International Journal of Refrigeration-revue Internationale Du Froid最新文献

英文中文

Characterising airflow and heat transfer within a multi-package of horticultural produce using a validated CFD model

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-02-01 DOI: 10.1016/j.ijrefrig.2024.12.003

Ahmad Nasser eddine , Steven Duret , Denis Flick , Jean Moureh

Modified Atmosphere Packaging (MAP) is extensively used for highly perishable items to extend their shelf life by reducing their physiological activity. However, this solution involves non-ventilated packaging materials which hinder direct contact of cooling air with the product, thereby affecting the cooling rate of MAPs when packaged in ventilated trays. This research developed a Computational Fluid Dynamics (CFD) model to predict airflow within a half layer of a strawberry-ventilated pallet, consisting of two trays with 16 airtight clamshells (AC) each, representing modified atmosphere packaging. Within the ACs, the internal domain was modelled as an equivalent solid block representing both air and strawberries. Three tray designs were compared to assess the impact of vent holes and their positions on airflow behaviour and cooling rate. The model was validated using experimental data, showing a good agreement for air velocities and cooling characteristics.

The analysis revealed that in the current tray design (TD 1) with a single main trapezoidal orifice on the longitudinal surface, airflow was uneven, with 24 % traversing the headspace and 76 % through the channels between ACs. This design caused recirculation near the tray's edge and poor ventilation within the channels of this area, leading to heterogenous cooling among ACs. This heterogeneity in cooling resulted in differences of up to 2 h in Half Cooling Time. Numerical simulations indicated that adding vent holes to the tray does not guarantee an improved cooling rate and uniformity. The effectiveness of vent holes depended on their placement relative to ACs arrangement.

{"title":"Characterising airflow and heat transfer within a multi-package of horticultural produce using a validated CFD model","authors":"Ahmad Nasser eddine , Steven Duret , Denis Flick , Jean Moureh","doi":"10.1016/j.ijrefrig.2024.12.003","DOIUrl":"10.1016/j.ijrefrig.2024.12.003","url":null,"abstract":"<div><div>Modified Atmosphere Packaging (MAP) is extensively used for highly perishable items to extend their shelf life by reducing their physiological activity. However, this solution involves non-ventilated packaging materials which hinder direct contact of cooling air with the product, thereby affecting the cooling rate of MAPs when packaged in ventilated trays. This research developed a Computational Fluid Dynamics (CFD) model to predict airflow within a half layer of a strawberry-ventilated pallet, consisting of two trays with 16 airtight clamshells (AC) each, representing modified atmosphere packaging. Within the ACs, the internal domain was modelled as an equivalent solid block representing both air and strawberries. Three tray designs were compared to assess the impact of vent holes and their positions on airflow behaviour and cooling rate. The model was validated using experimental data, showing a good agreement for air velocities and cooling characteristics.</div><div>The analysis revealed that in the current tray design (TD 1) with a single main trapezoidal orifice on the longitudinal surface, airflow was uneven, with 24 % traversing the headspace and 76 % through the channels between ACs. This design caused recirculation near the tray's edge and poor ventilation within the channels of this area, leading to heterogenous cooling among ACs. This heterogeneity in cooling resulted in differences of up to 2 h in Half Cooling Time. Numerical simulations indicated that adding vent holes to the tray does not guarantee an improved cooling rate and uniformity. The effectiveness of vent holes depended on their placement relative to ACs arrangement.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"170 ","pages":"Pages 314-324"},"PeriodicalIF":3.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099184","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 research of heating characteristics on an air source heat pump system with capillary direct floor radiant

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-02-01 DOI: 10.1016/j.ijrefrig.2024.11.031

Jianhui Niu , Haichao Wang , Tianshu Lv , Shuxue Xu

A new-type air source heat pump system with capillary direct floor radiant (ASHPCFR) was proposed, in which the vapor refrigerant condensed directly in the capillary under the floor to heat the room. Theoretical calculation of heat transfer in the capillary floor was conducted. The results indicated that the optimal capillary spacing should be 100 mm and it was best for a thickness smaller than 60 mm with the floor cement layer. An experimental apparatus for the ASHPCFR system was developed, and its low-temperature heating process and normal heating process were experimentally investigated. Experimental results showed that when the outdoor temperature was -5 °C, the indoor air temperature reached 20 °C after 120 min of running, while the temperature difference of a 20 mm thick cement floor could reach 1.73 °C and its maximum temperature could reach 27.5 °C. When the outdoor temperature was -10 °C, the system heating COP was stable at 3.06.

