scholarly journals Improving Thermoeconomic and Environmental Performance of District Heating via Demand Pooling and Upscaling

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8546
Author(s):  
Jaume Fitó ◽  
Neha Dimri ◽  
Julien Ramousse
Keyword(s):  
Production Systems ◽  
District Heating ◽  
Heat Pumps ◽  
Environmental Indicators ◽  
Hot Water ◽  
Energy And Exergy ◽  
Total Investment ◽  
Solar Thermal Collectors ◽  
Levelized Cost Of Heat ◽  
Fuel Costs

This study evaluates the effects of pooling heat demands in a district for the purpose of upscaling heat production units by means of energy, exergy, economic, exergoeconomic, and environmental indicators, as well as the sensitivity to investment and fuel costs. The following production systems to satisfy the heat demands (domestic hot water production and space heating) of a mixed district composed of office (80%), residential (15%), and commercial (5%) buildings are considered: gas- and biomass-fired boilers, electric boilers and heat pumps (grid-powered or photovoltaic -powered), and solar thermal collectors. For comparison, three system sizing approaches are examined: at building scale, at sector scale (residential, office, and commerce), or at district scale. For the configurations studied, the upscaling benefits were up to 5% higher efficiency (energy and exergy), there was lower levelized cost of heat for all systems (between 20% and 54%), up to 55% lower exergy destruction costs, and up to 5% greater CO2 mitigations. In conclusion, upscaling and demand pooling tend to improve specific efficiencies, reduce specific costs, reduce total investment through the peak power sizing method, and mitigate temporal mismatch in solar-driven systems. Possible drawbacks are additional heat losses due to the distribution network and reduced performance in heat pumps due to the higher temperatures required. Nevertheless, the advantages outweigh the drawbacks in most cases.

scholarly journals Local Heating Networks with Waste Heat Utilization: Low or Medium Temperature Supply?

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 954 ◽  
Author(s):  
Hanne Kauko ◽  
Daniel Rohde ◽  
Armin Hafner
Keyword(s):  
Low Temperature ◽  
Heat Pump ◽  
Urban Areas ◽  
Waste Heat ◽  
Local Heating ◽  
District Heating ◽  
Heat Pumps ◽  
Hot Water ◽  
Local Network ◽  
Medium Temperature

District heating enables an economical use of energy sources that would otherwise be wasted to cover the heating demands of buildings in urban areas. For efficient utilization of local waste heat and renewable heat sources, low distribution temperatures are of crucial importance. This study evaluates a local heating network being planned for a new building area in Trondheim, Norway, with waste heat available from a nearby ice skating rink. Two alternative supply temperature levels have been evaluated with dynamic simulations: low temperature (40 °C), with direct utilization of waste heat and decentralized domestic hot water (DHW) production using heat pumps; and medium temperature (70 °C), applying a centralized heat pump to lift the temperature of the waste heat. The local network will be connected to the primary district heating network to cover the remaining heat demand. The simulation results show that with a medium temperature supply, the peak power demand is up to three times higher than with a low temperature supply. This results from the fact that the centralized heat pump lifts the temperature for the entire network, including space and DHW heating demands. With a low temperature supply, heat pumps are applied only for DHW production, which enables a low and even electricity demand. On the other hand, with a low temperature supply, the district heating demand is high in the wintertime, in particular if the waste heat temperature is low. The choice of a suitable supply temperature level for a local heating network is hence strongly dependent on the temperature of the available waste heat, but also on the costs and emissions related to the production of district heating and electricity in the different seasons.

scholarly journals Heat Pump Use in Rural District Heating Networks in Estonia

2021 ◽  
Vol 25 (1) ◽  
pp. 786-802
Author(s):  
Kertu Lepiksaar ◽  
Kiur Kalme ◽  
Andres Siirde ◽  
Anna Volkova
Keyword(s):  
Heat Pump ◽  
Renewable Energy Sources ◽  
District Heating ◽  
Ambient Air ◽  
Heat Pumps ◽  
Hot Water ◽  
Rural District ◽  
Low Grade ◽  
The Impact ◽  
Heating Networks

