1,720,964 research outputs found
5th generation district heating and cooling for holistic energy system decarbonisation: Novel system designs and detailed techno-economic assessment
Get PDFTo limit climate breakdown, decarbonising the heating and cooling sector in a cost effective manner represents a crucial challenge. Holistic energy system decarbonisation is recognised as a key solution, relying on sector coupling, energy reuse and energy storage. 5th Generation District Heating and Cooling (5GDHC) presents a promising pathway for holistic decarbonisation. It utilises an ambient temperature water network with decentralised heat pumps to exploit synergies between heating and cooling, to harness low temperature waste heat and allow sector coupling with the electricity grid. However, questions remain on 5GDHC’s hydraulic design, operational stability, economic viability, and overall performance against alternative supply options.
This PhD thesis addresses these gaps by developing and experimentally validating a novel hydraulic design and operational methodology for 5GDHC systems. This design focuses on decentralised variable speed pumping and a centralised passive balancing unit to ensure system stability. Detailed simulation models for the proposed design are also developed and experimentally validated, which are made open access. Additionally, a technoeconomic assessment tool, the Centralisation Analysis Tool for Heat Pump Systems (CATHeaPS), is created to evaluate the economic viability of 5GDHC against other thermal supply options. CATHeaPS is also made open access.
To complete these tasks,
1. A systematic literature review is conducted and integrated with views from leading industry and academic professionals in the field, collected during bespoke interviews on the opportunities and challenges of 5GDHC for holistic decarbonisation. It is found that further research is required on quantifying the range of operational boundaries that make 5GDHC more techno-economically viable, hydraulic design and operation standardisation as well as a business structure redefinition.
2. A novel hydraulic design and suitable control philosophies are developed and experimentally validated. The experiments showed stable operation over a period of 20 hours for all demand regimes without control instabilities. A discussion is conducted on generalisability of findings and full-scale implementations.
3. Bespoke Modelica models are created and validated by building a digital twin of the experiment. A stepwise validation of the assembled digital twin demonstrates that the developed Modelica components effectively capture the behaviour of 5GDHC, with a Coefficient of Determination (R²) for the primary pump flowrates exceeding 0.88 in all cases. The similarity of the results is also seen through an analysis of the overall system behaviour.
4. For the techno-economic comparison of 5GDHC against alternative energy supply strategies for decarbonising heating and cooling, CATHeaPS is employed. CATHeaPS is verified using a direct comparison of outputs and the theoretical results/analysis verification approaches. Economic and environmental analyses are conducted highlighting the impact of cooling and access to waste heat sources. When there is no cooling, 5GDHC performs worse than 4th Generation District Heating (4GDH) for any network topology and consumer class configuration. An annual cooling to heating demand share of 30% (with a demand overlap coefficient of 16%) is required for 5GDHC to start performing better for a higher number of connections per property.
5. A real-world case study with heating and cooling loads and a waste heat source/sink during the winter/summer is used to demonstrate the application of the developed models and methodologies. It quantifies the techno-economic performance of 5GDHC against alternative supply options for the project area. 5GDHC shows a better economic performance than 4GDH with individual Air Condition units for cooling (4GDH&AC) with 227£/MWh compared to 257£/MWh. It is less energy efficient than 4GDH&AC, having an additional 81 tonnes of CO2 over a 40-year period. However, having reversible BHP units at each prosumer allows for a smaller electric capacity requirement, reducing the impact on the electricity grid. A discussion is also present on space constraints, operational complexity, and expansion flexibility.
Altogether, this research delivers a comprehensive framework for designing, simulating, and assessing 5GDHC systems. It facilitates their understanding and ultimately assists the efforts for a holistic energy system decarbonisation
CATHeaPS-Kitten v1&2
No full textThis library contains CATHeaPS, a Centralisation Analysis Tool for Heat Pump Systems. CATHeaPS is an open access modelling tool for the technoeconomic assessment of (a) district heating networks with a centralised WSHP, and (b) ambient networks with decentralised dwelling or plantroom level WSHP against individual ASHPs and gas boilers for a range of consumer classes. This novel open access technoeconomic tool can complete a high-level energy, hydraulic and economic analysis for any building schedule provided in seconds. This work contributes to the ongoing efforts towards heat decarbonisation by quantifying the boundaries of beneficial operation of different energy system approaches
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
ProHMo
No full textThis library contains CoSES thermal Prosumer House Model (ProHMo). ProHMo is a library with detailed models of the heating system of 5 houses created with Modelica in SimulationX. The house models are representing the thermal system of the Center for Combined Smart Energy Systems (CoSES) laboratory and are validated by measurements from the laboratory. The library includes FMI models that can be integrated in other software environments. In addition, ProHMo includes models for simulating 5th Generation District Heating and Cooling systems, including prosumers, balancing unit and ambient grid models. The models have also been experimentally validated in the laboratory
Experimental validation of a hydraulic design and control philosophies for 5th Generation District Heating and Cooling Networks
No full textThese datasets are the outputs from two experiments conducted in the Combined Smart Energy Systems (CoSES) laboratory at the Technical University of Munich as part of the PhD of Orestis Angelidis. The experiments aim to experimentally validate novel hydraulic design and control philosophies for 5th Generation District Heating and Cooling Networks. One has fixed grid return temperatures (TGridFix) while the other free floating grid temperatures (TGridFloat). Both feature decentralised variable speed pumping and a centralised passive balancing unit aimed at alleviating control instabilities arising from pump hunting
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
