Issue 1/2010

Authors are engaged in an experimental verification regarding the effect of the flow cross-section of the upper covering grid in panel radiators at their heat output in their article. They submit measurement results in the graphic form, utilizable in the designing work at the design of panel radiators, adjusted in harmony with architects’ design requirements. The article brings theoretical findings of the convection part affecting the heat output of panel radiators, as well.

New concept of micro co-generation unit with hybrid Stirling solar motor (SSM) was presented in [1] together with its mathematical model created in the MATLAB environment. The result analysis of the mathematical model computer simulation in so called solar operation mode (production of electric energy and heat from the direct solar radiation, only), situated in Prague, determined a significant volume of electric and heat energy generated annually, nominally Qel = 13.38 MWh and Qtep = 36.74 MWh. Nevertheless, whether electric energy or heat energy, it was not in a time correlation with requirement. In the article, Author is engaged in so called hybrid mode of operation, in which the output of the gas burner, integrated in the SSM collector, is dependent upon the requirement of the electric energy and heat energy in a building (a single family house) and intensity of the direct solar radiation. The integration of the micro co-generation unit with hybrid SSM in the MATLAB environment was utilized for the simulation in the TRNSYS environment. Results of simulation have pointed out to the possibility of optimization of micro co-generation unit, and thus to increase the total effectiveness of co-generation with respect to the maximum utilization of the generated exhaust heat.

It is known that passive solar gains are high in rooms oriented southwards while in rooms oriented northwards are almost none gains. One of possibilities of how to utilize heat gained from the solar radiation in a more effective way is the redistribution of heat into spaces that are not exposed to the direct solar radiation. In the article are stated results of the analysis of factors affecting the heat redistribution from irradiated rooms into non-irradiated ones, and there are determined conditions, under which such heat distribution becomes effective.

The Author engages in his article in the technical and normative conditions with respect to fire-stopping insulations for ducts, which unfortunately are not enough known and experienced in practice. He synoptically and understandably introduces the principles and rules of the said problems and describes important design details, as well. Certain critical places fire-stopping insulation systems and their assemblies are correctly emphasized.

A serial of articles concerning technical standards and a legal relationship of such standards with the Czech legislation begins in this issue. Articles are based on a contribution and a lecture of Author read by him in the expert group 06 – Integrated designing and evaluation of buildings at the STP seminary that took place on 2 November 2009 in Prague. Author explains in the first part of the serial sense and purpose of the technical standardization and the liability of technical standards. The liability is understood the obligation to proceed in accordance with a stipulated rule that shall have a power to invoke legal consequences in the form of a sanction if the legal liability has not been performed. Obligatory documents are deemed to be a law, a governmental regulation, a state administration central body decree or a generally binding public notice. He specifies in the next part of the article a material and the legal framework with respect to the technical standardization as to the construction, the legal nature of technical standards and their use. He explains reasons, which in the year 1991 led to the abolition of the liability of the most of technical standards (ČSN); i.e. practically all of them that had been approved pursuant to the validity of former regulations. Then after 1 January 2000 the administrative liability of all technical standards was abolished. The most serious characteristics of technical standards can be considered their non binding nature after 1 January 2000. The Czech Technical Standard (ČSN) is generally characterized as a document approved by an appointed legal entity with respect to the repeated or permanent use. A standard becomes the harmonized standard pursuant to of the law, if it accepts requirements stipulated with the harmonized European Standard, in full. The law newly stipulates technical standards that are being characterized so that the technical regulation means the legal regulation promulgated by the publication in the Collection of Acts of the Czech Republic.

Every HVAC designer suffers of the dilemma while deciding an optimal design of ventilation or air conditioning system in administrative buildings, similarly as Hamlet suffered. The decision making process is affected with other circumstances, which rather complicate the option thereof. Readers are introduced with a system of cooling beams, which is not very extended (known) in the CR. In the introductory part, Author describes usable sorts of beams, their advantages as well as imperfections. He used the existing project of a nine storey administrative building, in which cooling beams have been used as an alternative solution for comparison of investment and operation costs of the system using fan convectors or cooling beams. Both systems are quite identical regarding the function viewpoint and correspond to the comparison of investment and operation cost used by Author. It concerns of foreign documents for an extensive administration building in the EU. Investment costs of both systems do not differ too, operation costs of the system with cooling beams are considerably lower. In the conclusion, Author summarizes costs of both systems, specifies priorities of the new system and recommends its use.

Author deals with one-parametric relation of the heat pump performance coefficient on the difference between the temperature of the heated substance at the heat pump outlet and the temperature of the incoming substance that exists as a source of low-potential heat. The possibility and suitability of introducing this relation, determined as TF-?t, has been documented in the file of measurements of heat pumps air – water performed by reputable testing laboratory WPZ in the Swiss town of Buchs. An advice for [4] and the declared “heat pump transformation efficiency” therein makes a significant issue. Parts dedicated to the measurement evaluations present a general character and exceed the framework of heat pumps.

Article originated from the result of a graduation thesis that had been engaged in the design of air conditioning in a sports hall. An emphasis was insisted on ensuring the optimal microclimatic conditions in the ice stadium in the framework of the solution. In particular, it related of places affected by the ice surface with respect to the generation of mist and condensation of humidity at construction structures as well as ensuring a necessary comfort for spectators in the area of stands and terraces. There in the article are stated discussions concerning the considered microclimatic conditions and methods for calculation of heat and humidity loads according to different authors, which have been engaged in problems of sports halls equipped with the ice surface. The analysis of heat fluxes between the ice surface and surrounding surfaces of construction structures by means of heat radiation and convection in the air into the area of the hall. Theoretic results were verified by measurements of humidity, air temperature, and the resulting temperature was measured with the globe Vernon thermometer in the vertical profile over the ice surface at the Ice Stadium in the town of Příbram. Obtained findings can be utilized during dimensioning the air handling equipment in sports halls, which shall serve for playing the ice hockey above all.

The presence of chemical pollutants indoors can affect the air quality and some health problems may occur to people working or living in that environment. The activities and materials used connected with the sources of harmful chemicals are described here. The particular groups of chemical pollutants are stated with respect to their appearance indoors, their characteristics and action in the indoor environment. The methods of sampling and analysis of the important chemical polutants (VOCs, PAHs, phthalates, carbonyl compounds, etc.) are summarized here together with published concentration ranges of that chemical pollutants indoors.

Author describes main types of the membrane filtration (micro-filtration, ultra-filtration, nano-filtration and reverse osmosis), their properties and possibilities for treatment of potable water, hot water or recreational water. He compares those types with the standard sand filtration and in addition to their advantages briefly mentions major disadvantages, however he does not engages in economic aspects of the operation.