International Journal of Refrigeration-revue Internationale Du Froid最新文献_第7页

Experimental campaign on non-fluorinated refrigerant mixtures in a low-charge heat pump

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-01-23 DOI: 10.1016/j.ijrefrig.2025.01.008

Matteo Caramaschi , Jonas Kjær Jensen , Kasper Korsholm Østergaard , Stefano Poppi , Laure Meljac , Ted Holmberg , Brian Elmegaard

This work experimentally investigated the energy performance of several non-fluorinated refrigerant mixtures and their pure components on a prototype of a low-refrigerant charge single-stage water-to-water heat pump. The pure refrigerants tested in the unit were Propane (R-290), Propylene (R-1270) and Dimethyl Ether (DME, R-E170). In addition, the tested mixtures were Propane-CO₂, Propylene-CO₂, DME-CO₂, Propylene-DME at different compositions and temperatures. Total refrigerant charge amounts, including auxiliary pipes and valves, ranged between 190 g and 290 g. Heating capacities ranged between 3.7 kW and 12.2 kW. The highest capacities were obtained by Propylene-CO₂ [0.93–0.07]. At high source and sink glide conditions, mixing low amounts of CO₂ showed performance enhancements, especially on Propylene and DME. Compared to Propane, DME mixed with 5 % CO₂, resulted in up to 12 % COP enhancement, 16 % lower capacity, and 50 % higher limit heating capacity (LHC). Propylene and the low-glide mixture Propylene-DME performed well at low source and sink glides compared to Propane. Measurements on the refrigerant cycle also suggest that the circulating composition of the mixture slightly shifted toward the most volatile component. The results suggest that well-designed refrigerant mixtures containing Propylene, DME and CO₂ may enhance efficiency, heating capacity, and the heating capacity at maximum charge while maintaining conventional operating pressures and discharge temperatures.

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引用次数: 0

Compressed liquid density and speed of sound measurements and correlation of the binary mixture {carbon dioxide (CO2) + 1,1-difluoroethene (R1132a)} at temperatures from 220 K to 350 K

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-01-22 DOI: 10.1016/j.ijrefrig.2025.01.014

Davide Menegazzo , Aaron J. Rowane , Giulia Lombardo , Sergio Bobbo , Laura Fedele , Mark O. McLinden

The blend of carbon dioxide (CO

_{2}

) and R1132a has been proposed as low-GWP refrigerant for low temperature refrigeration down to −60 °C, as an alternative to R23. This study provides new experimental data on the compressed-liquid density, vapour density, and compressed-liquid speed of sound for the CO

_{2}

+ R1132a binary system. These measurements were obtained using a two-sinker densimeter and a pulse-echo-type speed-of-sound instrument. The density measurements span a temperature range of 220 K to 350 K and pressures up to 30 MPa with an expanded uncertainty ranging from 0.031% to 0.132%, while the speed of sound measurements cover temperatures from 230 K to 350 K and pressures up to 65 MPa with an expanded uncertainty of 0.031% to 1%. For both properties, two different mixture compositions were tested corresponding to mole fractions of CO

_{2}

equal to 0.5942 and 0.7926. Due to the strong absorption of the sound pulse by the mixture, the standard dual-path analysis could not be employed. Therefore, a method utilizing only the short-path signal was developed. Additionally, we present a mixture model based on the experimental data, derived from a Helmholtz energy model, which demonstrates a good fit with the measurements. Finally, we applied this model to compare CO

_{2}

/R1132a mixtures with R23 and other alternatives. This preliminary analysis revealed the potential of CO

_{2}

/R1132a as possible low-GWP and near-azeotropic refrigerants, less flammable than hydrocarbon-based mixtures and capable of providing cold at −60 °C.

