Pub Date : 2024-08-20DOI: 10.1016/j.ijrefrig.2024.08.009
Ruiyang Tao , Zhengrong Li
Mass transfer resistance within the adsorbent felt, governed by pore diffusion, limits adsorption efficiency. Current gas and solid side resistance models, which cover both micro- and macro-pore diffusion, are complex due to their numerous parameters. Sometimes, adsorbate transfer in the felt is predominantly controlled by macro-pore diffusion. This paper uses two key assumptions to introduce a simplified macro-pore diffusion model, distilled from a detailed macro–micro pore diffusion model. The model’s accuracy was confirmed by simulating two desiccant wheels, demonstrating its effectiveness in streamlining adsorbent felt analysis and predicting mass transfer dynamics.
{"title":"Simplifying bidisperse pore diffusion model for adsorbent felt","authors":"Ruiyang Tao , Zhengrong Li","doi":"10.1016/j.ijrefrig.2024.08.009","DOIUrl":"10.1016/j.ijrefrig.2024.08.009","url":null,"abstract":"<div><p>Mass transfer resistance within the adsorbent felt, governed by pore diffusion, limits adsorption efficiency. Current gas and solid side resistance models, which cover both micro- and macro-pore diffusion, are complex due to their numerous parameters. Sometimes, adsorbate transfer in the felt is predominantly controlled by macro-pore diffusion. This paper uses two key assumptions to introduce a simplified macro-pore diffusion model, distilled from a detailed macro–micro pore diffusion model. The model’s accuracy was confirmed by simulating two desiccant wheels, demonstrating its effectiveness in streamlining adsorbent felt analysis and predicting mass transfer dynamics.</p></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"168 ","pages":"Pages 9-17"},"PeriodicalIF":3.5,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142240061","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}
Pub Date : 2024-08-19DOI: 10.1016/j.ijrefrig.2024.08.013
Xiaohong Gui , Shengwei Wang , Li Ding
To mitigate the effects of heat stress on electricians during outdoor activities such as inspection, circuit repair, and daily maintenance in high-temperature environments, a novel design for a portable, efficient, and ergonomic phase change cooling garment is presented. First, the optimal phase change material is selected considering economic and environmental factors. Then, based on the heat balance equation of the human body and Fourier's law, the required phase change material mass and the optimal thickness of the retarded heat-absorbing layer are obtained and verified by numerical simulations and experiments. The results indicate that in a high-temperature environment of 38 °C for 2 h, electricians require 2.39 kg of phase change material. To meet the protective duration requirements of electricians' daily tasks, the optimal thickness of the phase change material is 8 mm, and the optimal thickness of the slow-release heat absorption layer is 3 mm. The results of this study have significant implications for the safety and protection of electricians in high-temperature environments. It aims to provide theoretical guidance for the design and innovation of personal cooling garments for electricians.
