scholarly journals LS-SVM Based Modeling of Winter Time Apartment Hot Water Supply Load in District Heating System

Author(s):  
Young Chil Park
2014 ◽  
Vol 22 (02) ◽  
pp. 1450008 ◽  
Author(s):  
SUNG-HWAN CHO ◽  
SEONG-KI HONG ◽  
SANG-HO CHOI ◽  
M. ZAHEERUDDIN

In this study, the secondary side measured energy consumption of a district heating system (DHS) with different hot water supply temperature control methods was compared. Two control methods were evaluated: an outdoor temperature reset control (OTRC) and an outdoor temperature predictive control (OTPC). While the OTRC strategy has been widely used for energy savings in DHS, the results show that the OTPC strategy resulted in higher energy savings. In general, the OTPC strategy maintained lower supply water temperature, and thereby reduced standby losses and increased overall heat transfer rate to the heated spaces due to higher water mass flow rate to the spaces. During the actual energy consumption monitoring, the OTPC strategy saved about 6.6% more energy compared to that of OTRC strategy. Also, it was found that under partial load conditions, such as during the daytime, the fluctuations in hot water supply temperature with OTRC were more severe than OTPC strategy. Overall, the results showed that the OTPC strategy gave better control and was more stable under full load and partial load conditions.


2021 ◽  
Vol 7 (2(38)) ◽  
pp. 66-71
Author(s):  
Maxim Olegovich Maximov

ignificant heat losses in centralized heating and hot water supply systems during the transportation of heat carriers lead to the need for decentralization of heat generating installations. It is shown that steam and gas installations for combined heat and power generation deserve the greatest attention. The ways of increasing the efficiency of cogeneration plants of various capacities based on CCGT by utilizing the heat of the heating system by installing recuperative heat exchangers on the return lines of the heating system after heating devices that are connected to the hot water supply network are substantiated, which makes it possible to reduce heat losses to the environment. The proposed system of rational interaction of the power plant with the heating and hot water supply system, which allows increasing the thermal efficiency of the cogeneration plant by 2%, which corresponds to a fuel saving of 3% due to the more complete use of the thermal energy of steam, which is sent as a selection for district heating. This article discusses solutions aimed at increasing the efficiency of heat generation by cogeneration plants by maximizing the use of heat from the exhaust steam of turbines.


Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3350
Author(s):  
Theofanis Benakopoulos ◽  
William Vergo ◽  
Michele Tunzi ◽  
Robbe Salenbien ◽  
Svend Svendsen

The operation of typical domestic hot water (DHW) systems with a storage tank and circulation loop, according to the regulations for hygiene and comfort, results in a significant heat demand at high operating temperatures that leads to high return temperatures to the district heating system. This article presents the potential for the low-temperature operation of new DHW solutions based on energy balance calculations and some tests in real buildings. The main results are three recommended solutions depending on combinations of the following three criteria: district heating supply temperature, relative circulation heat loss due to the use of hot water, and the existence of a low-temperature space heating system. The first solution, based on a heating power limitation in DHW tanks, with a safety functionality, may secure the required DHW temperature at all times, resulting in the limited heating power of the tank, extended reheating periods, and a DH return temperature of below 30 °C. The second solution, based on the redirection of the return flow from the DHW system to the low-temperature space heating system, can cool the return temperature to the level of the space heating system return temperature below 35 °C. The third solution, based on the use of a micro-booster heat pump system, can deliver circulation heat loss and result in a low return temperature below 35 °C. These solutions can help in the transition to low-temperature district heating.


