The study deals with the possibility of elimination of stagnation of thermal systems. The state of stagnation of thermal systems leads to overheating and evaporation of the heat transfer medium, which increases pressure and can lead to damage to the solar thermal system. Stagnation can occur due to a fault and stopping of the circulation pump, which causes the circulation of the heat transfer medium to stop. Another possibility is to achieve thermal saturation in the system, which can be affected by low heat consumption from the system. Elimination of stagnation is possible by various construction designs of collectors or by using other technical means. This study describes an experiment verifying the usability of a thermal collector’s tilting system to eliminate thermal stagnation of the system. The system is fully automatic, and when recording the limit values, ensures that the panel is rotated out of the ideal position, thus reducing the amount of received energy. In this way, the temperature of the medium in the system can be reduced by up to 10% in one hour. In the case of thermal saturation of the system, the solution is the automatic circulation of heat-transfer fluid through the system during the night and the release of thermal energy to the outside. These results suggest that the methods used actively eliminate stagnation of thermal systems.

Alkylate produced by catalyzed reaction of isobutane and olefin-rich streams is a desired component for gasoline blending. Fractionation of the alkylation reactor effluent is energy demanding due to the presence of close boiling point components and solutions cutting its energy intensity; expenses associated with this process are investigated intensely nowadays. This paper presents a novel conceptual design and techno-economic analysis of alkylation reaction effluent fractionation revamp to reach a cut in energy costs of the fractionation process without the need to revamp the rectification columns themselves, providing thus an alternative approach to a more sustainable alkylation process. Two cases are considered—A. additional steam turbine installation or B. combustion engine-driven heat pump-assisted rectification. Mathematical modeling of the considered system and its revamp is applied using the “frozen technology” approach. Real system operation features and seasonal variations are included considering the refinery’s combined heat and power (CHP) unit operation and CO2 emissions balance both internal and external to the refinery. Case A yields an expectable yearly benefit (saved energy minus additionally consumed energy minus CO2 emissions increase; expressed in financial terms) of €110–140 thousand, net present value (NPV) of −€18 to €272 thousand and produces 3.3 GWh/year of electric energy. Case B delivers a benefit of €900–1200 thousand, NPV of −€293 to €2823 thousand while producing 33 GWh/year of electricity. Both cases exhibit analogous simple payback periods (8–10 years). Marginal electric efficiency of Case B (78.3%) documents the energy integration level in this case, exploiting the system and CHP unit operation synergies. CHP unit summer operation mode and steam network restrictions significantly affect the seasonal benefit of Case B. CO2 emissions increase in both cases, Case A and Case B, considering the refinery level. However, including external CO2 emissions leads to emissions decrease in both cases of up to 26 kton/year (Case B.) The presented results document the viability of the proposed concepts comparable to the traditional (reference) solution of a high performance (COP = 8) heat pump while their performance sensitivity stresses the need for complex techno-economic assessment.

The evaluation of the performance characteristics of the device has a many type, depending on the monitored parameters. In the field of continuous measurements there is a quantum of measurement systems that allow long-term tracking and feedback. Part of the submitted contribution concerns the creation of a cogeneration unit model to monitor the flue gas pathways in relation to the production of pollutants in a nondestructive method. In the case of non-destructive monitoring and interventions in the objects, the use of the virtual laboratories. Such laboratories represent a computergenerated virtual environment in which a model of a particular device is created and a simulation of specific aspects of the matter. The priority given in this paper focuses on the correctness of the operation of the existing system in the case of integration of an external device into the existing flue path and the subsequent analysis of the influence of the further course of the flue gas particles.

Presented paper is dedicated on issue of the operation of a cogeneration unit integrated in the central heating system. An evaluation of the efficiency of the cogeneration unit operation is performed during heat water preparation and later the heating season. Indicators are evaluated as the correlation between the primary fuel and the electrical and thermal energy consumption. The main idea is following combined generation of electricity and heat with look at efficiency of the cogeneration unit in the central heat supply system in terms of heat generation.

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The main idea of exploitation combined heat and energy production is to reduce usage of primary fuels and with that connected reducing of pollutions due to the integration of renewable energy sources and with regard to the natural environment. Presented work is analysis of CHP system producing electricity and compare to conventional systems.

This paper analyses practical exploitation of cogeneration unit in heat production. The main idea of using combined heat and energy production is to reduce usage of primary fuels. By integration of renewable energy sources, reduced usage of traditional primary fuels and with regard to the natural environment reduction of pollutions. Presented work is analysis of CHP system producing heat and comparison to conventional systems.

In the Visegrad group countries is district heating system the dominant wa of production and distribution of heat in residential sector.The European Union is currently suporting the development of district heating systems and the use of more renewable sources in heat production. The article describes the current status of distring heating in the Visegrad group countries.