Issue 5/2016

The paper is a continuation of parts 1, 2 and 3, published in the previous volumes of the journal. The fourth part deals with the common HVAC equipment and elements that are used in nuclear power plants, including several examples of their use in a nuclear power plant.

The paper provides a basic over view and description of the warm-air hea ting systems. It informs designers, preservationists and managers of historic buildings about the dangers caused by use or, on the other hand, decommissioning of outdated systems and also presents the possibility of their recovery or at least a partial use. Nevertheless, warm-air systems can not be understood solely as a source of heating, but also as a mean of ventilation, or more generally mean of the building’ s indoor environment mana gement.

The paper describes a design and implementation of proportional-integral-derivative (PID) controllers for airflow velocity control during fire ventilation of the already operated tunnel complex Blanka. The desired value and direction of longitudinal airflow velocity should be maintained in order to control the smoke propagation. The desired longitudinal airflow velocity is different for different sections of the tunnel due to the road gradient, cross-section area, occurrence of entrance and exit ramps and for the way of smoke extraction as well. The desired airflow velocity also changes in time. At first, a need of evacuation, and then requirements of emergency services are taken into account. For such a complex tunnel, it would be time consuming to tune the PID controller during the complex examinations before opening of the tunnel to traffic. For this reason, the simulation model was used for the tuning of the controller, which significantly saved time with the controller tuning. Moreover, the simulation model can be used for testing of extraordinary situations during the tunnel operation, e.g. failure of some equipment necessar y for fire ventilation control.

With the advent of the EU Commission Regulation 2015/1189 on the ecodesign of the solid fuel boilers, there are beginning to emerge questions and ambiguities regarding the conversion of the efficiency and emission values reported in the protocols from the testing laboratories. The EU Commission Regulation introduces new evaluation of boilers specifications, which are seasonal efficiency and seasonal emissions. The calculation of the seasonal efficiency takes into account also the electricity consumption and potential production of electricity in a cogeneration boiler. The article mentions the formulas for the conversion of the boilers specifications according to the requirements of the mentioned Regulation. It also includes a model example.

The paper presents the results of measurements of the aerodynamic noise produced by the low-speed air flow through the terminal blade grille. The noise of the blade grille and circular cylinder are compared. The results in the form of relative frequency spectra and the total sound power levels are mutually compared and commented.

The article deals with simulation analysis of utilization of heat pumps for domestic hot water preparation in residential buildings. Currently used heat pumps reach in such applications coefficient of performance 2.5. Mathematical simulations were performed with multi-exchanger heat pumps. Validated mathematical model of heat pump with vapour cooler and aftercooler was used for the simulations. The heat pump with aftercooler achieves 20 % higher seasonal performance factor SPF.

The article deals with amount of energy embodied in the systems of solar thermal collectors. Evaluation of concrete systems in the Czech climatic conditions is demonstrated on a sample of a system installed in a family house and an unusual system with long-term accumulation of heat. Economic aspects are not studied, all the assessments concern energy. Three sources of data about embodied energy have been considered in the article.

The article deals with the issue of safety valves installation for water heaters. Neglecting of the installation conditions often causes damage to the installed appliance, or (as shown in the paper) loss on the water and sewer charges in the case of a safety valve installed in the wa ter heater safety group.