{"title":"Simulation study of a novel phase change cooling garment for electricians in a high-temperature environment","authors":"Xiaohong Gui , Shengwei Wang , Li Ding","doi":"10.1016/j.ijrefrig.2024.08.013","DOIUrl":"10.1016/j.ijrefrig.2024.08.013","url":null,"abstract":"<div><p>To mitigate the effects of heat stress on electricians during outdoor activities such as inspection, circuit repair, and daily maintenance in high-temperature environments, a novel design for a portable, efficient, and ergonomic phase change cooling garment is presented. First, the optimal phase change material is selected considering economic and environmental factors. Then, based on the heat balance equation of the human body and Fourier's law, the required phase change material mass and the optimal thickness of the retarded heat-absorbing layer are obtained and verified by numerical simulations and experiments. The results indicate that in a high-temperature environment of 38 °C for 2 h, electricians require 2.39 kg of phase change material. To meet the protective duration requirements of electricians' daily tasks, the optimal thickness of the phase change material is 8 mm, and the optimal thickness of the slow-release heat absorption layer is 3 mm. The results of this study have significant implications for the safety and protection of electricians in high-temperature environments. It aims to provide theoretical guidance for the design and innovation of personal cooling garments for electricians.</p></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"168 ","pages":"Pages 79-88"},"PeriodicalIF":3.5,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142239277","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}
Pub Date : 2024-08-15DOI: 10.1016/j.ijrefrig.2024.08.010
Sami M. Ibn Shamsah
Ternary intermetallic rare-earth-based magnetocaloric compounds (RE2TM2Y, where RE = Gd, Tb, Dy, Ho, Er, Tm, TM= Ni, Cu, Co and Y = Sn, In, Cd, Ga, Al) have attracted attention lately as magnetic refrigerants in addressing major concerns of the conventional system of refrigeration. Assessment of the amount of heat transferred between cold and hot reservoirs at varying applied magnetic fields through relative cooling power (RCP) determination is costly and experimentally intensive which calls for predictive computational techniques with characteristic precision. In this contribution, intelligent-based predictive models are developed through sine activation function-based extreme learning machine (SELM) and genetically optimized support vector regression (GSVR) with Gaussian (GU) and polynomial (PY) kernel functions for data mapping and transformation using applied magnetic field and ionic radii of the constituent elements as descriptors. The GU-GSVR model exhibits superior performance compared to both the PY-GSVR and SELM models when validated using a testing set of ternary intermetallic rare-earth-based magnetocaloric compounds with improvement of 10.55% and 2.28%, respectively using correlation coefficient (CC) as assessment parameter. During model validation, the developed GU-GSVR also showcases enhanced performance across additional performance metrics, including root mean square error (RMSE) and mean absolute error (MAE). The impact of externally applied magnetic field on the RCP of different ternary intermetallic rare-earth-based magnetocaloric compounds was examined by utilizing the developed GU-GSVR model. The characteristic precision and accuracy of the developed computational intelligent models would enable adequate as well as comprehensive investigation of ternary intermetallic rare-earth-based magnetocaloric compounds for a clean system of refrigeration.
{"title":"Relative cooling power modeling of RE2TM2Y ternary intermetallic rare-earth-based magnetocaloric compounds for magnetic refrigeration application using extreme learning machine and hybrid intelligent method","authors":"Sami M. Ibn Shamsah","doi":"10.1016/j.ijrefrig.2024.08.010","DOIUrl":"10.1016/j.ijrefrig.2024.08.010","url":null,"abstract":"<div><div>Ternary intermetallic rare-earth-based magnetocaloric compounds (RE<sub>2</sub>TM<sub>2</sub>Y, where RE = Gd, Tb, Dy, Ho, Er, Tm, TM= Ni, Cu, Co and <em>Y</em> = Sn, In, Cd, Ga, Al) have attracted attention lately as magnetic refrigerants in addressing major concerns of the conventional system of refrigeration. Assessment of the amount of heat transferred between cold and hot reservoirs at varying applied magnetic fields through relative cooling power (RCP) determination is costly and experimentally intensive which calls for predictive computational techniques with characteristic precision. In this contribution, intelligent-based predictive models are developed through sine activation function-based extreme learning machine (SELM) and genetically optimized support vector regression (GSVR) with Gaussian (GU) and polynomial (PY) kernel functions for data mapping and transformation using applied magnetic field and ionic radii of the constituent elements as descriptors. The GU-GSVR model exhibits superior performance compared to both the PY-GSVR and SELM models when validated using a testing set of ternary intermetallic rare-earth-based magnetocaloric compounds with improvement of 10.55% and 2.28%, respectively using correlation coefficient (CC) as assessment parameter. During model validation, the developed GU-GSVR also showcases enhanced performance across additional performance metrics, including root mean square error (RMSE) and mean absolute error (MAE). The impact of externally applied magnetic field on the RCP of different ternary intermetallic rare-earth-based magnetocaloric compounds was examined by utilizing the developed GU-GSVR model. The characteristic precision and accuracy of the developed computational intelligent models would enable adequate as well as comprehensive investigation of ternary intermetallic rare-earth-based magnetocaloric compounds for a clean system of refrigeration.