Integrated CO2 system with HVAC and hot water for hotels: Field measurements and performance evaluation

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

doi:10.1016/j.ijrefrig.2020.03.021

Cited by 15 publications

(10 citation statements)

References 40 publications

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“…The DHW charging strategy is a key influencing factor to achieve a high overall system performance in CO 2 heat pumps [29]. The thermal storage of 6 m 3 provides a buffer that enables a high degree of flexibility with regard to operating strategy.…”

Section: Dhw Charging Strategymentioning

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%

“…CO 2 heat pumps are increasing their presence in the portfolio of different manufacturers in Europe, in some cases adapting existing compressor packs for commercial refrigeration. An example of this is shown in Smitt et al (2020) [29], with a performance analysis based on field measurements of a CO 2 heat pump for integrated production of heating and cooling with a 6 m 3 thermal storage. The study evaluates how different demands change during the specific year and how they affect the different performance indicators.…”

Section: Introductionmentioning

confidence: 99%

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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: Dhw Charging Strategymentioning

confidence: 99%

Section: Aggressive Chargingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…The specific enthalpies at the inlet and outlet of each component or process were determined using the respective measured inlet and outlet temperatures and assumed pressures. The average value of the calculated measurement uncertainty [%] based on the measurement system used is presented in the equation [29].…”

Section: Energy Analysismentioning

confidence: 99%

Integrated high temperature heat pumps and thermal storage tanks for combined heating and cooling in the industry

Ahrens

Foslie

Moen

et al. 2021

Applied Thermal Engineering

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This study investigates the integrated heat pump system of a green-field dairy located in Bergen, Norway. The purpose of the study is to determine the energy consumption and system performance. The dairy features a novel and innovative solution of a fully integrated energy system, employing high temperature heat pumps such as the hybrid absorption-compression heat pump (HACHP) with natural refrigerants to provide all temperature levels of heating and cooling demands. To evaluate the performance an energy analysis has been performed based on available process data for a comparatively energy-intensive week in February. The results have shown that the integrated system is able to meet the occurring demands. Furthermore, the specific energy consumption with 0.22 kWh l − 1 product can outperform the annual average value of the replaced dairy even under difficult conditions. However, it is expected that the specific energy consumption will be further reduced on an annual basis. Through measures such as the extensive use of waste heat recovery accounting for 32.7% of the energy used, energy consumption was reduced by 37.9% and greenhouse gas (GHG) emissions by up to 91.7% compared to conventional dairy systems. Simultaneous, the process achieves a waste heat recovery rate of over 95%. Furthermore, demand peaks were compensated and a system coefficient of performance (COP) of 4.1 was achieved along with the identification of existing potential for further improvements.

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Integrated CO2 system with HVAC and hot water for hotels: Field measurements and performance evaluation

Cited by 15 publications

References 40 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

Integrated high temperature heat pumps and thermal storage tanks for combined heating and cooling in the industry

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