Abstract District heating has proven to be an efficient way of providing space heating and domestic hot water in populated areas. It has also proven to be an excellent way to integrate various renewable energy sources (RES) into the energy system. In Estonia, biomass covers most of the heat demand, but carbon-intensive fuels are still used to cover peaks and lows. Heat pumps can be a good solution for rural areas, as there is usually plenty of land available for heat pump facilities. In addition, heat pumps require low-grade heat sources such as ambient air, groundwater, lakes, rivers, sea, sewage water, and industrial waste heat. One of the downsides of heat pumps is the need for large investments compared to boilers fired by natural gas and biomass, and electric boilers. This study examines the impact of heat pump use on consumer prices for district heating in rural district heating networks in Estonia.

scholarly journals Comparison of 4th and 5th generation district heating systems

2021 ◽  
Vol 246 ◽  
pp. 09004
Author(s):  
Oddgeir Gudmundsson ◽  
Anders Dyrelund ◽  
Jan Eric Thorsen
Keyword(s):  
District Heating ◽  
Heating System ◽  
Heat Pumps ◽  
District Heating System ◽  
Heating Systems ◽  
District Energy ◽  
District Heating Systems ◽  
Operating Temperatures ◽  
New Research ◽  
Levelized Cost Of Heat

In a pursuit to increase the efficiency of district heating system there has been a continuous focus to reduce the system operating temperatures. This has led to the current state of the art district heating systems, commonly referred to as the 4th generation district heating, also known as low temperature district heating (LTDH). The success of the LTDH has fuelled a lot of research interest in district energy systems, one of the new research topics has been focusing on reducing the operating temperatures down to the ambient temperature (ATDH), commonly referred as 5th generation district heating. In these systems the supply temperature is insufficient for fulfilling the heating demands of the connected buildings, which then requires end-user located heat pumps to raise the supply temperature to the level required by the buildings. As of today, number of ATDH systems have been realized as part of various research projects. The question however remains if ATDH brings additional benefits compared to LTDH. This paper compares the levelized cost of heat from these two systems types for two countries with different climate zones. The results of the analysis indicate that LTDH is the favourable solution in both countries.

scholarly journals Energy Retrofitting Effects on the Energy Flexibility of Dwellings

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2788 ◽  
Author(s):  
Francesco Mancini ◽  
Benedetto Nastasi
Keyword(s):  
Energy Demand ◽  
Production Systems ◽  
Residential Building ◽  
Energy Transition ◽  
Cost Effective ◽  
Heat Pumps ◽  
Building Envelope ◽  
Hot Water ◽  
Building Stock ◽  
Residential Building Stock

Electrification of the built environment is foreseen as a main driver for energy transition for more effective, electric renewable capacity firming. Direct and on-time use of electricity is the best way to integrate them, but the current energy demand of residential building stock is often mainly fuel-based. Switching from fuel to electric-driven heating systems could play a key role. Yet, it implies modifications in the building stock due to the change in the temperature of the supplied heat by new heat pumps compared to existing boilers and in power demand to the electricity meter. Conventional energy retrofitting scenarios are usually evaluated in terms of cost-effective energy saving, while the effects on the electrification and flexibility are neglected. In this paper, the improvement of the building envelope and the installations of electric-driven space heating and domestic hot water production systems is analyzed for 419 dwellings. The dwellings database was built by means of a survey among the students attending the Faculty of Architecture at Sapienza University of Rome. A set of key performance indicators were selected for energy and environmental performance. The changes in the energy flexibility led to the viable participation of all the dwellings to a demand response programme.

scholarly journals Energy and Exergy Analysis of the Air Source Transcritical CO2 Heat Pump Water Heater Using CO2-Based Mixture as Working Fluid

