Performance improvement of integrated CO2 systems with HVAC and hot water for hotels

Smitt, Silje Marie; Tolstorebrov, Ignat; Hafner, Armin

doi:10.1016/j.tsep.2021.100869

Cited by 7 publications

(7 citation statements)

References 29 publications

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“…During operations with low SH demand, most of the DHW load is rejected through GC DHW,2 . This configuration enables continuous low load production of DHW, which in turn reduces gas cooler outlet temperature and enhances overall system COP [30]. The requested DHW heating load is determined based on the energy reserve in the DHW storage, constituted by the temperature and volume in the storage tanks.…”

Section: Design and Operationmentioning

confidence: 99%

“…The aggressive charging strategy represents a common practice in regards to the operation of DHW thermal storage's [29,30]. The aim of the strategy is to charge the DHW storage tanks periodically from low to high temperature, which results in charging over several periods during the day, usually at high loads and intervals of 8 to 12 h. Typically, the aggressive charging strategy is applied when DHW is produced through heat recovery, e.g., from a supermarket, as the heat source is more available for particular hours of the day [44].…”

Section: Aggressive Chargingmentioning

confidence: 99%

“…One of the main conclusions of this study is that COPs improve with DHW charging (compared to SH only), meaning that DHW charging strategy is crucial to boost efficiency. A later numerical study of the same system demonstrated how the energy savings could be reduced with 5.8-13.2% for different seasonal scenarios when charging the DHW storage at low loads [30]. Additional perks of applying the low load charging strategy were reduced peak power usage, operational fluctuations, and ON/OFF cycles.…”

Section: Introductionmentioning

confidence: 97%

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Evaluation of Integrated Concepts with CO2 for Heating, Cooling and Hot Water Production

2021

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The hotel sector is characterized by high thermal demands and a large carbon footprint, which greatly contributes to the global warming effect. Consequently, there is a need to investigate solutions that can reduce energy usage within this sector by means of environmentally friendly and sustainable technologies. Integrated CO2 heat pump systems for heating, cooling, and hot water production in hotels have demonstrated promising results. This paper theoretically compares the energy consumption, environmental impact, and cost of three different design concepts for integrated CO2 units equipped with thermal storage. The main characteristics of the evaluated designs are single-stage compression, parallel compression, and ejector-supported parallel compression. Furthermore, two separate hot water charging strategies were implemented and investigated over a large span of ambient temperatures and loads. The evaluations were carried out by considering eight different European locations, ranging from Scandinavia to the Mediterranean. The results revealed that the ejector-supported parallel compression design was superior in terms of annual COP, which was found to be in the range of 4.27 to 5.01 for the Scandinavian locations and 5.03 to 5.71 for the other European locations. When accounting for investment cost and electricity prices, the payback period at the Scandinavian locations was 6.3 to 7.7 years. Payback periods of 3 and 4.5 to 7.5 were obtained for hotels located in the temperate and Mediterranean climates, respectively. The investigation also revealed that the hot water charging strategy, rather than the specific CO2 heat pump design, is the least expensive measure to enhance performance.

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Section: Design and Operationmentioning

confidence: 99%

Section: Aggressive Chargingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Evaluation of Integrated Concepts with CO2 for Heating, Cooling and Hot Water Production

2021

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“…Some other prominent issues covered by the industry include efforts to ensure energy efficiency (SDG 7). Achieving energy efficiency is critical if the world is to achieve net-zero, particularly in hotel buildings that consume substantial energy used for heating and cooling [78,79]. Because the efforts introduced to ensure energy efficiency are essential, there is a need to measure how the introduced measures are making a difference in pushing down energy demands and ensuring environmental efficiency.…”

Section: Discussionmentioning

confidence: 99%

Sustainable Development Goals Localisation in the Hospitality Sector in Botswana and Zimbabwe

Dube

2021

Sustainability

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Many countries have fronted tourism as a tool for achieving Sustainable Development Goals (SDGs) in their voluntary national reviews. Nevertheless, very few studies have examined how the tourism industry has been localising SDGs. Therefore, this study is borne out of that knowledge gap. A qualitative approach comprising the use of primary and secondary data from integrated annual reports was adopted. The study found some progress made by hotel companies in localising SDGs. It emerged that Cresta Hotels and the African Sun group of hotels are only at the inception stage of SDG localisation, focusing on several SDGs that respond to the socio-economic and environmental demands of the environments they work in. Given that most of the work under the SDGs only began inception between 2018 and 2019, there is still a long way to go before meaningful progress can be reported regarding SDG localization, with preliminary evidence showing that the hotel industry is likely to have made significant inroads when the SDGs lapse in 2030 if their efforts are not disturbed by the COVID-19 pandemic. The study recommends continuous monitoring and support for the sector as the SDG framework offers a better and more focused sector to achieve sustainable and responsible tourism in Zimbabwe and Botswana.

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“…Further, TIL-Suite 3.5 [33] model components such as ports were utilized, which are commonly used and provide reliable results. Smitt et al [42] used these libraries for a variety of components to study integrated energy systems and obtained less than 10 % deviation from the experimentally determined readings. Chamoun et al [30] used a Modelica-based model for the comprehensive analysis of an experimentally tested twin screw compressor.…”

Section: Model Validationmentioning

confidence: 99%

Numerical Investigation of an Oil-Free Liquid-Injected Screw Compressor with Ammonia-Water as Refrigerant for High Temperature Heat Pump Applications

et al. 2022

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Performance improvement of integrated CO2 systems with HVAC and hot water for hotels

Cited by 7 publications

References 29 publications

Evaluation of Integrated Concepts with CO2 for Heating, Cooling and Hot Water Production

Evaluation of Integrated Concepts with CO2 for Heating, Cooling and Hot Water Production

Sustainable Development Goals Localisation in the Hospitality Sector in Botswana and Zimbabwe

Numerical Investigation of an Oil-Free Liquid-Injected Screw Compressor with Ammonia-Water as Refrigerant for High Temperature Heat Pump Applications

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