引用次数: 0

Design optimisation of a screw compressor with a focus on rotor depth: A computational fluid dynamics approach

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-02-01 DOI: 10.1016/j.ijrefrig.2024.12.001

Ahmet Aydın , Tahsin Engin , Ahmed Kovacevic

The increasing demand for enhanced performance and reliability in twin-screw compressors necessitates the application of advanced optimisation tools to improve performance. This study employs response surface methodology (RSM) to optimise the profile parameters of a standard 5/6 compressor, specifically targeting reduction in specific power. Key factors such as axis distance between rotors and female rotor outer diameter, which define the rotor depth, were included in the present optimisation process.

Following the optimisation of the rotor profile, port optimisation was also conducted using the same methodology. A multi-chamber thermodynamic analysis was performed with SCORG™ software, which allowed for the calculation of geometric values and thermodynamic quantities. The results of the rotor optimisation revealed notable improvements: a 4.30 % reduction in specific power, a 2.73 % increase in volumetric efficiency, a 3.93 % enhancement in adiabatic efficiency, and a 2.88 % rise in volumetric flow rate compared to the reference design. After port optimisation, both volumetric and adiabatic efficiencies of the optimised rotor profile remained comparable, while specific power was further reduced by 1.37 %.

To validate the performance of the optimised compressor, computational fluid dynamics (CFD) analysis was conducted using a conformal mesh generated by SCORG™ and ANSYS CFX multiphase solver. The maximum deviation between the optimal results from SCORG™ and CFD was only 0.19 %, indicating strong agreement between the two methodologies. This study highlights the significant impact of optimisation techniques on the performance of twin-screw compressors.

{"title":"Design optimisation of a screw compressor with a focus on rotor depth: A computational fluid dynamics approach","authors":"Ahmet Aydın , Tahsin Engin , Ahmed Kovacevic","doi":"10.1016/j.ijrefrig.2024.12.001","DOIUrl":"10.1016/j.ijrefrig.2024.12.001","url":null,"abstract":"<div><div>The increasing demand for enhanced performance and reliability in twin-screw compressors necessitates the application of advanced optimisation tools to improve performance. This study employs response surface methodology (RSM) to optimise the profile parameters of a standard 5/6 compressor, specifically targeting reduction in specific power. Key factors such as axis distance between rotors and female rotor outer diameter, which define the rotor depth, were included in the present optimisation process.</div><div>Following the optimisation of the rotor profile, port optimisation was also conducted using the same methodology. A multi-chamber thermodynamic analysis was performed with SCORG™ software, which allowed for the calculation of geometric values and thermodynamic quantities. The results of the rotor optimisation revealed notable improvements: a 4.30 % reduction in specific power, a 2.73 % increase in volumetric efficiency, a 3.93 % enhancement in adiabatic efficiency, and a 2.88 % rise in volumetric flow rate compared to the reference design. After port optimisation, both volumetric and adiabatic efficiencies of the optimised rotor profile remained comparable, while specific power was further reduced by 1.37 %.</div><div>To validate the performance of the optimised compressor, computational fluid dynamics (CFD) analysis was conducted using a conformal mesh generated by SCORG™ and ANSYS CFX multiphase solver. The maximum deviation between the optimal results from SCORG™ and CFD was only 0.19 %, indicating strong agreement between the two methodologies. This study highlights the significant impact of optimisation techniques on the performance of twin-screw compressors.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"170 ","pages":"Pages 385-397"},"PeriodicalIF":3.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099770","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 the structural optimization of R290 two-phase ejector with a non-equilibrium CFD model

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-02-01 DOI: 10.1016/j.ijrefrig.2024.11.027

Tao Bai , Yu Lu , Zhidong Wen , Jianlin Yu

As one of the key components in the ejector-expansion refrigeration system, the operating characteristic of the ejector directly affects the performance of the refrigeration system. In this paper, the internal flow characteristic of R290 two-phase ejector under different structural parameters, including the nozzle outlet diameter, the nozzle diffuser length, the converging angle of the suction chamber, and the length of the ejector diffuser, were analyzed by non-equilibrium CFD method, and the corresponding structural optimization scheme was proposed. Numerical simulation results showed that the length of the nozzle divergent section and the suction chamber's converging angle had little influence on the performance of the ejector. The nozzle outlet diameter has a significant impact on the performance of the ejector. Meanwhile, within the range of nozzle outlet diameters and length of the ejector diffuser studied, the ejector performance increased first and then decreased. In addition, it was found that the vortex flow generated by the fluid inside the suction chamber was the main factor affecting the performance of the ejector. This paper proposed a curved wall of the suction chamber of optimized ejectors. The result showed that the vortex flow area of the optimized ejector was effectively reduced, and the entrainment ratio and total efficiency of the optimized ejector could be increased by up to 25.6 % and 27.5 % compared to those of the baseline ejector.