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"168 ","pages":"Pages 122-134"},"PeriodicalIF":3.5,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142264526","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}
Pub Date : 2024-08-14DOI: 10.1016/j.ijrefrig.2024.08.008
Daniel Calleja-Anta, Manel Martínez-Ángeles, Laura Nebot-Andres, Daniel Sánchez, Rodrigo Llopis
Isobutane (R600a) is the most used refrigerant for low-capacity refrigeration systems, as it combines excellent environmental properties and offers good energy performance. A real possibility to increase the efficiency of these systems is using new refrigerant mixtures offering energy improvements (being compatible with existing systems). This work, from an experimental perspective, proposes mixtures of dimethyl ether and butane (RE170/R600) as potential drop-in refrigerants of R600a systems. For a given operating condition, the energy performance of RE170/R600 mixtures with maximum proportion of 27.5 % of RE170 has been tested using a water-to-water single-stage compression cycle, measuring COP increments from 10.1 to 17.6 % in relation to R600a. Then, the blend RE170/R600 (15/85 %), considered as the potential drop-in fluid of R600a, has been tested in a wide range of operating conditions, concluding that it offers the same cooling capacity than R600a but with COP increments from 12.6 % to 17.6 %.
{"title":"Experimental validation of RE170 / R600 (Dimethyl Ether / Butane) mixture as a superior refrigerant compared to R600a (Isobutane)","authors":"Daniel Calleja-Anta, Manel Martínez-Ángeles, Laura Nebot-Andres, Daniel Sánchez, Rodrigo Llopis","doi":"10.1016/j.ijrefrig.2024.08.008","DOIUrl":"10.1016/j.ijrefrig.2024.08.008","url":null,"abstract":"<div><div>Isobutane (R600a) is the most used refrigerant for low-capacity refrigeration systems, as it combines excellent environmental properties and offers good energy performance. A real possibility to increase the efficiency of these systems is using new refrigerant mixtures offering energy improvements (being compatible with existing systems). This work, from an experimental perspective, proposes mixtures of dimethyl ether and butane (RE170/R600) as potential drop-in refrigerants of R600a systems. For a given operating condition, the energy performance of RE170/R600 mixtures with maximum proportion of 27.5 % of RE170 has been tested using a water-to-water single-stage compression cycle, measuring COP increments from 10.1 to 17.6 % in relation to R600a. Then, the blend RE170/R600 (15/85 %), considered as the potential drop-in fluid of R600a, has been tested in a wide range of operating conditions, concluding that it offers the same cooling capacity than R600a but with COP increments from 12.6 % to 17.6 %.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"168 ","pages":"Pages 208-219"},"PeriodicalIF":3.5,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0140700724002822/pdfft?md5=c1ce2ba429bbb5bc2f29e787ee6ef494&pid=1-s2.0-S0140700724002822-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312538","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}
Pub Date : 2024-08-12DOI: 10.1016/j.ijrefrig.2024.07.024
Yifeng Hu, Bo Shen
This study delineates a meticulous exploration of technologies to enhance the energy efficiency of rooftop air conditioning units, employing the DOE/ORNL heat pump design model for comprehensive engineering design and optimization. A baseline rooftop air conditioning unit, featuring a 13 ton (45.7 kW) cooling capacity and a 17.9 integrated energy efficiency ratio, served as the point of departure for substantive efficiency enhancements. Key modifications included the consolidation of two refrigerant circuits into one, integrating three parallel 2-stage (dual-speed) compressors, fan replacements with high-efficiency substitutes. Notably, a lower global warming potential refrigerant, R452B, was evaluated as a substitute for R-410A, demonstrating better performance in the lab prototype. The achieved measured integrated energy efficiency ratio of 21.4 in the lab prototype surpassed the baseline integrated energy efficiency ratio. Comparative evaluations between R410A and R452B indicated heightened efficiency with the latter, showcasing a lab-demonstrated integrated energy efficiency ratio of 22.4 at the rated capacity of 13.8 ton (48.5 kW) and 23.9 integrated energy efficiency ratio at the rated capacity of 10 ton (35.2 kW). This research underscores the successful development of a rigorous, energy efficient rooftop air conditioning unit prototype with noteworthy environmental and economic implications.
