Field tests, model validation and performance of a CO2 commercial refrigeration plant integrated with HVAC system

D’Agaro, Paola; Coppola, Michele A.; Cortella, Giovanni

doi:10.1016/j.ijrefrig.2019.01.030

Cited by 22 publications

(14 citation statements)

References 15 publications

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“…The findings suggest that also other designing procedures of building systems could be influenced by these differences (considering also the extreme temperatures variations). Among the others, the systems whose efficiency depends on weather conditions should be studied, for example heat pumps [35][36][37], evaporative cooling systems [13,14] or dry coolers [15][16][17] systems, that are relevant for large scale planning, energy savings, water and carbon footprint reduction [38,39].…”

Section: Discussionmentioning

confidence: 99%

Influence of the Meteorological Record Length on the Generation of Representative Weather Files

et al. 2020

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Heat and moisture (HM) transfer simulations of building envelopes and whole building energy simulations require adequate weather files. The common approach is to use weather data of reference years constructed from meteorological records. The weather record affects the capability of representing the real weather of the resulting reference years. In this paper the problem of the influence of the length of the records on the representativeness of the reference years is addressed and its effects are evaluated also for the applicative case of the moisture accumulation risk analysis with the Glaser Method and with DELPHIN 6, confirming that records shorter than 10 years could lead to less representative reference years. On the other hand, it is shown that reference years obtained from longer periods are not representative of the most recent years, which present higher dry-bulb air temperatures due to a short-term climate change effect observed in all the considered weather records. An alternative representative year (Moisture Representative Year) to be used in building energy simulations with a strong dependence on moisture is presented. This requirement could be very restrictive, for example, for the regions with only recently installed weather stations. The aim of this work is to investigate the influence of the MY length on the moisture accumulation risk assessment performed using reference years for four cities of the Northern Italy. In addition, a reference year, alternative to the TMY for the moisture related building simulations is presented. Heat and Moisture Transfer SimulationsThe simulation of the building envelope could be performed considering the coupled transfer of heat and moisture. The resulting simulation provides an accurate calculation of the heat losses, including in the calculations also the variability of the thermal material properties due to the variation of the moisture content and the temperature and the latent heat losses due to the moisture migration. These types of models have been introduced in the whole building energy simulations and their influence has been proven to be relevant in several situations. A review on the effects of an inappropriate estimation of moisture content in materials is presented in [2]. Several examples of calculation methods and tools used to perform these simulations, with different hypotheses, are presented in literature (a review of the simulation methods is presented in [3]). A comparison between the effects of using different models of heat and moisture transfer in EnergyPlus whole building simulations is presented in [4], where the models are used to compare the moisture buffering effect of the hygroscopic materials calculated with different models on the internal environmental conditions. In [5], the implementation of the heat and moisture transfer model that considers the moisture hysteresis of hygroscopic materials (described in [6] and implemented in the software MATCH) is implemented in a whole building simulation tool, BSim). Similarly, [7] presents ...

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Section: Discussionmentioning

confidence: 99%

Influence of the Meteorological Record Length on the Generation of Representative Weather Files

et al. 2020

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“…The refrigerant properties at the principal states of thermodynamic cycle are calculated by linking our in-house routines in the TRNSYS environment to the CoolProp libraries [32]; the instantaneous mass flow rate is calculated in order to satisfy the cooling capacity estimated by the time dependent models of the display cabinets and cold rooms [11], and it defines the status of the compressor racks; the compressors themselves have been described using the manufacturer correlations, while the heat exchangers are modelled via the approach temperature. The detailed description of the refrigeration system, including information on the configuration of the LS and HS compressor racks and activation rules, is given in D'Agaro et al [30], where a thorough calibration and validation process of the model and control rules has been carried out against the yearly field data available from the real plant. The schematic and the thermodynamic cycle in a (p-h) chart are given if Figs.…”

Section: Refrigeration System Modelmentioning

confidence: 99%

“…The mild weather data typical of Modena (Italy) has been considered. It is important to point out that, for the sake of annual energy demand prediction, the booster model includes the electrical demand for auxiliaries, which has been calibrated against monitored data and accounts on average around 3.2 kW [30]. This leads to a reduction of 31.6% for the COP at optimal conditions (pGC, Δtsub)opt with respect to the value of Eq.…”