{"title":"Numerical study on the structural optimization of R290 two-phase ejector with a non-equilibrium CFD model","authors":"Tao Bai , Yu Lu , Zhidong Wen , Jianlin Yu","doi":"10.1016/j.ijrefrig.2024.11.027","DOIUrl":"10.1016/j.ijrefrig.2024.11.027","url":null,"abstract":"<div><div>As one of the key components in the ejector-expansion refrigeration system, the operating characteristic of the ejector directly affects the performance of the refrigeration system. In this paper, the internal flow characteristic of R290 two-phase ejector under different structural parameters, including the nozzle outlet diameter, the nozzle diffuser length, the converging angle of the suction chamber, and the length of the ejector diffuser, were analyzed by non-equilibrium CFD method, and the corresponding structural optimization scheme was proposed. Numerical simulation results showed that the length of the nozzle divergent section and the suction chamber's converging angle had little influence on the performance of the ejector. The nozzle outlet diameter has a significant impact on the performance of the ejector. Meanwhile, within the range of nozzle outlet diameters and length of the ejector diffuser studied, the ejector performance increased first and then decreased. In addition, it was found that the vortex flow generated by the fluid inside the suction chamber was the main factor affecting the performance of the ejector. This paper proposed a curved wall of the suction chamber of optimized ejectors. The result showed that the vortex flow area of the optimized ejector was effectively reduced, and the entrainment ratio and total efficiency of the optimized ejector could be increased by up to 25.6 % and 27.5 % compared to those of the baseline ejector.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"170 ","pages":"Pages 287-301"},"PeriodicalIF":3.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099182","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

Thermodynamic assessment and optimization of a solar and diesel engine exhaust-driven ORC-VCR system

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-02-01 DOI: 10.1016/j.ijrefrig.2024.11.035

Sandeep Kumar , B.B. Arora , Akhilesh Arora

Waste heat recovery is characterized as an appealing method to enhance overall energy efficiency. Therefore, in this paper, the Vapor Compression Refrigeration (VCR) system employs the diesel engine exhaust-powered Organic Rankine cycle (ORC) to generate the cooling effect. The ORC is further modified in order to generate additional power using solar energy. The source temperatures of diesel engine exhaust and solar heat are taken in the range of 690–810 K and 433–473 K, respectively. The thermodynamic investigation consists of an energy and exergy analysis to determine the effect of turbine inlet temperatures, condenser temperature, and evaporator temperature over the performance parameters of the ORC-VCR system. The study exhibits the coefficient of performance (COP) of the system for the Benzene-R601 refrigerant pair is maximum which is 1.18. The exergetic efficiency for the same refrigerant pair is 18 % more as compared to Cyclohexane-R1234yf refrigerant pair. A multi-objective optimization procedure was executed utilizing a genetic algorithm (GA), which suggested that at the temperature of the higher-pressure turbine is 548.33 K and the temperature of the lower-pressure turbine is 439.19 K, which delivered the maximum cooling effect i.e. of 33.72 TR. Moreover, the system exhibits better COP and cooling capacity at lower ambient temperatures.

{"title":"Thermodynamic assessment and optimization of a solar and diesel engine exhaust-driven ORC-VCR system","authors":"Sandeep Kumar , B.B. Arora , Akhilesh Arora","doi":"10.1016/j.ijrefrig.2024.11.035","DOIUrl":"10.1016/j.ijrefrig.2024.11.035","url":null,"abstract":"<div><div>Waste heat recovery is characterized as an appealing method to enhance overall energy efficiency. Therefore, in this paper, the Vapor Compression Refrigeration (VCR) system employs the diesel engine exhaust-powered Organic Rankine cycle (ORC) to generate the cooling effect. The ORC is further modified in order to generate additional power using solar energy. The source temperatures of diesel engine exhaust and solar heat are taken in the range of 690–810 K and 433–473 K, respectively. The thermodynamic investigation consists of an energy and exergy analysis to determine the effect of turbine inlet temperatures, condenser temperature, and evaporator temperature over the performance parameters of the ORC-VCR system. The study exhibits the coefficient of performance (COP) of the system for the Benzene-R601 refrigerant pair is maximum which is 1.18. The exergetic efficiency for the same refrigerant pair is 18 % more as compared to Cyclohexane-R1234yf refrigerant pair. A multi-objective optimization procedure was executed utilizing a genetic algorithm (GA), which suggested that at the temperature of the higher-pressure turbine is 548.33 K and the temperature of the lower-pressure turbine is 439.19 K, which delivered the maximum cooling effect i.e. of 33.72 TR. Moreover, the system exhibits better COP and cooling capacity at lower ambient temperatures.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"170 ","pages":"Pages 325-339"},"PeriodicalIF":3.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099185","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