{"title":"A high efficiency rooftop air conditioning system using multi-speed compressors","authors":"Yifeng Hu, Bo Shen","doi":"10.1016/j.ijrefrig.2024.07.024","DOIUrl":"10.1016/j.ijrefrig.2024.07.024","url":null,"abstract":"<div><p>This study delineates a meticulous exploration of technologies to enhance the energy efficiency of rooftop air conditioning units, employing the DOE/ORNL heat pump design model for comprehensive engineering design and optimization. A baseline rooftop air conditioning unit, featuring a 13 ton (45.7 kW) cooling capacity and a 17.9 integrated energy efficiency ratio, served as the point of departure for substantive efficiency enhancements. Key modifications included the consolidation of two refrigerant circuits into one, integrating three parallel 2-stage (dual-speed) compressors, fan replacements with high-efficiency substitutes. Notably, a lower global warming potential refrigerant, R452B, was evaluated as a substitute for R-410A, demonstrating better performance in the lab prototype. The achieved measured integrated energy efficiency ratio of 21.4 in the lab prototype surpassed the baseline integrated energy efficiency ratio. Comparative evaluations between R410A and R452B indicated heightened efficiency with the latter, showcasing a lab-demonstrated integrated energy efficiency ratio of 22.4 at the rated capacity of 13.8 ton (48.5 kW) and 23.9 integrated energy efficiency ratio at the rated capacity of 10 ton (35.2 kW). This research underscores the successful development of a rigorous, energy efficient rooftop air conditioning unit prototype with noteworthy environmental and economic implications.</p></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"167 ","pages":"Pages 1-12"},"PeriodicalIF":3.5,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141985115","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}
Pub Date : 2024-08-08DOI: 10.1016/j.ijrefrig.2024.08.002
Arianna Passamonti , Paola Bombarda , Alexander Cohr Pachai , Stefan Klein , Clemens Schneider , Rolf Bracke
The research aims to prove that renewable energy sources in the heating sector can enable the energy transition towards European and German CO2 reduction targets.
To do so, at the premises of the Fraunhofer IEG Institute in Bochum a demonstrator for high-temperature heat pumps (HTHPs), coupled with seasonal high-temperature mine thermal energy storage (MTES), was developed.
The goal is achieved by demonstrating the feasibility of the technology by connecting mine water present in a small flooded coal colliery (MTES) to solar parabolic trough collectors (SPTCs) and also to a HTHP system that serves the local district heating (DH) grid of Bochum south.
The MTES, with an estimated water volume of approximately 20000 m3 is employed as seasonal storage for a 500 kW HTHP system that can reach a supply temperature of 120°C, as needed by the existing DH grid when the ambient temperature is lower or equal to -10°C.
During the summer operation, the heat is injected into the MTES from the SPTCs to obtain a mine water temperature of 60°C; and in the winter operation, the heat is extracted through the HTHP until the mine water reaches the unheated temperature of 12°C at the end of the heating season.
A literature review of the main components of the plant, the description of the installed system parts and performed tests are reported, along with the results of the successfully executed tests.
