Small Climate Chamber Research Articles

Exhaled Carbon Dioxide as a Physiological Source of Deterioration of Indoor Air Quality in Non-Industrial Environments: Influence of Air Temperature

People are the main reason for the deterioration of indoor air quality (IAQ) due to the continuous physiological metabolism processes in their bodies, including respiration. We present results from an investigation of the influence of indoor air temperature on the concentration of exhaled carbon dioxide (CO2). The investigation was preconditioned by previous findings on the effect of air temperature on human metabolism. However, our literature survey showed a lack of studies on the influence of the indoor air temperature on the exhaled CO2 (or metabolic CO2), which leads to the novelty of our results. Our experiments had two phases: measurement in a university classroom with an installed heating, ventilation, and air-conditioning (HVAC) system during regular classes and measurement in a specially designed small climate chamber, where the time variations of the CO2 concentrations, together with some physiological parameters, were measured. Two indoor air temperatures were set: 23 °C and 27 °C. The results obtained and their respective analyses show the strong effect of the two air temperatures on the CO2 concentration due to exhalation. In the classroom, the CO2 concentration at 27 °C was higher by 6.2% than at 23 °C. In the climate chamber, the CO2 concentration at 27 °C was higher by 9.6% than at 23 °C. Physiological parameters (oxygen saturation pressure, pulse rate, end-tidal CO2, and respiration rate) and their dependence on the air temperature were also measured in the climate chamber, establishing an effect of the temperature on the pulse rate.

Quantitative detection, sources exploration and reduction of in-cabin benzene series hazards of electric buses through climate chamber experiments

In this study, a large-scale in-cabin benzene series hazard detection is firstly performed on 20 electric buses by a full-scale climate chamber. The sources of BTEX are analyzed deeply by parts detection, and a series of effective measures are performed to reduce BTEX. Firstly, the in-cabin BTEX pollution with considerations of a series of parameters, such as interior configuration, environment temperature, vehicle age, and ventilation mode, is analyzed. The result shows that: 1) The VOCs concentrations decrease with vehicle age, higher configuration level and better ventilation system (particularly, fresh wind mode reduce VOCs fastly), while increases with environment temperature; 2) BTEX in bus cabins occupy approximatively 70.1% of TVOC, thus the BTEX overproof is the main culprit which causes VOCs to exceed standard. Then, measurements on components/materials VOCs releases were performed in a small climate chamber to discriminate key species and their sources. Xylene released from glues materials is found as a key species that causes BTEX/VOC to exceed limitation. Lastly, some measures, such as optimizations of materials selection and manufacturing crafts, are adopted to improve in-cabin pollution, and positive effects are obtained. For example, ethylbenzene and xylene released from HL 125 (a polyurethane adhesive) decrease by 2456% and 1930% respectively after improvement. And in-cabin xylene and TVOC decrease by 2274% and 222%, respectively, and all of them are lower than limitation value.

DESIGNING A SMALL CLIMATE CHAMBER TO CHARACTERIZE PEOPLE AS A SOURCE OF DETERIORATION OF INDOOR AIR QUALITY BY RESPIRATION

: People are one of the sources for deterioration of the indoor air quality. They worsen indoor air quality by their presence (respiration, bio-effluents), activities and habits. Through respiration, people decrease the oxygen concentration in the air of the occupied space and increase carbon dioxide and water vapor concentration in the indoor air as well as its temperature. The goal of the AIRMEN project is to find out if the rate of consumption of oxygen and emission of carbon dioxide (and water vapor) by people depends on the indoor air temperature as well as carbon dioxide concentration in the inhaled air. In order to achieve this goal a small climate chamber must be designed and constructed which allows for controlling and measuring both inflow and exposure parameters as well as for measuring outflow parameters. The principal goal of this paper is to present some important details, obtained by CFD simulations, from the design process of the climate chamber which precondition the air distribution in the chamber and hence the exposure parameters.

The thermal performance of window coverings in a whole house test facility with single-glazed sash windows

The residential sector is responsible for 29% of the total energy consumption of the UK, with 62% of this energy being used for space heating. Heat loss through the fabric of building elements is a crucial factor in the energy efficiency of homes, and a wide number of studies have looked at physical interventions to improve the energy efficiency of existing buildings, commonly called retrofit. This research considers the impact of window coverings on reducing heat loss from homes, a measure that is not commonly considered an energy efficiency intervention. Although the amount of glazing varies widely between homes, all windows are a significant factor contributing to heat loss. While physical changes such as double and triple glazing can improve the energy performance of buildings, the impact of curtains and blinds is not well characterised. Previous research into window coverings has been undertaken using laboratory tests, such as hotbox and small climatic chamber environments. This study presents the impact of window coverings on heat loss within a unique whole house test facility. This allows for a better replication of a real heating system and the effects that it has on localised heat transfer. This gives a more detailed picture of in situ performance, similar to that which may be found in the field.