{"title":"Compressed liquid density and speed of sound measurements and correlation of the binary mixture {carbon dioxide (CO2) + 1,1-difluoroethene (R1132a)} at temperatures from 220 K to 350 K","authors":"Davide Menegazzo , Aaron J. Rowane , Giulia Lombardo , Sergio Bobbo , Laura Fedele , Mark O. McLinden","doi":"10.1016/j.ijrefrig.2025.01.014","DOIUrl":"10.1016/j.ijrefrig.2025.01.014","url":null,"abstract":"<div><div>The blend of carbon dioxide (CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>) and R1132a has been proposed as low-GWP refrigerant for low temperature refrigeration down to −60 °C, as an alternative to R23. This study provides new experimental data on the compressed-liquid density, vapour density, and compressed-liquid speed of sound for the CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> + R1132a binary system. These measurements were obtained using a two-sinker densimeter and a pulse-echo-type speed-of-sound instrument. The density measurements span a temperature range of 220 K to 350 K and pressures up to 30 MPa with an expanded uncertainty ranging from 0.031% to 0.132%, while the speed of sound measurements cover temperatures from 230 K to 350 K and pressures up to 65 MPa with an expanded uncertainty of 0.031% to 1%. For both properties, two different mixture compositions were tested corresponding to mole fractions of CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> equal to 0.5942 and 0.7926. Due to the strong absorption of the sound pulse by the mixture, the standard dual-path analysis could not be employed. Therefore, a method utilizing only the short-path signal was developed. Additionally, we present a mixture model based on the experimental data, derived from a Helmholtz energy model, which demonstrates a good fit with the measurements. Finally, we applied this model to compare CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>/R1132a mixtures with R23 and other alternatives. This preliminary analysis revealed the potential of CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>/R1132a as possible low-GWP and near-azeotropic refrigerants, less flammable than hydrocarbon-based mixtures and capable of providing cold at −60 °C.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"172 ","pages":"Pages 1-16"},"PeriodicalIF":3.5,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143173648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental compressed liquid density measurements and correlation of the binary mixture {3,3,3-trifuoropropene (R1243zf) + isobutane (R600a)}

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-01-21 DOI: 10.1016/j.ijrefrig.2025.01.013

Davide Menegazzo , Giulia Lombardo , Laura Vallese , Mauro Scattolini , Sergio Bobbo , Laura Fedele

In the context of evolving regulations such as the F-gas Regulation and the Kigali Amendment to the Montreal Protocol, the exploration of alternatives to fluorinated greenhouse gases in air conditioning and refrigeration has garnered significant attention. Essential attributes sought in viable refrigerants encompass low Global Warming Potential (GWP), thermodynamic cycle efficiency, non-flammability, non-toxicity, material compatibility, and cost-effectiveness. Hydrofluoroolefins (HFOs) have emerged as promising replacements for hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) in HVAC and refrigeration systems. Simultaneously, the quest for low GWP refrigerants has prompted a revaluation of hydrocarbons (HCs) like propane (R290) and isobutane (R600a), renowned for their efficiency, minimal charge requirements, and affordability despite their flammability. While extensive data and reliable Equations of State (EoS) are available for HCs, HFOs lack comprehensive information. This study contributes empirical measurements on the compressed liquid density of the 3,3,3-trifluoropropene (R1243zf) + isobutane (R600a) binary system. Utilizing a vibrating tube densimeter, measurements were conducted on three mixture compositions within the temperature range of 283.15 K to 353.15 K and at pressures ranging from near saturation to 35 MPa. The obtained dataset, combined with existing literature, served as the basis for a new mixture model developed using the Helmholtz-energy-explicit EoS. This model accurately represents the behaviour of the binary mixture, enhancing the available understanding of its thermodynamic properties.

