Listar EMC_Articles por autoría "b59c227e-3dc5-4b49-a045-27c8897575d8"
Mostrando ítems 1-20 de 78
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A dynamic model of a shell-and-tube condenser operating in a vapour compression refrigeration plant
Llopis, Rodrigo; Cabello López, Ramón; Torrella Alcaraz, Enrique Elsevier (2008)This work presents a mathematical model of a shell-and-tube condenser based on mass continuity, energy conservation and heat transfer physical fundamentals, whose methodology can be easily adapted for modelling any type ... -
A new approach to optimize the energy efficiency of CO2 transcritical refrigeration plants
Peñarrocha-Alós, Ignacio; Llopis, Rodrigo; Tárrega Ruiz, Luis; Sánchez García-Vacas, Daniel; Cabello López, Ramón Elsevier (2014-06)This paper proposes a model-free real-time optimization and control strategy for CO2 transcritical refrigeration plants that assures covering the cooling demand and continuous tracking of conditions for maximum efficiency. ... -
A novel method to measure the energy efficiency and performance of an auto-cascade refrigeration cycle
Llopis, Rodrigo; Martínez Ángeles, Manel; García-Valero, Marc Elsevier (2023-10)Auto-cascade refrigeration systems are the most used cycles to maintain spaces at ultra-low temperature conditions (-80 to −60 °C). The interest in these systems has risen due to the need to maintain and distribute COVID-19 ... -
A simplified model for shell-and-tubes heat exchangers: Practical application
Vera García, Francisco José; García Cascales, J.R.; Gonzálvez Maciá, J.; Cabello López, Ramón; Llopis, Rodrigo; Sánchez García-Vacas, Daniel; Torrella Alcaraz, Enrique Elsevier (2010)In this paper, a simplified model for the study of shell-and-tubes heat exchangers (HXs) is proposed. The model aims to agree with the HXs when they are working as condensers or evaporators. Despite its simplicity, the ... -
A3 and A2 refrigerants: Border determination and hunt for A2 low-GWP blends
Calleja-Anta, Daniel; Nebot-Andres, Laura; Cabello López, Ramón; Sánchez García-Vacas, Daniel; Llopis, Rodrigo Elsevier Ltd. (2021-11-26)The hunt for new refrigerant blends has been concentrated to locate A1 refrigerants. However, the investigation for A2 or A2L blends to replace hydrocarbons (A3) has not attracted attention yet, although these mixtures ... -
Alternative blends of CO2 for transcritical refrigeration systems. Experimental approach and energy analysis
Sánchez García-Vacas, Daniel; Vidan-Falomir, Francisco; Nebot-Andres, Laura; Llopis, Rodrigo; Cabello López, Ramón Elsevier (2023-02-10)As a natural refrigerant, Carbon Dioxide (CO2) has been extended in almost all refrigeration fields due to its environmental friendliness, high availability, and high technological development in the main components of the ... -
Alternative CO2-based blends for transcritical refrigeration systems
Sánchez García-Vacas, Daniel; Vidan-Falomir, Francisco; Larrondo Sancho, Rafael; Llopis, Rodrigo; Cabello López, Ramón Elsevier (2023-03-21)The extensive use of CO2 in commercial refrigeration system has grown in the last two decade thanks to the development of new components and configurations that allows working in transcritical conditions efficiently. ... -
Alternative mixtures to R-600a. Theoretical assessment and experimental energy evaluation of binary mixtures in a commercial cooler
Calleja-Anta, Daniel; Sánchez García-Vacas, Daniel; Nebot Andrés, Laura; Cabello López, Ramón; Llopis, Rodrigo Elsevier (2023-08-01)This work focuses on the exploration of binary mixtures as alternative to isobutane (R-600a) from a theoretical and experimental point of view. To predict the most energy efficient blends, a theoretical model was used that ... -
CO2 with Mechanical Subcooling vs. CO2 Cascade Cycles for Medium Temperature Commercial Refrigeration Applications Thermodynamic Analysis
Nebot-Andres, Laura; Llopis, Rodrigo; Sánchez García-Vacas, Daniel; Catalán-Gil, Jesús; Cabello López, Ramón MDPI (2017-09)A recent trend to spread the use of CO2 refrigeration cycles in warm regions of the world is to combine a CO2 cycle with another one using a high performance refrigerant. Two alternatives are being considered: cascade and ... -
Comparative evaluation of the intermediate systems employed in two-stage refrigeration cycles driven by compound compressors
Cabello López, Ramón; Torrella Alcaraz, Enrique; Llopis, Rodrigo; Sánchez García-Vacas, Daniel Elsevier (2010)This work presents an experimental evaluation, from an energy analysis point of view, for two of the most used inter-stage systems in two-stage vapour compression cycles driven by compound compressors: the direct liquid ... -
