négatifs sur la santé, mais également un impact environnemental. La production de tabac nécessite 22 000 milliards de litres d’eau par année, principalement pour la culture. La surface de déforestation, en grande partie pour le processus de dessiccation des feuilles de tabac concerne des milliers d’hectares par an. La production de cigarettes est à l’origine de 84 millions de tonnes d’équivalent CO
- Published
- 2019
6. Methods to validate the accuracy of an indirect calorimeter in the in-vitro setting
- Author
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Yves M. Dupertuis, Claude Pichard, Taku Oshima, Marco Ragusa, Claudia Paula Heidegger, and S. Graf
- Subjects
0301 basic medicine ,Adult ,Endocrinology, Diabetes and Metabolism ,Nuclear engineering ,Calorimetry ,Indirect calorimetry ,Standard deviation ,03 medical and health sciences ,Expired air ,In-vitro ,0302 clinical medicine ,Oxygen Consumption ,Mechanical ventilator ,Co2 concentration ,Validation ,Medicine ,Humans ,Gas composition ,ddc:616 ,030109 nutrition & dietetics ,Nutrition and Dietetics ,Ventilators, Mechanical ,business.industry ,030208 emergency & critical care medicine ,Calorimetry, Indirect ,Carbon Dioxide ,Calorimeter ,Dilution ,Oxygen ,Gas exchange simulation ,business - Abstract
Summary Introduction The international ICALIC initiative aims at developing a new indirect calorimeter according to the needs of the clinicians and researchers in the field of clinical nutrition and metabolism. The project initially focuses on validating the calorimeter for use in mechanically ventilated acutely ill adult patient. However, standard methods to validate the accuracy of calorimeters have not yet been established. This paper describes the procedures for the in-vitro tests to validate the accuracy of the new indirect calorimeter, and defines the ranges for the parameters to be evaluated in each test to optimize the validation for clinical and research calorimetry measurements. Methods Two in-vitro tests have been defined to validate the accuracy of the gas analyzers and the overall function of the new calorimeter. 1) Gas composition analysis allows validating the accuracy of O2 and CO2 analyzers. Reference gas of known O2 (or CO2) concentration is diluted by pure nitrogen gas to achieve predefined O2 (or CO2) concentration, to be measured by the indirect calorimeter. O2 and CO2 concentrations to be tested were determined according to their expected ranges of concentrations during calorimetry measurements. 2) Gas exchange simulator analysis validates O2 consumption (VO2) and CO2 production (VCO2) measurements. CO2 gas injection into artificial breath gas provided by the mechanical ventilator simulates VCO2. Resulting dilution of O2 concentration in the expiratory air is analyzed by the calorimeter as VO2. CO2 gas of identical concentration to the fraction of inspired O2 (FiO2) is used to simulate identical VO2 and VCO2. Indirect calorimetry results from publications were analyzed to determine the VO2 and VCO2 values to be tested for the validation. Results O2 concentration in respiratory air is highest at inspiration, and can decrease to 15% during expiration. CO2 concentration can be as high as 5% in expired air. To validate analyzers for measurements of FiO2 up to 70%, ranges of O2 and CO2 concentrations to be tested were defined as 15–70% and 0.5–5.0%, respectively. The mean VO2 in 426 adult mechanically ventilated patients was 270 ml/min, with 2 standard deviation (SD) ranges of 150–391 ml/min. Thus, VO2 and VCO2 to be simulated for the validation were defined as 150, 250, and 400 ml/min. Conclusion The procedures for the in-vitro tests of the new indirect calorimeter and the ranges for the parameters to be evaluated in each test have been defined to optimize the validation of accuracy for clinical and research indirect calorimetry measurements. The combined methods will be used to validate the accuracy of the new indirect calorimeter developed by the ICALIC initiative, and should become the standard method to validate the accuracy of any future indirect calorimeters.
- Published
- 2017
7. Experimental investigation on the performance of a transcritical CO2 heat pump with multi-ejector expansion system [Étude expérimentale sur la performance d'une pompe à chaleur au CO2 transcritique équipée d'un système d'expansion multi-éjecteur]
- Author
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Trinchieri, R., Boccardi, G., Trinchieri, R., and Boccardi, G.
- Subjects
Heat pump ,Transcritical cycle ,Carbon dioxide ,Ejector ,Space heating - Abstract
ambient temperature in the range of −15–12 °C according to the standard UNI EN 14511/2011. The results show the possibility to reach an optimum of the COP by varying the ejector area, once the other parameters are fixed, as a consequence of the ejector regulation on the pressures at the inlet and outlet of the compressor. © 2017 Elsevier Ltd and IIR, compressor frequency in the range of 30–60 Hz, Carbon dioxide is becoming an interesting option also for HVAC heating appliances due to its eco-friendly characteristics. The incurrence of transcritical cycles makes the use of ejectors attractive to improve performance. Part load conditions and varied ambient temperatures imply the use of variable geometry systems of appropriate design to keep their efficiency high. This paper investigates experimentally a multi-ejector air-to-water CO2 heat pump for heating needs, measuring the performance of the system and of each component under partial and full load conditions. A sensitivity analysis was run varying, separately or in a combined way, the following parameters or operating conditions: ejector area ratio in a range of 33.1–86.6%
- Published
- 2017
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