scholarly journals Modeling of a CO2-Based Integrated Refrigeration System for Supermarkets

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6926
Author(s):  
Ángel Á. Pardiñas ◽  
Michael Jokiel ◽  
Christian Schlemminger ◽  
Håkon Selvnes ◽  
Armin Hafner

An integrated energy system that consists of a centralized refrigeration unit can deliver the entire HVAC&R (heating, ventilation, air conditioning, and refrigeration) demand for a supermarket. CO2 (R744) is a natural refrigerant that is becoming increasingly popular for these centralized units due to significant energy and cost savings, while also being sustainable, safe, and non-toxic. This study focuses on the fully integrated CO2 refrigeration system configuration for a supermarket in Porto de Mos, Portugal, which was equipped and fully monitored through the EU-funded project MultiPACK. A dynamic system model was developed in Modelica and validated against measurement data from the site recorded for one week. The model is used to provide additional ejector performance data supporting the obtained measurement data and to evaluate the system configuration at equivalent boundary conditions. The simulation results show that the installation of a vapor ejector (high-pressure lift) is sufficient to improve the efficiency of the unit compared to an ejector-less (high-pressure valve) system. However, more notable enhancements are achieved by including additional flooded evaporation with liquid ejectors and smart regulation of the receiver pressure, adding up to a global efficiency increase of 15% if compared to the high-pressure valve system during the validation week.

Author(s):  
Anita Rønne

Increasing focus on sustainable societies and ‘smart cities’ due to emphasis on mitigation of climate change is simultaneous with ‘smart regulation’ reaching the forefront of the political agenda. Consequently, the energy sector and its regulation are undergoing significant innovation and change. Energy innovations include transition from fossil fuels to more renewable energy sources and application of new computer technology, interactively matching production with consumer demand. Smart cities are growing and projects are being initiated for development of urban areas and energy systems. Analysis from ‘Smart Cities Accelerator’, developed under the EU Interreg funding programme that includes Climate-KIC,——provides background for the focus on a smart energy system. Analysis ensures the energy supply systems support the integration of renewables with the need for new technologies and investments. ‘Smart’ is trendy, but when becoming ‘smart’ leads to motivation that is an important step towards mitigating climate change.


Author(s):  
Sai Liu ◽  
Cheng Zhou ◽  
Haomin Guo ◽  
Qingxin Shi ◽  
Tiancheng E. Song ◽  
...  

AbstractAs a key component of an integrated energy system (IES), energy storage can effectively alleviate the problem of the times between energy production and consumption. Exploiting the benefits of energy storage can improve the competitiveness of multi-energy systems. This paper proposes a method for day-ahead operation optimization of a building-level integrated energy system (BIES) considering additional potential benefits of energy storage. Based on the characteristics of peak-shaving and valley-filling of energy storage, and further consideration of the changes in the system’s load and real-time electricity price, a model of additional potential benefits of energy storage is developed. Aiming at the lowest total operating cost, a bi-level optimal operational model for day-ahead operation of BIES is developed. A case analysis of different dispatch strategies verifies that the addition of the proposed battery scheduling strategy improves economic operation. The results demonstrate that the model can exploit energy storage’s potential, further optimize the power output of BIES and reduce the economic cost.


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