Issue 2/2006

-

The article reports on a survey of fossil fuels and electric energy prices in the Czech Republic and them in the European context.

In the article, the influence of dimensions and temperature of radiant panels on their efficiency of radiation are specified and discussed.

In the article the basic properties of industrial refrigerating installations are generalized and a mathematical model is proposed for their operating evaluation in depending on required temperature of evaporation and climatic conditions. For Prague, as the reference place, evaporative and air cooled condensers are compared. For the given operating conditions the consumptions of electrical energy and cooling water (for only in the case of evaporative condenser) were determined for both variants. The calculation documents savings in for the case of air cooled condenser.

The article describes selected ways applied for long-time monitoring of an inner environment in buildings, which were used by authors in the past. Namely, data loggers Testo 175/177, distributed data acquisition systems based on ADAM 4000 modules and measuring “nests” of ADAM 5000 series, respectively, were used for these purposes. Authors present experience with their operation, as well as examples of acquired data.

In replying to readers questions the author draws attention to regulations valid at present time, concerning licensing of engineers and technicians and its use in construction activities. The legislative determination of controlling competencies and duties of licensed engineers and technicians remains to be an issue.

In the recent years advancements in global illumination simulation and modeling as well as in computer power have brought new type of design tools capable of predicting light propagation in a complex three dimensional spaces with very high degree of accuracy. In this paper short introduction is given to the related available methods for global and local illumination simulation. To demonstrate the power and capabilities of these methods some selected examples are given. These examples include problems with day lighting and artificial lighting as well as.

The aim of this part is to review if, where and with what kind of results the principles of legionella development prevention were successfully implemented, or if and to what extent the reduction of legionella-related illness occurred with the use of principles indicated in Parts 1 and 2 of this or the previous works of the author. Clarifying the problems of legionella prevention and showing what can be considered to be a success when fighting legionella is followed by cases and examples.

The aim of this paper is to describe shortly properties of a particulate matter and its health impact with respect to the different approach to evaluation of particulates matter in occupational, ambient and indoor atmospheres. Basic definitions and terms used in the evaluation of particulate matter are summarized too.

The article presents a survey of air solar collectors and examples of their design and utilization.

For design of pipe and duct dimension is most frequently used friction factor – for each section more times. Inside water pipes and air ducts HVAC installation are flow conditions in transition field, where friction factors are presented in terms of Reynolds number and relative roughness. As most accurate is used implicit Colebrook-White equation, for its solution is necessary iterative procedure. For technical application has been adopted number of easier to use equations, which results are many times very different. The contribution deals with comparison of the friction factor based on calculation deviation.

According to specific operation conditions, ventilation control of a highway tunnel has to keep exhaust concentration below legal limits. In the proposed control method, this is achived with minimum electrical energy consumption for the jet fans used in a tunnel with axial ventilation. The proposed algorithm has been verified by simulation of a selected tunnel section.