Issue 3/2007

The author deals with hydraulic connection of the heat source with the heating system and of individual boilers one another through the hydraulic ring (HV). He analyses HV both in the theoretical function respect and in the practical use respect. The hydraulic connection of two serial-ranged boilers appears as the high preference recommended variant of HV use.

In the article the author brings the complex information about the approach to the heating designing of large-sized buildings in the form of optimized methodology for designing the light and dark emitters. In an integral and brief form he informs the reader both about known facts and about knowledge gained by his own research.

The applications of built in facades solar collectors have a great potential at the construction and reconstructions of residential buildings for the warm water heating systems. The integration of solar collector in the vertical peripheral building structure brings a number of advantages (higher collector affectivity, replacing the facade part by energy active element, markedly lower frequency of extreme stagnation conditions, visually acceptable solution) and problematic aspects (lower energy fall in the course of the year, influence of existing or future shading). The facade collectors shading by close neighbouring buildings (constant shading) or by high-grown green vegetation (variable shading) may markedly influence the total energy gains of the designed solar system. In the facade collectors shading analysis the authors deal with the influence of the distance and height of surrounding buildings on the annual earnings of solar energy by the facade of the building located in larger group of buildings. As a case study three typical groups of residential buildings in Prague were chosen; Barrandov housing estate, Chodov housing estate and central town part (Vinohrady).

The authors analyze the possibilities of the controllable ejector use for heating sphere. They acquaint the readers with methodology of controllable ejector design both in the theoretical respect and in the practical use respect of the created design program.

The automotive industry is facing a tough decision. The European Union has adopted a directictive, which aim is to gradually phase-out the HFC-134a refrigerant. Refrigeration cycles using carbon dioxide are one of the options. They have already been developed, however, they are not economically feasible. Alternatives are seen in the three new artifical refrigerants announced by the chemical corporations in 2006. Preferences of the automotive industry, which plans to decide in the second half of 2007, may have an impact on other industries as well.

Field hospital is a military mobile complex to be deployed in almost any climate around the world. Heating, ventilation and air-conditioning (HVAC) system for the field hospital units is being re-designed. State-of-the-art computer simulation software will be used for design of system under variety of specific outdoor conditions. In order to calculate energy balance, simulation software requires weather data to which buildings are exposed to. Currently there are several weather data sets available on the market. All contain weather data but they may differ significantly. Therefore they should be carefully selected prior their use. Even though lots of databases are available, there is poor access to proper data outside of U.S.,Western Europe and Japan, and in non-typical regions in terms of simulation exercises (e.g. South America, Africa and South Asia). This paper reviews weather data sets and recommends suitable data for energy simulations to design and analyze long-term performance of HVAC unit in various non-typical geographical locations around the world.

The article deals with problems of PM10 articles emissions. This fraction of fine particles has been gaining importance in the course of the last years because even their share of imissions has been increasing. The authors put more precisely the definition of the PM10 particles fraction and clarifies why even well functioning solid particles separators are source of PM10 particles. In conclusion they state that after certain operation time the separation equipments often operate with worse effectivity than the approved and installed one.

The article deals with buildings HVAC systems control and monitoring their function in context of integrated systems in buildings, above all with a view to residential buildings and buildings at the tertiary sphere. Especially at these buildings a great potential exists for the use of the fully integrated control systems. Well (optimally) controlled and operated system, creating the internal environment plays the basic part at building energy management. Buildings with integrated controlling, monitoring and communication system are usually called intelligent (clever) buildings. By system intelligence in information and control technique the ability of autonomous direct communication, monitoring and response of the system is generally meant, whereas the system is created by addressable elements with communication ability, decision-making ability and memory. The requirements concerning the intelligent buildings are indicated in the material of the Standard organization CENELEC – “Smart House Code of Practice CWA 50487:2005” [1]. These requirements are satisfied only by the so called open control systems. In the article the requirements concerning these control systems and possible effects of the introduction of these systems at HVAC and heating systems on building energy parameters are briefly described.

Thermal comfort in a vehicle interior is one of the most important factors influencing driver's concentration. The article deals with standard procedures of thermal comfort evaluation in homogenous microenvironment and with a special approach to non-uniform thermal environments (Nilsson’s thermal comfort chart). Thermal comfort indices for the car interior were predicted using CFD simulations and User Defined Functions programmed for the solver Fluent.

The author deals with the attractive theme as the search is of ways for limiting the risk of building interior overheating due to heat gains from persons present for a short time and technologies and from passive solar gains penetrating through glazed surfaces. After exhausting all possibilities of the above mentioned loading decrease by suitable architectural-structural conception, controlled solar windows protection, etc., it is worth to search further possibilities. As promising it is possible to designate the efforts to utilize the effect of the phase change in materials in building structures, especially in cases when the location of heat accumulating surfaces is limited due to the unacceptable mass. The article brings the survey of the so called PCM materials suitable for use in buildings.

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In the article the knowledge from the renewable sources equipment project and erection at the Czech scientific station in Antarctic are indicated. The station has been commonly operating since Christmas 2006. The evaluation of the fulfillment or no fulfillment of the project presumptions of fossil fuels savings will be possible after the return of scientists to the Czech Republic towards the end of March 2007.