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Stabilization of supply air temperature by using granulated phase change materials and application to ventilation system of a house during summer

The authors have proposed a system for stabilizing air temperature using direct heat exchange between granulated phase change materials (PCM) and air. This paper describes experiments in which air whose temperature is periodically changed to simulate changes of outdoor air temperature is passed through a bed of granulated PCM. These experiments demonstrate that output air temperature is stabilized and remains within the phase change temperature range. Results calculated by a computer simulation program described in a previous paper duplicate the experimental results.

Optimal design of all-air systems price sensitivity

This paper shows that it is possible to calculate the optimal outdoor air rate at different outdoor temperatures in the economiser cycle. The price of heat must increase 3 times before the optimal outdoor air rate during heating gets lower than during cooling. The optimal outdoor air rate during heating is determined primarily by the price of heat. The optimal outdoor air rate during cooling is determined primarily by the price of cooling capacity.

Some control issues of VAV systems

To obtain stable control of VAV systems, many considerations must be accommodated properly. Local and central control loops affect each other in ways that in many cases can lead to problems of poor control and even instability. In a VAV system (utilizing demand controlled ventilation), the stability of the supply air temperature must be very carefully commissioned. While stable control can be obtained more easily at full flow rates, instability can often become a problem during reduced flow rates.

Low winter humidity indoors has a negative effect on the performance of office work

Thirty subjects (17 female) were exposed for 5 hours in a climate chamber to clean air at 5%, 15%, 25% and 35% RH at 22 °C, in balanced order. Another 30 subjects (15 female) were similarly exposed to air polluted by carpet and linoleum at 18, 22 and 26 °

Thermal comfort. NF ISO 7730 a standard to discuss

The technical literature very often refers to the international standard ISO 7730. That reference seems to have been accepted too quickly several years ago, without consulting the experts of the profession and without a real critical examination.Now we are facing a difficult situation because the profession recommends (and it is right) temperatures that are lower of several degrees to the ones advised by the standard. Furthermore, an important number of concrete researches demonstrate the very big uncertainties of the data the standard relies on. A serious warning is necessary.

The effect of air temperature on labour productivity in call centres - a case study -

A study on the effect of air temperature on productivity was carried out in telecommunications offices with an observational approach in call centre 1 and an intervention approach in the second call center by installing cooling units.The study shows that the productivity can be reduced by 5 to 7 % when the indoor temperatures increase.

Influence of temperature and humidity on the perception of odours Einfluss von temperatur und Feuchte auf die Wahrnehmung von Geruchsstoffen

Experiments were operated to estimate the influence of temperature and humidity on the perception of odours in the air by trained and untrained persons .

Passive ventilation and heating by natural convection in a multi-storey building

Natural convection in a heated vertical duct is studied in this paper.First experimental study and computer simulations were performed in a scaled down laboratory model. Then temperature fields and average temperatures were obtained at all levels of the multi-storey building.

Prediction of indoor gaseous pollutant dispersion by nesting sub-zones within a multizone model

A zonal model has been nested within a multizone model to allow increased resolution in the prediction of local air flow velocities, temperature and concentration distributions between and within rooms. Simulations from the new program have been compared with measurements and results from other models.

Measurements of air temperatures close to a low-velocity diffuser in displacement ventilation using an infrared camera

The authors have developed a whole-field measuring technique that allows the visualization of air temperatures and airflow patterns over a large cross-section. For that measurement, an infrared camera and a measuring screen placed in the airflow are used. Thanks to that technique, real-time images within large areas can be recorded and transient events can be captured. The method was applied to a flow from a low-velocity diffuser in displacement ventilation.