{"title":"Experimental compressed liquid density measurements and correlation of the binary mixture {3,3,3-trifuoropropene (R1243zf) + isobutane (R600a)}","authors":"Davide Menegazzo , Giulia Lombardo , Laura Vallese , Mauro Scattolini , Sergio Bobbo , Laura Fedele","doi":"10.1016/j.ijrefrig.2025.01.013","DOIUrl":"10.1016/j.ijrefrig.2025.01.013","url":null,"abstract":"<div><div>In the context of evolving regulations such as the F-gas Regulation and the Kigali Amendment to the Montreal Protocol, the exploration of alternatives to fluorinated greenhouse gases in air conditioning and refrigeration has garnered significant attention. Essential attributes sought in viable refrigerants encompass low Global Warming Potential (GWP), thermodynamic cycle efficiency, non-flammability, non-toxicity, material compatibility, and cost-effectiveness. Hydrofluoroolefins (HFOs) have emerged as promising replacements for hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) in HVAC and refrigeration systems. Simultaneously, the quest for low GWP refrigerants has prompted a revaluation of hydrocarbons (HCs) like propane (R290) and isobutane (R600a), renowned for their efficiency, minimal charge requirements, and affordability despite their flammability. While extensive data and reliable Equations of State (EoS) are available for HCs, HFOs lack comprehensive information. This study contributes empirical measurements on the compressed liquid density of the 3,3,3-trifluoropropene (R1243zf) + isobutane (R600a) binary system. Utilizing a vibrating tube densimeter, measurements were conducted on three mixture compositions within the temperature range of 283.15 K to 353.15 K and at pressures ranging from near saturation to 35 MPa. The obtained dataset, combined with existing literature, served as the basis for a new mixture model developed using the Helmholtz-energy-explicit EoS. This model accurately represents the behaviour of the binary mixture, enhancing the available understanding of its thermodynamic properties.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"172 ","pages":"Pages 64-74"},"PeriodicalIF":3.5,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143173647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Performance investigation of a novel multi-parameter adjustable ejector with a broad operating range

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-01-20 DOI: 10.1016/j.ijrefrig.2025.01.020

Xinyue Hao , Dejiang Liu , Neng Gao , Guangming Chen , Lina Zhang , Qiu Tu

Ejectors can be extensively used in industry and other fields, such as fuel cells, etc., to reduce pressure energy loss or recover low-pressure fluids. However, constant-dimension ejectors are difficult to meet with high efficiency under different operating conditions. This paper investigates the dimensional adjustment strategy of adjustable ejectors under varying fluid flow rates and working pressures, analyzing performance before and after adjustment. Computational Fluid Dynamics (CFD) simulations and experiments were conducted for performance testing and verification. The performance advantages of adjustable ejectors under varying operating conditions are highlighted in a new study, which offers both theoretical and experimental backing for broader implementation. The actual working region is innovatively divided according to the working performance of the ejector. The findings reveal that maintaining optimal dimensions is crucial for high performance, especially under fluctuating primary fluid pressures, where nozzle and mixing chamber dimensional adjustments are essential to maintaining efficiency. Experimental results show that adjusting the ejector dimensions (B2) in response to primary fluid pressure increases (1000 kPa to 1300 kPa) maintains the entrainment ratio and improves performance by up to 28.5 %, preventing significant efficiency drops. This research offers significant insights into the practical application and tuning of ejectors in dynamic systems.

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引用次数: 0

Numerical investigation on flow characteristics and working performance in oil-injected sliding vane rotary compressors

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-01-16 DOI: 10.1016/j.ijrefrig.2025.01.018

Yuande Dai , Huiyang Zhu , Giuseppe Bianchi , Sham Rane , Fanghua Ye

Oil is injected into Sliding Vane Rotary Compressors (SVRCs) for cooling, sealing and lubrication purposes. This paper presents numerical investigations on the oil-gas two-phase flow characteristics of the SVRC followed by studying the effects of the oil injection parameters on the compressor performance. The analytical grid generation methodology was employed to discretise the rotating and deforming rotor fluid domain. The Computational Fluid Dynamics (CFD) model of the SVRC was developed and validated with experimental test data. The flow topology was analyzed to illustrate the flow and oil distribution features within the compressor. Moreover, the influence of the oil injection parameters (oil to gas ratio, oil injection angle, oil injection temperature and rotational speed) on the compressor performance were explored. The results show that the oil accumulates at the leading sides of the blades and then flows into the blade tip region, which helps to reduce the internal leakage. In the reference case, the compressor achieves the volumetric efficiency of 95.1 %, the adiabatic efficiency of 60.3 %, the exhaust temperature of 337.4 K and the specific power of 9.86 kW/(m³ min^-1). Furthermore, increasing oil to gas ratio leads to better cooling and sealing performance, but also results in higher specific power. Oil to gas mass ratio has higher sensitivity than oil injection temperature or angle. About 8° shift in oil injection angle results in 4.2 % decrease in specific power. The lubricating oil capacity should be increased accordingly to the increasing rotational speed.