Two phase frictional pressure drop in horizontal and vertical return bends with Ammonia

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-02-01 DOI: 10.1016/j.ijrefrig.2024.11.021

Atif Muzaffar , Ahmad Abbas , Lorenzo Cremaschi , Zahid Ayub , Taqi A. Cheema

Air handling units in refrigeration systems have U-bends that significantly affect pressure drops but have little impact on heat transfer. This study experimentally investigated the two-phase pressure drop performance of ammonia in horizontal and vertical return bends. The study was performed on three tubes with nominal outer diameter of 9.5, 15.9, and 22.2 mm. The bend radius to tube diameter ratio (R/d_o) for each tube was kept at 1.2, 1.9 and 2.5. Experiments were conducted at two saturation temperatures of -15 and 10 °C with mass flux between 10 and 50 kg m⁻² s⁻¹ and vapor quality between 0.1 and 0.9. A classical trend of increase in pressure drop with mass flux and vapor quality was observed. Results showed a decrease in pressure drop with saturation temperature, tube diameter and bend curvature ratio. In vertical orientations, the influence of gravity was significant, leading to higher pressure drop particularly at low mass flux and vapor quality regions, especially for medium and large tubes. Moreover, bend curvature ratio exhibited minimal effect on pressure drop at high saturation temperature, low mass flux, and vapor quality in vertical orientations. Overall, the pressure drop in vertical upward flow was found to be higher than the vertical downward and horizontal flows. Additionally, the effect of tube diameter was less effective at higher mass flux and vapor quality particularly at low saturation temperatures. These findings contribute to a better understanding of pressure drop behavior in U-bends, which is crucial for the design and optimization of refrigeration systems.

{"title":"Two phase frictional pressure drop in horizontal and vertical return bends with Ammonia","authors":"Atif Muzaffar , Ahmad Abbas , Lorenzo Cremaschi , Zahid Ayub , Taqi A. Cheema","doi":"10.1016/j.ijrefrig.2024.11.021","DOIUrl":"10.1016/j.ijrefrig.2024.11.021","url":null,"abstract":"<div><div>Air handling units in refrigeration systems have U-bends that significantly affect pressure drops but have little impact on heat transfer. This study experimentally investigated the two-phase pressure drop performance of ammonia in horizontal and vertical return bends. The study was performed on three tubes with nominal outer diameter of 9.5, 15.9, and 22.2 mm. The bend radius to tube diameter ratio (R/d<sub>o</sub>) for each tube was kept at 1.2, 1.9 and 2.5. Experiments were conducted at two saturation temperatures of -15 and 10 °C with mass flux between 10 and 50 kg m<sup>−2</sup> s<sup>−1</sup> and vapor quality between 0.1 and 0.9. A classical trend of increase in pressure drop with mass flux and vapor quality was observed. Results showed a decrease in pressure drop with saturation temperature, tube diameter and bend curvature ratio. In vertical orientations, the influence of gravity was significant, leading to higher pressure drop particularly at low mass flux and vapor quality regions, especially for medium and large tubes. Moreover, bend curvature ratio exhibited minimal effect on pressure drop at high saturation temperature, low mass flux, and vapor quality in vertical orientations. Overall, the pressure drop in vertical upward flow was found to be higher than the vertical downward and horizontal flows. Additionally, the effect of tube diameter was less effective at higher mass flux and vapor quality particularly at low saturation temperatures. These findings contribute to a better understanding of pressure drop behavior in U-bends, which is crucial for the design and optimization of refrigeration systems.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"170 ","pages":"Pages 255-272"},"PeriodicalIF":3.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099180","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

An experimental investigation of secondary fluid parameters on heat pumps with higher temperature lift and zeotropic working fluid

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-02-01 DOI: 10.1016/j.ijrefrig.2024.11.034