Compressor model for CO2-doped blends. Correction factor of EN 12900 for mixtures with R152a, R290, R1233zd(E)
Martínez-Ángeles, Manel; Calleja-Anta, Daniel; Nebot-Andres, Laura; Llopis, Rodrigo Elsevier (2024-08-15)It has been experimentally verified that doping CO2 with small amounts of other fluids enhances the COP of refrigeration systems thanks to the modification of the thermophysical properties, as it increases the critical ... -
Conversion of a direct to an indirect commercial (HFC134a/CO2) cascade refrigeration system: Energy impact analysis
Sánchez García-Vacas, Daniel; Llopis, Rodrigo; Cabello López, Ramón; Catalán-Gil, Jesús; Nebot-Andres, Laura Elsevier (2017)Energy impact of conversion of a direct HFC134a/CO2 cascade refrigeration system to an indirect HFC134a-secondary fluid / CO2 cascade for commercial applications is experimentally analysed. Refrigeration systems, fully ... -
Conversion of a Direct to an Indirect Refrigeration System at Medium Temperature Using R-134a and R-507A: An Energy Impact Analysis
Llopis, Rodrigo; Sánchez García-Vacas, Daniel; Cabello López, Ramón; Catalán-Gil, Jesús; Nebot-Andres, Laura MDPI (2018-02-06)This work presents the experimental evaluation of energy consumption and refrigerant charge reduction when a commercial direct expansion refrigeration system is converted into an indirect system. The evaluation (with R-134a ... -
Development and validation of a finite element model for water – CO2 coaxial gas-coolers
Sánchez García-Vacas, Daniel; Cabello López, Ramón; Llopis, Rodrigo; Torrella Alcaraz, Enrique Elsevier (2012-05)The gas-cooler heat exchanger is a characteristic device of the refrigeration plants that use CO2 as the working fluid in transcritical conditions. The proper gas-cooler sizing, allows getting the maximum effectiveness in ... -
Drop-in substitutes for R-600a. Experimental evaluation and optimization of a commercial fridge
Calleja-Anta, Daniel; Nebot-Andres, Laura; Sánchez García-Vacas, Daniel; Cabello López, Ramón; Llopis, Rodrigo Elsevier (2022-07-05)This work aims to validate the hypothesis that refrigerant blends could allow energy savings in real refrigeration systems. For that purpose, five selected blends have been evaluated as drop-in substitutes in a domestic ... -
Effects caused by the internal heat exchanger at the low temperature cycle in a cascade refrigeration plant
Llopis, Rodrigo; Sanz Kock, Carlos; Cabello López, Ramón; Sánchez García-Vacas, Daniel; Nebot-Andres, Laura; Catalán-Gil, Jesús Elsevier (2016)This work analyses and quantifies the effects caused by the use of an internal heat exchanger (IHX) at the CO2 subcritical cycle in an HFC134a/CO2 cascade refrigeration plant that incorporates a gas-cooler at the exit ... -
Energetic evaluation of a CO2 refrigeration plant working in supercritical and subcritical conditions
Sánchez García-Vacas, Daniel; Patiño Pérez, Jorge; Sanz Kock, Carlos; Llopis, Rodrigo; Cabello López, Ramón; Torrella Alcaraz, Enrique Elsevier (2014-05)Unlike other refrigerants, R744 (or carbon dioxide) has a very low critical temperature (30.98 °C) which hampers working in subcritical conditions especially when the environment is used as a heat rejection sink. Accordingly, ... -
Energetic evaluation of an internal heat exchanger in a CO2 transcritical refrigeration plant using experimental data
Torrella Alcaraz, Enrique; Sánchez García-Vacas, Daniel; Llopis, Rodrigo; Cabello López, Ramón Elsevier (2011)The performance of an Internal Heat Exchanger (IHX) operating in a CO2 transcritical refrigeration plant is analysed, from an energetic point of view, in this work. The evaluation is based on experimental data by contrasting ... -
Energy analysis of dedicated and integrated mechanical subcooled CO2 boosters for supermarket applications
Catalán-Gil, Jesús; Llopis, Rodrigo; Sánchez García-Vacas, Daniel; Nebot-Andres, Laura; Cabello López, Ramón Elsevier (2019-03)Energy improvements offered by dedicated and integrated mechanical subcooling systems in CO2 booster systems for supermarket applications are analyzed here through the use of thermodynamic models close to reality. Using a ... -
Energy and environmental comparison of two-stage solutions for commercial refrigeration at low temperature: Fluids and systems
Llopis, Rodrigo; Sánchez García-Vacas, Daniel; Sanz Kock, Carlos; Cabello López, Ramón; Torrella Alcaraz, Enrique Elsevier (2015-01-15)International agreements will restrict in the near future the use of high-GWP refrigerants in Europe. These restrictions will favour the implantation of refrigeration systems with low-GWP fluids, especially in applications ...