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引用次数: 0

Impact of freezing technologies on the quality of catfish (Ictalurus punctatus) fillets: Insights from protein properties and ice crystal analysis

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-01-16 DOI: 10.1016/j.ijrefrig.2025.01.009

Huiyuan Jin , Yajin Zhang , Miao Shi , Tao Yin , Ru Liu , Youming Liu , Juan You

The effects of air freezing (AF), saline immersion freezing (SIF), composite immersion freezing (CIF), and liquid nitrogen spray freezing (LNSF) on the muscle quality, protein properties, and microstructure of catfish fillets were investigated. The results indicated that LNSF improved water retention of frozen catfish fillets, maintained hardness, reduced water migration, and exhibited lower fat oxidation and protein denaturation levels compared to other freezing methods. Ice crystals observations through polarizing light microscopy revealed that dendritic ice crystals between muscle fascicles grew vertically to the direction of the muscle fascicles. In contrast, ice crystals within the muscle fascicles grew parallel to them. The LNSF effectively reduced pore and ice crystal sizes, resulting in a denser muscle fiber structure. These findings suggested that LNSF effectively preserved the moisture and freshness of the samples and was the most energy-efficient method for maintaining the quality of catfish fillets compared to the other treatments.

{"title":"Impact of freezing technologies on the quality of catfish (Ictalurus punctatus) fillets: Insights from protein properties and ice crystal analysis","authors":"Huiyuan Jin , Yajin Zhang , Miao Shi , Tao Yin , Ru Liu , Youming Liu , Juan You","doi":"10.1016/j.ijrefrig.2025.01.009","DOIUrl":"10.1016/j.ijrefrig.2025.01.009","url":null,"abstract":"<div><div>The effects of air freezing (AF), saline immersion freezing (SIF), composite immersion freezing (CIF), and liquid nitrogen spray freezing (LNSF) on the muscle quality, protein properties, and microstructure of catfish fillets were investigated. The results indicated that LNSF improved water retention of frozen catfish fillets, maintained hardness, reduced water migration, and exhibited lower fat oxidation and protein denaturation levels compared to other freezing methods. Ice crystals observations through polarizing light microscopy revealed that dendritic ice crystals between muscle fascicles grew vertically to the direction of the muscle fascicles. In contrast, ice crystals within the muscle fascicles grew parallel to them. The LNSF effectively reduced pore and ice crystal sizes, resulting in a denser muscle fiber structure. These findings suggested that LNSF effectively preserved the moisture and freshness of the samples and was the most energy-efficient method for maintaining the quality of catfish fillets compared to the other treatments.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"173 ","pages":"Pages 44-54"},"PeriodicalIF":3.5,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical study on effects of wettability on performances of CO2 ejector

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-01-16 DOI: 10.1016/j.ijrefrig.2025.01.015

Fang Liu , Wei Yang , Shuai Jia , Pengfei Li

Inner wall surface wettability could affect ejector performances, however, no-slip wall boundary conditions were mostly assumed in CO₂ ejector simulation studies. In this study, we introduced velocity slip boundary condition into the 3D heterogeneous mixture model for a two-phase CO₂ ejector, by using different apparent contact angle at the inner wall of mixing chamber, motive nozzle or diffuser. Numerical simulation results show that the inner wall wettability of mixing chamber and diffuser affects flow and mass transfer in a CO₂ ejector significantly, while the inner wall wettability of motive nozzle affects ejector performances very slightly. As apparent contact angle increases from 5° to 175°, resulting in the change of slip condition from negative slip to no-slip then to positive slip, velocity in mixing chamber increases, pressure in mixing chamber decreases, expansion angle after motive nozzle outlet decreases, thus backflow vortices become smaller then disappear. This leads to an increase in suction mass flow rate, and entrainment ratio can be enhanced over 15 %. Correlations between entrainment ratio and apparent contact angle at the wall of different parts in ejector were developed. As the wall wettability changes from hydrophilic to superhydrophobic, the variation trends of ejector performances are similar under different operating conditions with motive nozzle inlet in the supercritical, near-critical, and subcritical regions. This study is helpful to understand flow mechanisms inside the CO₂ ejector with different wall wettability, and provides a new approach to improve the performances of a two-phase CO₂ ejector by changing wall surface wettability.