Author(s):  
Stanislav Chicherin

Introduction. Renovation of housing stock supposes construction of new buildings, where the main utilities consuming heat energy will be heating and hot water supply (HWS) systems. Under such conditions the task of heat consumption reduction by transfer to low-temperature and use of the associated procedures is relevant. Materials and Methods. Research was performed on the basis of residential and administration buildings designed within the whole Russia, the facilities were selected based on the year of putting into operation and their purpose. The source of data concerning buildings became documents included into the scope of the design and detailed documentation: plans, drawings and explanatory notes. As meeting the demands of hot water supply makes the main contribution to daily nonuniformities of heat energy consumption, the attention was paid to equipment of hot water supply systems. For calculations, the commercial product of Microsoft Office Excel 2010 was used. Results. During selection of roof boiler house as a source of heat supply increase in consumption of equivalent fuel in relation to the variant of connection to heat power plant operating on solid fuel by 187,314 tons of fuel oil equivalent is possible. General refusal from power-and-heat generation complicates operation of large district heat supply systems. The design parameters of coolant in building heating system differ from project to project: from 95/70 °С, used everywhere till the beginning of the XXI century, up to 90/65 °С corresponding to existing practice of designing or 80/60 °С as at the facility in Sevastopol. Reduction of design temperatures by 5 % is insufficient to decrease general heat consumption of the building. Reduction of heat consumption is explained by selection of advanced materials for pipeline heat insulation. Use of automation diagrams for heat points on the basis of regulator ECL Comfort 310 contributes to improvement of hydraulic control for heating systems, however, concealed automation results in violation of high-quality mode for heat network control and decrease of coolant parameters on adjacent (often non-automated) consumers. Conclusions. Supplement of central high-quality control by local constant temperature/variable flow control at individual heat unit and installation of temperature controllers on heating radiators with mechanical thermostatic head have potential for reduction of the heat energy volume used ineffectively. Increase in level of controllability for heating system together with cheaper and responsive automation systems are basic conditions for increase in quality of heat supply in future.


2020 ◽  
Vol 160 ◽  
pp. 01004 ◽  
Author(s):  
Stanislav Chicherin ◽  
Lyazzat Junussova ◽  
Timur Junussov

Proper adjustment of domestic hot water (DHW) load structure can balance energy demand with the supply. Inefficiency in primary energy use prompted Omsk DH company to be a strong proponent of a flow controller at each substation. Here the return temperature is fixed to the lowest possible value and the supply temperature is solved. Thirty-five design scenarios are defined for each load deviation index with equally distributed outdoor temperature ranging from +8 for the start of a heating season towards extreme load at temperature of -26°C. All the calculation results are listed. If a flow controller is installed, the customers might find it suitable to switch to this type of DHW supply. Considering an option with direct hot water extraction as usual and a flow controller installed, the result indicates that the annual heat consumption will be lower once network temperatures during the fall or spring months are higher. The heat load profiles obtained here may be used as input for a simulation of a DH substation, including a heat pump and a tank for thermal energy storage. This design approach offers a quantitative way of sizing temperature levels in each DH system according to the listed methodology and the designer's preference.


Vestnik MGSU ◽  
2019 ◽  
pp. 748-755 ◽  
Author(s):  
Saule K. Abildinova ◽  
Stanislav V. Chicherin

Introduction. The purpose of this investigation is to show what changes introduced in the mathematical model of a district heating system are capable of considerable improving the convergence of simulation results and actual data. The study evaluates the work of heating supply establishments with their customers as well as analysis of the ways of enhancing pump equipment efficiency that allows saving electric energy or increasing output at the same energy consumption. Materials and methods. Engineering acceptance of newly introduced and reconstructed facilities is conducted, heat loads are corrected, disconnections and recurrent connections of indebted consumers are carried out. Studying data submitted by a local heat supply establishment shows that pump seals made from iron and steel are subject accelerated wear in the course of operation. Results. Three variants of the problem solution are suggested: making seals from bronze or stainless steel, prevention of unjustified increase of seal clearances as well as using labyrinth pump seals. This will allow increasing pump equipment efficiency by 5 to 7 % and save about 2 × 105 kW∙h of electrical energy for every pump or increase of output at the same energy consumption. Taking into account that a pump station is a part of the district heating system and unmachined inner surfaces of the pumps have a significant roughness, grinding of these surfaces can improve their hydraulic characteristics of the pumps. In the scope of the suggested method, the entire district heating system is considered not in the situation when actual load is equal to the sum of all the design loads and the pump equipment has manufacturer’s parameters, but accounting actual loads and characteristics. Conclusions. Mathematical model of district heating system heating and hydraulic mode that takes issues mentioned above into consideration would allow simulating joint operation of the heating and hot water supply systems at transient operation modes with higher accuracy.


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