Model predictive control for demand response of domestic hot water preparation in ultra-low temperature district heating systems

2017 ◽  
Vol 146 ◽  
pp. 55-64 ◽  
Author(s):  
Michael Dahl Knudsen ◽  
Steffen Petersen
Keyword(s):  
Low Temperature ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Demand Response ◽  
District Heating ◽  
Hot Water ◽  
Heating Systems ◽  
Domestic Hot Water ◽  
District Heating Systems

scholarly journals Exergy Analyses of Low-Temperature District Heating Systems With Different Sanitary Hot-Water Boosters

Entropy ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 388
Author(s):  
Poredoš ◽  
Kitanovski ◽  
Poredoš
Keyword(s):  
Low Temperature ◽  
Winter Season ◽  
District Heating ◽  
Intersection Point ◽  
Exergy Efficiency ◽  
Hot Water ◽  
Heating Systems ◽  
District Heating Systems ◽  
Different Types ◽  
Exergy Analyses

This paper presents an exergy-efficiency analysis of low-temperature district heating systems (DHSs) with different sanitary hot-water (SHW) boosters. The required temperature of the sanitary hot water (SHW) was set to 50 °C. The main objective of this study was to compare the exergy efficiencies of a DHS without a booster to DHSs with three different types of boosters, i.e., electric-, gas-boiler- and heat-pump-based, during the winter and summer seasons. To achieve this, we developed a generalized model for the calculation of the exergy efficiency of a DHS with or without the booster. The results show that during the winter season, for a very low relative share of SHW production, the DHS without the booster exhibits favorable exergy efficiencies compared to the DHSs with boosters. By increasing this share, an intersection point above 45 °C for the supply temperatures, at which the higher exergy efficiency of a DHS with a booster prevails, can be identified. In the summer season the results show that a DHS without a booster at a supply temperature above 70 °C achieves lower exergy efficiencies compared to DHSs with boosters at supply temperatures above 40 °C. The results also show that ultra-low supply and return temperatures should be avoided for the DHSs with boosters, due to higher rates of entropy generation.

scholarly journals Technology Pathways and Economic Analysis for Transforming High Temperature to Low Temperature District Heating Systems

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3218
Author(s):  
Pedro Durán ◽  
Herena Torio ◽  
Patrik Schönfeldt ◽  
Peter Klement ◽  
Benedikt Hanke ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Renewable Energy ◽  
High Temperature ◽  
Low Temperature ◽  
Economic Analysis ◽  
District Heating ◽  
Heating System ◽  
District Heating System ◽  
Heating Systems ◽  
District Heating Systems

There are 1454 district heating systems in Germany. Most of them are fossil based and with high temperature levels, which is neither efficient nor sustainable and needs to be changed for reaching the 2050 climate goals. In this paper, we present a case study for transforming a high to low temperature district heating system which is more suitable for renewable energy supply. With the Carnot Toolbox, a dynamic model of a potential district heating system is simulated and then transformed to a low temperature supply. A sensitivity analysis is carried out to see the system performance in case space constrains restrict the transformation. Finally, an economic comparison is performed. Results show that it is technically possible to perform the transformation until a very low temperature system. The use of decentralized renewable sources, decentralized heat storage tanks and the placement of a heat pump on each building are the key points to achieve the transformation. Regarding the sensitivity analysis, the transformation is worth doing until the seasonal storage and solar collector field sizes are reduced to 60% and 80% of their values in the reference case, respectively. The economic analysis shows, however, that it is hard for highly efficient low temperature renewable based heat networks to compete with district heating systems based on a centralized fossile CHP solution. Thus, though the presented transformation is technically possible, there is a strong need to change existing economic schemes and policies for fostering a stronger promotion of renewable energy policies in the heat sector.

scholarly journals Overview of Solutions for the Low-Temperature Operation of Domestic Hot-Water Systems with a Circulation Loop

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3350
Author(s):  
Theofanis Benakopoulos ◽  
William Vergo ◽  
Michele Tunzi ◽  
Robbe Salenbien ◽  
Svend Svendsen
Keyword(s):  
Low Temperature ◽  
Heat Loss ◽  
District Heating ◽  
Heating System ◽  
Hot Water ◽  
Heating Power ◽  
Circulation Loop ◽  
Space Heating ◽  
District Heating System ◽  
Domestic Hot Water

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.