Julian Quenel, Burak Atakan

Heat pumps are also discussed for replacing conventional house heating systems at higher temperatures. Their performance depends on the heat demand, heating system return temperature, as well as the heat source temperature, which determine the reversibly achievable coefficient of performance (COP). To approach reversibility in the heat exchangers, zeotropic mixtures are often investigated, but the mean temperature difference between both fluids also varies with the secondary fluid parameters and the heat load, which is less considered in the literature. Thus, this study experimentally investigates the impact of secondary fluid parameters, especially secondary fluid mass flow rate and temperature levels, on the performance of a water-water compression heat pump system with sink temperatures of 60 to 75 °C and source temperatures of 8 to 29 °C. The heat pump operates with a piston compressor and an isobutane-propane (R600a/R290) working fluid mixture (mole fractions: 0.25:0.75), while the system is adapted by variable throttling. COPs and exergy destruction rates of the individual components are evaluated, revealing the influence of secondary fluid parameters on the process, especially the cycle mass flow rate and the compressor efficiency. The COP rises by 63.4 %, if the heat flow demand rises from 1.17 to 3.17 kW. The variation in the working fluid throttling for matching the heat demand, influences pressure levels, mass flow rates, pressure ratios, and compressor efficiencies, often neglected in simple cycle calculations. Varying the evaporator water inlet temperature showed no significant change in COP, due to counteracting changes in compressor efficiency and evaporator exergy destruction.

{"title":"An experimental investigation of secondary fluid parameters on heat pumps with higher temperature lift and zeotropic working fluid","authors":"Julian Quenel, Burak Atakan","doi":"10.1016/j.ijrefrig.2024.11.034","DOIUrl":"10.1016/j.ijrefrig.2024.11.034","url":null,"abstract":"<div><div>Heat pumps are also discussed for replacing conventional house heating systems at higher temperatures. Their performance depends on the heat demand, heating system return temperature, as well as the heat source temperature, which determine the reversibly achievable coefficient of performance (<em>COP</em>). To approach reversibility in the heat exchangers, zeotropic mixtures are often investigated, but the mean temperature difference between both fluids also varies with the secondary fluid parameters and the heat load, which is less considered in the literature. Thus, this study experimentally investigates the impact of secondary fluid parameters, especially secondary fluid mass flow rate and temperature levels, on the performance of a water-water compression heat pump system with sink temperatures of 60 to 75 °C and source temperatures of 8 to 29 °C. The heat pump operates with a piston compressor and an isobutane-propane (R600a/R290) working fluid mixture (mole fractions: 0.25:0.75), while the system is adapted by variable throttling. <em>COP</em>s and exergy destruction rates of the individual components are evaluated, revealing the influence of secondary fluid parameters on the process, especially the cycle mass flow rate and the compressor efficiency. The <em>COP</em> rises by 63.4 %<em>,</em> if the heat flow demand rises from 1.17 to 3.17 kW. The variation in the working fluid throttling for matching the heat demand, influences pressure levels, mass flow rates, pressure ratios, and compressor efficiencies, often neglected in simple cycle calculations. Varying the evaporator water inlet temperature showed no significant change in <em>COP</em>, due to counteracting changes in compressor efficiency and evaporator exergy destruction.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"170 ","pages":"Pages 302-313"},"PeriodicalIF":3.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099183","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

Numerical simulation of active magnetic regenerative refrigeration using Gyroid structured regenerator at room temperature

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-02-01 DOI: 10.1016/j.ijrefrig.2024.11.018

Sotaro Nishioka, Hossein Sepehri-Amin, Akiko T․ Saito

The packed sphere bed regenerator is often utilized in active magnetic regenerative refrigeration (AMRR) because of its high heat transfer coefficient. However, the complex flow between the spheres in this regenerator causes an undesirable high pressure drop. In this study, we propose to adopt the Gyroid structure as a regenerator, which has a more structural design flexibility and a smoother flow, resulting in a lower pressure drop. The basic characteristics of various Gyroid regenerators were investigated by numerical simulations taking into account of heat transfer coefficient, pressure drop, and thermal conductivity, for the purpose of applying such regenerator in the AMRR system. The result of AMRR simulation shows that the standard Gyroid regenerator reduces the pressure drop by 45% while maintaining the cooling performance. In addition, two modified Gyroid regenerators have succeeded in further reducing the pressure drop with small decrease in cooling performance. This study shows that the Gyroid regenerator can serve as a potential regenerator to improve the energy efficiency of the AMRR system.

