Issue 2/2007

The article indicates the rules of the heat accumulator needed size at heating systems with low capacity and solid fuels boilers. The established dependences may be used also for the same heating systems with monovalent heat pumps of the water – water or earth – water types that provide practically constant output in the course of the heating period.

Animal houses are buildings with high heat generation inside and integrated equipment for intensive ventilation. Because of the high dust concentration in animal houses, the “classical” heat recovery systems have not been successful in practice. This paper describes the results of experiments using regenerative heat exchangers with fixed-matrix of special construction suitable for agricultural purposes. The tested regenerative heat exchangers were constructed from non-metallic materials (CETRIS and CEMVIN). Main dimensions and parameters of regenerative heat exchangers were verified by experimental measurements in the laboratory, and also under real conditions in the animal houses at poultry and pig farms.

An experimental study of thermal plumes of typical kitchen appliances was conducted. In this study, an Extrapolation method was used to analyze plume characteristics. The effect of the convection load on the maximum velocity and excess temperature was analyzed at different heights above appliances. The correlation between convection load and both the momentum flux and the kinetic energy flux was analyzed. In the measurements, the maximum air velocity stayed nearly constant from the surface of the appliance up to the height of 2 m. This demonstrates that the generic plume equation derived in the region of complete flow similarity is not exactly valid in the intermediate zone.

The author deals with sound transmission loss of ventilation slots in relation to sound transmission loss of windows. The presented calculation relations make possible to compare the sound transmission loss of ventilation slots of different dimensions with the sound transmission loss of windows of standard dimensions. Derived are then conditions at which the slot sound transmission does not affect the sound transmission loss of the window as a whole in an important way.

The Luxembourg Plaza is a modern multi-functional building of the highest standard in terms of the achieved microclimatic conditions. Situated at Prague 3, Žižkov, it has the front facade facing the Jičínská Street (vis-ŕ-vis the Flora Palace Shopping Centre), replacing the former large-area garage that burn out in 1970s. The complex contains ca. 24 000 m2 of office floor space and the Mariott hotel with 160 rooms. At the complex, the offices belong to the reputable firms active on the world and Czech markets (GTS-Novera, Exxon-Mobile, ORCO Group, etc.). In the comprehensive article the author describes the steps of conceptual solutions in designing the office space air conditioning (AC) system investors demands for reading higher that standard micro-climate conditions of optimized investment and operating costs. Presented is a detailed suitability analysis of using inlet elements under variable air flow, including the adjustment of vortex anemostat. At the same time the use of ceiling fan convectors under extreme demands on air conditioning is evaluated. In conclusion, very interesting results of flow simulation in the simulated space of a typical office, and an experience with equipment operations are presented.

A ventilation study conducted in laboratory chambers and in one family house is described in the paper. In both buildings the ventilation rate and CO2 distribution was evaluated by means of CO2 method and simulation in Contam 2.4. Analyses and results comparisons show that program Contam 2.4 can be a useful tool for evaluation of pollutant distribution in simple objects. However, its application for ventilation evaluation in complicated buildings is limited. The results are strongly dependent on definition of building components and therefore it is recommended to complement the simulation with measurements.

The article shortly describes metering methodology and conditions at cooling ceilings testing. Also described is the way a standardized cooling output is determined on the basis of the European Standard of 2004. In the second part of the contribution the author describes principles of dimensioning cooling ceilings, supplemented with a practical example.

The article deals with thermal comfort general requirements of passengers and driver at bus transport. It deals with factors decisive for the appropriate air conditioning equipment size design and illustrates a typical solution on an example of a tourist-bus case. In conclusion, the author outlines the future trends in bus transport thermal comfort of passengers and drivers.

Structural design of Blanka tunnel exit and entryway portals forms a part of the Malovanka traffic interchange as a continuation of the tunnel structures complex of the city by-pass road system (MO). Ventilation system of this tunnel has to ensure the sanitarily admissible atmosphere inside the structure and to restrict as much as possible, or directly prevent the exhalations from leaving the exit portals into the housing area. A structure form was designed that ensures, under the anticipated MO traffic loading, that these requirements in were met dependence on economical operation of the designed ventilation system. In this contribution, the way of Malovanka junction portal section design based on a simulation model of one-dimensional ventilation flow of an incompressible viscous fluid is shortly described.

The author summarizes hygiene problems involved in swimming pool water treatment. He describes the infection risks connected with the use of non treated water and suggests the possibilities of their treatment. He draws the attention to risks of using chemical substances that decompose into disinfection by-products. These by-products can have an important and negative impact on health. Above all the author draws the attention to trichloramin that gets to the atmosphere when chloramines in used.

In the swimming pools milieu trichloramin is the most important reaction product of chlorine with nitrogen substances (ammonia, urea). It is created in water but it is quickly liberated into the air where it can create rather high concentrations of up to tens orders of magnitude in units of mg/m3. Trichloramine irritates and breaks epithelium of the upper respiratory passages, it evokes a higher inclination to asthma (especially in children) and allergic symptoms of susceptible persons. Under the long lasting exposure, for example at swimming pools personally, it can lead to a work-related disease. These new pieces of knowledge lead onwards to a higher interest in ventilation engineering problems at swimming pools and generally in the management of swimming pools operation in the way of minimizing the production of undesirable by-products of water chlorination. The article deals with the interaction of chlorine with ammonia and urea, with balance considerations, and it also presents author’s own measuring results of trichloramin content in the atmosphere of some Prague swimming pools as related to their visit rate. The author also proposes procedures that would lead to reducing the trichloramin production.

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The author presents properties of the heat insulating types of glass and their use in building industry. Further, protective coatings and the technology of their application on glass in hot or cold state are illustrated. A quote of the accepted European Standards related to this technology is also contributed. The evaluation of glass types is completed by a practical calculation example of heat losses for different glazing types and heat gains of glazed surfaces of 25m2 size oriented toward the basic geographic directions.

Personalized ventilation allows for improving the atmosphere quality at the person’s immediate vicinity. The air supply elements have to ensure not only the air quality at the breathing area but also be favorably assessed by the individuals as to their thermal comfort and ergonomic conditions. The article deals with the air flow around the human body and also with conditions for the design of effective air supply to breathing area of persons. The author presents the results of experimental work concerning the development of air supply elements at the Danish Technical University, and in conclusion he presents the prototype design, which, according to authors, of the design, fulfils the air quality requirements and is also acceptable from the point of view of ergonomics

In the article, the author presents a solution to air flow in a panel building, three-room apartment in winter period for the overpressure and under pressure forced ventilations by means of CFD simulation. Windows in the apartment were equipped with ventilation dampers located either at the lower or upper window part. In the model the ceiling outlet at the anteroom served alternatively for the air inlet or outlet. In conclusion, the author evaluates the individual designs, particularly from the point of view of the air temperature distribution close to the window, and the risk of water vapour condensation.