Section: Yearly Performance Simulationsmentioning

confidence: 99%

“…A comprehensive model was thus built in the TRNSYS environment [26], which includes the transcritical CO2 booster refrigeration unit, as well as the display cabinets and cold rooms, and the possibility of mutual heat exchange with the HVAC plant to perform heat recovery [27,28]. The model has been calibrated and validated against the field data gathered during a whole year from the monitoring of an actual refrigerating system in operation in a small sized supermarket located in Northern Italy as described by Cortella et al [29] and D'Agaro et al [30]. In this paper, the performance of this booster system with a R1234yf DMS unit is analysed.…”

Section: Introductionmentioning

confidence: 99%

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Effect of dedicated mechanical subcooler size and gas cooler pressure control on transcritical CO2 booster systems

D’Agaro

Coppola

Cortella

2021

Applied Thermal Engineering

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Dedicated Mechanical Subcooling (DMS) is one of the most investigated and effective strategies applied to increase the performance of CO2 commercial refrigeration systems in transcritical operation. Further performance benefits can be obtained by a reduction of the gas cooler pressure of the main cycle at transcritical conditions. In this work the most important parameters for the design and operation of such a system, i.e. the DMS cooling capacity, the subcooling degree and the gas cooler pressure, are considered and their effect on the annual energy use of the plant is estimated in warm and hot climate conditions by means of a validated model. DMS is also compared to the parallel compression scheme and subcooling performed through a water chiller dedicated to HVAC. DMS results to be the most effective solution among those investigated, and the choice of the best design and operating parameters allows further energy saving and cost reduction.

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“…Other studies focused on heat recovery from CO2 refrigeration systems to district heating (Raka Adrianto, Grandjean & Sawalha, 2018) or integration of geothermal storage to CO2 refrigeration systems (Mateu-Royo et al, 2018). Two studies that used a similar configuration were carried out by Noding et al (2016) andD'Agaro, Coppola &Cortella (2019). The model developed by Noding et al (2016) aimed to maintain the tank temperature above 32 °C compared to the 45 °C adopted for the model of this paper based on the HVAC system requirements of the supermarket used as a case study.…”

Section: Limitations and Validity Of The Modelmentioning

confidence: 99%

CO2 refrigeration system heat recovery and thermal storage modelling for space heating provision in supermarkets: An integrated approach

et al. 2020

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The large amount of recoverable heat from CO2 refrigeration systems has led UK food retailers to examine the prospect of using refrigeration integrated heating and cooling systems to provide both the space heating and cooling to food cabinets in supermarkets. This study assesses the performance of a refrigeration integrated heating and cooling system installation with thermal storage in a UK supermarket. This is achieved by developing a thermal storage model and integrating it into a pre-existing CO2 booster refrigeration model. Five scenarios involving different configurations and operation strategies are assessed to understand the techoeconomic implications. The results indicate that the integrated heating and cooling system with thermal storage has the potential to reduce energy consumption by 17-18% and GHG emissions by 12-13% compared to conventional systems using a gas boiler for space heating. These reductions are achieved despite a marginal increase of 2-3% in annual operating costs. The maximum amount of heat that can be stored and utilised is constrained by the refrigeration system compressor capacity. These findings suggest that refrigeration integrated heating and cooling systems with thermal storage are a viable heating and cooling strategy that can significantly reduce the environmental footprint of supermarket space heating provision and under the adequate circumstances can forsake the use of conventional fossil-fuel (natural gas) boiler systems in food retail buildings.

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Field tests, model validation and performance of a CO2 commercial refrigeration plant integrated with HVAC system

Cited by 22 publications

References 15 publications

Influence of the Meteorological Record Length on the Generation of Representative Weather Files

Influence of the Meteorological Record Length on the Generation of Representative Weather Files

Effect of dedicated mechanical subcooler size and gas cooler pressure control on transcritical CO2 booster systems

CO2 refrigeration system heat recovery and thermal storage modelling for space heating provision in supermarkets: An integrated approach

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