{"title":"Overview of a newly-installed high-temperature heat pump demonstrator coupled with high-temperature mine thermal energy storage","authors":"Arianna Passamonti , Paola Bombarda , Alexander Cohr Pachai , Stefan Klein , Clemens Schneider , Rolf Bracke","doi":"10.1016/j.ijrefrig.2024.08.002","DOIUrl":"10.1016/j.ijrefrig.2024.08.002","url":null,"abstract":"<div><p>The research aims to prove that renewable energy sources in the heating sector can enable the energy transition towards European and German CO<sub>2</sub> reduction targets.</p><p>To do so, at the premises of the Fraunhofer IEG Institute in Bochum a demonstrator for high-temperature heat pumps (HTHPs), coupled with seasonal high-temperature mine thermal energy storage (MTES), was developed.</p><p>The goal is achieved by demonstrating the feasibility of the technology by connecting mine water present in a small flooded coal colliery (MTES) to solar parabolic trough collectors (SPTCs) and also to a HTHP system that serves the local district heating (DH) grid of Bochum south.</p><p>The MTES, with an estimated water volume of approximately 20000 m<sup>3</sup> is employed as seasonal storage for a 500 kW HTHP system that can reach a supply temperature of 120°C, as needed by the existing DH grid when the ambient temperature is lower or equal to -10°C.</p><p>During the summer operation, the heat is injected into the MTES from the SPTCs to obtain a mine water temperature of 60°C; and in the winter operation, the heat is extracted through the HTHP until the mine water reaches the unheated temperature of 12°C at the end of the heating season.</p><p>A literature review of the main components of the plant, the description of the installed system parts and performed tests are reported, along with the results of the successfully executed tests.</p></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"167 ","pages":"Pages 269-279"},"PeriodicalIF":3.5,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0140700724002706/pdfft?md5=8bd13f34fa4a473178ad7788989d99e8&pid=1-s2.0-S0140700724002706-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142128729","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}
Pub Date : 2024-08-06DOI: 10.1016/j.ijrefrig.2024.08.003
Tian Yafen , Liu Zhixiang , Xia Yang , Jiang Ziqi , Li Kang , Liu Ni , Zhang Hua
Scroll compressor with short scroll profile length shows great potential in electric vehicles for its compact structure and better reliability, while shorter scroll profile results in less compression time and under-compression in most cases. To investigate the influence of discharge port structure on compressor performance, a three-dimensional transient model of scroll compressor for electric vehicle is established. The theoretical and experimental results exhibit good consistency within a deviation of 9.5 %. With this validated model, the effects of discharge port size and shape on compressor performance are studied respectively. When the circular discharge port diameter increases from 5.2 mm to 9.0 mm, the power consumption and discharge temperature can be reduced respectively by 5.82 % and 5.29 %. The discharge mass flow rate can be promoted by 1.09 %. The discharge pressure fluctuation and imbalance between the upside and downside chambers enhanced obviously. To further improve the discharge flow characteristics, different discharge port shapes were employed including waist-shaped, arc-shaped and composite-shaped port. Compared with 5.2 mm circular port, the power consumption with composite-shaped port reduces by 5.81 % and mass flow grows by 1.26 %. Results indicated changes in discharge port structure parameters have greater influence on power consumption rather than mass flow rate.
{"title":"Investigation on the flow characteristics through different discharge port in scroll compressor for electric vehicles","authors":"Tian Yafen , Liu Zhixiang , Xia Yang , Jiang Ziqi , Li Kang , Liu Ni , Zhang Hua","doi":"10.1016/j.ijrefrig.2024.08.003","DOIUrl":"10.1016/j.ijrefrig.2024.08.003","url":null,"abstract":"<div><div>Scroll compressor with short scroll profile length shows great potential in electric vehicles for its compact structure and better reliability, while shorter scroll profile results in less compression time and under-compression in most cases. To investigate the influence of discharge port structure on compressor performance, a three-dimensional transient model of scroll compressor for electric vehicle is established. The theoretical and experimental results exhibit good consistency within a deviation of 9.5 %. With this validated model, the effects of discharge port size and shape on compressor performance are studied respectively. When the circular discharge port diameter increases from 5.2 mm to 9.0 mm, the power consumption and discharge temperature can be reduced respectively by 5.82 % and 5.29 %. The discharge mass flow rate can be promoted by 1.09 %. The discharge pressure fluctuation and imbalance between the upside and downside chambers enhanced obviously. To further improve the discharge flow characteristics, different discharge port shapes were employed including waist-shaped, arc-shaped and composite-shaped port. Compared with 5.2 mm circular port, the power consumption with composite-shaped port reduces by 5.81 % and mass flow grows by 1.26 %. Results indicated changes in discharge port structure parameters have greater influence on power consumption rather than mass flow rate.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"168 ","pages":"Pages 135-148"},"PeriodicalIF":3.5,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142264659","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}
