An Intelligent On-Off Regulation Method by Predicting the Valve On-Time Ratio in District Heating

Author(s):  
Lanbin Liu ◽  
Yufei Ma

Good room temperature control is beneficial for user thermal comfort and health. It also helps reduce energy consumption and carbon dioxide emissions inside the buildings. However, there are certain limitations with the current thermostatic valves commonly used in central heating systems, especially the ones used in China, since they cannot satisfactorily adjust room temperatures. In response to such problems, an intelligent on-off regulation method is presented in this paper. The room temperature can be maintained by controlling the valves according to the on-time ratio predicted by this method. The on-time ratio is predicted for each cycle, and the current ratio is decided by checking a 6-order fuzzy-control table with room temperature deviations in the last step, as well as room temperature set points. The design of the fuzzy-control table as a major factor that may affect the controlling effect is also discussed. A proper controlling cycle and optimal controlling table have been worked out. Finally, this paper discusses the application effectiveness of this strategy. Results show that the room temperature can be maintained in the range of set point ±0.5°C using this method in different conditions. It is fair to say that this method is a stable, reliable and advanced controlling method with accurate control.

1999 ◽  
Vol 5 (5) ◽  
pp. 318-322
Author(s):  
Edvardas Tuomas ◽  
Saulius Neverbickas

The majority of dwellings in Lithuania are situated in blocks of flats. The dwellings were built after World War II and they are heated by single pipe central heating systems, connected to district heating. The dwellers are not quite satisfied with such a heating system and try to improve it, but do that in a wrong way, by increasing the surface of radiators. Such means lead to violation of thermal regime and comfort conditions for other dwellers. There exists sometimes the necessity of reconstructing premises and together—the heating system. During the reconstruction the primary heat fluxes from radiators should be known, but very often such data are lost and only the size of radiators (number of sections) are known. To reconstruct the required primary data for single pipe systems is complicated because the temperatures of inlet and outlet water for radiators are unknown. In this article the methodology is proposed how to perform the calculations leading to the required data. The aim of calculations is the establishment of heat fluxes from each radiator connected to the riser. Heat flux from radiator can be calculated according the formula (1) but the complex coefficient is unknown. It could be found from formulae (2) but some magnitudes are unknown. According to the proposed methodology the values of unknown magnitudes are taken approximately and calculations are performed with iterations. In such a way the flow rate of water in riser is established from formula (3), which is the same for each radiator (the property of single pipe system). From formulas (3) and (4) an equation is produced (5), and is used for calculations of unknown temperatures. The equation (6) is used for calculation of heat fluxes from radiators. To carry out the above-mentioned calculations without computer practically is impossible due to many cycles of iteration. The programme was prepared to make easy all these calculations. The scheme of algorithm of programme is given in Fig 1. An example of calculation is given in this article. Calculations were fulfilled by newly created programme. The riser chosen for calculation is shown in Fig 2. The results of calculation are given in Table 1. The table shows that according to the proposed methodology the programme based on it can be used for reconstruction of primary data of single pipe heating systems successfully.


Author(s):  
C. H. Doherty

The paper briefly sketches the background to domestic heating in Britain from Roman times to contemporary awareness of the desirability of better heating. The extent of the domestic market now awaiting satisfaction, and the influences of fuel policy are discussed. The effect of contemporary building methods on the choice of heating systems is considered, and the available systems discussed. Present practices in both public and private sectors of housing are noted, together with comments on the reasons for past and prevailing techniques. Topics leading to considerations of the fuel suppliers' interest in the capital goods market in central heating systems are given, and, finally, some remarks on the potential role of district heating in the domestic central heating field are presented.


2021 ◽  
Vol 23 ◽  
pp. 493-502
Author(s):  
Alina Konyk ◽  
Vladimir Demchenko

Global trends in the efficiency, safety of energy systems and energy conservation actualize the task of developing new technologies for energy storage and transportation. The article considers current technologies of storage and accumulation of thermal energy, which can be used in central heating systems, and draws conclusions about the feasibility of their use. Also, the classification of energy storage systems is presented. The most perspective thermal energy storage, which can be used to equalize the load on the energy source to ensure the peak demand for heat with a high coefficient of utilization of the equipment capacity, is noted.


Author(s):  
Ye.Ye. Nikitin

The current situation in the sphere of district heating is analysed on the basis of use of the cognitive approach. The presence of closed chains of cause-effect relationships of negative factors and conflicts of target settings of the subjects in the field of district heating is shown. The conceptual model of energy efficient modernization of district heating systems is proposed. This model includes indicators of the current status of heat sources, networks and heat consumers, energetic and economic models, restrictions, procedure of forming and analysis of the mutual influence of the recommended projects. The quantitative data on indicators of the current state of district heating systems of the cities of Ukraine are presented. The interrelation between indicators of the current state and projects of energy efficient modernization of district heating systems is shown. Assessment of energy self-sufficiency of municipal district heating systems on condition of thermal modernization of buildings is carried out. The creation of energy management systems at the district heating enterprises is proposed. Bib. 6, Fig. 7, Tab. 5.


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