{"title":"Numerical study on effects of wettability on performances of CO2 ejector","authors":"Fang Liu , Wei Yang , Shuai Jia , Pengfei Li","doi":"10.1016/j.ijrefrig.2025.01.015","DOIUrl":"10.1016/j.ijrefrig.2025.01.015","url":null,"abstract":"<div><div>Inner wall surface wettability could affect ejector performances, however, no-slip wall boundary conditions were mostly assumed in CO<sub>2</sub> ejector simulation studies. In this study, we introduced velocity slip boundary condition into the 3D heterogeneous mixture model for a two-phase CO<sub>2</sub> ejector, by using different apparent contact angle at the inner wall of mixing chamber, motive nozzle or diffuser. Numerical simulation results show that the inner wall wettability of mixing chamber and diffuser affects flow and mass transfer in a CO<sub>2</sub> ejector significantly, while the inner wall wettability of motive nozzle affects ejector performances very slightly. As apparent contact angle increases from 5° to 175°, resulting in the change of slip condition from negative slip to no-slip then to positive slip, velocity in mixing chamber increases, pressure in mixing chamber decreases, expansion angle after motive nozzle outlet decreases, thus backflow vortices become smaller then disappear. This leads to an increase in suction mass flow rate, and entrainment ratio can be enhanced over 15 %. Correlations between entrainment ratio and apparent contact angle at the wall of different parts in ejector were developed. As the wall wettability changes from hydrophilic to superhydrophobic, the variation trends of ejector performances are similar under different operating conditions with motive nozzle inlet in the supercritical, near-critical, and subcritical regions. This study is helpful to understand flow mechanisms inside the CO<sub>2</sub> ejector with different wall wettability, and provides a new approach to improve the performances of a two-phase CO<sub>2</sub> ejector by changing wall surface wettability.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"171 ","pages":"Pages 267-283"},"PeriodicalIF":3.5,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143149126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental retrofit of an R404A/R23 ultra-low temperature freezer using R448A and electronic expansion valves

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-01-16 DOI: 10.1016/j.ijrefrig.2025.01.017

Pau Giménez-Prades, Joaquín Navarro-Esbrí, Cosmin-Mihai Udroiu, Adrián Mota-Babiloni

The lack of regulations that limit the GWP of refrigerants operating in vapour compression systems with a target temperature below –50°C has caused slower market development. Therefore, limited refrigerants and technologies for ultra-low temperature (ULT) refrigeration have been studied. In this work, an experimental assessment of R448A as a lower-GWP alternative to R404A in the high-temperature stage of a ULT two-stage cascade refrigeration system is done using R23 as the low-temperature stage refrigerant. Furthermore, capillary tubes and electronic expansion valves are compared as expansion devices. First, the pull-down performance starting from three room temperatures (15, 20, and 25°C) down to –80°C is analysed. Then, the hysteresis operation with those ambient temperatures and set freezer temperatures of –80, –70, –60, and –50°C is studied. The pull-down time was higher (38 to 55 min slower) using the capillary tubes compared to the electronic expansion valves. Also, the energy consumption of the hysteresis operation was higher (up to 32.3% higher) using the capillary tubes. The electronic expansion valves obtained comparable energy consumption and cooling capacity with R404A/R23 and R448A/R23. The highest COP is achieved by R448A/R23 (up to 10.2% higher than R404A/R23). Therefore, the suitability of R448A as a replacement for R404A in ULT refrigeration is confirmed.