scholarly journals Energy efficient modernization of KVG and TGV boilers

2021 ◽  
Vol 36 ◽  
pp. 22-35
Author(s):  
P. Glamazdin ◽  
D. Glamazdin
Keyword(s):  
Operating Time ◽  
Small Diameter ◽  
District Heating ◽  
Hot Water ◽  
Automation System ◽  
Convective Heating ◽  
Optimized Design ◽  
Efficient Design ◽  
Heating Systems ◽  
District Heating Systems

At present, the district heating systems of Ukrainian cities are in a critical state. They need significant modernization. This especially applies to very important components of district heating systems – heating water boilers. Unsatisfactory condition of boilers is mainly due to the obsolescence of basic equipment, including boilers. The operating time of them exceeds the passport lifetime. There ia a lack of modern automation, especially in terms of controlling operating modes. Nominal power of them exceeds the real heat loads. The range of hot water boilers used is not large. These are low-power boilers of the series NDIST, "Universal", "Energiia", "Fakel" and others, medium-power boilers of the series TVG and KVG and high-power boilers of series PTVM and KVGM. According to their prevalence, special attention should be paid to boilers of the series TVG and KVG. The series are installed on quarter boiler houses. The boilers of these series have an efficient design of the furnace volume and an optimized design of the convective part. Nevertheless, in terms of automation, gas supply and air supply systems, they no longer meet today's requirements. They are outdated comparing to the achieved level of technical solutions. The article discusses the main shortcomings of the design of boilers: insufficient durability of the gas collector in the hearth burner, small diameter of the pipes of the convective part and the use of fireclay materials in the setting of the burners. The first two shortcomings were overcome by the developers by the increase in the diameter of the pipes of convective packages and the modernization of MPIG-3 hearth burners. The third shortcoming should be overcomed by replacing the setting with a modern one during off-season repairs. Reserves for improving the energy efficiency of boilers of these series are found. To do this, it is necessary to install additional convective heating surfaces (economizers or air-heaters), replace the setting and equip the boilers with a modern automation system with cascading the burners. It allows improving efficiency up to 94...95 % and environmental performance according to the modern requirements.

scholarly journals Trends in the development of the district heating systems of Ukraine

2021 ◽  
Vol 2021 (1) ◽  
pp. 52-59
Author(s):  
V.O. Derii ◽  
Keyword(s):  
Thermal Energy ◽  
Heat Supply ◽  
District Heating ◽  
Hot Water ◽  
Low Carbon ◽  
Heating Systems ◽  
Fuel Balance ◽  
Generation Structure ◽  
District Heating Systems ◽  
Low Carbon Development

We considered trends in the development of district heating systems (DHS) in Europe and Ukraine. It was established that DHS are widely used and make a significant contribution to the heat supply of European countries. In the European Union as a whole, the share of DHS is 13%, and there are plans to increase it to 50% in 2050 with a wide use of cogeneration and renewable sources of energy, including environmental energy with using heat pumps. Ukraine is one of the countries with a high level of DHS, but, at present, there are negative trends to reducing their contribution to the total heat supply for heating and hot water supply – from 65.2% in 2014 to 52% in 2017. In several cities, DHS ceased to function at all. The main equipment of the DHS of Ukraine is physically worn out and technologically obsolete and needs to be renewed by means of wide reconstruction, modernization, and technological re-equipment. We determined factors and the level of their influence on the demand in thermal energy of DHS. It was established that the factors reducing demand have a much greater potential. We created forecasts of demand for thermal energy, fuel balance, and the structure of DHS generation by 2050. It is shown that the demand for thermal energy from DHS will decrease and reach about 35 million Gcal in 2050. To ensure the low-carbon development of Ukraine in the structure of thermal energy generation in DHS, the use of coal-fired CHPs and boilers, as well as boilers on petroleum products will be significantly reduced. The share of natural gas in the fuel balance of DHS of Ukraine will also decrease, but it will be the main fuel for the period of technological transformation of generating capacities under conditions of the low-carbon development of Ukraine. The use of technologies for the production of thermal energy from biomass, waste, environment, and electricity will gradually increase, and in 2050, using these sources will produce about 23.8 million Gcal, which is more than 60% of the total thermal energy of DHS. Keywords: district heating systems, thermal energy, factors of influence, demand, fuel balance, generation structure

Demand response of district heating using model predictive control to prevent the draught risk of cold window in an office building

2021 ◽  
Vol 33 ◽  
pp. 101855 ◽  
Author(s):  
Yuxin Wu ◽  
Aleksi Mäki ◽  
Juha Jokisalo ◽  
Risto Kosonen ◽  
Simo Kilpeläinen ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Demand Response ◽  
District Heating ◽  
Office Building
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