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4470
Author(s):  
Yikai Wang ◽  
Yifan He ◽  
Yulong Song ◽  
Xiang Yin ◽  
Feng Cao ◽  
...  
Keyword(s):  
Exergy Analysis ◽  
Heat Pumps ◽  
Exergy Efficiency ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Domestic Hot Water ◽  
Practical Applications ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis

Given the large demand nowadays for domestic hot water, and its impact on modern building energy consumption, air source transcritical CO2 heat pumps have been extensively adopted for hot water production. Since their system efficiency is limited by significant irreversibility, a CO2-based mixture could offer a promising drop-in technology to overcome this deficiency without increasing system complexity. Although many CO2 blends have been studied in previously published literature, little has been presented about the CO2/R32 mixture. Therefore, a proposed mixture for use in transcritical CO2 heat pumps was analyzed using energy and exergy analysis. Results showed that the coefficient of performance and exergy efficiency variation displayed an “M” shape trend, and the optimal CO2/R32 mixture concentration was determined as 0.9/0.1 with regard to flammability and efficiency. The irreversibility of the throttling valve was reduced from 0.031 to 0.009 kW⋅kW−1 and the total irreversibility reduction was more notable with ambient temperature variation. A case study was also conducted to examine domestic hot water demand during the year. Pure CO2 and the proposed CO2 blend were compared with regard to annual performance factor and annual exergy efficiency, and the findings could provide guidance for practical applications in the future.

A New Type of District Heating System Based on Distributed Absorption Heat Pumps

2009 ◽  
Author(s):  
Lin Fu ◽  
Yan Li
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
District Heating ◽  
Heating System ◽  
Heat Pumps ◽  
Hot Water ◽  
Conventional Heating ◽  
Low Grade ◽  
District Heating System ◽  
New Approach

This paper presents a new approach to utilize geothermal energy with absorption heat pump in district heating system. The heat pump is driven by the temperature-difference between primary and secondary heating loops. In this method, the low-grade thermal energy can be used in district heating system effectively, as a result, the heating capacity and energy efficiency of district heating system can be improved more than 20%. On one hand, it could relieve the existing dilemma (shortage) of central heat source, as well enhance the delivery capacity of heating network dramatically. On the other hand, heating cost may be reduced remarkably, due to the reduction in both coal consumption of central heat and energy consumption of delivery pump. Firstly, this paper introduces the district heating method based on distributed absorption heat pumps through the analysis on the parameter characteristics of low-grade energy, hot water of primary and secondary heating network, as well as the operation parameters of absorption heat pumps. Secondly, an economic and energy consumption analysis was discussed by comparing the new approach with conventional heating system. Finally, this paper presents several system configurations, discusses the operation strategies in various conditions, and proposes the operation modes for heating season.

scholarly journals Design methodology for combined production and distribution for domestic hot water and space heating

2019 ◽  
Vol 111 ◽  
pp. 01089
Author(s):  
Ivan Verhaert
Keyword(s):  
Distribution Systems ◽  
Production Systems ◽  
District Heating ◽  
Local Heat ◽  
Hot Water ◽  
Space Heating ◽  
Heating Systems ◽  
Domestic Hot Water ◽  
Production And Distribution ◽  
Collective Housing

As local heat demand is reducing due to an increased insulation rate, investing in sustainable heat production becomes less interesting. Nevertheless a substantial demand of heat remains in which the thermal energy needed for the generation of domestic hot water grows relatively in importance. In the last two years standards to size production and distribution systems were revised and methods based on tap patterns were elaborated. Nevertheless, some aspects were not covered yet, e.g. how to deal with decentralized storage and how to use these results and new insights in combined heating systems, taking into account that modifications in standards for both space heating and domestic hot water installations are reducing the oversizing. In this paper, first some critical points of attention due to this evolution are illustrated with a case example. Next it is shown how different rules of thumb often developed by different manufacturers deal with these aspects, but lacking however compatibility with existing standards and/or new insights. Finally, a methodology is proposed and illustrated how to size distribution and production systems for combined heating systems taking into account central and decentralized storage and different kind of end users. The method can be used to size heating systems in collective housing or in district heating networks.

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