{"title":"Experimental retrofit of an R404A/R23 ultra-low temperature freezer using R448A and electronic expansion valves","authors":"Pau Giménez-Prades, Joaquín Navarro-Esbrí, Cosmin-Mihai Udroiu, Adrián Mota-Babiloni","doi":"10.1016/j.ijrefrig.2025.01.017","DOIUrl":"10.1016/j.ijrefrig.2025.01.017","url":null,"abstract":"<div><div>The lack of regulations that limit the GWP of refrigerants operating in vapour compression systems with a target temperature below –50°C has caused slower market development. Therefore, limited refrigerants and technologies for ultra-low temperature (ULT) refrigeration have been studied. In this work, an experimental assessment of R448A as a lower-GWP alternative to R404A in the high-temperature stage of a ULT two-stage cascade refrigeration system is done using R23 as the low-temperature stage refrigerant. Furthermore, capillary tubes and electronic expansion valves are compared as expansion devices. First, the pull-down performance starting from three room temperatures (15, 20, and 25°C) down to –80°C is analysed. Then, the hysteresis operation with those ambient temperatures and set freezer temperatures of –80, –70, –60, and –50°C is studied. The pull-down time was higher (38 to 55 min slower) using the capillary tubes compared to the electronic expansion valves. Also, the energy consumption of the hysteresis operation was higher (up to 32.3% higher) using the capillary tubes. The electronic expansion valves obtained comparable energy consumption and cooling capacity with R404A/R23 and R448A/R23. The highest COP is achieved by R448A/R23 (up to 10.2% higher than R404A/R23). Therefore, the suitability of R448A as a replacement for R404A in ULT refrigeration is confirmed.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"171 ","pages":"Pages 217-227"},"PeriodicalIF":3.5,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143149081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Cryoprotective potential of vegetable powders and polydextrose in frozen bread doughs

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-01-16 DOI: 10.1016/j.ijrefrig.2025.01.010

Diana Jessica Souza Guimarães, Rafael Audino Zambelli, Marcos Rodrigues Amorim Afonso, Dorasílvia Ferreira Pontes

This study investigates the impact of adding vegetable powders (tomato, broccoli, and açaí) and polydextrose on the quality of bread made from doughs frozen for up to 60 days. Analyses included yeast cell viability, dough expansion factor, bread's specific volume, instrumental texture, and scanning electron microscopy. Freezing significantly alters gluten structure and yeast cell viability. Control bread showed an 88 % reduction in viable yeast cells after 60 days of frozen storage, whereas bread supplemented with vegetable powders exhibited a maximum reduction of 74 %. The best results were obtained with the addition of 10 % açaí powder and 5 % polydextrose, with only a 48 % reduction in viable cells after 60 days. The fermentative capacity of frozen doughs declined by approximately 30–50 %, leading to denser, less uniform bread texture. Control doughs showed a 67 % reduction in expansion capacity. Dough formulations with polydextrose and vegetable powders initially demonstrated enhanced characteristics, with specific volume increased and softness retained up to 30 % more than in control samples. Although all formulations experienced changes after extended frozen storage, those supplemented with vegetable powders and polydextrose showed less damage to both the gluten and starch networks, preserving a smoother internal crumb structure. After 60 days, control doughs exhibited irregular holes in the gluten network, while doughs containing these ingredients displayed fewer structural disruptions. This study confirms the cryoprotective potential of vegetable powders and polydextrose in improving the shelf life and textural quality of breads from frozen doughs.