Pub Date : 2024-08-06DOI: 10.1016/j.ijrefrig.2024.08.007
Honghao Huang , Jinzhe Nie , Fuqun He
This study investigates the water vapor sorption performance of five metal organic framework materials (MIL-101(Cr), MIL-100(Fe), aluminum fumarate, MOF-303(Al), PCN-333(Al)) for indoor environment humidity control through experiment measurements, aims to identify materials that enhance water vapor adsorption capacity and allow for low temperature regeneration. The results show that MIL-101(Cr) exhibits highest water vapor adsorption capacity which is 3.5 to 6 times of conventional desiccant materials. The adsorption isotherm of MIL-101(Cr) exhibits an "S" type change, with a steep point between 30 % and 60 % RH which falls within the indoor thermal comfortable range. The experiment results also show that MIL-101(Cr) is nearly completely desorbed at relative humidity of 20 %, indicating its potential for low-temperature regeneration. Based on its strong water vapor sorption performance, the green and low-cost synthesis method will be the key for its utilization to improve the efficiency of solid desiccant air conditioning system.
{"title":"Experimental study on water vapor sorption performance of metal organic frameworks and their application potential for indoor air dehumidification","authors":"Honghao Huang , Jinzhe Nie , Fuqun He","doi":"10.1016/j.ijrefrig.2024.08.007","DOIUrl":"10.1016/j.ijrefrig.2024.08.007","url":null,"abstract":"<div><p>This study investigates the water vapor sorption performance of five metal organic framework materials (MIL-101(Cr), MIL-100(Fe), aluminum fumarate, MOF-303(Al), PCN-333(Al)) for indoor environment humidity control through experiment measurements, aims to identify materials that enhance water vapor adsorption capacity and allow for low temperature regeneration. The results show that MIL-101(Cr) exhibits highest water vapor adsorption capacity which is 3.5 to 6 times of conventional desiccant materials. The adsorption isotherm of MIL-101(Cr) exhibits an \"S\" type change, with a steep point between 30 % and 60 % RH which falls within the indoor thermal comfortable range. The experiment results also show that MIL-101(Cr) is nearly completely desorbed at relative humidity of 20 %, indicating its potential for low-temperature regeneration. Based on its strong water vapor sorption performance, the green and low-cost synthesis method will be the key for its utilization to improve the efficiency of solid desiccant air conditioning system.</p></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"168 ","pages":"Pages 51-58"},"PeriodicalIF":3.5,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142240065","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}
Pub Date : 2024-08-06DOI: 10.1016/j.ijrefrig.2024.08.004
Neeraj Kumar Vidhyarthi , Sandipan Deb , Sagnik Pal , Ajoy Kumar Das
Currently, although significant advancements have been made in understanding heat transfer coefficients and pressure decreases in different tube shapes, there is still a noticeable lack of detailed studies on the generation of entropy under flow boiling conditions. In this work, the entropy generation in micro-fin tubes (MFT1 and MFT2) and smooth tubes (ST1 and ST2) in flow boiling conditions experimentally investigated with refrigerant R513A. Research focused on evaluating influence of different input parameters on entropy generation, specifically contribution of heat transfer coefficient (HTC) and total pressure drop (TPD) on entropy generation for all testing tubes. As at a heat flux of 6 kW·m−² and a saturation temperature of 12 °C, MFT1 shows HTC contributions to entropy generation ranging from 0.032 to 0.156 W·K−1, while MFT2 ranges from 0.03 to 0.14 W·K−1. TPD contributions for both MFT1 and MFT2 range from 0.001 to 0.04 W·K−1. Hence, MFT2 shows better results than MFT1 as low entropy generation required for a good heat exchanger. Among input parameters, heat flux displays the highest sensitivity, indicating its significant influence on total entropy generation variations, while vapor quality, mass flux, and saturation temperature also demonstrate notable sensitivity. This research helps us design systems that transfer heat more effectively while using less energy. Understanding these factors can lead to more efficient heat exchangers and other thermal systems.