Numerical study of crack path by MMCG specimen using M integral

The mixed mode loading configuration occurs in many civil engineering and mechanical applications. In wood material, the study of this problem is very important due to the orthotropic character and the heterogeneity of the material. In order to study the mixed mode loading in wood material, Moutou Pitti et al [1] have proposed a new specimen called Mixed Mode Crack Growth (MMCG). The main goal of this geometry is to propose a decrease of the energy release rate during the crack growth process. In this case, the fracture parameters can be decoupled into Mode I and Mode II in order to determine the impact of time during creep crack test. The present work proposes to study the crack path stability in MMCG specimen for different sizes and thicknesses. The M? integral, combining real and virtual mechanical displacement fields is used in order to separate numerically mode I and mode II in the mixed mode ratio. The stability is shown for the opening mode (Mode I), the shear mode (Mode II), and the mixed mode of 15°, 30°, 45°, 60°, 75° by computing the energy release rate versus the crack length. Finally, it is shown that the MMCG specimen can be reduced in various shape and used for example in small climate chamber in order to perform creep test at different temperature and moisture content levels.

Simultaneous determination of mass and thermal accommodation coefficients from temporal evolution of an evaporating water microdroplet

Scattering of coherent light by an evaporating droplet of pure water several micrometres in size was investigated. The droplet was levitated in an electrodynamic trap placed in a small climatic chamber. The evolution of the droplet radius and the evolution dynamics were investigated by means of analysing the scattering patterns with the aid of Mie theory. A numerical model of droplet evolution, incorporating the kinetic effects near the droplet surface, was constructed. Application of this model to the experimental data allowed us to determine the mass and thermal accommodation coefficients to be αC = 0.12 ± 0.02 and αT = 0.65 ± 0.09, respectively. This model enabled us to determine with high precision the temperature evolution of the droplet and the relative humidity in the droplet vicinity.

Evaluation of hand and finger heat loss with a heated hand model.

A heated full-scale hand model has been used to determine indirectly hand and finger heat losses of human subjects exposed to four ambient cold conditions (0, 4, 10 and 16 degrees C, air velocity approximately 0.3 m/s). Heat transfer coefficients determined with the hand model, were used to calculate heat flux based on measured skin to ambient temperature gradients. The responses of eight subjects from a previous study were used for the analysis. The measurements were carried out in a small climate chamber which was cooled by evaporating liquid carbon dioxide. The thermal hand was put into the chamber in a vertical position with the thumb up. The surface temperature of the thermal hand was controlled at 21, 25, 28, 31 and 34 degrees C under each of the four ambient cold conditions, in order to investigate possible temperature dependence of the calculated combined convective and radiate heat transfer coefficient (hCR). The value of hCR varied between approximately 9-13 W/m2 degree C for fingers and palm and back of hand, respectively. Calculated heat losses showed significant individual variation, corresponding to the maintained skin to ambient temperature gradient. Individual values from about 50 to more than 300 W/m2 were calculated. Several subjects showed CIVD and heat fluxes associated with this phenomenon were sometimes doubled. The measurement results showed realistic and comparable with literature date. The advantages of the thermal hand model can be counted as easy to use; directly measures the heat loss; highly reproducible and no interruption. It appears that a heated hand model provides a useful methods for analysis and quantification of hand heat loss.

Application of the Field and Laboratory Emission Cell "FLEC" - Performance Study, Intercomparison Study, and Case Study of Damaged Linoleum in an Office#

The Field and Laboratory Emission Cell (FLEC) has been tested and evaluated for qualitative and quantitative emission testing of volatile organic compounds (VOCs) from building products. An air supply control unit has been developed and its performance is reported in the range of 100 to 500 mllmin airflows. The recovery in the FLEC has been tested with a new performance test kit with dodecane and 2-ethylhexanol, respectively. Additionally, five VOCs emitted from a liquid floor wax were measured in the FLEC and in a small climate chamber. The first order rate constants (k1) and the initial emission rates (R0) obtained from the time versus concentration data measured over 24 hours proved to be comparable. The application of FLEC in a complaint case of malodorous linoleum in an office building showed that artificial wetting of the linoleum had a marked influence on the qualitative offgassing of odorous VOCs such as fatty acids, glycol ethers, and 2-decenal.

Volatile organic compounds from used building materials in a simulated chamber study

Building materials emit volatile organic compounds (VOCs) indoors. They may also adsorb compounds so that an equilibrium with indoor air is reached. Samples were taken from the floor, walls, and ceiling of one room in a seven-year-old preschool building. They were placed in a small climate chamber for a period of 41 days. Samples from the air in the room and the chamber were analysed by gas chromatography and mass spectrometry, and about 60 compounds were identified. The composition of organics in the room air was reestablished in the chamber the first day. Since most of the compounds disappeared within 2 to 23 days, they are believed to have been adsorbed from the room air onto the material surfaces. During the last 10 days, 17 compounds remained at constant concentrations, implying that they are representative of the building material samples.

Initiation and inhibition of shivering in the rat: interaction between peripheral and central factors.

1. Unanaesthetized, female white laboratory rats were subjected to almost square-wave changes in ambient temperature, from 20 degrees C to 35 degrees C, in a small climatic chamber. 2. Intracerebroventricular injections of serotonin and methysergide were made in shivering, unanaesthetized rats. 3. The integrated electromyogram of m. suprascapularis was recorded as a quantitative measure of shivering activity to monitor the effects of the above procedures. 4. Both warm transients and serotonin inhibited shivering, but methysergide blocked only the effect of serotonin.