{"title":"Numerical simulation of active magnetic regenerative refrigeration using Gyroid structured regenerator at room temperature","authors":"Sotaro Nishioka, Hossein Sepehri-Amin, Akiko T․ Saito","doi":"10.1016/j.ijrefrig.2024.11.018","DOIUrl":"10.1016/j.ijrefrig.2024.11.018","url":null,"abstract":"<div><div>The packed sphere bed regenerator is often utilized in active magnetic regenerative refrigeration (AMRR) because of its high heat transfer coefficient. However, the complex flow between the spheres in this regenerator causes an undesirable high pressure drop. In this study, we propose to adopt the Gyroid structure as a regenerator, which has a more structural design flexibility and a smoother flow, resulting in a lower pressure drop. The basic characteristics of various Gyroid regenerators were investigated by numerical simulations taking into account of heat transfer coefficient, pressure drop, and thermal conductivity, for the purpose of applying such regenerator in the AMRR system. The result of AMRR simulation shows that the standard Gyroid regenerator reduces the pressure drop by 45% while maintaining the cooling performance. In addition, two modified Gyroid regenerators have succeeded in further reducing the pressure drop with small decrease in cooling performance. This study shows that the Gyroid regenerator can serve as a potential regenerator to improve the energy efficiency of the AMRR system.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"170 ","pages":"Pages 468-476"},"PeriodicalIF":3.5,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099763","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 study on the output characteristics of valved linear compressor with intermittently connecting compression chamber and back chamber

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-02-01 DOI: 10.1016/j.ijrefrig.2024.12.006

Lei Ding , Xinquan Sha , Ran Hu , Shaoshuai Liu , Zhenhua Jiang , Yinong Wu

Piston offset will affect the output characteristics of valved linear compressors. It will lead to reduced effective piston stroke and increase the risk of cylinder collision. In order to suppress the piston offset, the compression chamber and the back chamber are intermittently connected by a external bypass pipe, and the connection time is controlled by a solenoid valve. The effect of solenoid valve operating frequency on the offset value and compressor output characteristics was studied. The results show that the piston offset can be effectively suppressed when the bypass pipe is connected at high frequency (≥1 Hz). Meanwhile, the effective stroke is increased by about 1.49 mm, the pressure ratio is increased by 10.7 %, and the mass flow rate is increased by 14.2 %. Moreover, the suppression effect of piston offset remains basically unchanged when the operating frequency of the solenoid valve exceeds 1 Hz. Another interesting result is that the higher the frequency of the solenoid valve operation, the smaller the fluctuation caused by this method. This research provides a basis for machining the anti-offset hole in the piston instead of the external bypass pipe to suppress the offset.

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引用次数: 0

Experimental study of the effect of low GWP refrigerant R449A on the heat transfer performance of a multi-branch direct expansion (DX) evaporator

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid

Pub Date : 2025-02-01 DOI: 10.1016/j.ijrefrig.2025.01.037

Zhili Sun, Jiale Chen, Wenfu Zhang, Liangyu Zhu, Yan Shi, Ziyi Zheng, Yaojia Li, Jiaqi Lu, Longyue Zhang

The performance comparison experiment of R449A replacing R507A and R22 refrigerant was carried out for the multi-branch direct expansion (DX) evaporator, and a new rectifier nozzle type distributor was proposed to be applied in the experimental research to study the effects of different refrigerants on the heat transfer performance of the evaporator and the distribution performance of the distributor. The parameters such as cooling capacity, pressure drop, heat transfer coefficient of the evaporator as well as superheat inhomogeneity and pressure drop of the new rectifier nozzle type distributor were analyzed using heat balance method. The results show that the application of R449A as alternative refrigerant can effectively reduce the pressure difference between the evaporator inlet and outlet and the superheat inhomogeneity of the distributor, and the evaporator refrigeration capacity and heat transfer coefficient were decreased. We further analyzed the gas-liquid state of the refrigerant and found that the R449A refrigerant had the smallest percentage of liquid volume before distribution. There is a strong correlation between the refrigerant liquid volume percentage situation and the uniformity of distributor distribution, the smaller the liquid volume percentage, the more uniform the refrigerant distribution. At the -18 °C test temperature, the superheat inhomogeneity of the distributor with R449A was reduced by 49.89 % and 40.48 %, and the cooling capacity was reduced by 3.01 % and 8.61 % compared to the use of R507A and R22, respectively. At low temperatures, R449A refrigerant can be considered as one of the alternatives to R507A and R22 refrigerants.

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