Issue 5/2022

The article discusses in detail the various hydraulic connections of consumer circuits of heating systems. It presents the advantages and disadvantages of the different designs as well as the suitability of using individual hydraulic connections. A sample example of a control valve design is given for almost every connection method.

The article deals with the issue of the safety of using mildly flammable refrigerants in refrigerant air conditioning systems. On the basis of available documents, it describes the procedure of evaluation and calculation of maximum refrigerant charge in these systems. The article provides a commentary on the current version of EN 378, including the background.

The article deals with optimizing the operation of the cooling plant with respect to electricity consumption. Optimization compares several variants of operation (switching of individual sources of cold) and two basic operating modes. The results are presented both by the predicted cooling factors of the plant room and by the sa vings potential obtained from the measured required cooling loa d of the building.

The paper focuses on the evaluation of the benefits of implementing predictive control in district heating systems (DHS). The method has already been applied in several DHS networks. This paper presents the results of the deployment at the Beethoven DHS site in Teplice, including a comparison with the initial control.

The second part of the contribution deals with simulations and real experiments concerning the operation control of an autonomous power and heat generation system. The system consists of a Wave OR C cogeneration unit, photovoltaic panels, battery storage and a virtual heat storage. The whole system is located at the University Centre for Energy Efficient Buildings of the Czech Technical University in Prague. The aim of the experiment is to maintain the heat and electricity supply and minimize the operating costs with the highest possible efficienc y of the whole system.

The paper presents the assessment of the operational behaviour of the heater depending on the hot water consumption profile. It is based on previous work where a simulation model of a hot water heater with direct heating was described. The behaviour of the simulation model in the TRN SYS environment is verified by experimental measurements.