An exergy-rational district energy model for 100% renewable cities with distance limitations

Kılkış, Birol

doi:10.2298/tsci200412287k

Cited by 7 publications

(6 citation statements)

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“…The holistic model addresses the maximum allowable oneway district piping distance, namely L max , by comparing the exergy of the thermal power, namely . Q D , which is shared among the prosumers and the central district plant by the district consuming exergy for district pumping, P E [37]. The following formulations show that L max must be determined first from the 2nd Law [37].…”

Section: Pv Lifementioning

confidence: 99%

“…Q D , which is shared among the prosumers and the central district plant by the district consuming exergy for district pumping, P E [37]. The following formulations show that L max must be determined first from the 2nd Law [37]. If the average number of floors in prosumers, n increases, the total piping length decreases but the thermal energy transfer in the pipes increases, and solar insolation area per building floor decreases with n. A direct relationship between the pumping power per piping length and the average number of floors has been developed.…”

Section: Pv Lifementioning

confidence: 99%

“…However, 5DE systems between 35 • C to 45 • C offer an advantage for thermal durability. Fire retarding organic material may also be used [37]. liquid, only in the hydronic supply pipe at the bottom, which is slightly larger in diameter, D when compared to standard radiators (SR).…”

Section: = Ln L N `mentioning

confidence: 99%

“…However, 5DE systems between 35 °C to 45 °C offer an advantage for thermal durability. Fire retarding organic material may also be used [37].…”

Section: Economic Optimizationmentioning

confidence: 99%

“…(a) District circuit loop length is optimal concerning pumping exergy spending and thermal exergy distribution. This issue has already been answered (Refer to Reference [37]…”

mentioning

confidence: 98%

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Energy Benefits of Heat Pipe Technology for Achieving 100% Renewable Heating and Cooling for Fifth-Generation, Low-Temperature District Heating Systems

Kılkış

Çağlar²,

Sengul³

2021

Energies

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This paper addresses the challenges the policymakers face concerning the EU decarbonization and total electrification roadmaps towards the Paris Agreement set forth to solve the global warming problem within the framework of a 100% renewable heating and cooling target. A new holistic model was developed based on the Rational Exergy Management Model (REMM). This model optimally solves the energy and exergy conflicts between the benefits of using widely available, low-temperature, low-exergy waste and renewable energy sources, like solar energy, and the inability of existing heating equipment, which requires higher exergy to cope with such low temperatures. In recognition of the challenges of retrofitting existing buildings in the EU stock, most of which are more than fifty years old, this study has developed a multi-pronged solution set. The first prong is the development of heating and cooling equipment with heat pipes that may be customized for supply temperatures as low as 35 °C in heating and as high as 17 °C in cooling, by which equipment oversizing is kept minimal, compared to standard equipment like conventional radiators or fan coils. It is shown that circulating pump capacity requirements are also minimized, leading to an overall reduction of CO2 emissions responsibility in terms of both direct, avoidable, and embodied terms. In this respect, a new heat pipe radiator prototype is presented, performance analyses are given, and the results are compared with a standard radiator. Comparative results show that such a new heat pipe radiator may be less than half of the weight of the conventional radiator, which needs to be oversized three times more to operate at 35 °C below the rated capacity. The application of heat pipes in renewable energy systems with the highest energy efficiency and exergy rationality establishes the second prong of the paper. A next-generation solar photo-voltaic-thermal (PVT) panel design is aimed to maximize the solar exergy utilization and minimize the exergy destruction taking place between the heating equipment. This solar panel design has an optimum power to heat ratio at low temperatures, perfectly fitting the heat pipe radiator demand. This design eliminates the onboard circulation pump, includes a phase-changing material (PCM) layer and thermoelectric generator (TEG) units for additional power generation, all sandwiched in a single panel. As a third prong, the paper introduces an optimum district sizing algorithm for minimum CO2 emissions responsibility for low-temperature heating systems by minimizing the exergy destructions. A solar prosumer house example is given addressing the three prongs with a heat pipe radiator system, next-generation solar PVT panels on the roof, and heat piped on-site thermal energy storage (TES). Results showed that total CO2 emissions responsibility is reduced by 96.8%. The results are discussed, aiming at recommendations, especially directed to policymakers, to satisfy the Paris Agreement.

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Section: Pv Lifementioning

confidence: 99%

Section: Pv Lifementioning

confidence: 99%

Section: = Ln L N `mentioning

confidence: 99%

“…However, 5DE systems between 35 °C to 45 °C offer an advantage for thermal durability. Fire retarding organic material may also be used [37].…”

Section: Economic Optimizationmentioning

confidence: 99%

“…(a) District circuit loop length is optimal concerning pumping exergy spending and thermal exergy distribution. This issue has already been answered (Refer to Reference [37]…”

mentioning

confidence: 98%

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