{"title":"Comparative analysis of entropy generation in smooth and micro-fin tubes using R513A refrigerant: A parametric study","authors":"Neeraj Kumar Vidhyarthi , Sandipan Deb , Sagnik Pal , Ajoy Kumar Das","doi":"10.1016/j.ijrefrig.2024.08.004","DOIUrl":"10.1016/j.ijrefrig.2024.08.004","url":null,"abstract":"<div><div>Currently, although significant advancements have been made in understanding heat transfer coefficients and pressure decreases in different tube shapes, there is still a noticeable lack of detailed studies on the generation of entropy under flow boiling conditions. In this work, the entropy generation in micro-fin tubes (MFT1 and MFT2) and smooth tubes (ST1 and ST2) in flow boiling conditions experimentally investigated with refrigerant R513A. Research focused on evaluating influence of different input parameters on entropy generation, specifically contribution of heat transfer coefficient (HTC) and total pressure drop (TPD) on entropy generation for all testing tubes. As at a heat flux of 6 kW·<em>m</em><sup>−</sup>² and a saturation temperature of 12 °C, MFT1 shows HTC contributions to entropy generation ranging from 0.032 to 0.156 W·<em>K</em><sup>−1</sup>, while MFT2 ranges from 0.03 to 0.14 W·<em>K</em><sup>−1</sup>. TPD contributions for both MFT1 and MFT2 range from 0.001 to 0.04 W·<em>K</em><sup>−1</sup>. Hence, MFT2 shows better results than MFT1 as low entropy generation required for a good heat exchanger. Among input parameters, heat flux displays the highest sensitivity, indicating its significant influence on total entropy generation variations, while vapor quality, mass flux, and saturation temperature also demonstrate notable sensitivity. This research helps us design systems that transfer heat more effectively while using less energy. Understanding these factors can lead to more efficient heat exchangers and other thermal systems.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"168 ","pages":"Pages 95-108"},"PeriodicalIF":3.5,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142264529","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}
Pub Date : 2024-08-06DOI: 10.1016/j.ijrefrig.2024.08.005
Guang Li , Dawei Zhuang , Liyi Xie , Guoliang Ding , Jiansheng Liao , Siqing Liao , Wang Kan , Ji Song , Yifeng Gao
R32 commonly applied in room air-conditioners has flammability, and the ways to decrease the charging amount, e.g. reducing the dissolution of refrigerant in the lubricating oil, are important to reduce combustion risk. The application of partially miscible oil rather than completely miscible oil can decrease R32 solubility but may deteriorate the heat transfer by the forming of pure oil layer, and thus the understanding of the stratification and flow boiling heat transfer characteristics of R32-partially miscible oil mixture is necessary. The purpose of this study is to experimentally investigate the stratification and flow boiling heat transfer characteristics of a mixture of R32 and partially miscible POE oil, and to propose a new heat transfer correlation. The experiments are carried out at evaporation temperature varying from -5 °C – 15 °C, total oil concentration varying from 1 % to 5 %, vapor quality varying from 0.1 – 0.9 and mass flux varying from 200 kg m-2 s-1 to 400 kg m-2 s-1.The results indicate that the stratification of R32-partially miscible oil mixture occurs at the high liquid oil concentrations, and an oil-poor layer and an oil-rich layer are involved in the stratified annular layer. R32-partially miscible oil mixture has higher flow boiling heat transfer coefficients than R32-completely miscible oil mixture due to the low viscosity of the oil-poor layer. A new flow boiling heat transfer correlation reflecting the effect of stratification is developed, and the predicted results agree with 91 % of the test results as the relative deviation ranges in ±20%.
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