{"title":"Cryoprotective potential of vegetable powders and polydextrose in frozen bread doughs","authors":"Diana Jessica Souza Guimarães, Rafael Audino Zambelli, Marcos Rodrigues Amorim Afonso, Dorasílvia Ferreira Pontes","doi":"10.1016/j.ijrefrig.2025.01.010","DOIUrl":"10.1016/j.ijrefrig.2025.01.010","url":null,"abstract":"<div><div>This study investigates the impact of adding vegetable powders (tomato, broccoli, and açaí) and polydextrose on the quality of bread made from doughs frozen for up to 60 days. Analyses included yeast cell viability, dough expansion factor, bread's specific volume, instrumental texture, and scanning electron microscopy. Freezing significantly alters gluten structure and yeast cell viability. Control bread showed an 88 % reduction in viable yeast cells after 60 days of frozen storage, whereas bread supplemented with vegetable powders exhibited a maximum reduction of 74 %. The best results were obtained with the addition of 10 % açaí powder and 5 % polydextrose, with only a 48 % reduction in viable cells after 60 days. The fermentative capacity of frozen doughs declined by approximately 30–50 %, leading to denser, less uniform bread texture. Control doughs showed a 67 % reduction in expansion capacity. Dough formulations with polydextrose and vegetable powders initially demonstrated enhanced characteristics, with specific volume increased and softness retained up to 30 % more than in control samples. Although all formulations experienced changes after extended frozen storage, those supplemented with vegetable powders and polydextrose showed less damage to both the gluten and starch networks, preserving a smoother internal crumb structure. After 60 days, control doughs exhibited irregular holes in the gluten network, while doughs containing these ingredients displayed fewer structural disruptions. This study confirms the cryoprotective potential of vegetable powders and polydextrose in improving the shelf life and textural quality of breads from frozen doughs.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"172 ","pages":"Pages 108-119"},"PeriodicalIF":3.5,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143175228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Fault diagnosis in split-system air conditioner by analyzing the chaos in the electrical current signal

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-01-15 DOI: 10.1016/j.ijrefrig.2025.01.011

Anderson Carlos de Oliveira , Abel Cavalcante Lima Filho , Julio Cesar da Silva , Francisco Antonio Belo , Alisson Vasconcelos de Brito , Jorge Gabriel Gomes de Souza Ramos

Computational technological advances for data processing have increasingly contributed to the evolution of predictive techniques for fault detection and diagnosis (FDD) of motors and machines. As a novelty, this article presents the application of the Signal Analysis based on Chaos using Density of Maxima (SAC-DM) technique in split-system air conditioner equipment to diagnose the occurrence of faults. To this end, a short-term acquisition of the electrical signal at the equipment input was carried out in a non-invasive way, subsequently, the proposed technique is used for diagnosing compressor capacitor degradation and incrustation in the condenser and evaporator units at different blocking levels. The results prove a better accuracy compared to the Fast Fourier transform (FFT), making it possible to detect and diagnose air conditioner faults, with an accuracy of 100 % for FDD of single faults, 96.55 % for detection and 82.76 % for diagnosis of dual faults. In addition, the technique demands only short-term data acquisition and a single experiment to detect and diagnose the faults.

{"title":"Fault diagnosis in split-system air conditioner by analyzing the chaos in the electrical current signal","authors":"Anderson Carlos de Oliveira , Abel Cavalcante Lima Filho , Julio Cesar da Silva , Francisco Antonio Belo , Alisson Vasconcelos de Brito , Jorge Gabriel Gomes de Souza Ramos","doi":"10.1016/j.ijrefrig.2025.01.011","DOIUrl":"10.1016/j.ijrefrig.2025.01.011","url":null,"abstract":"<div><div>Computational technological advances for data processing have increasingly contributed to the evolution of predictive techniques for fault detection and diagnosis (FDD) of motors and machines. As a novelty, this article presents the application of the Signal Analysis based on Chaos using Density of Maxima (SAC-DM) technique in split-system air conditioner equipment to diagnose the occurrence of faults. To this end, a short-term acquisition of the electrical signal at the equipment input was carried out in a non-invasive way, subsequently, the proposed technique is used for diagnosing compressor capacitor degradation and incrustation in the condenser and evaporator units at different blocking levels. The results prove a better accuracy compared to the Fast Fourier transform (FFT), making it possible to detect and diagnose air conditioner faults, with an accuracy of 100 % for FDD of single faults, 96.55 % for detection and 82.76 % for diagnosis of dual faults. In addition, the technique demands only short-term data acquisition and a single experiment to detect and diagnose the faults.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"172 ","pages":"Pages 228-239"},"PeriodicalIF":3.5,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143372712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0